pg_checksums.c

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/*-------------------------------------------------------------------------
 *
 * pg_checksums.c
 *    Checks, enables or disables page level checksums for an offline
 *    cluster
 *
 * Copyright (c) 2010-2025, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *    src/bin/pg_checksums/pg_checksums.c
 *
 *-------------------------------------------------------------------------
 */
 
#include "postgres_fe.h"
 
#include <dirent.h>
#include <limits.h>
#include <sys/stat.h>
#include <time.h>
#include <unistd.h>
 
#include "common/controldata_utils.h"
#include "common/file_utils.h"
#include "common/logging.h"
#include "common/relpath.h"
#include "fe_utils/option_utils.h"
#include "getopt_long.h"
#include "pg_getopt.h"
#include "storage/bufpage.h"
#include "storage/checksum.h"
#include "storage/checksum_impl.h"
 
 
static int64 files_scanned = 0;
static int64 files_written = 0;
static int64 blocks_scanned = 0;
static int64 blocks_written = 0;
static int64 badblocks = 0;
static ControlFileData *ControlFile;
 
static char *only_filenode = NULL;
static bool do_sync = true;
static bool verbose = false;
static bool showprogress = false;
static DataDirSyncMethod sync_method = DATA_DIR_SYNC_METHOD_FSYNC;
 
typedef enum
{
    PG_MODE_CHECK,
    PG_MODE_DISABLE,
    PG_MODE_ENABLE,
} PgChecksumMode;
 
static PgChecksumMode mode = PG_MODE_CHECK;
 
static const char *progname;
 
/*
 * Progress status information.
 */
static int64 total_size = 0;
static int64 current_size = 0;
static pg_time_t last_progress_report = 0;
 
static void
usage(void)
{
    printf(_("%s enables, disables, or verifies data checksums in a PostgreSQL database cluster.\n\n"), progname);
    printf(_("Usage:\n"));
    printf(_("  %s [OPTION]... [DATADIR]\n"), progname);
    printf(_("\nOptions:\n"));
    printf(_(" [-D, --pgdata=]DATADIR    data directory\n"));
    printf(_("  -c, --check              check data checksums (default)\n"));
    printf(_("  -d, --disable            disable data checksums\n"));
    printf(_("  -e, --enable             enable data checksums\n"));
    printf(_("  -f, --filenode=FILENODE  check only relation with specified filenode\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(_("      --sync-method=METHOD set method for syncing files to disk\n"));
    printf(_("  -v, --verbose            output verbose messages\n"));
    printf(_("  -V, --version            output version information, then exit\n"));
    printf(_("  -?, --help               show this help, then exit\n"));
    printf(_("\nIf no data directory (DATADIR) is specified, "
             "the environment variable PGDATA\nis used.\n\n"));
    printf(_("Report bugs to <%s>.\n"), PACKAGE_BUGREPORT);
    printf(_("%s home page: <%s>\n"), PACKAGE_NAME, PACKAGE_URL);
}
 
/*
 * Definition of one element part of an exclusion list, used for files
 * to exclude from checksum validation.  "name" is the name of the file
 * or path to check for exclusion.  If "match_prefix" is true, any items
 * matching the name as prefix are excluded.
 */
struct exclude_list_item
{
    const char *name;
    bool        match_prefix;
};
 
/*
 * List of files excluded from checksum validation.
 *
 * Note: this list should be kept in sync with what basebackup.c includes.
 */
static const struct exclude_list_item skip[] = {
    {"pg_control", false},
    {"pg_filenode.map", false},
    {"pg_internal.init", true},
    {"PG_VERSION", false},
#ifdef EXEC_BACKEND
    {"config_exec_params", true},
#endif
    {NULL, false}
};
 
/*
 * Report current progress status.  Parts borrowed from
 * src/bin/pg_basebackup/pg_basebackup.c.
 */
static void
progress_report(bool finished)
{
    int         percent;
    pg_time_t   now;
 
