src/fe_utils/archive.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * archive.c
   4  *        Routines to access WAL archives from frontend
   5  *
   6  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        src/fe_utils/archive.c
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15
  16 #include "postgres_fe.h"
  17
  18 #include <unistd.h>
  19 #include <sys/stat.h>
  20
  21 #include "access/xlog_internal.h"
  22 #include "common/archive.h"
  23 #include "common/logging.h"
  24 #include "fe_utils/archive.h"
  25
  26
  27 /*
  28  * RestoreArchivedFile
  29  *
  30  * Attempt to retrieve the specified file from off-line archival storage.
  31  * If successful, return a file descriptor of the restored file, else
  32  * return -1.
  33  *
  34  * For fixed-size files, the caller may pass the expected size as an
  35  * additional crosscheck on successful recovery.  If the file size is not
  36  * known, set expectedSize = 0.
  37  */
  38 int
  39 RestoreArchivedFile(const char *path, const char *xlogfname,
  40                                         off_t expectedSize, const char *restoreCommand)
  41 {
  42         char            xlogpath[MAXPGPATH];
  43         char       *xlogRestoreCmd;
  44         int                     rc;
  45         struct stat stat_buf;
  46
  47         snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
  48
  49         xlogRestoreCmd = BuildRestoreCommand(restoreCommand, xlogpath,
  50                                                                                  xlogfname, NULL);
  51
  52         /*
  53          * Execute restore_command, which should copy the missing file from
  54          * archival storage.
  55          */
  56         fflush(NULL);
  57         rc = system(xlogRestoreCmd);
  58         pfree(xlogRestoreCmd);
  59
  60         if (rc == 0)
  61         {
  62                 /*
  63                  * Command apparently succeeded, but let's make sure the file is
  64                  * really there now and has the correct size.
  65                  */
  66                 if (stat(xlogpath, &stat_buf) == 0)
  67                 {
  68                         if (expectedSize > 0 && stat_buf.st_size != expectedSize)
  69                                 pg_fatal("unexpected file size for \"%s\": %lld instead of %lld",
  70                                                  xlogfname, (long long int) stat_buf.st_size,
  71                                                  (long long int) expectedSize);
  72                         else
  73                         {
  74                                 int                     xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
  75
  76                                 if (xlogfd < 0)
  77                                         pg_fatal("could not open file \"%s\" restored from archive: %m",
  78                                                          xlogpath);
  79                                 else
  80                                         return xlogfd;
  81                         }
  82                 }
  83                 else
  84                 {
  85                         if (errno != ENOENT)
  86                                 pg_fatal("could not stat file \"%s\": %m",
  87                                                  xlogpath);
  88                 }
  89         }
  90
  91         /*
  92          * If the failure was due to a signal, then it would be misleading to
  93          * return with a failure at restoring the file.  So just bail out and
  94          * exit.  Hard shell errors such as "command not found" are treated as
  95          * fatal too.
  96          */
  97         if (wait_result_is_any_signal(rc, true))
  98                 pg_fatal("\"restore_command\" failed: %s",
  99                                  wait_result_to_str(rc));
 100
 101         /*
 102          * The file is not available, so just let the caller decide what to do
 103          * next.
 104          */
 105         pg_log_error("could not restore file \"%s\" from archive",
 106                                  xlogfname);
 107         return -1;
 108 }