pg_archivecleanup.c

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/*
 * pg_archivecleanup.c
 *
 * To be used as archive_cleanup_command to clean an archive when using
 * standby mode.
 *
 * src/bin/pg_archivecleanup/pg_archivecleanup.c
 */
#include "postgres_fe.h"

#include <ctype.h>
#include <dirent.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/time.h>

#include "access/xlog_internal.h"
#include "common/logging.h"
#include "pg_getopt.h"

const char *progname;

/* Options and defaults */
bool        dryrun = false;     /* are we performing a dry-run operation? */
char       *additional_ext = NULL;  /* Extension to remove from filenames */

char       *archiveLocation;    /* where to find the archive? */
char       *restartWALFileName; /* the file from which we can restart restore */
char        exclusiveCleanupFileName[MAXFNAMELEN];  /* the oldest file we want
                                                     * to remain in archive */


/* =====================================================================
 *
 *        Customizable section
 *
 * =====================================================================
 *
 *  Currently, this section assumes that the Archive is a locally
 *  accessible directory. If you want to make other assumptions,
 *  such as using a vendor-specific archive and access API, these
 *  routines are the ones you'll need to change. You're
 *  encouraged to submit any changes to pgsql-hackers@lists.postgresql.org
 *  or personally to the current maintainer. Those changes may be
 *  folded in to later versions of this program.
 */

/*
 *  Initialize allows customized commands into the archive cleanup program.
 *
 *  You may wish to add code to check for tape libraries, etc..
 */
static void
Initialize(void)
{
    /*
     * This code assumes that archiveLocation is a directory, so we use stat
     * to test if it's accessible.
     */
    struct stat stat_buf;

    if (stat(archiveLocation, &stat_buf) != 0 ||
        !S_ISDIR(stat_buf.st_mode))
    {
        pg_log_error("archive location \"%s\" does not exist",
                     archiveLocation);
        exit(2);
    }
}

static void
TrimExtension(char *filename, char *extension)
{
    int         flen;
    int         elen;

    if (extension == NULL)
        return;

    elen = strlen(extension);
    flen = strlen(filename);

    if (flen > elen && strcmp(filename + flen - elen, extension) == 0)
        filename[flen - elen] = '\0';
}

static void
CleanupPriorWALFiles(void)
{
    int         rc;
    DIR        *xldir;
    struct dirent *xlde;
    char        walfile[MAXPGPATH];

    if ((xldir = opendir(archiveLocation)) != NULL)
    {
        while (errno = 0, (xlde = readdir(xldir)) != NULL)
        {
            /*
             * Truncation is essentially harmless, because we skip names of
             * length other than XLOG_FNAME_LEN.  (In principle, one could use
             * a 1000-character additional_ext and get trouble.)
             */
            strlcpy(walfile, xlde->d_name, MAXPGPATH);
            TrimExtension(walfile, additional_ext);

            /*
             * We ignore the timeline part of the XLOG segment identifiers in
             * deciding whether a segment is still needed.  This ensures that
             * we won't prematurely remove a segment from a parent timeline.
             * We could probably be a little more proactive about removing
             * segments of non-parent timelines, but that would be a whole lot
             * more complicated.
             *
             * We use the alphanumeric sorting property of the filenames to
             * decide which ones are earlier than the exclusiveCleanupFileName
             * file. Note that this means files are not removed in the order
             * they were originally written, in case this worries you.
             */
            if ((IsXLogFileName(walfile) || IsPartialXLogFileName(walfile)) &&
                strcmp(walfile + 8, exclusiveCleanupFileName + 8) < 0)
            {
                char        WALFilePath[MAXPGPATH * 2]; /* the file path
                                                         * including archive */

                /*
                 * Use the original file name again now, including any
                 * extension that might have been chopped off before testing
                 * the sequence.
                 */
                snprintf(WALFilePath, sizeof(WALFilePath), "%s/%s",
                         archiveLocation, xlde->d_name);

                if (dryrun)
                {
                    /*
                     * Prints the name of the file to be removed and skips the
                     * actual removal.  The regular printout is so that the
                     * user can pipe the output into some other program.
                     */
                    printf("%s\n", WALFilePath);
                    pg_log_debug("file \"%s\" would be removed", WALFilePath);
                    continue;
                }

                pg_log_debug("removing file \"%s\"", WALFilePath);

                rc = unlink(WALFilePath);
                if (rc != 0)
                {
                    pg_log_error("could not remove file \"%s\": %m",
                                 WALFilePath);
                    break;
                }
            }
        }

        if (errno)
            pg_log_error("could not read archive location \"%s\": %m",
                         archiveLocation);
        if (closedir(xldir))
            pg_log_error("could not close archive location \"%s\": %m",
                         archiveLocation);
    }
    else
        pg_log_error("could not open archive location \"%s\": %m",
                     archiveLocation);
}

/*
 * SetWALFileNameForCleanup()
 *
 *    Set the earliest WAL filename that we want to keep on the archive
 *    and decide whether we need cleanup
 */
static void
SetWALFileNameForCleanup(void)
{
    bool        fnameOK = false;