    Assert(showprogress);
 
    now = time(NULL);
    if (now == last_progress_report && !finished)
        return;                 /* Max once per second */
 
    /* Save current time */
    last_progress_report = now;
 
    /* Adjust total size if current_size is larger */
    if (current_size > total_size)
        total_size = current_size;
 
    /* Calculate current percentage of size done */
    percent = total_size ? (int) ((current_size) * 100 / total_size) : 0;
 
    fprintf(stderr, _("%" PRId64 "/%" PRId64 " MB (%d%%) computed"),
            (current_size / (1024 * 1024)),
            (total_size / (1024 * 1024)),
            percent);
 
    /*
     * 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 bool
skipfile(const char *fn)
{
    int         excludeIdx;
 
    for (excludeIdx = 0; skip[excludeIdx].name != NULL; excludeIdx++)
    {
        int         cmplen = strlen(skip[excludeIdx].name);
 
        if (!skip[excludeIdx].match_prefix)
            cmplen++;
        if (strncmp(skip[excludeIdx].name, fn, cmplen) == 0)
            return true;
    }
 
    return false;
}
 
static void
scan_file(const char *fn, int segmentno)
{
    PGIOAlignedBlock buf;
    PageHeader  header = (PageHeader) buf.data;
    int         f;
    BlockNumber blockno;
    int         flags;
    int64       blocks_written_in_file = 0;
 
    Assert(mode == PG_MODE_ENABLE ||
           mode == PG_MODE_CHECK);
 
    flags = (mode == PG_MODE_ENABLE) ? O_RDWR : O_RDONLY;
    f = open(fn, PG_BINARY | flags, 0);
 
    if (f < 0)
        pg_fatal("could not open file \"%s\": %m", fn);
 
    files_scanned++;
 
    for (blockno = 0;; blockno++)
    {
        uint16      csum;
        int         r = read(f, buf.data, BLCKSZ);
 
        if (r == 0)
            break;
        if (r != BLCKSZ)
        {
            if (r < 0)
                pg_fatal("could not read block %u in file \"%s\": %m",
                         blockno, fn);
            else
                pg_fatal("could not read block %u in file \"%s\": read %d of %d",
                         blockno, fn, r, BLCKSZ);
        }
        blocks_scanned++;
 
        /*
         * Since the file size is counted as total_size for progress status
         * information, the sizes of all pages including new ones in the file
         * should be counted as current_size. Otherwise the progress reporting
         * calculated using those counters may not reach 100%.
         */
        current_size += r;
 
        /* New pages have no checksum yet */
        if (PageIsNew(buf.data))
            continue;
 
        csum = pg_checksum_page(buf.data, blockno + segmentno * RELSEG_SIZE);
        if (mode == PG_MODE_CHECK)
        {
            if (csum != header->pd_checksum)
            {
                if (ControlFile->data_checksum_version == PG_DATA_CHECKSUM_VERSION)
                    pg_log_error("checksum verification failed in file \"%s\", block %u: calculated checksum %X but block contains %X",
                                 fn, blockno, csum, header->pd_checksum);
                badblocks++;
            }
        }
        else if (mode == PG_MODE_ENABLE)
        {
            int         w;
 
            /*
             * Do not rewrite if the checksum is already set to the expected
             * value.
             */
            if (header->pd_checksum == csum)
                continue;
 
            blocks_written_in_file++;
 
            /* Set checksum in page header */
            header->pd_checksum = csum;
 
            /* Seek back to beginning of block */
            if (lseek(f, -BLCKSZ, SEEK_CUR) < 0)
                pg_fatal("seek failed for block %u in file \"%s\": %m", blockno, fn);
 
            /* Write block with checksum */
            w = write(f, buf.data, BLCKSZ);
            if (w != BLCKSZ)
            {
                if (w < 0)
                    pg_fatal("could not write block %u in file \"%s\": %m",
                             blockno, fn);
                else
                    pg_fatal("could not write block %u in file \"%s\": wrote %d of %d",
                             blockno, fn, w, BLCKSZ);
            }
        }
 
        if (showprogress)
            progress_report(false);
    }
 
    if (verbose)
    {
        if (mode == PG_MODE_CHECK)
            pg_log_info("checksums verified in file \"%s\"", fn);
        if (mode == PG_MODE_ENABLE)
            pg_log_info("checksums enabled in file \"%s\"", fn);
    }
 
