pg_basebackup.c

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/*-------------------------------------------------------------------------
 *
 * pg_basebackup.c - receive a base backup using streaming replication protocol
 *
 * Author: Magnus Hagander <magnus@hagander.net>
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *        src/bin/pg_basebackup/pg_basebackup.c
 *-------------------------------------------------------------------------
 */
 
#include "postgres_fe.h"
 
#include <unistd.h>
#include <dirent.h>
#include <limits.h>
#include <sys/select.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <signal.h>
#include <time.h>
#ifdef HAVE_LIBZ
#include <zlib.h>
#endif
 
#include "access/xlog_internal.h"
#include "astreamer_inject.h"
#include "backup/basebackup.h"
#include "common/compression.h"
#include "common/file_perm.h"
#include "common/file_utils.h"
#include "common/logging.h"
#include "fe_utils/option_utils.h"
#include "fe_utils/recovery_gen.h"
#include "getopt_long.h"
#include "receivelog.h"
#include "streamutil.h"
 
#define ERRCODE_DATA_CORRUPTED  "XX001"
 
typedef struct TablespaceListCell
{
    struct TablespaceListCell *next;
    char        old_dir[MAXPGPATH];
    char        new_dir[MAXPGPATH];
} TablespaceListCell;
 
typedef struct TablespaceList
{
    TablespaceListCell *head;
    TablespaceListCell *tail;
} TablespaceList;
 
typedef struct ArchiveStreamState
{
    int         tablespacenum;
    pg_compress_specification *compress;
    astreamer  *streamer;
    astreamer  *manifest_inject_streamer;
    PQExpBuffer manifest_buffer;
    char        manifest_filename[MAXPGPATH];
    FILE       *manifest_file;
} ArchiveStreamState;
 
typedef struct WriteTarState
{
    int         tablespacenum;
    astreamer  *streamer;
} WriteTarState;
 
typedef struct WriteManifestState
{
    char        filename[MAXPGPATH];
    FILE       *file;
} WriteManifestState;
 
typedef void (*WriteDataCallback) (size_t nbytes, char *buf,
                                   void *callback_data);
 
/*
 * pg_xlog has been renamed to pg_wal in version 10.  This version number
 * should be compared with PQserverVersion().
 */
#define MINIMUM_VERSION_FOR_PG_WAL  100000
 
/*
 * Temporary replication slots are supported from version 10.
 */
#define MINIMUM_VERSION_FOR_TEMP_SLOTS 100000
 
/*
 * Backup manifests are supported from version 13.
 */
#define MINIMUM_VERSION_FOR_MANIFESTS   130000
 
/*
 * Before v15, tar files received from the server will be improperly
 * terminated.
 */
#define MINIMUM_VERSION_FOR_TERMINATED_TARFILE 150000
 
/*
 * pg_wal/summaries exists beginning with version 17.
 */
#define MINIMUM_VERSION_FOR_WAL_SUMMARIES 170000
 
/*
 * Different ways to include WAL
 */
typedef enum
{
    NO_WAL,
    FETCH_WAL,
    STREAM_WAL,
} IncludeWal;
 
/*
 * Different places to perform compression
 */
typedef enum
{
    COMPRESS_LOCATION_UNSPECIFIED,
    COMPRESS_LOCATION_CLIENT,
    COMPRESS_LOCATION_SERVER,
} CompressionLocation;
 
/* Global options */
static char *basedir = NULL;
static TablespaceList tablespace_dirs = {NULL, NULL};
static char *xlog_dir = NULL;
static char format = '\0';      /* p(lain)/t(ar) */
static char *label = "pg_basebackup base backup";
static bool noclean = false;
static bool checksum_failure = false;
static bool showprogress = false;
static bool estimatesize = true;
static int  verbose = 0;
static IncludeWal includewal = STREAM_WAL;
static bool fastcheckpoint = false;
static bool writerecoveryconf = false;
static bool do_sync = true;
static int  standby_message_timeout = 10 * 1000;    /* 10 sec = default */
static pg_time_t last_progress_report = 0;
static int32 maxrate = 0;       /* no limit by default */
static char *replication_slot = NULL;
static bool temp_replication_slot = true;
static char *backup_target = NULL;
static bool create_slot = false;
static bool no_slot = false;
static bool verify_checksums = true;
static bool manifest = true;
static bool manifest_force_encode = false;
static char *manifest_checksums = NULL;
static DataDirSyncMethod sync_method = DATA_DIR_SYNC_METHOD_FSYNC;
 
static bool success = false;
static bool made_new_pgdata = false;
static bool found_existing_pgdata = false;
static bool made_new_xlogdir = false;
static bool found_existing_xlogdir = false;
static bool made_tablespace_dirs = false;
static bool found_tablespace_dirs = false;
 
/* Progress indicators */
static uint64 totalsize_kb;
static uint64 totaldone;
static int  tablespacecount;
static char *progress_filename = NULL;
 
/* Pipe to communicate with background wal receiver process */
#ifndef WIN32
static int  bgpipe[2] = {-1, -1};
#endif
 
/* Handle to child process */
static pid_t bgchild = -1;
static bool in_log_streamer = false;
 
/* Flag to indicate if child process exited unexpectedly */
static volatile sig_atomic_t bgchild_exited = false;
 
/* End position for xlog streaming, empty string if unknown yet */
static XLogRecPtr xlogendptr;
 
#ifndef WIN32
static int  has_xlogendptr = 0;
#else
static volatile LONG has_xlogendptr = 0;
#endif
 
/* Contents of configuration file to be generated */
static PQExpBuffer recoveryconfcontents = NULL;
 
/* Function headers */
static void usage(void);
static void verify_dir_is_empty_or_create(char *dirname, bool *created, bool *found);
static void progress_update_filename(const char *filename);
static void progress_report(int tablespacenum, bool force, bool finished);
 
static astreamer *CreateBackupStreamer(char *archive_name, char *spclocation,
                                       astreamer **manifest_inject_streamer_p,
                                       bool is_recovery_guc_supported,
                                       bool expect_unterminated_tarfile,
                                       pg_compress_specification *compress);
static void ReceiveArchiveStreamChunk(size_t r, char *copybuf,
                                      void *callback_data);
static char GetCopyDataByte(size_t r, char *copybuf, size_t *cursor);
static char *GetCopyDataString(size_t r, char *copybuf, size_t *cursor);
static uint64 GetCopyDataUInt64(size_t r, char *copybuf, size_t *cursor);
static void GetCopyDataEnd(size_t r, char *copybuf, size_t cursor);
static void ReportCopyDataParseError(size_t r, char *copybuf);
static void ReceiveTarFile(PGconn *conn, char *archive_name, char *spclocation,
                           bool tablespacenum, pg_compress_specification *compress);
static void ReceiveTarCopyChunk(size_t r, char *copybuf, void *callback_data);
static void ReceiveBackupManifest(PGconn *conn);
static void ReceiveBackupManifestChunk(size_t r, char *copybuf,
                                       void *callback_data);
static void ReceiveBackupManifestInMemory(PGconn *conn, PQExpBuffer buf);
static void ReceiveBackupManifestInMemoryChunk(size_t r, char *copybuf,
                                               void *callback_data);
static void BaseBackup(char *compression_algorithm, char *compression_detail,
                       CompressionLocation compressloc,
                       pg_compress_specification *client_compress,
                       char *incremental_manifest);
 
static bool reached_end_position(XLogRecPtr segendpos, uint32 timeline,
                                 bool segment_finished);
 
static const char *get_tablespace_mapping(const char *dir);
static void tablespace_list_append(const char *arg);
 
 
static void
cleanup_directories_atexit(void)
{
    if (success || in_log_streamer)
        return;
 
    if (!noclean && !checksum_failure)
    {
        if (made_new_pgdata)
        {
            pg_log_info("removing data directory \"%s\"", basedir);
            if (!rmtree(basedir, true))
                pg_log_error("failed to remove data directory");
        }
        else if (found_existing_pgdata)
        {
            pg_log_info("removing contents of data directory \"%s\"", basedir);
            if (!rmtree(basedir, false))
                pg_log_error("failed to remove contents of data directory");
        }
 
        if (made_new_xlogdir)
        {
            pg_log_info("removing WAL directory \"%s\"", xlog_dir);
            if (!rmtree(xlog_dir, true))
                pg_log_error("failed to remove WAL directory");
        }
        else if (found_existing_xlogdir)
        {
            pg_log_info("removing contents of WAL directory \"%s\"", xlog_dir);
            if (!rmtree(xlog_dir, false))
                pg_log_error("failed to remove contents of WAL directory");
        }
    }
    else
    {
        if ((made_new_pgdata || found_existing_pgdata) && !checksum_failure)
            pg_log_info("data directory \"%s\" not removed at user's request", basedir);
 
        if (made_new_xlogdir || found_existing_xlogdir)
            pg_log_info("WAL directory \"%s\" not removed at user's request", xlog_dir);
    }
 
    if ((made_tablespace_dirs || found_tablespace_dirs) && !checksum_failure)
        pg_log_info("changes to tablespace directories will not be undone");
}
 
static void
disconnect_atexit(void)
{
    if (conn != NULL)
        PQfinish(conn);
}
 
#ifndef WIN32
/*
 * If the bgchild exits prematurely and raises a SIGCHLD signal, we can abort
 * processing rather than wait until the backup has finished and error out at
 * that time. On Windows, we use a background thread which can communicate
 * without the need for a signal handler.
 */
static void
sigchld_handler(SIGNAL_ARGS)
{
    bgchild_exited = true;
}
 
/*
 * On windows, our background thread dies along with the process. But on
 * Unix, if we have started a subprocess, we want to kill it off so it
 * doesn't remain running trying to stream data.
 */
static void
kill_bgchild_atexit(void)
{
    if (bgchild > 0 && !bgchild_exited)
        kill(bgchild, SIGTERM);
}
#endif
 
/*
 * Split argument into old_dir and new_dir and append to tablespace mapping
 * list.
 */
static void
tablespace_list_append(const char *arg)
{
    TablespaceListCell *cell = (TablespaceListCell *) pg_malloc0(sizeof(TablespaceListCell));
    char       *dst;
    char       *dst_ptr;
    const char *arg_ptr;
 
    dst_ptr = dst = cell->old_dir;
    for (arg_ptr = arg; *arg_ptr; arg_ptr++)
    {
        if (dst_ptr - dst >= MAXPGPATH)
            pg_fatal("directory name too long");
 
        if (*arg_ptr == '\\' && *(arg_ptr + 1) == '=')
            ;                   /* skip backslash escaping = */
        else if (*arg_ptr == '=' && (arg_ptr == arg || *(arg_ptr - 1) != '\\'))
        {
            if (*cell->new_dir)
                pg_fatal("multiple \"=\" signs in tablespace mapping");
            else
                dst = dst_ptr = cell->new_dir;
        }
        else
            *dst_ptr++ = *arg_ptr;
    }
 
    if (!*cell->old_dir || !*cell->new_dir)
        pg_fatal("invalid tablespace mapping format \"%s\", must be \"OLDDIR=NEWDIR\"", arg);
 
    /*
     * All tablespaces are created with absolute directories, so specifying a
     * non-absolute path here would just never match, possibly confusing
     * users. Since we don't know whether the remote side is Windows or not,
     * and it might be different than the local side, permit any path that
     * could be absolute under either set of rules.
     *
     * (There is little practical risk of confusion here, because someone
     * running entirely on Linux isn't likely to have a relative path that
     * begins with a backslash or something that looks like a drive
     * specification. If they do, and they also incorrectly believe that a
     * relative path is acceptable here, we'll silently fail to warn them of
     * their mistake, and the -T option will just not get applied, same as if
     * they'd specified -T for a nonexistent tablespace.)
     */
    if (!is_nonwindows_absolute_path(cell->old_dir) &&
        !is_windows_absolute_path(cell->old_dir))
        pg_fatal("old directory is not an absolute path in tablespace mapping: %s",
                 cell->old_dir);
 
    if (!is_absolute_path(cell->new_dir))
        pg_fatal("new directory is not an absolute path in tablespace mapping: %s",
                 cell->new_dir);
 
