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, 10 insertions, 16 deletions

diff --git a/cmds-filesystem.c b/cmds-filesystem.c
index 25d3c0cf..467aff11 100644
--- a/cmds-filesystem.c
+++ b/cmds-filesystem.c
@@ -71,7 +71,7 @@ static int get_df(int fd, struct btrfs_ioctl_space_args **sargs_ret)
 
 	ret = ioctl(fd, BTRFS_IOC_SPACE_INFO, sargs);
 	if (ret < 0) {
-		error("cannot get space info: %s", strerror(errno));
+		error("cannot get space info: %m");
 		free(sargs);
 		return -errno;
 	}
@@ -92,8 +92,8 @@ static int get_df(int fd, struct btrfs_ioctl_space_args **sargs_ret)
 	sargs->total_spaces = 0;
 	ret = ioctl(fd, BTRFS_IOC_SPACE_INFO, sargs);
 	if (ret < 0) {
-		error("cannot get space info with %llu slots: %s",
-				count, strerror(errno));
+		error("cannot get space info with %llu slots: %m",
+				count);
 		free(sargs);
 		return -errno;
 	}
@@ -813,7 +813,7 @@ static const char * const cmd_filesystem_sync_usage[] = {
 
 static int cmd_filesystem_sync(int argc, char **argv)
 {
-	int 	fd, res, e;
+	int 	fd, res;
 	char	*path;
 	DIR	*dirstream = NULL;
 
@@ -829,10 +829,9 @@ static int cmd_filesystem_sync(int argc, char **argv)
 		return 1;
 
 	res = ioctl(fd, BTRFS_IOC_SYNC);
-	e = errno;
 	close_file_or_dir(fd, dirstream);
 	if( res < 0 ){
-		error("sync ioctl failed on '%s': %s", path, strerror(e));
+		error("sync ioctl failed on '%s': %m", path);
 		return 1;
 	}
 
@@ -879,7 +878,6 @@ static int defrag_callback(const char *fpath, const struct stat *sb,
 		int typeflag, struct FTW *ftwbuf)
 {
 	int ret = 0;
-	int err = 0;
 	int fd = 0;
 
 	if ((typeflag == FTW_F) && S_ISREG(sb->st_mode)) {
@@ -887,7 +885,6 @@ static int defrag_callback(const char *fpath, const struct stat *sb,
 			printf("%s\n", fpath);
 		fd = open(fpath, O_RDWR);
 		if (fd < 0) {
-			err = errno;
 			goto error;
 		}
 		ret = ioctl(fd, BTRFS_IOC_DEFRAG_RANGE, &defrag_global_range);
@@ -899,14 +896,13 @@ static int defrag_callback(const char *fpath, const struct stat *sb,
 			return ENOTTY;
 		}
 		if (ret) {
-			err = errno;
 			goto error;
 		}
 	}
 	return 0;
 
 error:
-	error("defrag failed on %s: %s", fpath, strerror(err));
+	error("defrag failed on %s: %m", fpath);
 	defrag_global_errors++;
 	return 0;
 }
@@ -1025,16 +1021,14 @@ static int cmd_filesystem_defrag(int argc, char **argv)
 		dirstream = NULL;
 		fd = open_file_or_dir(argv[i], &dirstream);
 		if (fd < 0) {
-			error("cannot open %s: %s", argv[i],
-					strerror(errno));
+			error("cannot open %s: %m", argv[i]);
 			ret = -errno;
 			goto next;
 		}
 
 		ret = fstat(fd, &st);
 		if (ret) {
-			error("failed to stat %s: %s",
-					argv[i], strerror(errno));
+			error("failed to stat %s: %m", argv[i]);
 			ret = -errno;
 			goto next;
 		}
@@ -1115,7 +1109,7 @@ static int cmd_filesystem_resize(int argc, char **argv)
 
 	res = stat(path, &st);
 	if (res < 0) {
-		error("resize: cannot stat %s: %s", path, strerror(errno));
+		error("resize: cannot stat %s: %m", path);
 		return 1;
 	}
 	if (!S_ISDIR(st.st_mode)) {
@@ -1142,7 +1136,7 @@ static int cmd_filesystem_resize(int argc, char **argv)
 				path);
 			break;
 		default:
-			error("unable to resize '%s': %s", path, strerror(e));
+			error("unable to resize '%s': %m", path);
 			break;
 		}
 		return 1;