Skip .DS_Store files in server side utils

The macOS Finder application creates .DS_Store files in directories
when opened,  which creates problems for serverside utilities which
expect all files to be PostgreSQL specific files.  Skip these files
when encountered in pg_checksums, pg_rewind and pg_basebackup.

This was extracted from a larger patchset for skipping hidden files
and system files, where the concencus was to just skip these. Since
this is equally likely to happen in every version, backpatch to all
supported versions.

Reported-by: Mark Guertin <markguertin@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Tobias Bussmann <t.bussmann@gmx.net>
Discussion: https://postgr.es/m/E258CE50-AB0E-455D-8AAD-BB4FE8F882FB@gmail.com
Backpatch-through: v12

6 files changed, 40 insertions, 0 deletions

diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
index d142cc21319..7ed82a76ff8 100644
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -1272,6 +1272,10 @@ sendDir(const char *path, int basepathlen, bool sizeonly, List *tablespaces,
 					strlen(PG_TEMP_FILE_PREFIX)) == 0)
 			continue;
 
+		/* Skip macOS system files */
+		if (strcmp(de->d_name, ".DS_Store") == 0)
+			continue;
+
 		/*
 		 * Check if the postmaster has signaled us to exit, and abort with an
 		 * error in that case. The error handler further up will call
diff --git a/src/bin/pg_basebackup/t/010_pg_basebackup.pl b/src/bin/pg_basebackup/t/010_pg_basebackup.pl
index e23ac607aae..43d18fe4ccf 100644
--- a/src/bin/pg_basebackup/t/010_pg_basebackup.pl
+++ b/src/bin/pg_basebackup/t/010_pg_basebackup.pl
@@ -76,6 +76,16 @@ foreach my $filename (
 	close $file;
 }
 
+# Test that macOS system files are skipped. Only test on non-macOS systems
+# however since creating incorrect .DS_Store files on a macOS system may have
+# unintended side effects.
+if ($Config{osname} ne 'darwin')
+{
+	open my $file, '>>', "$pgdata/.DS_Store";
+	print $file "DONOTCOPY";
+	close $file;
+}
+
 # Connect to a database to create global/pg_internal.init.  If this is removed
 # the test to ensure global/pg_internal.init is not copied will return a false
 # positive.
@@ -144,6 +154,12 @@ foreach my $filename (
 	ok(!-f "$tempdir/backup/$filename", "$filename not copied");
 }
 
+# We only test .DS_Store files being skipped on non-macOS systems
+if ($Config{osname} ne 'darwin')
+{
+	ok(!-f "$tempdir/backup/.DS_Store", ".DS_Store not copied");
+}
+
 # Unlogged relation forks other than init should not be copied
 ok(-f "$tempdir/backup/${baseUnloggedPath}_init",
 	'unlogged init fork in backup');
diff --git a/src/bin/pg_checksums/pg_checksums.c b/src/bin/pg_checksums/pg_checksums.c
index 831cf42d3ad..b97d0f32903 100644
--- a/src/bin/pg_checksums/pg_checksums.c
+++ b/src/bin/pg_checksums/pg_checksums.c
@@ -338,6 +338,10 @@ scan_directory(const char *basedir, const char *subdir, bool sizeonly)
 					strlen(PG_TEMP_FILES_DIR)) == 0)
 			continue;
 
+		/* Skip macOS system files */
+		if (strcmp(de->d_name, ".DS_Store") == 0)
+			continue;
+
 		snprintf(fn, sizeof(fn), "%s/%s", path, de->d_name);
 		if (lstat(fn, &st) < 0)
 		{
diff --git a/src/bin/pg_checksums/t/002_actions.pl b/src/bin/pg_checksums/t/002_actions.pl
index 761f7ab53b6..a8ced3b4bed 100644
--- a/src/bin/pg_checksums/t/002_actions.pl
+++ b/src/bin/pg_checksums/t/002_actions.pl
@@ -6,6 +6,7 @@
 
 use strict;
 use warnings;
+use Config;
 use PostgresNode;
 use TestLib;
 
@@ -114,6 +115,12 @@ append_to_file "$pgdata/global/pgsql_tmp/1.1",        "foo";
 append_to_file "$pgdata/global/pg_internal.init",     "foo";
 append_to_file "$pgdata/global/pg_internal.init.123", "foo";
 
+# These are non-postgres macOS files, which should be ignored by the scan.
+# Only perform this test on non-macOS systems though as creating incorrect
+# system files may have side effects on macOS.
+append_to_file "$pgdata/global/.DS_Store", "foo"
+	unless ($Config{osname} eq 'darwin');
+
 # Enable checksums.
 command_ok([ 'pg_checksums', '--enable', '--no-sync', '-D', $pgdata ],
 	"checksums successfully enabled in cluster");
diff --git a/src/bin/pg_rewind/filemap.c b/src/bin/pg_rewind/filemap.c
index 2618b4c957b..f3ce4f68288 100644
--- a/src/bin/pg_rewind/filemap.c
+++ b/src/bin/pg_rewind/filemap.c
@@ -648,6 +648,10 @@ decide_file_action(file_entry_t *entry)
 	if (strcmp(path, "global/pg_control") == 0)
 		return FILE_ACTION_NONE;
 
+	/* Skip macOS system files */
+	if (strstr(path, ".DS_Store") != NULL)
+		return FILE_ACTION_NONE;
+
 	/*
 	 * Remove all files matching the exclusion filters in the target.
 	 */
diff --git a/src/bin/pg_rewind/t/003_extrafiles.pl b/src/bin/pg_rewind/t/003_extrafiles.pl
index baea3836b6f..be60ecaaee4 100644
--- a/src/bin/pg_rewind/t/003_extrafiles.pl
+++ b/src/bin/pg_rewind/t/003_extrafiles.pl
@@ -5,6 +5,7 @@
 
 use strict;
 use warnings;
+use Config;
 use TestLib;
 use Test::More tests => 5;
 
@@ -53,6 +54,10 @@ sub run_test
 	append_to_file
 	  "$test_standby_datadir/tst_standby_dir/standby_subdir/standby_file4",
 	  "in standby4";
+	# Skip testing .DS_Store files on macOS to avoid risk of side effects
+	append_to_file
+	  "$test_standby_datadir/tst_standby_dir/.DS_Store",
+	  "macOS system file" unless ($Config{osname} eq 'darwin');
 
 	mkdir "$test_primary_datadir/tst_primary_dir";
 	append_to_file "$test_primary_datadir/tst_primary_dir/primary_file1",