    /*
     * Comparisons done with these values should involve similarly
     * canonicalized path values.  This is particularly sensitive on Windows
     * where path values may not necessarily use Unix slashes.
     */
    canonicalize_path(cell->old_dir);
    canonicalize_path(cell->new_dir);
 
    if (tablespace_dirs.tail)
        tablespace_dirs.tail->next = cell;
    else
        tablespace_dirs.head = cell;
    tablespace_dirs.tail = cell;
}
 
 
static void
usage(void)
{
    printf(_("%s takes a base backup of a running PostgreSQL server.\n\n"),
           progname);
    printf(_("Usage:\n"));
    printf(_("  %s [OPTION]...\n"), progname);
    printf(_("\nOptions controlling the output:\n"));
    printf(_("  -D, --pgdata=DIRECTORY receive base backup into directory\n"));
    printf(_("  -F, --format=p|t       output format (plain (default), tar)\n"));
    printf(_("  -i, --incremental=OLDMANIFEST\n"
             "                         take incremental backup\n"));
    printf(_("  -r, --max-rate=RATE    maximum transfer rate to transfer data directory\n"
             "                         (in kB/s, or use suffix \"k\" or \"M\")\n"));
    printf(_("  -R, --write-recovery-conf\n"
             "                         write configuration for replication\n"));
    printf(_("  -t, --target=TARGET[:DETAIL]\n"
             "                         backup target (if other than client)\n"));
    printf(_("  -T, --tablespace-mapping=OLDDIR=NEWDIR\n"
             "                         relocate tablespace in OLDDIR to NEWDIR\n"));
    printf(_("      --waldir=WALDIR    location for the write-ahead log directory\n"));
    printf(_("  -X, --wal-method=none|fetch|stream\n"
             "                         include required WAL files with specified method\n"));
    printf(_("  -z, --gzip             compress tar output\n"));
    printf(_("  -Z, --compress=[{client|server}-]METHOD[:DETAIL]\n"
             "                         compress on client or server as specified\n"));
    printf(_("  -Z, --compress=none    do not compress tar output\n"));
    printf(_("\nGeneral options:\n"));
    printf(_("  -c, --checkpoint=fast|spread\n"
             "                         set fast or spread (default) checkpointing\n"));
    printf(_("  -C, --create-slot      create replication slot\n"));
    printf(_("  -l, --label=LABEL      set backup label\n"));
    printf(_("  -n, --no-clean         do not clean up after errors\n"));
    printf(_("  -N, --no-sync          do not wait for changes to be written safely to disk\n"));
    printf(_("  -P, --progress         show progress information\n"));
    printf(_("  -S, --slot=SLOTNAME    replication slot to use\n"));
    printf(_("  -v, --verbose          output verbose messages\n"));
    printf(_("  -V, --version          output version information, then exit\n"));
    printf(_("      --manifest-checksums=SHA{224,256,384,512}|CRC32C|NONE\n"
             "                         use algorithm for manifest checksums\n"));
    printf(_("      --manifest-force-encode\n"
             "                         hex encode all file names in manifest\n"));
    printf(_("      --no-estimate-size do not estimate backup size in server side\n"));
    printf(_("      --no-manifest      suppress generation of backup manifest\n"));
    printf(_("      --no-slot          prevent creation of temporary replication slot\n"));
    printf(_("      --no-verify-checksums\n"
             "                         do not verify checksums\n"));
    printf(_("      --sync-method=METHOD\n"
             "                         set method for syncing files to disk\n"));
    printf(_("  -?, --help             show this help, then exit\n"));
    printf(_("\nConnection options:\n"));
    printf(_("  -d, --dbname=CONNSTR   connection string\n"));
    printf(_("  -h, --host=HOSTNAME    database server host or socket directory\n"));
    printf(_("  -p, --port=PORT        database server port number\n"));
    printf(_("  -s, --status-interval=INTERVAL\n"
             "                         time between status packets sent to server (in seconds)\n"));
    printf(_("  -U, --username=NAME    connect as specified database user\n"));
    printf(_("  -w, --no-password      never prompt for password\n"));
    printf(_("  -W, --password         force password prompt (should happen automatically)\n"));
    printf(_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
    printf(_("%s home page: <%s>\n"), PACKAGE_NAME, PACKAGE_URL);
}
 
 
/*
 * Called in the background process every time data is received.
 * On Unix, we check to see if there is any data on our pipe
 * (which would mean we have a stop position), and if it is, check if
 * it is time to stop.
 * On Windows, we are in a single process, so we can just check if it's
 * time to stop.
 */
static bool
reached_end_position(XLogRecPtr segendpos, uint32 timeline,
                     bool segment_finished)
{
    if (!has_xlogendptr)
    {
#ifndef WIN32
        fd_set      fds;
        struct timeval tv = {0};
        int         r;
 
        /*
         * Don't have the end pointer yet - check our pipe to see if it has
         * been sent yet.
         */
        FD_ZERO(&fds);
        FD_SET(bgpipe[0], &fds);
 
        r = select(bgpipe[0] + 1, &fds, NULL, NULL, &tv);
        if (r == 1)
        {
            char        xlogend[64] = {0};
            uint32      hi,
                        lo;
 
            r = read(bgpipe[0], xlogend, sizeof(xlogend) - 1);
            if (r < 0)
                pg_fatal("could not read from ready pipe: %m");
 
            if (sscanf(xlogend, "%X/%X", &hi, &lo) != 2)
                pg_fatal("could not parse write-ahead log location \"%s\"",
                         xlogend);
            xlogendptr = ((uint64) hi) << 32 | lo;
            has_xlogendptr = 1;
 
            /*
             * Fall through to check if we've reached the point further
             * already.
             */
        }
        else
        {
            /*
             * No data received on the pipe means we don't know the end
             * position yet - so just say it's not time to stop yet.
             */
            return false;
        }
#else
 
        /*
         * On win32, has_xlogendptr is set by the main thread, so if it's not
         * set here, we just go back and wait until it shows up.
         */
        return false;
#endif
    }
 
    /*
     * At this point we have an end pointer, so compare it to the current
     * position to figure out if it's time to stop.
     */
    if (segendpos >= xlogendptr)
        return true;
 
    /*
     * Have end pointer, but haven't reached it yet - so tell the caller to
     * keep streaming.
     */
    return false;
}
 
typedef struct
{
    PGconn     *bgconn;
    XLogRecPtr  startptr;
    char        xlog[MAXPGPATH];    /* directory or tarfile depending on mode */
    char       *sysidentifier;
    int         timeline;
    pg_compress_algorithm wal_compress_algorithm;
    int         wal_compress_level;
} logstreamer_param;
 
static int
LogStreamerMain(logstreamer_param *param)
{
    StreamCtl   stream = {0};
 
    in_log_streamer = true;
 
    stream.startpos = param->startptr;
    stream.timeline = param->timeline;
    stream.sysidentifier = param->sysidentifier;
    stream.stream_stop = reached_end_position;
#ifndef WIN32
    stream.stop_socket = bgpipe[0];
#else
    stream.stop_socket = PGINVALID_SOCKET;
#endif
    stream.standby_message_timeout = standby_message_timeout;
    stream.synchronous = false;
    /* fsync happens at the end of pg_basebackup for all data */
    stream.do_sync = false;
    stream.mark_done = true;
    stream.partial_suffix = NULL;
    stream.replication_slot = replication_slot;
    if (format == 'p')
        stream.walmethod = CreateWalDirectoryMethod(param->xlog,
                                                    PG_COMPRESSION_NONE, 0,
                                                    stream.do_sync);
    else
        stream.walmethod = CreateWalTarMethod(param->xlog,
                                              param->wal_compress_algorithm,
                                              param->wal_compress_level,
                                              stream.do_sync);
 
    if (!ReceiveXlogStream(param->bgconn, &stream))
    {
        /*
         * Any errors will already have been reported in the function process,
         * but we need to tell the parent that we didn't shutdown in a nice
         * way.
         */
#ifdef WIN32
        /*
         * In order to signal the main thread of an ungraceful exit we set the
         * same flag that we use on Unix to signal SIGCHLD.
         */
        bgchild_exited = true;
#endif
        return 1;
    }
 
    if (!stream.walmethod->ops->finish(stream.walmethod))
    {
        pg_log_error("could not finish writing WAL files: %m");
#ifdef WIN32
        bgchild_exited = true;
#endif
        return 1;
    }
 
    PQfinish(param->bgconn);
 
    stream.walmethod->ops->free(stream.walmethod);
 
    return 0;
}
 
/*
 * Initiate background process for receiving xlog during the backup.
 * The background stream will use its own database connection so we can
 * stream the logfile in parallel with the backups.
 */
static void
StartLogStreamer(char *startpos, uint32 timeline, char *sysidentifier,
                 pg_compress_algorithm wal_compress_algorithm,
                 int wal_compress_level)
{
    logstreamer_param *param;
    uint32      hi,
                lo;
    char        statusdir[MAXPGPATH];
 
    param = pg_malloc0(sizeof(logstreamer_param));
    param->timeline = timeline;
    param->sysidentifier = sysidentifier;
    param->wal_compress_algorithm = wal_compress_algorithm;
    param->wal_compress_level = wal_compress_level;
 
    /* Convert the starting position */
    if (sscanf(startpos, "%X/%X", &hi, &lo) != 2)
        pg_fatal("could not parse write-ahead log location \"%s\"",
                 startpos);
    param->startptr = ((uint64) hi) << 32 | lo;
    /* Round off to even segment position */
    param->startptr -= XLogSegmentOffset(param->startptr, WalSegSz);
 
#ifndef WIN32
    /* Create our background pipe */
    if (pipe(bgpipe) < 0)
        pg_fatal("could not create pipe for background process: %m");
#endif
 
    /* Get a second connection */
    param->bgconn = GetConnection();
    if (!param->bgconn)
        /* Error message already written in GetConnection() */
        exit(1);
 
    /* In post-10 cluster, pg_xlog has been renamed to pg_wal */
    snprintf(param->xlog, sizeof(param->xlog), "%s/%s",
             basedir,
             PQserverVersion(conn) < MINIMUM_VERSION_FOR_PG_WAL ?
             "pg_xlog" : "pg_wal");
 
    /* Temporary replication slots are only supported in 10 and newer */
    if (PQserverVersion(conn) < MINIMUM_VERSION_FOR_TEMP_SLOTS)
        temp_replication_slot = false;
 
