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, 11 deletions

diff --git a/cmds-restore.c b/cmds-restore.c
index 6196a1ed..ade35f0f 100644
--- a/cmds-restore.c
+++ b/cmds-restore.c
@@ -442,7 +442,7 @@ again:
 				      pos+total);
 			if (done < 0) {
 				ret = -1;
-				error("cannot write data: %d %s", errno, strerror(errno));
+				error("cannot write data: %d %m", errno);
 				goto out;
 			}
 			total += done;
@@ -587,8 +587,8 @@ static int set_file_xattrs(struct btrfs_root *root, u64 inode,
 			data_len = len;
 
 			if (fsetxattr(fd, name, data, data_len, 0))
-				error("setting extended attribute %s on file %s: %s",
-					name, file_name, strerror(errno));
+				error("setting extended attribute %s on file %s: %m",
+					name, file_name);
 
 			len = sizeof(*di) + name_len + data_len;
 			cur += len;
@@ -624,13 +624,13 @@ static int copy_metadata(struct btrfs_root *root, int fd,
 		ret = fchown(fd, btrfs_inode_uid(path.nodes[0], inode_item),
 				btrfs_inode_gid(path.nodes[0], inode_item));
 		if (ret) {
-			error("failed to change owner: %s", strerror(errno));
+			error("failed to change owner: %m");
 			goto out;
 		}
 
 		ret = fchmod(fd, btrfs_inode_mode(path.nodes[0], inode_item));
 		if (ret) {
-			error("failed to change mode: %s", strerror(errno));
+			error("failed to change mode: %m");
 			goto out;
 		}
 
@@ -644,7 +644,7 @@ static int copy_metadata(struct btrfs_root *root, int fd,
 
 		ret = futimens(fd, times);
 		if (ret) {
-			error("failed to set times: %s", strerror(errno));
+			error("failed to set times: %m");
 			goto out;
 		}
 	}
@@ -904,8 +904,8 @@ static int copy_symlink(struct btrfs_root *root, struct btrfs_key *key,
 	if (!dry_run) {
 		ret = symlink(symlink_target, path_name);
 		if (ret < 0) {
-			fprintf(stderr, "Failed to restore symlink '%s': %s\n",
-					path_name, strerror(errno));
+			fprintf(stderr, "Failed to restore symlink '%s': %m\n",
+					path_name);
 			goto out;
 		}
 	}
@@ -937,8 +937,7 @@ static int copy_symlink(struct btrfs_root *root, struct btrfs_key *key,
 				   btrfs_inode_gid(path.nodes[0], inode_item),
 				   AT_SYMLINK_NOFOLLOW);
 	if (ret) {
-		fprintf(stderr, "Failed to change owner: %s\n",
-				strerror(errno));
+		fprintf(stderr, "Failed to change owner: %m\n");
 		goto out;
 	}
 
@@ -952,7 +951,7 @@ static int copy_symlink(struct btrfs_root *root, struct btrfs_key *key,
 
 	ret = utimensat(-1, file, times, AT_SYMLINK_NOFOLLOW);
 	if (ret)
-		fprintf(stderr, "Failed to set times: %s\n", strerror(errno));
+		fprintf(stderr, "Failed to set times: %m\n");
 out:
 	btrfs_release_path(&path);
 	return ret;