Common function for percent placeholder replacement

There are a number of places where a shell command is constructed with
percent-placeholders (like %x).  It's cumbersome to have to open-code
this several times.  This factors out this logic into a separate
function.  This also allows us to ensure consistency for and document
some subtle behaviors, such as what to do with unrecognized
placeholders.

The unified handling is now that incorrect and unknown placeholders
are an error, where previously in most cases they were skipped or
ignored.  This affects the following settings:

- archive_cleanup_command
- archive_command
- recovery_end_command
- restore_command
- ssl_passphrase_command

The following settings are part of this refactoring but already had
stricter error handling and should be unchanged in their behavior:

- basebackup_to_shell.command

Reviewed-by: Nathan Bossart <nathandbossart@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/5238bbed-0b01-83a6-d4b2-7eb0562a054e%40enterprisedb.com

1 files changed, 5 insertions, 40 deletions

diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 76abc74c678..f911e8c3a6f 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -23,6 +23,7 @@
 #include "access/xlog_internal.h"
 #include "access/xlogarchive.h"
 #include "common/archive.h"
+#include "common/percentrepl.h"
 #include "miscadmin.h"
 #include "pgstat.h"
 #include "postmaster/startup.h"
@@ -291,11 +292,8 @@ void
 ExecuteRecoveryCommand(const char *command, const char *commandName,
 					   bool failOnSignal, uint32 wait_event_info)
 {
-	char		xlogRecoveryCmd[MAXPGPATH];
+	char	   *xlogRecoveryCmd;
 	char		lastRestartPointFname[MAXPGPATH];
-	char	   *dp;
-	char	   *endp;
-	const char *sp;
 	int			rc;
 	XLogSegNo	restartSegNo;
 	XLogRecPtr	restartRedoPtr;
@@ -316,42 +314,7 @@ ExecuteRecoveryCommand(const char *command, const char *commandName,
 	/*
 	 * construct the command to be executed
 	 */
-	dp = xlogRecoveryCmd;
-	endp = xlogRecoveryCmd + MAXPGPATH - 1;
-	*endp = '\0';
-
-	for (sp = command; *sp; sp++)
-	{
-		if (*sp == '%')
-		{
-			switch (sp[1])
-			{
-				case 'r':
-					/* %r: filename of last restartpoint */
-					sp++;
-					strlcpy(dp, lastRestartPointFname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case '%':
-					/* convert %% to a single % */
-					sp++;
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-				default:
-					/* otherwise treat the % as not special */
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-			}
-		}
-		else
-		{
-			if (dp < endp)
-				*dp++ = *sp;
-		}
-	}
-	*dp = '\0';
+	xlogRecoveryCmd = replace_percent_placeholders(command, commandName, "r", lastRestartPointFname);
 
 	ereport(DEBUG3,
 			(errmsg_internal("executing %s \"%s\"", commandName, command)));
@@ -364,6 +327,8 @@ ExecuteRecoveryCommand(const char *command, const char *commandName,
 	rc = system(xlogRecoveryCmd);
 	pgstat_report_wait_end();
 
+	pfree(xlogRecoveryCmd);
+
 	if (rc != 0)
 	{
 		/*