    /*
     * Create replication slot if requested
     */
    if (temp_replication_slot && !replication_slot)
        replication_slot = psprintf("pg_basebackup_%u",
                                    (unsigned int) PQbackendPID(param->bgconn));
    if (temp_replication_slot || create_slot)
    {
        if (!CreateReplicationSlot(param->bgconn, replication_slot, NULL,
                                   temp_replication_slot, true, true, false,
                                   false, false))
            exit(1);
 
        if (verbose)
        {
            if (temp_replication_slot)
                pg_log_info("created temporary replication slot \"%s\"",
                            replication_slot);
            else
                pg_log_info("created replication slot \"%s\"",
                            replication_slot);
        }
    }
 
    if (format == 'p')
    {
        /*
         * Create pg_wal/archive_status or pg_xlog/archive_status (and thus
         * pg_wal or pg_xlog) depending on the target server so we can write
         * to basedir/pg_wal or basedir/pg_xlog as the directory entry in the
         * tar file may arrive later.
         */
        snprintf(statusdir, sizeof(statusdir), "%s/%s/archive_status",
                 basedir,
                 PQserverVersion(conn) < MINIMUM_VERSION_FOR_PG_WAL ?
                 "pg_xlog" : "pg_wal");
 
        if (pg_mkdir_p(statusdir, pg_dir_create_mode) != 0 && errno != EEXIST)
            pg_fatal("could not create directory \"%s\": %m", statusdir);
 
        /*
         * For newer server versions, likewise create pg_wal/summaries
         */
        if (PQserverVersion(conn) >= MINIMUM_VERSION_FOR_WAL_SUMMARIES)
        {
            char        summarydir[MAXPGPATH];
 
            snprintf(summarydir, sizeof(summarydir), "%s/%s/summaries",
                     basedir, "pg_wal");
 
            if (pg_mkdir_p(summarydir, pg_dir_create_mode) != 0 &&
                errno != EEXIST)
                pg_fatal("could not create directory \"%s\": %m", summarydir);
        }
    }
 
    /*
     * Start a child process and tell it to start streaming. On Unix, this is
     * a fork(). On Windows, we create a thread.
     */
#ifndef WIN32
    bgchild = fork();
    if (bgchild == 0)
    {
        /* in child process */
        exit(LogStreamerMain(param));
    }
    else if (bgchild < 0)
        pg_fatal("could not create background process: %m");
 
    /*
     * Else we are in the parent process and all is well.
     */
    atexit(kill_bgchild_atexit);
#else                           /* WIN32 */
    bgchild = _beginthreadex(NULL, 0, (void *) LogStreamerMain, param, 0, NULL);
    if (bgchild == 0)
        pg_fatal("could not create background thread: %m");
#endif
}
 
/*
 * Verify that the given directory exists and is empty. If it does not
 * exist, it is created. If it exists but is not empty, an error will
 * be given and the process ended.
 */
static void
verify_dir_is_empty_or_create(char *dirname, bool *created, bool *found)
{
    switch (pg_check_dir(dirname))
    {
        case 0:
 
            /*
             * Does not exist, so create
             */
            if (pg_mkdir_p(dirname, pg_dir_create_mode) == -1)
                pg_fatal("could not create directory \"%s\": %m", dirname);
            if (created)
                *created = true;
            return;
        case 1:
 
            /*
             * Exists, empty
             */
            if (found)
                *found = true;
            return;
        case 2:
        case 3:
        case 4:
 
            /*
             * Exists, not empty
             */
            pg_fatal("directory \"%s\" exists but is not empty", dirname);
        case -1:
 
            /*
             * Access problem
             */
            pg_fatal("could not access directory \"%s\": %m", dirname);
    }
}
 
/*
 * Callback to update our notion of the current filename.
 *
 * No other code should modify progress_filename!
 */
static void
progress_update_filename(const char *filename)
{
    /* We needn't maintain this variable if not doing verbose reports. */
    if (showprogress && verbose)
    {
        free(progress_filename);
        if (filename)
            progress_filename = pg_strdup(filename);
        else
            progress_filename = NULL;
    }
}
 
/*
 * Print a progress report based on the global variables. If verbose output
 * is enabled, also print the current file name.
 *
 * Progress report is written at maximum once per second, unless the force
 * parameter is set to true.
 *
 * If finished is set to true, this is the last progress report. The cursor
 * is moved to the next line.
 */
static void
progress_report(int tablespacenum, bool force, bool finished)
{
    int         percent;
    char        totaldone_str[32];
    char        totalsize_str[32];
    pg_time_t   now;
 
    if (!showprogress)
        return;
 
    now = time(NULL);
    if (now == last_progress_report && !force && !finished)
        return;                 /* Max once per second */
 
    last_progress_report = now;
    percent = totalsize_kb ? (int) ((totaldone / 1024) * 100 / totalsize_kb) : 0;
 
    /*
     * Avoid overflowing past 100% or the full size. This may make the total
     * size number change as we approach the end of the backup (the estimate
     * will always be wrong if WAL is included), but that's better than having
     * the done column be bigger than the total.
     */
    if (percent > 100)
        percent = 100;
    if (totaldone / 1024 > totalsize_kb)
        totalsize_kb = totaldone / 1024;
 
    snprintf(totaldone_str, sizeof(totaldone_str), UINT64_FORMAT,
             totaldone / 1024);
    snprintf(totalsize_str, sizeof(totalsize_str), UINT64_FORMAT, totalsize_kb);
 
#define VERBOSE_FILENAME_LENGTH 35
    if (verbose)
    {
        if (!progress_filename)
 
            /*
             * No filename given, so clear the status line (used for last
             * call)
             */
            fprintf(stderr,
                    ngettext("%*s/%s kB (100%%), %d/%d tablespace %*s",
                             "%*s/%s kB (100%%), %d/%d tablespaces %*s",
                             tablespacecount),
                    (int) strlen(totalsize_str),
                    totaldone_str, totalsize_str,
                    tablespacenum, tablespacecount,
                    VERBOSE_FILENAME_LENGTH + 5, "");
        else
        {
            bool        truncate = (strlen(progress_filename) > VERBOSE_FILENAME_LENGTH);
 
            fprintf(stderr,
                    ngettext("%*s/%s kB (%d%%), %d/%d tablespace (%s%-*.*s)",
                             "%*s/%s kB (%d%%), %d/%d tablespaces (%s%-*.*s)",
                             tablespacecount),
                    (int) strlen(totalsize_str),
                    totaldone_str, totalsize_str, percent,
                    tablespacenum, tablespacecount,
            /* Prefix with "..." if we do leading truncation */
                    truncate ? "..." : "",
                    truncate ? VERBOSE_FILENAME_LENGTH - 3 : VERBOSE_FILENAME_LENGTH,
                    truncate ? VERBOSE_FILENAME_LENGTH - 3 : VERBOSE_FILENAME_LENGTH,
            /* Truncate filename at beginning if it's too long */
                    truncate ? progress_filename + strlen(progress_filename) - VERBOSE_FILENAME_LENGTH + 3 : progress_filename);
        }
    }
    else
        fprintf(stderr,
                ngettext("%*s/%s kB (%d%%), %d/%d tablespace",
                         "%*s/%s kB (%d%%), %d/%d tablespaces",
                         tablespacecount),
                (int) strlen(totalsize_str),
                totaldone_str, totalsize_str, percent,
                tablespacenum, tablespacecount);
 
    /*
     * Stay on the same line if reporting to a terminal and we're not done
     * yet.
     */
    fputc((!finished && isatty(fileno(stderr))) ? '\r' : '\n', stderr);
}
 
static int32
parse_max_rate(char *src)
{
    double      result;
    char       *after_num;
    char       *suffix = NULL;
 
    errno = 0;
    result = strtod(src, &after_num);
    if (src == after_num)
        pg_fatal("transfer rate \"%s\" is not a valid value", src);
    if (errno != 0)
        pg_fatal("invalid transfer rate \"%s\": %m", src);
 
    if (result <= 0)
    {
        /*
         * Reject obviously wrong values here.
         */
        pg_fatal("transfer rate must be greater than zero");
    }
 
    /*
     * Evaluate suffix, after skipping over possible whitespace. Lack of
     * suffix means kilobytes.
     */
    while (*after_num != '\0' && isspace((unsigned char) *after_num))
        after_num++;
 
    if (*after_num != '\0')
    {
        suffix = after_num;
        if (*after_num == 'k')
        {
            /* kilobyte is the expected unit. */
            after_num++;
        }
        else if (*after_num == 'M')
        {
            after_num++;
            result *= 1024.0;
        }
    }
 
    /* The rest can only consist of white space. */
    while (*after_num != '\0' && isspace((unsigned char) *after_num))
        after_num++;
 
    if (*after_num != '\0')
        pg_fatal("invalid --max-rate unit: \"%s\"", suffix);
 
    /* Valid integer? */
    if ((uint64) result != (uint64) ((uint32) result))
        pg_fatal("transfer rate \"%s\" exceeds integer range", src);
 
    /*
     * The range is checked on the server side too, but avoid the server
     * connection if a nonsensical value was passed.
     */
    if (result < MAX_RATE_LOWER || result > MAX_RATE_UPPER)
        pg_fatal("transfer rate \"%s\" is out of range", src);
 
    return (int32) result;
}
 
/*
 * Basic parsing of a value specified for -Z/--compress.
 *
 * We're not concerned here with understanding exactly what behavior the
 * user wants, but we do need to know whether the user is requesting client
 * or server side compression or leaving it unspecified, and we need to
 * separate the name of the compression algorithm from the detail string.
 *
 * For instance, if the user writes --compress client-lz4:6, we want to
 * separate that into (a) client-side compression, (b) algorithm "lz4",
 * and (c) detail "6". Note, however, that all the client/server prefix is
 * optional, and so is the detail. The algorithm name is required, unless
 * the whole string is an integer, in which case we assume "gzip" as the
 * algorithm and use the integer as the detail.
 *
 * We're not concerned with validation at this stage, so if the user writes
 * --compress client-turkey:sandwich, the requested algorithm is "turkey"
 * and the detail string is "sandwich". We'll sort out whether that's legal
 * at a later stage.
 */
static void
backup_parse_compress_options(char *option, char **algorithm, char **detail,
                              CompressionLocation *locationres)
{
    /*
     * Strip off any "client-" or "server-" prefix, calculating the location.
     */
    if (strncmp(option, "server-", 7) == 0)
    {
        *locationres = COMPRESS_LOCATION_SERVER;
        option += 7;
    }
    else if (strncmp(option, "client-", 7) == 0)
    {
        *locationres = COMPRESS_LOCATION_CLIENT;
        option += 7;
    }
    else
        *locationres = COMPRESS_LOCATION_UNSPECIFIED;
 
    /* fallback to the common parsing for the algorithm and detail */
    parse_compress_options(option, algorithm, detail);
}
 
/*
 * Read a stream of COPY data and invoke the provided callback for each
 * chunk.
 */
static void
ReceiveCopyData(PGconn *conn, WriteDataCallback callback,
                void *callback_data)
{
    PGresult   *res;
 
    /* Get the COPY data stream. */
    res = PQgetResult(conn);
    if (PQresultStatus(res) != PGRES_COPY_OUT)
        pg_fatal("could not get COPY data stream: %s",
                 PQerrorMessage(conn));
    PQclear(res);
 
    /* Loop over chunks until done. */
    while (1)
    {
        int         r;
        char       *copybuf;
 
        r = PQgetCopyData(conn, &copybuf, 0);
        if (r == -1)
        {
            /* End of chunk. */
            break;
        }
        else if (r == -2)
            pg_fatal("could not read COPY data: %s",
                     PQerrorMessage(conn));
 
        if (bgchild_exited)
            pg_fatal("background process terminated unexpectedly");
 
        (*callback) (r, copybuf, callback_data);
 