    /* Update write counters if any write activity has happened */
    if (blocks_written_in_file > 0)
    {
        files_written++;
        blocks_written += blocks_written_in_file;
    }
 
    close(f);
}
 
/*
 * Scan the given directory for items which can be checksummed and
 * operate on each one of them.  If "sizeonly" is true, the size of
 * all the items which have checksums is computed and returned back
 * to the caller without operating on the files.  This is used to compile
 * the total size of the data directory for progress reports.
 */
static int64
scan_directory(const char *basedir, const char *subdir, bool sizeonly)
{
    int64       dirsize = 0;
    char        path[MAXPGPATH];
    DIR        *dir;
    struct dirent *de;
 
    snprintf(path, sizeof(path), "%s/%s", basedir, subdir);
    dir = opendir(path);
    if (!dir)
        pg_fatal("could not open directory \"%s\": %m", path);
    while ((de = readdir(dir)) != NULL)
    {
        char        fn[MAXPGPATH];
        struct stat st;
 
        if (strcmp(de->d_name, ".") == 0 ||
            strcmp(de->d_name, "..") == 0)
            continue;
 
        /* Skip temporary files */
        if (strncmp(de->d_name,
                    PG_TEMP_FILE_PREFIX,
                    strlen(PG_TEMP_FILE_PREFIX)) == 0)
            continue;
 
        /* Skip temporary folders */
        if (strncmp(de->d_name,
                    PG_TEMP_FILES_DIR,
                    strlen(PG_TEMP_FILES_DIR)) == 0)
            continue;
 
        /* Skip macOS system files */
        if (strcmp(de->d_name, ".DS_Store") == 0)
            continue;
 
        snprintf(fn, sizeof(fn), "%s/%s", path, de->d_name);
        if (lstat(fn, &st) < 0)
            pg_fatal("could not stat file \"%s\": %m", fn);
        if (S_ISREG(st.st_mode))
        {
            char        fnonly[MAXPGPATH];
            char       *forkpath,
                       *segmentpath;
            int         segmentno = 0;
 
            if (skipfile(de->d_name))
                continue;
 
            /*
             * Cut off at the segment boundary (".") to get the segment number
             * in order to mix it into the checksum. Then also cut off at the
             * fork boundary, to get the filenode the file belongs to for
             * filtering.
             */
            strlcpy(fnonly, de->d_name, sizeof(fnonly));
            segmentpath = strchr(fnonly, '.');
            if (segmentpath != NULL)
            {
                *segmentpath++ = '\0';
                segmentno = atoi(segmentpath);
                if (segmentno == 0)
                    pg_fatal("invalid segment number %d in file name \"%s\"",
                             segmentno, fn);
            }
 
            forkpath = strchr(fnonly, '_');
            if (forkpath != NULL)
                *forkpath++ = '\0';
 
            if (only_filenode && strcmp(only_filenode, fnonly) != 0)
                /* filenode not to be included */
                continue;
 
            dirsize += st.st_size;
 
            /*
             * No need to work on the file when calculating only the size of
             * the items in the data folder.
             */
            if (!sizeonly)
                scan_file(fn, segmentno);
        }
        else if (S_ISDIR(st.st_mode) || S_ISLNK(st.st_mode))
        {
            /*
             * If going through the entries of pg_tblspc, we assume to operate
             * on tablespace locations where only TABLESPACE_VERSION_DIRECTORY
             * is valid, resolving the linked locations and dive into them
             * directly.
             */
            if (strncmp(PG_TBLSPC_DIR, subdir, strlen(PG_TBLSPC_DIR)) == 0)
            {
                char        tblspc_path[MAXPGPATH];
                struct stat tblspc_st;
 
