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, 7 insertions, 10 deletions

diff --git a/send-utils.c b/send-utils.c
index 384cc5b7..b5289e76 100644
--- a/send-utils.c
+++ b/send-utils.c
@@ -83,8 +83,7 @@ static int btrfs_read_root_item_raw(int mnt_fd, u64 root_id, size_t buf_len,
 		ret = ioctl(mnt_fd, BTRFS_IOC_TREE_SEARCH, &args);
 		if (ret < 0) {
 			fprintf(stderr,
-				"ERROR: can't perform the search - %s\n",
-				strerror(errno));
+				"ERROR: can't perform the search - %m\n");
 			return 0;
 		}
 		/* the ioctl returns the number of item it found in nr_items */
@@ -267,8 +266,8 @@ static int btrfs_subvolid_resolve_sub(int fd, char *path, size_t *path_len,
 	ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &search_arg);
 	if (ret < 0) {
 		fprintf(stderr,
-			"ioctl(BTRFS_IOC_TREE_SEARCH, subvol_id %llu) ret=%d, error: %s\n",
-			(unsigned long long)subvol_id, ret, strerror(errno));
+			"ioctl(BTRFS_IOC_TREE_SEARCH, subvol_id %llu) ret=%d, error: %m\n",
+			(unsigned long long)subvol_id, ret);
 		return ret;
 	}
 
@@ -306,8 +305,8 @@ static int btrfs_subvolid_resolve_sub(int fd, char *path, size_t *path_len,
 		ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &ino_lookup_arg);
 		if (ret < 0) {
 			fprintf(stderr,
-				"ioctl(BTRFS_IOC_INO_LOOKUP) ret=%d, error: %s\n",
-				ret, strerror(errno));
+				"ioctl(BTRFS_IOC_INO_LOOKUP) ret=%d, error: %m\n",
+				ret);
 			return ret;
 		}
 
@@ -586,8 +585,7 @@ int subvol_uuid_search_init(int mnt_fd, struct subvol_uuid_search *s)
 	ret = is_uuid_tree_supported(mnt_fd);
 	if (ret < 0) {
 		fprintf(stderr,
-			"ERROR: check if we support uuid tree fails - %s\n",
-			strerror(errno));
+			"ERROR: check if we support uuid tree fails - %m\n");
 		return ret;
 	} else if (ret) {
 		/* uuid tree is supported */
@@ -608,8 +606,7 @@ int subvol_uuid_search_init(int mnt_fd, struct subvol_uuid_search *s)
 	while (1) {
 		ret = ioctl(mnt_fd, BTRFS_IOC_TREE_SEARCH, &args);
 		if (ret < 0) {
-			fprintf(stderr, "ERROR: can't perform the search - %s\n",
-				strerror(errno));
+			fprintf(stderr, "ERROR: can't perform the search - %m\n");
 			return ret;
 		}
 		if (sk->nr_items == 0)