        PQfreemem(copybuf);
    }
}
 
/*
 * Figure out what to do with an archive received from the server based on
 * the options selected by the user.  We may just write the results directly
 * to a file, or we might compress first, or we might extract the tar file
 * and write each member separately. This function doesn't do any of that
 * directly, but it works out what kind of astreamer we need to create so
 * that the right stuff happens when, down the road, we actually receive
 * the data.
 */
static astreamer *
CreateBackupStreamer(char *archive_name, char *spclocation,
                     astreamer **manifest_inject_streamer_p,
                     bool is_recovery_guc_supported,
                     bool expect_unterminated_tarfile,
                     pg_compress_specification *compress)
{
    astreamer  *streamer = NULL;
    astreamer  *manifest_inject_streamer = NULL;
    bool        inject_manifest;
    bool        is_tar,
                is_tar_gz,
                is_tar_lz4,
                is_tar_zstd,
                is_compressed_tar;
    bool        must_parse_archive;
    int         archive_name_len = strlen(archive_name);
 
    /*
     * Normally, we emit the backup manifest as a separate file, but when
     * we're writing a tarfile to stdout, we don't have that option, so
     * include it in the one tarfile we've got.
     */
    inject_manifest = (format == 't' && strcmp(basedir, "-") == 0 && manifest);
 
    /* Is this a tar archive? */
    is_tar = (archive_name_len > 4 &&
              strcmp(archive_name + archive_name_len - 4, ".tar") == 0);
 
    /* Is this a .tar.gz archive? */
    is_tar_gz = (archive_name_len > 7 &&
                 strcmp(archive_name + archive_name_len - 7, ".tar.gz") == 0);
 
    /* Is this a .tar.lz4 archive? */
    is_tar_lz4 = (archive_name_len > 8 &&
                  strcmp(archive_name + archive_name_len - 8, ".tar.lz4") == 0);
 
    /* Is this a .tar.zst archive? */
    is_tar_zstd = (archive_name_len > 8 &&
                   strcmp(archive_name + archive_name_len - 8, ".tar.zst") == 0);
 
    /* Is this any kind of compressed tar? */
    is_compressed_tar = is_tar_gz || is_tar_lz4 || is_tar_zstd;
 
    /*
     * Injecting the manifest into a compressed tar file would be possible if
     * we decompressed it, parsed the tarfile, generated a new tarfile, and
     * recompressed it, but compressing and decompressing multiple times just
     * to inject the manifest seems inefficient enough that it's probably not
     * what the user wants. So, instead, reject the request and tell the user
     * to specify something more reasonable.
     */
    if (inject_manifest && is_compressed_tar)
    {
        pg_log_error("cannot inject manifest into a compressed tar file");
        pg_log_error_hint("Use client-side compression, send the output to a directory rather than standard output, or use %s.",
                          "--no-manifest");
        exit(1);
    }
 
    /*
     * We have to parse the archive if (1) we're suppose to extract it, or if
     * (2) we need to inject backup_manifest or recovery configuration into
     * it. However, we only know how to parse tar archives.
     */
    must_parse_archive = (format == 'p' || inject_manifest ||
                          (spclocation == NULL && writerecoveryconf));
 
    /* At present, we only know how to parse tar archives. */
    if (must_parse_archive && !is_tar && !is_compressed_tar)
    {
        pg_log_error("cannot parse archive \"%s\"", archive_name);
        pg_log_error_detail("Only tar archives can be parsed.");
        if (format == 'p')
            pg_log_error_detail("Plain format requires pg_basebackup to parse the archive.");
        if (inject_manifest)
            pg_log_error_detail("Using - as the output directory requires pg_basebackup to parse the archive.");
        if (writerecoveryconf)
            pg_log_error_detail("The -R option requires pg_basebackup to parse the archive.");
        exit(1);
    }
 
    if (format == 'p')
    {
        const char *directory;
 
        /*
         * In plain format, we must extract the archive. The data for the main
         * tablespace will be written to the base directory, and the data for
         * other tablespaces will be written to the directory where they're
         * located on the server, after applying any user-specified tablespace
         * mappings.
         *
         * In the case of an in-place tablespace, spclocation will be a
         * relative path. We just convert it to an absolute path by prepending
         * basedir.
         */
        if (spclocation == NULL)
            directory = basedir;
        else if (!is_absolute_path(spclocation))
            directory = psprintf("%s/%s", basedir, spclocation);
        else
            directory = get_tablespace_mapping(spclocation);
        streamer = astreamer_extractor_new(directory,
                                           get_tablespace_mapping,
                                           progress_update_filename);
    }
    else
    {
        FILE       *archive_file;
        char        archive_filename[MAXPGPATH];
 
        /*
         * In tar format, we just write the archive without extracting it.
         * Normally, we write it to the archive name provided by the caller,
         * but when the base directory is "-" that means we need to write to
         * standard output.
         */
        if (strcmp(basedir, "-") == 0)
        {
            snprintf(archive_filename, sizeof(archive_filename), "-");
            archive_file = stdout;
        }
        else
        {
            snprintf(archive_filename, sizeof(archive_filename),
                     "%s/%s", basedir, archive_name);
            archive_file = NULL;
        }
 
        if (compress->algorithm == PG_COMPRESSION_NONE)
            streamer = astreamer_plain_writer_new(archive_filename,
                                                  archive_file);
        else if (compress->algorithm == PG_COMPRESSION_GZIP)
        {
            strlcat(archive_filename, ".gz", sizeof(archive_filename));
            streamer = astreamer_gzip_writer_new(archive_filename,
                                                 archive_file, compress);
        }
        else if (compress->algorithm == PG_COMPRESSION_LZ4)
        {
            strlcat(archive_filename, ".lz4", sizeof(archive_filename));
            streamer = astreamer_plain_writer_new(archive_filename,
                                                  archive_file);
            streamer = astreamer_lz4_compressor_new(streamer, compress);
        }
        else if (compress->algorithm == PG_COMPRESSION_ZSTD)
        {
            strlcat(archive_filename, ".zst", sizeof(archive_filename));
            streamer = astreamer_plain_writer_new(archive_filename,
                                                  archive_file);
            streamer = astreamer_zstd_compressor_new(streamer, compress);
        }
        else
        {
            Assert(false);      /* not reachable */
        }
 
        /*
         * If we need to parse the archive for whatever reason, then we'll
         * also need to re-archive, because, if the output format is tar, the
         * only point of parsing the archive is to be able to inject stuff
         * into it.
         */
        if (must_parse_archive)
            streamer = astreamer_tar_archiver_new(streamer);
        progress_update_filename(archive_filename);
    }
 
    /*
     * If we're supposed to inject the backup manifest into the results, it
     * should be done here, so that the file content can be injected directly,
     * without worrying about the details of the tar format.
     */
    if (inject_manifest)
        manifest_inject_streamer = streamer;
 
    /*
     * If this is the main tablespace and we're supposed to write recovery
     * information, arrange to do that.
     */
    if (spclocation == NULL && writerecoveryconf)
    {
        Assert(must_parse_archive);
        streamer = astreamer_recovery_injector_new(streamer,
                                                   is_recovery_guc_supported,
                                                   recoveryconfcontents);
    }
 
    /*
     * If we're doing anything that involves understanding the contents of the
     * archive, we'll need to parse it. If not, we can skip parsing it, but
     * old versions of the server send improperly terminated tarfiles, so if
     * we're talking to such a server we'll need to add the terminator here.
     */
    if (must_parse_archive)
        streamer = astreamer_tar_parser_new(streamer);
    else if (expect_unterminated_tarfile)
        streamer = astreamer_tar_terminator_new(streamer);
 
    /*
     * If the user has requested a server compressed archive along with
     * archive extraction at client then we need to decompress it.
     */
    if (format == 'p')
    {
        if (is_tar_gz)
            streamer = astreamer_gzip_decompressor_new(streamer);
        else if (is_tar_lz4)
            streamer = astreamer_lz4_decompressor_new(streamer);
        else if (is_tar_zstd)
            streamer = astreamer_zstd_decompressor_new(streamer);
    }
 
    /* Return the results. */
    *manifest_inject_streamer_p = manifest_inject_streamer;
    return streamer;
}
 
/*
 * Receive all of the archives the server wants to send - and the backup
 * manifest if present - as a single COPY stream.
 */
static void
ReceiveArchiveStream(PGconn *conn, pg_compress_specification *compress)
{
    ArchiveStreamState state;
 
    /* Set up initial state. */
    memset(&state, 0, sizeof(state));
    state.tablespacenum = -1;
    state.compress = compress;
 
    /* All the real work happens in ReceiveArchiveStreamChunk. */
    ReceiveCopyData(conn, ReceiveArchiveStreamChunk, &state);
 
    /* If we wrote the backup manifest to a file, close the file. */
    if (state.manifest_file !=NULL)
    {
        fclose(state.manifest_file);
        state.manifest_file = NULL;
    }
 
    /*
     * If we buffered the backup manifest in order to inject it into the
     * output tarfile, do that now.
     */
    if (state.manifest_inject_streamer != NULL &&
        state.manifest_buffer != NULL)
    {
        astreamer_inject_file(state.manifest_inject_streamer,
                              "backup_manifest",
                              state.manifest_buffer->data,
                              state.manifest_buffer->len);
        destroyPQExpBuffer(state.manifest_buffer);
        state.manifest_buffer = NULL;
    }
 
    /* If there's still an archive in progress, end processing. */
    if (state.streamer != NULL)
    {
        astreamer_finalize(state.streamer);
        astreamer_free(state.streamer);
        state.streamer = NULL;
    }
}
 
/*
 * Receive one chunk of data sent by the server as part of a single COPY
 * stream that includes all archives and the manifest.
 */
static void
ReceiveArchiveStreamChunk(size_t r, char *copybuf, void *callback_data)
{
    ArchiveStreamState *state = callback_data;
    size_t      cursor = 0;
 
    /* Each CopyData message begins with a type byte. */
    switch (GetCopyDataByte(r, copybuf, &cursor))
    {
        case 'n':
            {
                /* New archive. */
                char       *archive_name;
                char       *spclocation;
 
                /*
                 * We force a progress report at the end of each tablespace. A
                 * new tablespace starts when the previous one ends, except in
                 * the case of the very first one.
                 */
                if (++state->tablespacenum > 0)
                    progress_report(state->tablespacenum, true, false);
 
                /* Sanity check. */
                if (state->manifest_buffer != NULL ||
                    state->manifest_file !=NULL)
                    pg_fatal("archives must precede manifest");
 
                /* Parse the rest of the CopyData message. */
                archive_name = GetCopyDataString(r, copybuf, &cursor);
                spclocation = GetCopyDataString(r, copybuf, &cursor);
                GetCopyDataEnd(r, copybuf, cursor);
 
                /*
                 * Basic sanity checks on the archive name: it shouldn't be
                 * empty, it shouldn't start with a dot, and it shouldn't
                 * contain a path separator.
                 */
                if (archive_name[0] == '\0' || archive_name[0] == '.' ||
                    strchr(archive_name, '/') != NULL ||
                    strchr(archive_name, '\\') != NULL)
                    pg_fatal("invalid archive name: \"%s\"",
                             archive_name);
 
                /*
                 * An empty spclocation is treated as NULL. We expect this
                 * case to occur for the data directory itself, but not for
                 * any archives that correspond to tablespaces.
                 */
                if (spclocation[0] == '\0')
                    spclocation = NULL;
 
                /* End processing of any prior archive. */
                if (state->streamer != NULL)
                {
                    astreamer_finalize(state->streamer);
                    astreamer_free(state->streamer);
                    state->streamer = NULL;
                }
 
