From 8c5c624fa89eaa42e8812dad840842b30ec35ec7 Mon Sep 17 00:00:00 2001
From: Amul Sul <amul.sul@enterprisedb.com>
Date: Wed, 14 Aug 2024 10:42:37 +0530
Subject: [PATCH v12 06/12] Refactor: split verify_backup_file() function and
 rename it.

The function verify_backup_file() has now been renamed to
verify_plain_backup_file() to make it clearer that it is specifically
used for verifying files in a plain backup. Similarly, in a future
patch, we would have a verify_tar_backup_file() function for
verifying TAR backup files.

In addition to that, moved the manifest entry verification code into a
new function called verify_manifest_entry() so that it can be reused
for tar backup verification. If verify_manifest_entry() doesn't find
an entry, it reports an error as before and returns NULL to the
caller. This is why a NULL check is added to should_verify_checksum().
---
 src/bin/pg_verifybackup/pg_verifybackup.c | 58 +++++++++++++++--------
 src/bin/pg_verifybackup/pg_verifybackup.h |  6 ++-
 2 files changed, 42 insertions(+), 22 deletions(-)

diff --git a/src/bin/pg_verifybackup/pg_verifybackup.c b/src/bin/pg_verifybackup/pg_verifybackup.c
index 3fcfb167217..5bfc98e7874 100644
--- a/src/bin/pg_verifybackup/pg_verifybackup.c
+++ b/src/bin/pg_verifybackup/pg_verifybackup.c
@@ -64,8 +64,8 @@ static void report_manifest_error(JsonManifestParseContext *context,
 
 static void verify_backup_directory(verifier_context *context,
 									char *relpath, char *fullpath);
-static void verify_backup_file(verifier_context *context,
-							   char *relpath, char *fullpath);
+static void verify_plain_backup_file(verifier_context *context,
+									 char *relpath, char *fullpath);
 static void verify_control_file(const char *controlpath,
 								uint64 manifest_system_identifier);
 static void report_extra_backup_files(verifier_context *context);
@@ -570,7 +570,7 @@ verify_backup_directory(verifier_context *context, char *relpath,
 			newrelpath = psprintf("%s/%s", relpath, filename);
 
 		if (!should_ignore_relpath(context, newrelpath))
-			verify_backup_file(context, newrelpath, newfullpath);
+			verify_plain_backup_file(context, newrelpath, newfullpath);
 
 		pfree(newfullpath);
 		pfree(newrelpath);
@@ -591,7 +591,8 @@ verify_backup_directory(verifier_context *context, char *relpath,
  * verify_backup_directory.
  */
 static void
-verify_backup_file(verifier_context *context, char *relpath, char *fullpath)
+verify_plain_backup_file(verifier_context *context, char *relpath,
+						 char *fullpath)
 {
 	struct stat sb;
 	manifest_file *m;
@@ -627,6 +628,32 @@ verify_backup_file(verifier_context *context, char *relpath, char *fullpath)
 		return;
 	}
 
+	/* Check the backup manifest entry for this file. */
+	m = verify_manifest_entry(context, relpath, sb.st_size);
+
+	/*
+	 * Validate the manifest system identifier, not available in manifest
+	 * version 1.
+	 */
+	if (context->manifest->version != 1 &&
+		strcmp(relpath, "global/pg_control") == 0 &&
+		m != NULL && m->matched && !m->bad)
+		verify_control_file(fullpath, context->manifest->system_identifier);
+
+	/* Update statistics for progress report, if necessary */
+	if (show_progress && !context->skip_checksums &&
+		should_verify_checksum(m))
+		total_size += m->size;
+}
+
+/*
+ * Verify file and its size entry in the manifest.
+ */
+manifest_file *
+verify_manifest_entry(verifier_context *context, char *relpath, int64 filesize)
+{
+	manifest_file *m;
+
 	/* Check whether there's an entry in the manifest hash. */
 	m = manifest_files_lookup(context->manifest->files, relpath);
 	if (m == NULL)
@@ -634,40 +661,29 @@ verify_backup_file(verifier_context *context, char *relpath, char *fullpath)
 		report_backup_error(context,
 							"\"%s\" is present on disk but not in the manifest",
 							relpath);
-		return;
+		return NULL;
 	}
 
 	/* Flag this entry as having been encountered in the filesystem. */
 	m->matched = true;
 
 	/* Check that the size matches. */
-	if (m->size != sb.st_size)
+	if (m->size != filesize)
 	{
 		report_backup_error(context,
 							"\"%s\" has size %lld on disk but size %zu in the manifest",
-							relpath, (long long int) sb.st_size, m->size);
+							relpath, (long long int) filesize, m->size);
 		m->bad = true;
 	}
 
-	/*
-	 * Validate the manifest system identifier, not available in manifest
-	 * version 1.
-	 */
-	if (context->manifest->version != 1 &&
-		strcmp(relpath, "global/pg_control") == 0)
-		verify_control_file(fullpath, context->manifest->system_identifier);
-
-	/* Update statistics for progress report, if necessary */
-	if (show_progress && !context->skip_checksums &&
-		should_verify_checksum(m))
-		total_size += m->size;
-
 	/*
 	 * We don't verify checksums at this stage. We first finish verifying that
 	 * we have the expected set of files with the expected sizes, and only
 	 * afterwards verify the checksums. That's because computing checksums may
 	 * take a while, and we'd like to report more obvious problems quickly.
 	 */
+
+	return m;
 }
 
 /*
@@ -830,7 +846,7 @@ verify_file_checksum(verifier_context *context, manifest_file *m,
 
 	/*
 	 * Double-check that we read the expected number of bytes from the file.
-	 * Normally, a file size mismatch would be caught in verify_backup_file
+	 * Normally, a file size mismatch would be caught in verify_manifest_entry
 	 * and this check would never be reached, but this provides additional
 	 * safety and clarity in the event of concurrent modifications or
 	 * filesystem misbehavior.
diff --git a/src/bin/pg_verifybackup/pg_verifybackup.h b/src/bin/pg_verifybackup/pg_verifybackup.h
index d8c566ed587..ff9476e356e 100644
--- a/src/bin/pg_verifybackup/pg_verifybackup.h
+++ b/src/bin/pg_verifybackup/pg_verifybackup.h
@@ -37,7 +37,8 @@ typedef struct manifest_file
 } manifest_file;
 
 #define should_verify_checksum(m) \
-	(((m)->matched) && !((m)->bad) && (((m)->checksum_type) != CHECKSUM_TYPE_NONE))
+	(((m) != NULL) && ((m)->matched) && !((m)->bad) && \
+	 (((m)->checksum_type) != CHECKSUM_TYPE_NONE))
 
 /*
  * Define a hash table which we can use to store information about the files
@@ -93,6 +94,9 @@ typedef struct verifier_context
 	bool		saw_any_error;
 } verifier_context;
 
+extern manifest_file *verify_manifest_entry(verifier_context *context,
+											char *relpath, int64 filesize);
+
 extern void report_backup_error(verifier_context *context,
 								const char *pg_restrict fmt,...)
 			pg_attribute_printf(2, 3);
-- 
2.18.0