                /*
                 * Resolve tablespace location path and check whether
                 * TABLESPACE_VERSION_DIRECTORY exists.  Not finding a valid
                 * location is unexpected, since there should be no orphaned
                 * links and no links pointing to something else than a
                 * directory.
                 */
                snprintf(tblspc_path, sizeof(tblspc_path), "%s/%s/%s",
                         path, de->d_name, TABLESPACE_VERSION_DIRECTORY);
 
                if (lstat(tblspc_path, &tblspc_st) < 0)
                    pg_fatal("could not stat file \"%s\": %m",
                             tblspc_path);
 
                /*
                 * Move backwards once as the scan needs to happen for the
                 * contents of TABLESPACE_VERSION_DIRECTORY.
                 */
                snprintf(tblspc_path, sizeof(tblspc_path), "%s/%s",
                         path, de->d_name);
 
                /* Looks like a valid tablespace location */
                dirsize += scan_directory(tblspc_path,
                                          TABLESPACE_VERSION_DIRECTORY,
                                          sizeonly);
            }
            else
            {
                dirsize += scan_directory(path, de->d_name, sizeonly);
            }
        }
    }
    closedir(dir);
    return dirsize;
}
 
int
main(int argc, char *argv[])
{
    static struct option long_options[] = {
        {"check", no_argument, NULL, 'c'},
        {"pgdata", required_argument, NULL, 'D'},
        {"disable", no_argument, NULL, 'd'},
        {"enable", no_argument, NULL, 'e'},
        {"filenode", required_argument, NULL, 'f'},
        {"no-sync", no_argument, NULL, 'N'},
        {"progress", no_argument, NULL, 'P'},
        {"verbose", no_argument, NULL, 'v'},
        {"sync-method", required_argument, NULL, 1},
        {NULL, 0, NULL, 0}
    };
 
    char       *DataDir = NULL;
    int         c;
    int         option_index;
    bool        crc_ok;
 
    pg_logging_init(argv[0]);
    set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("pg_checksums"));
    progname = get_progname(argv[0]);
 
    if (argc > 1)
    {
        if (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") == 0)
        {
            usage();
            exit(0);
        }
        if (strcmp(argv[1], "--version") == 0 || strcmp(argv[1], "-V") == 0)
        {
            puts("pg_checksums (PostgreSQL) " PG_VERSION);
            exit(0);
        }
    }
 
    while ((c = getopt_long(argc, argv, "cdD:ef:NPv", long_options, &option_index)) != -1)
    {
        switch (c)
        {
            case 'c':
                mode = PG_MODE_CHECK;
                break;
            case 'd':
                mode = PG_MODE_DISABLE;
                break;
            case 'D':
                DataDir = optarg;
                break;
            case 'e':
                mode = PG_MODE_ENABLE;
                break;
            case 'f':
                if (!option_parse_int(optarg, "-f/--filenode", 0,
                                      INT_MAX,
                                      NULL))
                    exit(1);
                only_filenode = pstrdup(optarg);
                break;
            case 'N':
                do_sync = false;
                break;
            case 'P':
                showprogress = true;
                break;
            case 'v':
                verbose = true;
                break;
            case 1:
                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);
        }
    }
 
    if (DataDir == NULL)
    {
        if (optind < argc)
            DataDir = argv[optind++];
        else
            DataDir = getenv("PGDATA");
 
        /* If no DataDir was specified, and none could be found, error out */
        if (DataDir == NULL)
        {
            pg_log_error("no data directory specified");
            pg_log_error_hint("Try \"%s --help\" for more information.", progname);
            exit(1);
        }
    }
 
    /* Complain if any arguments remain */
    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);
    }
 
    /* filenode checking only works in --check mode */
    if (mode != PG_MODE_CHECK && only_filenode)
    {
        pg_log_error("option -f/--filenode can only be used with --check");
        pg_log_error_hint("Try \"%s --help\" for more information.", progname);
        exit(1);
    }
 