    TrimExtension(restartWALFileName, additional_ext);

    /*
     * If restartWALFileName is a WAL file name then just use it directly. If
     * restartWALFileName is a .partial or .backup filename, make sure we use
     * the prefix of the filename, otherwise we will remove wrong files since
     * 000000010000000000000010.partial and
     * 000000010000000000000010.00000020.backup are after
     * 000000010000000000000010.
     */
    if (IsXLogFileName(restartWALFileName))
    {
        strcpy(exclusiveCleanupFileName, restartWALFileName);
        fnameOK = true;
    }
    else if (IsPartialXLogFileName(restartWALFileName))
    {
        int         args;
        uint32      tli = 1,
                    log = 0,
                    seg = 0;

        args = sscanf(restartWALFileName, "%08X%08X%08X.partial",
                      &tli, &log, &seg);
        if (args == 3)
        {
            fnameOK = true;

            /*
             * Use just the prefix of the filename, ignore everything after
             * first period
             */
            XLogFileNameById(exclusiveCleanupFileName, tli, log, seg);
        }
    }
    else if (IsBackupHistoryFileName(restartWALFileName))
    {
        int         args;
        uint32      tli = 1,
                    log = 0,
                    seg = 0,
                    offset = 0;

        args = sscanf(restartWALFileName, "%08X%08X%08X.%08X.backup", &tli, &log, &seg, &offset);
        if (args == 4)
        {
            fnameOK = true;

            /*
             * Use just the prefix of the filename, ignore everything after
             * first period
             */
            XLogFileNameById(exclusiveCleanupFileName, tli, log, seg);
        }
    }

    if (!fnameOK)
    {
        pg_log_error("invalid file name argument");
        fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
        exit(2);
    }
}

/* =====================================================================
 *        End of Customizable section
 * =====================================================================
 */

static void
usage(void)
{
    printf(_("%s removes older WAL files from PostgreSQL archives.\n\n"), progname);
    printf(_("Usage:\n"));
    printf(_("  %s [OPTION]... ARCHIVELOCATION OLDESTKEPTWALFILE\n"), progname);
    printf(_("\nOptions:\n"));
    printf(_("  -d             generate debug output (verbose mode)\n"));
    printf(_("  -n             dry run, show the names of the files that would be removed\n"));
    printf(_("  -V, --version  output version information, then exit\n"));
    printf(_("  -x EXT         clean up files if they have this extension\n"));
    printf(_("  -?, --help     show this help, then exit\n"));
    printf(_("\n"
             "For use as archive_cleanup_command in postgresql.conf:\n"
             "  archive_cleanup_command = 'pg_archivecleanup [OPTION]... ARCHIVELOCATION %%r'\n"
             "e.g.\n"
             "  archive_cleanup_command = 'pg_archivecleanup /mnt/server/archiverdir %%r'\n"));
    printf(_("\n"
             "Or for use as a standalone archive cleaner:\n"
             "e.g.\n"
             "  pg_archivecleanup /mnt/server/archiverdir 000000010000000000000010.00000020.backup\n"));
    printf(_("\nReport bugs to <pgsql-bugs@lists.postgresql.org>.\n"));
}

/*------------ MAIN ----------------------------------------*/
int
main(int argc, char **argv)
{
    int         c;

    pg_logging_init(argv[0]);
    set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("pg_archivecleanup"));
    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_archivecleanup (PostgreSQL) " PG_VERSION);
            exit(0);
        }
    }

    while ((c = getopt(argc, argv, "x:dn")) != -1)
    {
        switch (c)
        {
            case 'd':           /* Debug mode */
                pg_logging_set_level(PG_LOG_DEBUG);
                break;
            case 'n':           /* Dry-Run mode */
                dryrun = true;
                break;
            case 'x':
                additional_ext = pg_strdup(optarg); /* Extension to remove
                                                     * from xlogfile names */
                break;
            default:
                fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
                exit(2);
                break;
        }
    }

    /*
     * We will go to the archiveLocation to check restartWALFileName.
     * restartWALFileName may not exist anymore, which would not be an error,
     * so we separate the archiveLocation and restartWALFileName so we can
     * check separately whether archiveLocation exists, if not that is an
     * error
     */
    if (optind < argc)
    {
        archiveLocation = argv[optind];
        optind++;
    }
    else
    {
        pg_log_error("must specify archive location");
        fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
        exit(2);
    }

    if (optind < argc)
    {
        restartWALFileName = argv[optind];
        optind++;
    }
    else
    {
        pg_log_error("must specify oldest kept WAL file");
        fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
        exit(2);
    }

    if (optind < argc)
    {
        pg_log_error("too many command-line arguments");
        fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
        exit(2);
    }

    /*
     * Check archive exists and other initialization if required.
     */
    Initialize();

    /*
     * Check filename is a valid name, then process to find cut-off
     */
    SetWALFileNameForCleanup();

    pg_log_debug("keeping WAL file \"%s/%s\" and later",
                 archiveLocation, exclusiveCleanupFileName);

    /*
     * Remove WAL files older than cut-off
     */
    CleanupPriorWALFiles();

    exit(0);
}