                /*
                 * Create an appropriate backup streamer, unless a backup
                 * target was specified. In that case, it's up to the server
                 * to put the backup wherever it needs to go.
                 */
                if (backup_target == NULL)
                {
                    /*
                     * We know that recovery GUCs are supported, because this
                     * protocol can only be used on v15+.
                     */
                    state->streamer =
                        CreateBackupStreamer(archive_name,
                                             spclocation,
                                             &state->manifest_inject_streamer,
                                             true, false,
                                             state->compress);
                }
                break;
            }
 
        case 'd':
            {
                /* Archive or manifest data. */
                if (state->manifest_buffer != NULL)
                {
                    /* Manifest data, buffer in memory. */
                    appendPQExpBuffer(state->manifest_buffer, copybuf + 1,
                                      r - 1);
                }
                else if (state->manifest_file !=NULL)
                {
                    /* Manifest data, write to disk. */
                    if (fwrite(copybuf + 1, r - 1, 1,
                               state->manifest_file) != 1)
                    {
                        /*
                         * If fwrite() didn't set errno, assume that the
                         * problem is that we're out of disk space.
                         */
                        if (errno == 0)
                            errno = ENOSPC;
                        pg_fatal("could not write to file \"%s\": %m",
                                 state->manifest_filename);
                    }
                }
                else if (state->streamer != NULL)
                {
                    /* Archive data. */
                    astreamer_content(state->streamer, NULL, copybuf + 1,
                                      r - 1, ASTREAMER_UNKNOWN);
                }
                else
                    pg_fatal("unexpected payload data");
                break;
            }
 
        case 'p':
            {
                /*
                 * Progress report.
                 *
                 * The remainder of the message is expected to be an 8-byte
                 * count of bytes completed.
                 */
                totaldone = GetCopyDataUInt64(r, copybuf, &cursor);
                GetCopyDataEnd(r, copybuf, cursor);
 
                /*
                 * The server shouldn't send progress report messages too
                 * often, so we force an update each time we receive one.
                 */
                progress_report(state->tablespacenum, true, false);
                break;
            }
 
        case 'm':
            {
                /*
                 * Manifest data will be sent next. This message is not
                 * expected to have any further payload data.
                 */
                GetCopyDataEnd(r, copybuf, cursor);
 
                /*
                 * If a backup target was specified, figuring out where to put
                 * the manifest is the server's problem. Otherwise, we need to
                 * deal with it.
                 */
                if (backup_target == NULL)
                {
                    /*
                     * If we're supposed inject the manifest into the archive,
                     * we prepare to buffer it in memory; otherwise, we
                     * prepare to write it to a temporary file.
                     */
                    if (state->manifest_inject_streamer != NULL)
                        state->manifest_buffer = createPQExpBuffer();
                    else
                    {
                        snprintf(state->manifest_filename,
                                 sizeof(state->manifest_filename),
                                 "%s/backup_manifest.tmp", basedir);
                        state->manifest_file =
                            fopen(state->manifest_filename, "wb");
                        if (state->manifest_file == NULL)
                            pg_fatal("could not create file \"%s\": %m",
                                     state->manifest_filename);
                    }
                }
                break;
            }
 
        default:
            ReportCopyDataParseError(r, copybuf);
            break;
    }
}
 
/*
 * Get a single byte from a CopyData message.
 *
 * Bail out if none remain.
 */
static char
GetCopyDataByte(size_t r, char *copybuf, size_t *cursor)
{
    if (*cursor >= r)
        ReportCopyDataParseError(r, copybuf);
 
    return copybuf[(*cursor)++];
}
 
/*
 * Get a NUL-terminated string from a CopyData message.
 *
 * Bail out if the terminating NUL cannot be found.
 */
static char *
GetCopyDataString(size_t r, char *copybuf, size_t *cursor)
{
    size_t      startpos = *cursor;
    size_t      endpos = startpos;
 
    while (1)
    {
        if (endpos >= r)
            ReportCopyDataParseError(r, copybuf);
        if (copybuf[endpos] == '\0')
            break;
        ++endpos;
    }
 
    *cursor = endpos + 1;
    return &copybuf[startpos];
}
 
/*
 * Get an unsigned 64-bit integer from a CopyData message.
 *
 * Bail out if there are not at least 8 bytes remaining.
 */
static uint64
GetCopyDataUInt64(size_t r, char *copybuf, size_t *cursor)
{
    uint64      result;
 
    if (*cursor + sizeof(uint64) > r)
        ReportCopyDataParseError(r, copybuf);
    memcpy(&result, &copybuf[*cursor], sizeof(uint64));
    *cursor += sizeof(uint64);
    return pg_ntoh64(result);
}
 
/*
 * Bail out if we didn't parse the whole message.
 */
static void
GetCopyDataEnd(size_t r, char *copybuf, size_t cursor)
{
    if (r != cursor)
        ReportCopyDataParseError(r, copybuf);
}
 
/*
 * Report failure to parse a CopyData message from the server. Then exit.
 *
 * As a debugging aid, we try to give some hint about what kind of message
 * provoked the failure. Perhaps this is not detailed enough, but it's not
 * clear that it's worth expending any more code on what should be a
 * can't-happen case.
 */
static void
ReportCopyDataParseError(size_t r, char *copybuf)
{
    if (r == 0)
        pg_fatal("empty COPY message");
    else
        pg_fatal("malformed COPY message of type %d, length %zu",
                 copybuf[0], r);
}
 
/*
 * Receive raw tar data from the server, and stream it to the appropriate
 * location. If we're writing a single tarfile to standard output, also
 * receive the backup manifest and inject it into that tarfile.
 */
static void
ReceiveTarFile(PGconn *conn, char *archive_name, char *spclocation,
               bool tablespacenum, pg_compress_specification *compress)
{
    WriteTarState state;
    astreamer  *manifest_inject_streamer;
    bool        is_recovery_guc_supported;
    bool        expect_unterminated_tarfile;
 
    /* Pass all COPY data through to the backup streamer. */
    memset(&state, 0, sizeof(state));
    is_recovery_guc_supported =
        PQserverVersion(conn) >= MINIMUM_VERSION_FOR_RECOVERY_GUC;
    expect_unterminated_tarfile =
        PQserverVersion(conn) < MINIMUM_VERSION_FOR_TERMINATED_TARFILE;
    state.streamer = CreateBackupStreamer(archive_name, spclocation,
                                          &manifest_inject_streamer,
                                          is_recovery_guc_supported,
                                          expect_unterminated_tarfile,
                                          compress);
    state.tablespacenum = tablespacenum;
    ReceiveCopyData(conn, ReceiveTarCopyChunk, &state);
    progress_update_filename(NULL);
 
    /*
     * The decision as to whether we need to inject the backup manifest into
     * the output at this stage is made by CreateBackupStreamer; if that is
     * needed, manifest_inject_streamer will be non-NULL; otherwise, it will
     * be NULL.
     */
    if (manifest_inject_streamer != NULL)
    {
        PQExpBufferData buf;
 
        /* Slurp the entire backup manifest into a buffer. */
        initPQExpBuffer(&buf);
        ReceiveBackupManifestInMemory(conn, &buf);
        if (PQExpBufferDataBroken(buf))
            pg_fatal("out of memory");
 
        /* Inject it into the output tarfile. */
        astreamer_inject_file(manifest_inject_streamer, "backup_manifest",
                              buf.data, buf.len);
 
        /* Free memory. */
        termPQExpBuffer(&buf);
    }
 
    /* Cleanup. */
    astreamer_finalize(state.streamer);
    astreamer_free(state.streamer);
 
    progress_report(tablespacenum, true, false);
 
    /*
     * Do not sync the resulting tar file yet, all files are synced once at
     * the end.
     */
}
 
/*
 * Receive one chunk of tar-format data from the server.
 */
static void
ReceiveTarCopyChunk(size_t r, char *copybuf, void *callback_data)
{
    WriteTarState *state = callback_data;
 
    astreamer_content(state->streamer, NULL, copybuf, r, ASTREAMER_UNKNOWN);
 
    totaldone += r;
    progress_report(state->tablespacenum, false, false);
}
 
 
/*
 * Retrieve tablespace path, either relocated or original depending on whether
 * -T was passed or not.
 */
static const char *
get_tablespace_mapping(const char *dir)
{
    TablespaceListCell *cell;
    char        canon_dir[MAXPGPATH];
 
    /* Canonicalize path for comparison consistency */
    strlcpy(canon_dir, dir, sizeof(canon_dir));
    canonicalize_path(canon_dir);
 
    for (cell = tablespace_dirs.head; cell; cell = cell->next)
        if (strcmp(canon_dir, cell->old_dir) == 0)
            return cell->new_dir;
 
    return dir;
}
 
/*
 * Receive the backup manifest file and write it out to a file.
 */
static void
ReceiveBackupManifest(PGconn *conn)
{
    WriteManifestState state;
 
    snprintf(state.filename, sizeof(state.filename),
             "%s/backup_manifest.tmp", basedir);
    state.file = fopen(state.filename, "wb");
    if (state.file == NULL)
        pg_fatal("could not create file \"%s\": %m", state.filename);
 
    ReceiveCopyData(conn, ReceiveBackupManifestChunk, &state);
 
    fclose(state.file);
}
 
/*
 * Receive one chunk of the backup manifest file and write it out to a file.
 */
static void
ReceiveBackupManifestChunk(size_t r, char *copybuf, void *callback_data)
{
    WriteManifestState *state = callback_data;
 
    errno = 0;
    if (fwrite(copybuf, r, 1, state->file) != 1)
    {
        /* if write didn't set errno, assume problem is no disk space */
        if (errno == 0)
            errno = ENOSPC;
        pg_fatal("could not write to file \"%s\": %m", state->filename);
    }
}
 
/*
 * Receive the backup manifest file and write it out to a file.
 */
static void
ReceiveBackupManifestInMemory(PGconn *conn, PQExpBuffer buf)
{
    ReceiveCopyData(conn, ReceiveBackupManifestInMemoryChunk, buf);
}
 
/*
 * Receive one chunk of the backup manifest file and write it out to a file.
 */
static void
ReceiveBackupManifestInMemoryChunk(size_t r, char *copybuf,
                                   void *callback_data)
{
    PQExpBuffer buf = callback_data;
 
    appendPQExpBuffer(buf, copybuf, r);
}
 
static void
BaseBackup(char *compression_algorithm, char *compression_detail,
           CompressionLocation compressloc,
           pg_compress_specification *client_compress,
           char *incremental_manifest)
{
    PGresult   *res;
    char       *sysidentifier;
    TimeLineID  latesttli;
    TimeLineID  starttli;
    char       *basebkp;
    int         i;
    char        xlogstart[64];
    char        xlogend[64] = {0};
    int         minServerMajor,
                maxServerMajor;
    int         serverVersion,
                serverMajor;
    int         writing_to_stdout;
    bool        use_new_option_syntax = false;
    PQExpBufferData buf;
 
    Assert(conn != NULL);
    initPQExpBuffer(&buf);
 
    /*
     * Check server version. BASE_BACKUP command was introduced in 9.1, so we
     * can't work with servers older than 9.1.
     */
    minServerMajor = 901;
    maxServerMajor = PG_VERSION_NUM / 100;
    serverVersion = PQserverVersion(conn);
    serverMajor = serverVersion / 100;
    if (serverMajor < minServerMajor || serverMajor > maxServerMajor)
    {
        const char *serverver = PQparameterStatus(conn, "server_version");
 
        pg_fatal("incompatible server version %s",
                 serverver ? serverver : "'unknown'");
    }
    if (serverMajor >= 1500)
        use_new_option_syntax = true;
 
    /*
     * If WAL streaming was requested, also check that the server is new
     * enough for that.
     */
    if (includewal == STREAM_WAL && !CheckServerVersionForStreaming(conn))
    {
        /*
         * Error message already written in CheckServerVersionForStreaming(),
         * but add a hint about using -X none.
         */
        pg_log_error_hint("Use -X none or -X fetch to disable log streaming.");
        exit(1);
    }
 