    /* Read the control file and check compatibility */
    ControlFile = get_controlfile(DataDir, &crc_ok);
    if (!crc_ok)
        pg_fatal("pg_control CRC value is incorrect");
 
    if (ControlFile->pg_control_version != PG_CONTROL_VERSION)
        pg_fatal("cluster is not compatible with this version of pg_checksums");
 
    if (ControlFile->blcksz != BLCKSZ)
    {
        pg_log_error("database cluster is not compatible");
        pg_log_error_detail("The database cluster was initialized with block size %u, but pg_checksums was compiled with block size %u.",
                            ControlFile->blcksz, BLCKSZ);
        exit(1);
    }
 
    /*
     * Check if cluster is running.  A clean shutdown is required to avoid
     * random checksum failures caused by torn pages.  Note that this doesn't
     * guard against someone starting the cluster concurrently.
     */
    if (ControlFile->state != DB_SHUTDOWNED &&
        ControlFile->state != DB_SHUTDOWNED_IN_RECOVERY)
        pg_fatal("cluster must be shut down");
 
    if (ControlFile->data_checksum_version == 0 &&
        mode == PG_MODE_CHECK)
        pg_fatal("data checksums are not enabled in cluster");
 
    if (ControlFile->data_checksum_version == 0 &&
        mode == PG_MODE_DISABLE)
        pg_fatal("data checksums are already disabled in cluster");
 
    if (ControlFile->data_checksum_version > 0 &&
        mode == PG_MODE_ENABLE)
        pg_fatal("data checksums are already enabled in cluster");
 
    /* Operate on all files if checking or enabling checksums */
    if (mode == PG_MODE_CHECK || mode == PG_MODE_ENABLE)
    {
        /*
         * If progress status information is requested, we need to scan the
         * directory tree twice: once to know how much total data needs to be
         * processed and once to do the real work.
         */
        if (showprogress)
        {
            total_size = scan_directory(DataDir, "global", true);
            total_size += scan_directory(DataDir, "base", true);
            total_size += scan_directory(DataDir, PG_TBLSPC_DIR, true);
        }
 
        (void) scan_directory(DataDir, "global", false);
        (void) scan_directory(DataDir, "base", false);
        (void) scan_directory(DataDir, PG_TBLSPC_DIR, false);
 
        if (showprogress)
            progress_report(true);
 
        printf(_("Checksum operation completed\n"));
        printf(_("Files scanned:   %" PRId64 "\n"), files_scanned);
        printf(_("Blocks scanned:  %" PRId64 "\n"), blocks_scanned);
        if (mode == PG_MODE_CHECK)
        {
            printf(_("Bad checksums:  %" PRId64 "\n"), badblocks);
            printf(_("Data checksum version: %u\n"), ControlFile->data_checksum_version);
 
            if (badblocks > 0)
                exit(1);
        }
        else if (mode == PG_MODE_ENABLE)
        {
            printf(_("Files written:  %" PRId64 "\n"), files_written);
            printf(_("Blocks written: %" PRId64 "\n"), blocks_written);
        }
    }
 
    /*
     * Finally make the data durable on disk if enabling or disabling
     * checksums.  Flush first the data directory for safety, and then update
     * the control file to keep the switch consistent.
     */
    if (mode == PG_MODE_ENABLE || mode == PG_MODE_DISABLE)
    {
        ControlFile->data_checksum_version =
            (mode == PG_MODE_ENABLE) ? PG_DATA_CHECKSUM_VERSION : 0;
 
        if (do_sync)
        {
            pg_log_info("syncing data directory");
            sync_pgdata(DataDir, PG_VERSION_NUM, sync_method, true);
        }
 
        pg_log_info("updating control file");
        update_controlfile(DataDir, ControlFile, do_sync);
 
        if (verbose)
            printf(_("Data checksum version: %u\n"), ControlFile->data_checksum_version);
        if (mode == PG_MODE_ENABLE)
            printf(_("Checksums enabled in cluster\n"));
        else
            printf(_("Checksums disabled in cluster\n"));
    }
 
    return 0;
}