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/*-------------------------------------------------------------------------
*
* archive.c
* Routines to access WAL archives from frontend
*
* Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/fe_utils/archive.c
*
*-------------------------------------------------------------------------
*/
#include "postgres_fe.h"
#include <unistd.h>
#include <sys/stat.h>
#include "access/xlog_internal.h"
#include "common/archive.h"
#include "common/logging.h"
#include "fe_utils/archive.h"
/*
* RestoreArchivedFile
*
* Attempt to retrieve the specified file from off-line archival storage.
* If successful, return a file descriptor of the restored file, else
* return -1.
*
* For fixed-size files, the caller may pass the expected size as an
* additional crosscheck on successful recovery. If the file size is not
* known, set expectedSize = 0.
*/
int
RestoreArchivedFile(const char *path, const char *xlogfname,
off_t expectedSize, const char *restoreCommand)
{
char xlogpath[MAXPGPATH];
char *xlogRestoreCmd;
int rc;
struct stat stat_buf;
snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
xlogRestoreCmd = BuildRestoreCommand(restoreCommand, xlogpath,
xlogfname, NULL);
if (xlogRestoreCmd == NULL)
{
pg_log_fatal("cannot use restore_command with %%r placeholder");
exit(1);
}
/*
* Execute restore_command, which should copy the missing file from
* archival storage.
*/
rc = system(xlogRestoreCmd);
pfree(xlogRestoreCmd);
if (rc == 0)
{
/*
* Command apparently succeeded, but let's make sure the file is
* really there now and has the correct size.
*/
if (stat(xlogpath, &stat_buf) == 0)
{
if (expectedSize > 0 && stat_buf.st_size != expectedSize)
{
pg_log_fatal("unexpected file size for \"%s\": %lu instead of %lu",
xlogfname, (unsigned long) stat_buf.st_size,
(unsigned long) expectedSize);
exit(1);
}
else
{
int xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
if (xlogfd < 0)
{
pg_log_fatal("could not open file \"%s\" restored from archive: %m",
xlogpath);
exit(1);
}
else
return xlogfd;
}
}
else
{
if (errno != ENOENT)
{
pg_log_fatal("could not stat file \"%s\": %m",
xlogpath);
exit(1);
}
}
}
/*
* If the failure was due to a signal, then it would be misleading to
* return with a failure at restoring the file. So just bail out and
* exit. Hard shell errors such as "command not found" are treated as
* fatal too.
*/
if (wait_result_is_any_signal(rc, true))
{
pg_log_fatal("restore_command failed: %s",
wait_result_to_str(rc));
exit(1);
}
/*
* The file is not available, so just let the caller decide what to do
* next.
*/
pg_log_error("could not restore file \"%s\" from archive",
xlogfname);
return -1;
}
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