    /*
     * Build contents of configuration file if requested.
     *
     * Note that we don't use the dbname from key-value pair in conn as that
     * would have been filled by the default dbname (dbname=replication) in
     * case the user didn't specify the one. The dbname written in the config
     * file as part of primary_conninfo would be used by slotsync worker which
     * doesn't use a replication connection so the default won't work for it.
     */
    if (writerecoveryconf)
        recoveryconfcontents = GenerateRecoveryConfig(conn,
                                                      replication_slot,
                                                      GetDbnameFromConnectionOptions(connection_string));
 
    /*
     * Run IDENTIFY_SYSTEM so we can get the timeline
     */
    if (!RunIdentifySystem(conn, &sysidentifier, &latesttli, NULL, NULL))
        exit(1);
 
    /*
     * If the user wants an incremental backup, we must upload the manifest
     * for the previous backup upon which it is to be based.
     */
    if (incremental_manifest != NULL)
    {
        int         fd;
        char        mbuf[65536];
        int         nbytes;
 
        /* Reject if server is too old. */
        if (serverVersion < MINIMUM_VERSION_FOR_WAL_SUMMARIES)
            pg_fatal("server does not support incremental backup");
 
        /* Open the file. */
        fd = open(incremental_manifest, O_RDONLY | PG_BINARY, 0);
        if (fd < 0)
            pg_fatal("could not open file \"%s\": %m", incremental_manifest);
 
        /* Tell the server what we want to do. */
        if (PQsendQuery(conn, "UPLOAD_MANIFEST") == 0)
            pg_fatal("could not send replication command \"%s\": %s",
                     "UPLOAD_MANIFEST", PQerrorMessage(conn));
        res = PQgetResult(conn);
        if (PQresultStatus(res) != PGRES_COPY_IN)
        {
            if (PQresultStatus(res) == PGRES_FATAL_ERROR)
                pg_fatal("could not upload manifest: %s",
                         PQerrorMessage(conn));
            else
                pg_fatal("could not upload manifest: unexpected status %s",
                         PQresStatus(PQresultStatus(res)));
        }
 
        /* Loop, reading from the file and sending the data to the server. */
        while ((nbytes = read(fd, mbuf, sizeof mbuf)) > 0)
        {
            if (PQputCopyData(conn, mbuf, nbytes) < 0)
                pg_fatal("could not send COPY data: %s",
                         PQerrorMessage(conn));
        }
 
        /* Bail out if we exited the loop due to an error. */
        if (nbytes < 0)
            pg_fatal("could not read file \"%s\": %m", incremental_manifest);
 
        /* End the COPY operation. */
        if (PQputCopyEnd(conn, NULL) < 0)
            pg_fatal("could not send end-of-COPY: %s",
                     PQerrorMessage(conn));
 
        /* See whether the server is happy with what we sent. */
        res = PQgetResult(conn);
        if (PQresultStatus(res) == PGRES_FATAL_ERROR)
            pg_fatal("could not upload manifest: %s",
                     PQerrorMessage(conn));
        else if (PQresultStatus(res) != PGRES_COMMAND_OK)
            pg_fatal("could not upload manifest: unexpected status %s",
                     PQresStatus(PQresultStatus(res)));
 
        /* Consume ReadyForQuery message from server. */
        res = PQgetResult(conn);
        if (res != NULL)
            pg_fatal("unexpected extra result while sending manifest");
 
        /* Add INCREMENTAL option to BASE_BACKUP command. */
        AppendPlainCommandOption(&buf, use_new_option_syntax, "INCREMENTAL");
    }
 
    /*
     * Continue building up the options list for the BASE_BACKUP command.
     */
    AppendStringCommandOption(&buf, use_new_option_syntax, "LABEL", label);
    if (estimatesize)
        AppendPlainCommandOption(&buf, use_new_option_syntax, "PROGRESS");
    if (includewal == FETCH_WAL)
        AppendPlainCommandOption(&buf, use_new_option_syntax, "WAL");
    if (fastcheckpoint)
    {
        if (use_new_option_syntax)
            AppendStringCommandOption(&buf, use_new_option_syntax,
                                      "CHECKPOINT", "fast");
        else
            AppendPlainCommandOption(&buf, use_new_option_syntax, "FAST");
    }
    if (includewal != NO_WAL)
    {
        if (use_new_option_syntax)
            AppendIntegerCommandOption(&buf, use_new_option_syntax, "WAIT", 0);
        else
            AppendPlainCommandOption(&buf, use_new_option_syntax, "NOWAIT");
    }
    if (maxrate > 0)
        AppendIntegerCommandOption(&buf, use_new_option_syntax, "MAX_RATE",
                                   maxrate);
    if (format == 't')
        AppendPlainCommandOption(&buf, use_new_option_syntax, "TABLESPACE_MAP");
    if (!verify_checksums)
    {
        if (use_new_option_syntax)
            AppendIntegerCommandOption(&buf, use_new_option_syntax,
                                       "VERIFY_CHECKSUMS", 0);
        else
            AppendPlainCommandOption(&buf, use_new_option_syntax,
                                     "NOVERIFY_CHECKSUMS");
    }
 
    if (manifest)
    {
        AppendStringCommandOption(&buf, use_new_option_syntax, "MANIFEST",
                                  manifest_force_encode ? "force-encode" : "yes");
        if (manifest_checksums != NULL)
            AppendStringCommandOption(&buf, use_new_option_syntax,
                                      "MANIFEST_CHECKSUMS", manifest_checksums);
    }
 
    if (backup_target != NULL)
    {
        char       *colon;
 
        if (serverMajor < 1500)
            pg_fatal("backup targets are not supported by this server version");
 
        if (writerecoveryconf)
            pg_fatal("recovery configuration cannot be written when a backup target is used");
 
        AppendPlainCommandOption(&buf, use_new_option_syntax, "TABLESPACE_MAP");
 
        if ((colon = strchr(backup_target, ':')) == NULL)
        {
            AppendStringCommandOption(&buf, use_new_option_syntax,
                                      "TARGET", backup_target);
        }
        else
        {
            char       *target;
 
            target = pnstrdup(backup_target, colon - backup_target);
            AppendStringCommandOption(&buf, use_new_option_syntax,
                                      "TARGET", target);
            AppendStringCommandOption(&buf, use_new_option_syntax,
                                      "TARGET_DETAIL", colon + 1);
        }
    }
    else if (serverMajor >= 1500)
        AppendStringCommandOption(&buf, use_new_option_syntax,
                                  "TARGET", "client");
 
    if (compressloc == COMPRESS_LOCATION_SERVER)
    {
        if (!use_new_option_syntax)
            pg_fatal("server does not support server-side compression");
        AppendStringCommandOption(&buf, use_new_option_syntax,
                                  "COMPRESSION", compression_algorithm);
        if (compression_detail != NULL)
            AppendStringCommandOption(&buf, use_new_option_syntax,
                                      "COMPRESSION_DETAIL",
                                      compression_detail);
    }
 
    if (verbose)
        pg_log_info("initiating base backup, waiting for checkpoint to complete");
 
    if (showprogress && !verbose)
    {
        fprintf(stderr, _("waiting for checkpoint"));
        if (isatty(fileno(stderr)))
            fprintf(stderr, "\r");
        else
            fprintf(stderr, "\n");
    }
 
    if (use_new_option_syntax && buf.len > 0)
        basebkp = psprintf("BASE_BACKUP (%s)", buf.data);
    else
        basebkp = psprintf("BASE_BACKUP %s", buf.data);
 
    /* OK, try to start the backup. */
    if (PQsendQuery(conn, basebkp) == 0)
        pg_fatal("could not send replication command \"%s\": %s",
                 "BASE_BACKUP", PQerrorMessage(conn));
 
    /*
     * Get the starting WAL location
     */
    res = PQgetResult(conn);
    if (PQresultStatus(res) != PGRES_TUPLES_OK)
        pg_fatal("could not initiate base backup: %s",
                 PQerrorMessage(conn));
    if (PQntuples(res) != 1)
        pg_fatal("server returned unexpected response to BASE_BACKUP command; got %d rows and %d fields, expected %d rows and %d fields",
                 PQntuples(res), PQnfields(res), 1, 2);
 
    strlcpy(xlogstart, PQgetvalue(res, 0, 0), sizeof(xlogstart));
 
    if (verbose)
        pg_log_info("checkpoint completed");
 
    /*
     * 9.3 and later sends the TLI of the starting point. With older servers,
     * assume it's the same as the latest timeline reported by
     * IDENTIFY_SYSTEM.
     */
    if (PQnfields(res) >= 2)
        starttli = atoi(PQgetvalue(res, 0, 1));
    else
        starttli = latesttli;
    PQclear(res);
 
    if (verbose && includewal != NO_WAL)
        pg_log_info("write-ahead log start point: %s on timeline %u",
                    xlogstart, starttli);
 
    /*
     * Get the header
     */
    res = PQgetResult(conn);
    if (PQresultStatus(res) != PGRES_TUPLES_OK)
        pg_fatal("could not get backup header: %s",
                 PQerrorMessage(conn));
    if (PQntuples(res) < 1)
        pg_fatal("no data returned from server");
 
    /*
     * Sum up the total size, for progress reporting
     */
    totalsize_kb = totaldone = 0;
    tablespacecount = PQntuples(res);
    for (i = 0; i < PQntuples(res); i++)
    {
        totalsize_kb += atoll(PQgetvalue(res, i, 2));
 
        /*
         * Verify tablespace directories are empty. Don't bother with the
         * first once since it can be relocated, and it will be checked before
         * we do anything anyway.
         *
         * Note that this is skipped for tar format backups and backups that
         * the server is storing to a target location, since in that case we
         * won't be storing anything into these directories and thus should
         * not create them.
         */
        if (backup_target == NULL && format == 'p' && !PQgetisnull(res, i, 1))
        {
            char       *path = PQgetvalue(res, i, 1);
 
            if (is_absolute_path(path))
                path = unconstify(char *, get_tablespace_mapping(path));
            else
            {
                /* This is an in-place tablespace, so prepend basedir. */
                path = psprintf("%s/%s", basedir, path);
            }
 
            verify_dir_is_empty_or_create(path, &made_tablespace_dirs, &found_tablespace_dirs);
        }
    }
 
    /*
     * When writing to stdout, require a single tablespace
     */
    writing_to_stdout = format == 't' && basedir != NULL &&
        strcmp(basedir, "-") == 0;
    if (writing_to_stdout && PQntuples(res) > 1)
        pg_fatal("can only write single tablespace to stdout, database has %d",
                 PQntuples(res));
 
    /*
     * If we're streaming WAL, start the streaming session before we start
     * receiving the actual data chunks.
     */
    if (includewal == STREAM_WAL)
    {
        pg_compress_algorithm wal_compress_algorithm;
        int         wal_compress_level;
 
        if (verbose)
            pg_log_info("starting background WAL receiver");
 
        if (client_compress->algorithm == PG_COMPRESSION_GZIP)
        {
            wal_compress_algorithm = PG_COMPRESSION_GZIP;
            wal_compress_level = client_compress->level;
        }
        else
        {
            wal_compress_algorithm = PG_COMPRESSION_NONE;
            wal_compress_level = 0;
        }
 
        StartLogStreamer(xlogstart, starttli, sysidentifier,
                         wal_compress_algorithm,
                         wal_compress_level);
    }
 
    if (serverMajor >= 1500)
    {
        /* Receive a single tar stream with everything. */
        ReceiveArchiveStream(conn, client_compress);
    }
    else
    {
        /* Receive a tar file for each tablespace in turn */
        for (i = 0; i < PQntuples(res); i++)
        {
            char        archive_name[MAXPGPATH];
            char       *spclocation;
 
