btrfs-progs: treewide: Replace strerror(errno) with %m.

As btrfs is specific to Linux, %m can be used instead of strerror(errno)
in format strings. This has some size reduction benefits for embedded
systems.

glibc, musl, and uclibc-ng all support %m as a modifier to printf.
A quick glance at the BIONIC libc source indicates that it has
support for %m as well. BSDs and Windows do not but I do believe
them to be beyond the scope of btrfs-progs.

Compiled sizes on Ubuntu 16.04:

Before:
3916512 btrfs
233688  libbtrfs.so.0.1
4899    bcp
2367672 btrfs-convert
2208488 btrfs-corrupt-block
13302   btrfs-debugfs
2152160 btrfs-debug-tree
2136024 btrfs-find-root
2287592 btrfs-image
2144600 btrfs-map-logical
2130760 btrfs-select-super
2152608 btrfstune
2131760 btrfs-zero-log
2277752 mkfs.btrfs
9166    show-blocks

After:
3908744 btrfs
233256  libbtrfs.so.0.1
4899    bcp
2366560 btrfs-convert
2207432 btrfs-corrupt-block
13302   btrfs-debugfs
2151104 btrfs-debug-tree
2134968 btrfs-find-root
2281864 btrfs-image
2143536 btrfs-map-logical
2129704 btrfs-select-super
2151552 btrfstune
2130696 btrfs-zero-log
2276272 mkfs.btrfs
9166    show-blocks

Total savings: 23928 (24 kilo)bytes

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 12 insertions, 14 deletions

diff --git a/cmds-replace.c b/cmds-replace.c
index a3ea977c..032a44fc 100644
--- a/cmds-replace.c
+++ b/cmds-replace.c
@@ -169,8 +169,8 @@ static int cmd_replace_start(int argc, char **argv)
 	ret = ioctl(fdmnt, BTRFS_IOC_DEV_REPLACE, &status_args);
 	if (ret < 0) {
 		fprintf(stderr,
-			"ERROR: ioctl(DEV_REPLACE_STATUS) failed on \"%s\": %s",
-			path, strerror(errno));
+			"ERROR: ioctl(DEV_REPLACE_STATUS) failed on \"%s\": %m",
+			path);
 		if (status_args.result != BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_RESULT)
 			fprintf(stderr, ", %s\n",
 				replace_dev_result2string(status_args.result));
@@ -194,8 +194,8 @@ static int cmd_replace_start(int argc, char **argv)
 	srcdev = argv[optind];
 	dstdev = canonicalize_path(argv[optind + 1]);
 	if (!dstdev) {
-		error("cannot canonicalize path '%s': %s",
-			argv[optind + 1], strerror(errno));
+		error("cannot canonicalize path '%s': %m",
+			argv[optind + 1]);
 		goto leave_with_error;
 	}
 
@@ -250,7 +250,7 @@ static int cmd_replace_start(int argc, char **argv)
 
 	fddstdev = open(dstdev, O_RDWR);
 	if (fddstdev < 0) {
-		error("unable to open %s: %s", dstdev, strerror(errno));
+		error("unable to open %s: %m", dstdev);
 		goto leave_with_error;
 	}
 	strncpy((char *)start_args.start.tgtdev_name, dstdev,
@@ -268,7 +268,7 @@ static int cmd_replace_start(int argc, char **argv)
 	dev_replace_handle_sigint(fdmnt);
 	if (!do_not_background) {
 		if (daemon(0, 0) < 0) {
-			error("backgrounding failed: %s", strerror(errno));
+			error("backgrounding failed: %m");
 			goto leave_with_error;
 		}
 	}
@@ -279,8 +279,8 @@ static int cmd_replace_start(int argc, char **argv)
 	if (do_not_background) {
 		if (ret < 0) {
 			fprintf(stderr,
-				"ERROR: ioctl(DEV_REPLACE_START) failed on \"%s\": %s",
-				path, strerror(errno));
+				"ERROR: ioctl(DEV_REPLACE_START) failed on \"%s\": %m",
+				path);
 			if (start_args.result != BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_RESULT)
 				fprintf(stderr, ", %s\n",
 					replace_dev_result2string(start_args.result));
@@ -374,8 +374,8 @@ static int print_replace_status(int fd, const char *path, int once)
 		args.result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_RESULT;
 		ret = ioctl(fd, BTRFS_IOC_DEV_REPLACE, &args);
 		if (ret < 0) {
-			fprintf(stderr, "ERROR: ioctl(DEV_REPLACE_STATUS) failed on \"%s\": %s",
-				path, strerror(errno));
+			fprintf(stderr, "ERROR: ioctl(DEV_REPLACE_STATUS) failed on \"%s\": %m",
+				path);
 			if (args.result != BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_RESULT)
 				fprintf(stderr, ", %s\n",
 					replace_dev_result2string(args.result));
@@ -498,7 +498,6 @@ static int cmd_replace_cancel(int argc, char **argv)
 	int ret;
 	int c;
 	int fd;
-	int e;
 	char *path;
 	DIR *dirstream = NULL;
 
@@ -521,11 +520,10 @@ static int cmd_replace_cancel(int argc, char **argv)
 	args.cmd = BTRFS_IOCTL_DEV_REPLACE_CMD_CANCEL;
 	args.result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_RESULT;
 	ret = ioctl(fd, BTRFS_IOC_DEV_REPLACE, &args);
-	e = errno;
 	close_file_or_dir(fd, dirstream);
 	if (ret < 0) {
-		fprintf(stderr, "ERROR: ioctl(DEV_REPLACE_CANCEL) failed on \"%s\": %s",
-			path, strerror(e));
+		fprintf(stderr, "ERROR: ioctl(DEV_REPLACE_CANCEL) failed on \"%s\": %m",
+			path);
 		if (args.result != BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_RESULT)
 			fprintf(stderr, ", %s\n",
 				replace_dev_result2string(args.result));