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, 12 insertions, 73 deletions

diff --git a/src/common/archive.c b/src/common/archive.c
index 1466f67ea6..de42e914f7 100644
--- a/src/common/archive.c
+++ b/src/common/archive.c
@@ -20,7 +20,7 @@
 #endif
 
 #include "common/archive.h"
-#include "lib/stringinfo.h"
+#include "common/percentrepl.h"
 
 /*
  * BuildRestoreCommand
@@ -41,81 +41,20 @@ BuildRestoreCommand(const char *restoreCommand,
 					const char *xlogfname,
 					const char *lastRestartPointFname)
 {
-	StringInfoData result;
-	const char *sp;
+	char	   *nativePath = NULL;
+	char	   *result;
 
-	/*
-	 * Build the command to be executed.
-	 */
-	initStringInfo(&result);
-
-	for (sp = restoreCommand; *sp; sp++)
+	if (xlogpath)
 	{
-		if (*sp == '%')
-		{
-			switch (sp[1])
-			{
-				case 'p':
-					{
-						char	   *nativePath;
+		nativePath = pstrdup(xlogpath);
+		make_native_path(nativePath);
+	}
 
-						/* %p: relative path of target file */
-						if (xlogpath == NULL)
-						{
-							pfree(result.data);
-							return NULL;
-						}
-						sp++;
+	result = replace_percent_placeholders(restoreCommand, "restore_command", "frp",
+										  xlogfname, lastRestartPointFname, nativePath);
 
-						/*
-						 * This needs to use a placeholder to not modify the
-						 * input with the conversion done via
-						 * make_native_path().
-						 */
-						nativePath = pstrdup(xlogpath);
-						make_native_path(nativePath);
-						appendStringInfoString(&result,
-											   nativePath);
-						pfree(nativePath);
-						break;
-					}
-				case 'f':
-					/* %f: filename of desired file */
-					if (xlogfname == NULL)
-					{
-						pfree(result.data);
-						return NULL;
-					}
-					sp++;
-					appendStringInfoString(&result, xlogfname);
-					break;
-				case 'r':
-					/* %r: filename of last restartpoint */
-					if (lastRestartPointFname == NULL)
-					{
-						pfree(result.data);
-						return NULL;
-					}
-					sp++;
-					appendStringInfoString(&result,
-										   lastRestartPointFname);
-					break;
-				case '%':
-					/* convert %% to a single % */
-					sp++;
-					appendStringInfoChar(&result, *sp);
-					break;
-				default:
-					/* otherwise treat the % as not special */
-					appendStringInfoChar(&result, *sp);
-					break;
-			}
-		}
-		else
-		{
-			appendStringInfoChar(&result, *sp);
-		}
-	}
+	if (nativePath)
+		pfree(nativePath);
 
-	return result.data;
+	return result;
 }