            /*
             * If we write the data out to a tar file, it will be named
             * base.tar if it's the main data directory or <tablespaceoid>.tar
             * if it's for another tablespace. CreateBackupStreamer() will
             * arrange to add an extension to the archive name if
             * pg_basebackup is performing compression, depending on the
             * compression type.
             */
            if (PQgetisnull(res, i, 0))
            {
                strlcpy(archive_name, "base.tar", sizeof(archive_name));
                spclocation = NULL;
            }
            else
            {
                snprintf(archive_name, sizeof(archive_name),
                         "%s.tar", PQgetvalue(res, i, 0));
                spclocation = PQgetvalue(res, i, 1);
            }
 
            ReceiveTarFile(conn, archive_name, spclocation, i,
                           client_compress);
        }
 
        /*
         * Now receive backup manifest, if appropriate.
         *
         * If we're writing a tarfile to stdout, ReceiveTarFile will have
         * already processed the backup manifest and included it in the output
         * tarfile.  Such a configuration doesn't allow for writing multiple
         * files.
         *
         * If we're talking to an older server, it won't send a backup
         * manifest, so don't try to receive one.
         */
        if (!writing_to_stdout && manifest)
            ReceiveBackupManifest(conn);
    }
 
    if (showprogress)
    {
        progress_update_filename(NULL);
        progress_report(PQntuples(res), true, true);
    }
 
    PQclear(res);
 
    /*
     * Get the stop position
     */
    res = PQgetResult(conn);
    if (PQresultStatus(res) != PGRES_TUPLES_OK)
        pg_fatal("backup failed: %s",
                 PQerrorMessage(conn));
    if (PQntuples(res) != 1)
        pg_fatal("no write-ahead log end position returned from server");
    strlcpy(xlogend, PQgetvalue(res, 0, 0), sizeof(xlogend));
    if (verbose && includewal != NO_WAL)
        pg_log_info("write-ahead log end point: %s", xlogend);
    PQclear(res);
 
    res = PQgetResult(conn);
    if (PQresultStatus(res) != PGRES_COMMAND_OK)
    {
        const char *sqlstate = PQresultErrorField(res, PG_DIAG_SQLSTATE);
 
        if (sqlstate &&
            strcmp(sqlstate, ERRCODE_DATA_CORRUPTED) == 0)
        {
            pg_log_error("checksum error occurred");
            checksum_failure = true;
        }
        else
        {
            pg_log_error("final receive failed: %s",
                         PQerrorMessage(conn));
        }
        exit(1);
    }
 
    if (bgchild > 0)
    {
#ifndef WIN32
        int         status;
        pid_t       r;
#else
        DWORD       status;
 
        /*
         * get a pointer sized version of bgchild to avoid warnings about
         * casting to a different size on WIN64.
         */
        intptr_t    bgchild_handle = bgchild;
        uint32      hi,
                    lo;
#endif
 
        if (verbose)
            pg_log_info("waiting for background process to finish streaming ...");
 
#ifndef WIN32
        if (write(bgpipe[1], xlogend, strlen(xlogend)) != strlen(xlogend))
            pg_fatal("could not send command to background pipe: %m");
 
        /* Just wait for the background process to exit */
        r = waitpid(bgchild, &status, 0);
        if (r == (pid_t) -1)
            pg_fatal("could not wait for child process: %m");
        if (r != bgchild)
            pg_fatal("child %d died, expected %d", (int) r, (int) bgchild);
        if (status != 0)
            pg_fatal("%s", wait_result_to_str(status));
        /* Exited normally, we're happy! */
#else                           /* WIN32 */
 
        /*
         * On Windows, since we are in the same process, we can just store the
         * value directly in the variable, and then set the flag that says
         * it's there.
         */
        if (sscanf(xlogend, "%X/%X", &hi, &lo) != 2)
            pg_fatal("could not parse write-ahead log location \"%s\"",
                     xlogend);
        xlogendptr = ((uint64) hi) << 32 | lo;
        InterlockedIncrement(&has_xlogendptr);
 
        /* First wait for the thread to exit */
        if (WaitForSingleObjectEx((HANDLE) bgchild_handle, INFINITE, FALSE) !=
            WAIT_OBJECT_0)
        {
            _dosmaperr(GetLastError());
            pg_fatal("could not wait for child thread: %m");
        }
        if (GetExitCodeThread((HANDLE) bgchild_handle, &status) == 0)
        {
            _dosmaperr(GetLastError());
            pg_fatal("could not get child thread exit status: %m");
        }
        if (status != 0)
            pg_fatal("child thread exited with error %u",
                     (unsigned int) status);
        /* Exited normally, we're happy */
#endif
    }
 
    /* Free the configuration file contents */
    destroyPQExpBuffer(recoveryconfcontents);
 
    /*
     * End of copy data. Final result is already checked inside the loop.
     */
    PQclear(res);
    PQfinish(conn);
    conn = NULL;
 
    /*
     * Make data persistent on disk once backup is completed. For tar format
     * sync the parent directory and all its contents as each tar file was not
     * synced after being completed.  In plain format, all the data of the
     * base directory is synced, taking into account all the tablespaces.
     * Errors are not considered fatal.
     *
     * If, however, there's a backup target, we're not writing anything
     * locally, so in that case we skip this step.
     */
    if (do_sync && backup_target == NULL)
    {
        if (verbose)
            pg_log_info("syncing data to disk ...");
        if (format == 't')
        {
            if (strcmp(basedir, "-") != 0)
                (void) sync_dir_recurse(basedir, sync_method);
        }
        else
        {
            (void) sync_pgdata(basedir, serverVersion, sync_method, true);
        }
    }
 
    /*
     * After synchronizing data to disk, perform a durable rename of
     * backup_manifest.tmp to backup_manifest, if we wrote such a file. This
     * way, a failure or system crash before we reach this point will leave us
     * without a backup_manifest file, decreasing the chances that a directory
     * we leave behind will be mistaken for a valid backup.
     */
    if (!writing_to_stdout && manifest && backup_target == NULL)
    {
        char        tmp_filename[MAXPGPATH];
        char        filename[MAXPGPATH];
 
        if (verbose)
            pg_log_info("renaming backup_manifest.tmp to backup_manifest");
 
        snprintf(tmp_filename, MAXPGPATH, "%s/backup_manifest.tmp", basedir);
        snprintf(filename, MAXPGPATH, "%s/backup_manifest", basedir);
 
        if (do_sync)
        {
            /* durable_rename emits its own log message in case of failure */
            if (durable_rename(tmp_filename, filename) != 0)
                exit(1);
        }
        else
        {
            if (rename(tmp_filename, filename) != 0)
                pg_fatal("could not rename file \"%s\" to \"%s\": %m",
                         tmp_filename, filename);
        }
    }
 
    if (verbose)
        pg_log_info("base backup completed");
}
 
 
int
main(int argc, char **argv)
{
    static struct option long_options[] = {
        {"help", no_argument, NULL, '?'},
        {"version", no_argument, NULL, 'V'},
        {"pgdata", required_argument, NULL, 'D'},
        {"format", required_argument, NULL, 'F'},
        {"incremental", required_argument, NULL, 'i'},
        {"checkpoint", required_argument, NULL, 'c'},
        {"create-slot", no_argument, NULL, 'C'},
        {"max-rate", required_argument, NULL, 'r'},
        {"write-recovery-conf", no_argument, NULL, 'R'},
        {"slot", required_argument, NULL, 'S'},
        {"target", required_argument, NULL, 't'},
        {"tablespace-mapping", required_argument, NULL, 'T'},
        {"wal-method", required_argument, NULL, 'X'},
        {"gzip", no_argument, NULL, 'z'},
        {"compress", required_argument, NULL, 'Z'},
        {"label", required_argument, NULL, 'l'},
        {"no-clean", no_argument, NULL, 'n'},
        {"no-sync", no_argument, NULL, 'N'},
        {"dbname", required_argument, NULL, 'd'},
        {"host", required_argument, NULL, 'h'},
        {"port", required_argument, NULL, 'p'},
        {"username", required_argument, NULL, 'U'},
        {"no-password", no_argument, NULL, 'w'},
        {"password", no_argument, NULL, 'W'},
        {"status-interval", required_argument, NULL, 's'},
        {"verbose", no_argument, NULL, 'v'},
        {"progress", no_argument, NULL, 'P'},
        {"waldir", required_argument, NULL, 1},
        {"no-slot", no_argument, NULL, 2},
        {"no-verify-checksums", no_argument, NULL, 3},
        {"no-estimate-size", no_argument, NULL, 4},
        {"no-manifest", no_argument, NULL, 5},
        {"manifest-force-encode", no_argument, NULL, 6},
        {"manifest-checksums", required_argument, NULL, 7},
        {"sync-method", required_argument, NULL, 8},
        {NULL, 0, NULL, 0}
    };
    int         c;
 
    int         option_index;
    char       *compression_algorithm = "none";
    char       *compression_detail = NULL;
    char       *incremental_manifest = NULL;
    CompressionLocation compressloc = COMPRESS_LOCATION_UNSPECIFIED;
    pg_compress_specification client_compress;
 
    pg_logging_init(argv[0]);
    progname = get_progname(argv[0]);
    set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("pg_basebackup"));
 
    if (argc > 1)
    {
        if (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") == 0)
        {
            usage();
            exit(0);
        }
        else if (strcmp(argv[1], "-V") == 0
                 || strcmp(argv[1], "--version") == 0)
        {
            puts("pg_basebackup (PostgreSQL) " PG_VERSION);
            exit(0);
        }
    }
 
    atexit(cleanup_directories_atexit);
 
    while ((c = getopt_long(argc, argv, "c:Cd:D:F:h:i:l:nNp:Pr:Rs:S:t:T:U:vwWX:zZ:",
                            long_options, &option_index)) != -1)
    {
        switch (c)
        {
            case 'c':
                if (pg_strcasecmp(optarg, "fast") == 0)
                    fastcheckpoint = true;
                else if (pg_strcasecmp(optarg, "spread") == 0)
                    fastcheckpoint = false;
                else
                    pg_fatal("invalid checkpoint argument \"%s\", must be \"fast\" or \"spread\"",
                             optarg);
                break;
            case 'C':
                create_slot = true;
                break;
            case 'd':
                connection_string = pg_strdup(optarg);
                break;
            case 'D':
                basedir = pg_strdup(optarg);
                break;
            case 'F':
                if (strcmp(optarg, "p") == 0 || strcmp(optarg, "plain") == 0)
                    format = 'p';
                else if (strcmp(optarg, "t") == 0 || strcmp(optarg, "tar") == 0)
                    format = 't';
                else
                    pg_fatal("invalid output format \"%s\", must be \"plain\" or \"tar\"",
                             optarg);
                break;
            case 'h':
                dbhost = pg_strdup(optarg);
                break;
            case 'i':
                incremental_manifest = pg_strdup(optarg);
                break;
            case 'l':
                label = pg_strdup(optarg);
                break;
            case 'n':
                noclean = true;
                break;
            case 'N':
                do_sync = false;
                break;
            case 'p':
                dbport = pg_strdup(optarg);
                break;
            case 'P':
                showprogress = true;
                break;
            case 'r':
                maxrate = parse_max_rate(optarg);
                break;
            case 'R':
                writerecoveryconf = true;
                break;
            case 's':
                if (!option_parse_int(optarg, "-s/--status-interval", 0,
                                      INT_MAX / 1000,
                                      &standby_message_timeout))
                    exit(1);
                standby_message_timeout *= 1000;
                break;
            case 'S':
 
