v12-0010-pg_verifybackup-Add-backup-format-and-compressio.patch

From 0ba8580c0ee6489f1195bae4d3d5427543479f76 Mon Sep 17 00:00:00 2001
From: Amul Sul <amul.sul@enterprisedb.com>
Date: Wed, 21 Aug 2024 11:03:44 +0530
Subject: [PATCH v12 10/12] pg_verifybackup: Add backup format and compression
 option

----
NOTE: This patch is not meant to be committed separately. It should
be squashed with the next patch that implements tar format support.
----
---
 src/bin/pg_verifybackup/pg_verifybackup.c | 73 ++++++++++++++++++++++-
 src/bin/pg_verifybackup/pg_verifybackup.h |  1 +
 2 files changed, 72 insertions(+), 2 deletions(-)

diff --git a/src/bin/pg_verifybackup/pg_verifybackup.c b/src/bin/pg_verifybackup/pg_verifybackup.c
index d04e1d8c8ac..c186678a592 100644
--- a/src/bin/pg_verifybackup/pg_verifybackup.c
+++ b/src/bin/pg_verifybackup/pg_verifybackup.c
@@ -62,6 +62,7 @@ static void report_manifest_error(JsonManifestParseContext *context,
 								  const char *fmt,...)
 			pg_attribute_printf(2, 3) pg_attribute_noreturn();
 
+static char find_backup_format(verifier_context *context);
 static void verify_backup_directory(verifier_context *context,
 									char *relpath, char *fullpath);
 static void verify_plain_backup_file(verifier_context *context,
@@ -97,6 +98,7 @@ main(int argc, char **argv)
 		{"exit-on-error", no_argument, NULL, 'e'},
 		{"ignore", required_argument, NULL, 'i'},
 		{"manifest-path", required_argument, NULL, 'm'},
+		{"format", required_argument, NULL, 'F'},
 		{"no-parse-wal", no_argument, NULL, 'n'},
 		{"progress", no_argument, NULL, 'P'},
 		{"quiet", no_argument, NULL, 'q'},
@@ -118,6 +120,7 @@ main(int argc, char **argv)
 	progname = get_progname(argv[0]);
 
 	memset(&context, 0, sizeof(context));
+	context.format = '\0';
 
 	if (argc > 1)
 	{
@@ -154,7 +157,7 @@ main(int argc, char **argv)
 	simple_string_list_append(&context.ignore_list, "recovery.signal");
 	simple_string_list_append(&context.ignore_list, "standby.signal");
 
-	while ((c = getopt_long(argc, argv, "ei:m:nPqsw:", long_options, NULL)) != -1)
+	while ((c = getopt_long(argc, argv, "eF:i:m:nPqsw:", long_options, NULL)) != -1)
 	{
 		switch (c)
 		{
@@ -173,6 +176,15 @@ main(int argc, char **argv)
 				manifest_path = pstrdup(optarg);
 				canonicalize_path(manifest_path);
 				break;
+			case 'F':
+				if (strcmp(optarg, "p") == 0 || strcmp(optarg, "plain") == 0)
+					context.format = 'p';
+				else if (strcmp(optarg, "t") == 0 || strcmp(optarg, "tar") == 0)
+					context.format = 't';
+				else
+					pg_fatal("invalid backup format \"%s\", must be \"plain\" or \"tar\"",
+							 optarg);
+				break;
 			case 'n':
 				no_parse_wal = true;
 				break;
@@ -220,11 +232,26 @@ main(int argc, char **argv)
 		pg_fatal("cannot specify both %s and %s",
 				 "-P/--progress", "-q/--quiet");
 
+	/* Determine the backup format if it hasn't been specified. */
+	if (context.format == '\0')
+		context.format = find_backup_format(&context);
+
 	/* Unless --no-parse-wal was specified, we will need pg_waldump. */
 	if (!no_parse_wal)
 	{
 		int			ret;
 
+		/*
+		 * XXX: In the future, we should consider enhancing pg_waldump to read
+		 * WAL files from the tar archive.
+		 */
+		if (context.format != 'p')
+		{
+			pg_log_error("pg_waldump cannot read from a tar archive");
+			pg_log_error_hint("You must use -n or --no-parse-wal when verifying a tar-format backup.");
+			exit(1);
+		}
+
 		pg_waldump_path = pg_malloc(MAXPGPATH);
 		ret = find_other_exec(argv[0], "pg_waldump",
 							  "pg_waldump (PostgreSQL) " PG_VERSION "\n",
@@ -279,8 +306,13 @@ main(int argc, char **argv)
 	/*
 	 * Now do the expensive work of verifying file checksums, unless we were
 	 * told to skip it.
+	 *
+	 * We were only checking the plain backup here. For the tar backup, file
+	 * checksums verification (if requested) will be done immediately when the
+	 * file is accessed, as we don't have random access to the files like we
+	 * do with plain backups.
 	 */
-	if (!context.skip_checksums)
+	if (!context.skip_checksums && context.format == 'p')
 		verify_backup_checksums(&context);
 
 	/*
@@ -981,6 +1013,42 @@ should_ignore_relpath(verifier_context *context, const char *relpath)
 	return false;
 }
 
+/*
+ * To detect the backup format, it checks for the PG_VERSION file in the backup
+ * directory. If found, it will be considered a plain-format backup; otherwise,
+ * it will be assumed to be a tar-format backup.
+ */
+static char
+find_backup_format(verifier_context *context)
+{
+	char		result;
+	char	   *path;
+	struct stat sb;
+
+	/* Should be here only if the backup format is unknown */
+	Assert(context->format == '\0');
+
+	/* Check PG_VERSION file. */
+	path = psprintf("%s/%s", context->backup_directory, "PG_VERSION");
+	if (stat(path, &sb) == 0)
+		result = 'p';
+	else
+	{
+		if (errno != ENOENT)
+		{
+			pg_log_error("cannot determine backup format : %m");
+			pg_log_error_hint("Try \"%s --help\" for more information.", progname);
+			exit(1);
+		}
+
+		/* Otherwise, it is assumed to be a tar format backup. */
+		result = 't';
+	}
+	pfree(path);
+
+	return result;
+}
+
 /*
  * Print a progress report based on the global variables.
  *
@@ -1038,6 +1106,7 @@ usage(void)
 	printf(_("  -e, --exit-on-error         exit immediately on error\n"));
 	printf(_("  -i, --ignore=RELATIVE_PATH  ignore indicated path\n"));
 	printf(_("  -m, --manifest-path=PATH    use specified path for manifest\n"));
+	printf(_("  -F, --format=p|t            backup format (plain, tar)\n"));
 	printf(_("  -n, --no-parse-wal          do not try to parse WAL files\n"));
 	printf(_("  -P, --progress              show progress information\n"));
 	printf(_("  -q, --quiet                 do not print any output, except for errors\n"));
diff --git a/src/bin/pg_verifybackup/pg_verifybackup.h b/src/bin/pg_verifybackup/pg_verifybackup.h
index 818064c6eed..80031ad4dbc 100644
--- a/src/bin/pg_verifybackup/pg_verifybackup.h
+++ b/src/bin/pg_verifybackup/pg_verifybackup.h
@@ -100,6 +100,7 @@ typedef struct verifier_context
 	manifest_data *manifest;
 	char	   *backup_directory;
 	SimpleStringList ignore_list;
+	char		format;			/* backup format:  p(lain)/t(ar) */
 	bool		skip_checksums;
 	bool		exit_on_error;
 	bool		saw_any_error;
-- 
2.18.0