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, 41 insertions, 0 deletions

diff --git a/src/backend/backup/basebackup.c b/src/backend/backup/basebackup.c
index 078a3fe99c2..847a52f599b 100644
--- a/src/backend/backup/basebackup.c
+++ b/src/backend/backup/basebackup.c
@@ -1185,6 +1185,10 @@ sendDir(bbsink *sink, const char *path, int basepathlen, bool sizeonly,
 					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 ec72282aae5..e0f34e16f92 100644
--- a/src/bin/pg_basebackup/t/010_pg_basebackup.pl
+++ b/src/bin/pg_basebackup/t/010_pg_basebackup.pl
@@ -3,6 +3,7 @@
 
 use strict;
 use warnings;
+use Config;
 use File::Basename qw(basename dirname);
 use File::Path qw(rmtree);
 use PostgreSQL::Test::Cluster;
@@ -173,6 +174,16 @@ 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.
@@ -242,6 +253,12 @@ 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 21dfe1b6ee5..1af65cd2de8 100644
--- a/src/bin/pg_checksums/pg_checksums.c
+++ b/src/bin/pg_checksums/pg_checksums.c
@@ -337,6 +337,10 @@ 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)
 			pg_fatal("could not stat file \"%s\": %m", fn);
diff --git a/src/bin/pg_checksums/t/002_actions.pl b/src/bin/pg_checksums/t/002_actions.pl
index 0309cbbaa33..792ac4823d3 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 PostgreSQL::Test::Cluster;
 use PostgreSQL::Test::Utils;
 
@@ -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 62529310415..24f508c6efa 100644
--- a/src/bin/pg_rewind/filemap.c
+++ b/src/bin/pg_rewind/filemap.c
@@ -647,6 +647,10 @@ 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 100c212a4db..54bb63ccec2 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 PostgreSQL::Test::Utils;
 use Test::More;
 
@@ -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",