                /*
                 * When specifying replication slot name, use a permanent
                 * slot.
                 */
                replication_slot = pg_strdup(optarg);
                temp_replication_slot = false;
                break;
            case 't':
                backup_target = pg_strdup(optarg);
                break;
            case 'T':
                tablespace_list_append(optarg);
                break;
            case 'U':
                dbuser = pg_strdup(optarg);
                break;
            case 'v':
                verbose++;
                break;
            case 'w':
                dbgetpassword = -1;
                break;
            case 'W':
                dbgetpassword = 1;
                break;
            case 'X':
                if (strcmp(optarg, "n") == 0 ||
                    strcmp(optarg, "none") == 0)
                {
                    includewal = NO_WAL;
                }
                else if (strcmp(optarg, "f") == 0 ||
                         strcmp(optarg, "fetch") == 0)
                {
                    includewal = FETCH_WAL;
                }
                else if (strcmp(optarg, "s") == 0 ||
                         strcmp(optarg, "stream") == 0)
                {
                    includewal = STREAM_WAL;
                }
                else
                    pg_fatal("invalid wal-method option \"%s\", must be \"fetch\", \"stream\", or \"none\"",
                             optarg);
                break;
            case 'z':
                compression_algorithm = "gzip";
                compression_detail = NULL;
                compressloc = COMPRESS_LOCATION_UNSPECIFIED;
                break;
            case 'Z':
                backup_parse_compress_options(optarg, &compression_algorithm,
                                              &compression_detail, &compressloc);
                break;
            case 1:
                xlog_dir = pg_strdup(optarg);
                break;
            case 2:
                no_slot = true;
                break;
            case 3:
                verify_checksums = false;
                break;
            case 4:
                estimatesize = false;
                break;
            case 5:
                manifest = false;
                break;
            case 6:
                manifest_force_encode = true;
                break;
            case 7:
                manifest_checksums = pg_strdup(optarg);
                break;
            case 8:
                if (!parse_sync_method(optarg, &sync_method))
                    exit(1);
                break;
            default:
                /* getopt_long already emitted a complaint */
                pg_log_error_hint("Try \"%s --help\" for more information.", progname);
                exit(1);
        }
    }
 
    /*
     * Any non-option arguments?
     */
    if (optind < argc)
    {
        pg_log_error("too many command-line arguments (first is \"%s\")",
                     argv[optind]);
        pg_log_error_hint("Try \"%s --help\" for more information.", progname);
        exit(1);
    }
 
    /*
     * Setting the backup target to 'client' is equivalent to leaving out the
     * option. This logic allows us to assume elsewhere that the backup is
     * being stored locally if and only if backup_target == NULL.
     */
    if (backup_target != NULL && strcmp(backup_target, "client") == 0)
    {
        pg_free(backup_target);
        backup_target = NULL;
    }
 
    /*
     * Can't use --format with --target. Without --target, default format is
     * tar.
     */
    if (backup_target != NULL && format != '\0')
    {
        pg_log_error("cannot specify both format and backup target");
        pg_log_error_hint("Try \"%s --help\" for more information.", progname);
        exit(1);
    }
    if (format == '\0')
        format = 'p';
 
    /*
     * Either directory or backup target should be specified, but not both
     */
    if (basedir == NULL && backup_target == NULL)
    {
        pg_log_error("must specify output directory or backup target");
        pg_log_error_hint("Try \"%s --help\" for more information.", progname);
        exit(1);
    }
    if (basedir != NULL && backup_target != NULL)
    {
        pg_log_error("cannot specify both output directory and backup target");
        pg_log_error_hint("Try \"%s --help\" for more information.", progname);
        exit(1);
    }
 
    /*
     * If the user has not specified where to perform backup compression,
     * default to the client, unless the user specified --target, in which
     * case the server is the only choice.
     */
    if (compressloc == COMPRESS_LOCATION_UNSPECIFIED)
    {
        if (backup_target == NULL)
            compressloc = COMPRESS_LOCATION_CLIENT;
        else
            compressloc = COMPRESS_LOCATION_SERVER;
    }
 
    /*
     * If any compression that we're doing is happening on the client side, we
     * must try to parse the compression algorithm and detail, but if it's all
     * on the server side, then we're just going to pass through whatever was
     * requested and let the server decide what to do.
     */
    if (compressloc == COMPRESS_LOCATION_CLIENT)
    {
        pg_compress_algorithm alg;
        char       *error_detail;
 
        if (!parse_compress_algorithm(compression_algorithm, &alg))
            pg_fatal("unrecognized compression algorithm: \"%s\"",
                     compression_algorithm);
 
        parse_compress_specification(alg, compression_detail, &client_compress);
        error_detail = validate_compress_specification(&client_compress);
        if (error_detail != NULL)
            pg_fatal("invalid compression specification: %s",
                     error_detail);
    }
    else
    {
        Assert(compressloc == COMPRESS_LOCATION_SERVER);
        client_compress.algorithm = PG_COMPRESSION_NONE;
        client_compress.options = 0;
    }
 
    /*
     * Can't perform client-side compression if the backup is not being sent
     * to the client.
     */
    if (backup_target != NULL && compressloc == COMPRESS_LOCATION_CLIENT)
    {
        pg_log_error("client-side compression is not possible when a backup target is specified");
        pg_log_error_hint("Try \"%s --help\" for more information.", progname);
        exit(1);
    }
 
    /*
     * Client-side compression doesn't make sense unless tar format is in use.
     */
    if (format == 'p' && compressloc == COMPRESS_LOCATION_CLIENT &&
        client_compress.algorithm != PG_COMPRESSION_NONE)
    {
        pg_log_error("only tar mode backups can be compressed");
        pg_log_error_hint("Try \"%s --help\" for more information.", progname);
        exit(1);
    }
 
    /*
     * Sanity checks for WAL method.
     */
    if (backup_target != NULL && includewal == STREAM_WAL)
    {
        pg_log_error("WAL cannot be streamed when a backup target is specified");
        pg_log_error_hint("Try \"%s --help\" for more information.", progname);
        exit(1);
    }
    if (format == 't' && includewal == STREAM_WAL && strcmp(basedir, "-") == 0)
    {
        pg_log_error("cannot stream write-ahead logs in tar mode to stdout");
        pg_log_error_hint("Try \"%s --help\" for more information.", progname);
        exit(1);
    }
 
    if (replication_slot && includewal != STREAM_WAL)
    {
        pg_log_error("replication slots can only be used with WAL streaming");
        pg_log_error_hint("Try \"%s --help\" for more information.", progname);
        exit(1);
    }
 
    /*
     * Sanity checks for replication slot options.
     */
    if (no_slot)
    {
        if (replication_slot)
        {
            pg_log_error("--no-slot cannot be used with slot name");
            pg_log_error_hint("Try \"%s --help\" for more information.", progname);
            exit(1);
        }
        temp_replication_slot = false;
    }
 
    if (create_slot)
    {
        if (!replication_slot)
        {
            pg_log_error("%s needs a slot to be specified using --slot",
                         "--create-slot");
            pg_log_error_hint("Try \"%s --help\" for more information.", progname);
            exit(1);
        }
 
        if (no_slot)
        {
            pg_log_error("%s and %s are incompatible options",
                         "--create-slot", "--no-slot");
            pg_log_error_hint("Try \"%s --help\" for more information.", progname);
            exit(1);
        }
    }
 
    /*
     * Sanity checks on WAL directory.
     */
    if (xlog_dir)
    {
        if (backup_target != NULL)
        {
            pg_log_error("WAL directory location cannot be specified along with a backup target");
            pg_log_error_hint("Try \"%s --help\" for more information.", progname);
            exit(1);
        }
        if (format != 'p')
        {
            pg_log_error("WAL directory location can only be specified in plain mode");
            pg_log_error_hint("Try \"%s --help\" for more information.", progname);
            exit(1);
        }
 
        /* clean up xlog directory name, check it's absolute */
        canonicalize_path(xlog_dir);
        if (!is_absolute_path(xlog_dir))
        {
            pg_log_error("WAL directory location must be an absolute path");
            pg_log_error_hint("Try \"%s --help\" for more information.", progname);
            exit(1);
        }
    }
 
    /*
     * Sanity checks for progress reporting options.
     */
    if (showprogress && !estimatesize)
    {
        pg_log_error("%s and %s are incompatible options",
                     "--progress", "--no-estimate-size");
        pg_log_error_hint("Try \"%s --help\" for more information.", progname);
        exit(1);
    }
 
    /*
     * Sanity checks for backup manifest options.
     */
    if (!manifest && manifest_checksums != NULL)
    {
        pg_log_error("%s and %s are incompatible options",
                     "--no-manifest", "--manifest-checksums");
        pg_log_error_hint("Try \"%s --help\" for more information.", progname);
        exit(1);
    }
 
    if (!manifest && manifest_force_encode)
    {
        pg_log_error("%s and %s are incompatible options",
                     "--no-manifest", "--manifest-force-encode");
        pg_log_error_hint("Try \"%s --help\" for more information.", progname);
        exit(1);
    }
 
    /* connection in replication mode to server */
    conn = GetConnection();
    if (!conn)
    {
        /* Error message already written in GetConnection() */
        exit(1);
    }
    atexit(disconnect_atexit);
 
#ifndef WIN32
 
    /*
     * Trap SIGCHLD to be able to handle the WAL stream process exiting. There
     * is no SIGCHLD on Windows, there we rely on the background thread
     * setting the signal variable on unexpected but graceful exit. If the WAL
     * stream thread crashes on Windows it will bring down the entire process
     * as it's a thread, so there is nothing to catch should that happen. A
     * crash on UNIX will be caught by the signal handler.
     */
    pqsignal(SIGCHLD, sigchld_handler);
#endif
 
    /*
     * Set umask so that directories/files are created with the same
     * permissions as directories/files in the source data directory.
     *
     * pg_mode_mask is set to owner-only by default and then updated in
     * GetConnection() where we get the mode from the server-side with
     * RetrieveDataDirCreatePerm() and then call SetDataDirectoryCreatePerm().
     */
    umask(pg_mode_mask);
 
    /* Backup manifests are supported in 13 and newer versions */
    if (PQserverVersion(conn) < MINIMUM_VERSION_FOR_MANIFESTS)
        manifest = false;
 
    /*
     * If an output directory was specified, verify that it exists, or create
     * it. Note that for a tar backup, an output directory of "-" means we are
     * writing to stdout, so do nothing in that case.
     */
    if (basedir != NULL && (format == 'p' || strcmp(basedir, "-") != 0))
        verify_dir_is_empty_or_create(basedir, &made_new_pgdata, &found_existing_pgdata);
 
    /* determine remote server's xlog segment size */
    if (!RetrieveWalSegSize(conn))
        exit(1);
 
    /* Create pg_wal symlink, if required */
    if (xlog_dir)
    {
        char       *linkloc;
 
        verify_dir_is_empty_or_create(xlog_dir, &made_new_xlogdir, &found_existing_xlogdir);
 
        /*
         * Form name of the place where the symlink must go. pg_xlog has been
         * renamed to pg_wal in post-10 clusters.
         */
        linkloc = psprintf("%s/%s", basedir,
                           PQserverVersion(conn) < MINIMUM_VERSION_FOR_PG_WAL ?
                           "pg_xlog" : "pg_wal");
 
        if (symlink(xlog_dir, linkloc) != 0)
            pg_fatal("could not create symbolic link \"%s\": %m", linkloc);
        free(linkloc);
    }
 
    BaseBackup(compression_algorithm, compression_detail, compressloc,
               &client_compress, incremental_manifest);
 
    success = true;
    return 0;
}