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/*-------------------------------------------------------------------------
*
* shell_restore.c
* Recovery functions for a user-specified shell command.
*
* These recovery functions use a user-specified shell command (e.g. based
* on the GUC restore_command).
*
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/backend/access/transam/shell_restore.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <signal.h>
#include "access/xlogarchive.h"
#include "access/xlogrecovery.h"
#include "common/percentrepl.h"
#include "storage/ipc.h"
#include "utils/wait_event.h"
static bool ExecuteRecoveryCommand(const char *command,
const char *commandName,
bool failOnSignal,
bool exitOnSigterm,
uint32 wait_event_info,
int fail_elevel);
/*
* Attempt to execute a shell-based restore command.
*
* Returns true if the command has succeeded, false otherwise.
*/
bool
shell_restore(const char *file, const char *path,
const char *lastRestartPointFileName)
{
char *nativePath = pstrdup(path);
char *cmd;
bool ret;
/* Build the restore command to execute */
make_native_path(nativePath);
cmd = replace_percent_placeholders(recoveryRestoreCommand,
"restore_command", "frp", file,
lastRestartPointFileName,
nativePath);
pfree(nativePath);
/*
* Remember, we rollforward UNTIL the restore fails so failure here is
* just part of the process... that makes it difficult to determine
* whether the restore failed because there isn't an archive to restore,
* or because the administrator has specified the restore program
* incorrectly. We have to assume the former.
*
* However, if the failure was due to any sort of signal, it's best to
* punt and abort recovery. (If we "return false" here, upper levels will
* assume that recovery is complete and start up the database!) It's
* essential to abort on child SIGINT and SIGQUIT, because per spec
* system() ignores SIGINT and SIGQUIT while waiting; if we see one of
* those it's a good bet we should have gotten it too.
*
* On SIGTERM, assume we have received a fast shutdown request, and exit
* cleanly. It's pure chance whether we receive the SIGTERM first, or the
* child process. If we receive it first, the signal handler will call
* proc_exit, otherwise we do it here. If we or the child process received
* SIGTERM for any other reason than a fast shutdown request, postmaster
* will perform an immediate shutdown when it sees us exiting
* unexpectedly.
*
* We treat hard shell errors such as "command not found" as fatal, too.
*/
ret = ExecuteRecoveryCommand(cmd, "restore_command",
true, /* failOnSignal */
true, /* exitOnSigterm */
WAIT_EVENT_RESTORE_COMMAND, DEBUG2);
pfree(cmd);
return ret;
}
/*
* Attempt to execute a shell-based archive cleanup command.
*/
void
shell_archive_cleanup(const char *lastRestartPointFileName)
{
char *cmd;
cmd = replace_percent_placeholders(archiveCleanupCommand,
"archive_cleanup_command",
"r", lastRestartPointFileName);
(void) ExecuteRecoveryCommand(cmd, "archive_cleanup_command", false, false,
WAIT_EVENT_ARCHIVE_CLEANUP_COMMAND, WARNING);
pfree(cmd);
}
/*
* Attempt to execute a shell-based end-of-recovery command.
*/
void
shell_recovery_end(const char *lastRestartPointFileName)
{
char *cmd;
cmd = replace_percent_placeholders(recoveryEndCommand,
"recovery_end_command",
"r", lastRestartPointFileName);
(void) ExecuteRecoveryCommand(cmd, "recovery_end_command", true, false,
WAIT_EVENT_RECOVERY_END_COMMAND, WARNING);
pfree(cmd);
}
/*
* Attempt to execute an external shell command during recovery.
*
* 'command' is the shell command to be executed, 'commandName' is a
* human-readable name describing the command emitted in the logs. If
* 'failOnSignal' is true and the command is killed by a signal, a FATAL
* error is thrown. Otherwise, 'fail_elevel' is used for the log message.
* If 'exitOnSigterm' is true and the command is killed by SIGTERM, we exit
* immediately.
*
* Returns whether the command succeeded.
*/
static bool
ExecuteRecoveryCommand(const char *command, const char *commandName,
bool failOnSignal, bool exitOnSigterm,
uint32 wait_event_info, int fail_elevel)
{
int rc;
Assert(command && commandName);
ereport(DEBUG3,
(errmsg_internal("executing %s \"%s\"", commandName, command)));
/*
* execute the constructed command
*/
fflush(NULL);
pgstat_report_wait_start(wait_event_info);
rc = system(command);
pgstat_report_wait_end();
if (rc != 0)
{
if (exitOnSigterm && wait_result_is_signal(rc, SIGTERM))
proc_exit(1);
/*
* If the failure was due to any sort of signal, it's best to punt and
* abort recovery. See comments in shell_restore().
*/
ereport((failOnSignal && wait_result_is_any_signal(rc, true)) ? FATAL : fail_elevel,
/*------
translator: First %s represents a postgresql.conf parameter name like
"recovery_end_command", the 2nd is the value of that parameter, the
third an already translated error message. */
(errmsg("%s \"%s\": %s", commandName,
command, wait_result_to_str(rc))));
}
return (rc == 0);
}
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