btrfs-progs: per-thread, per-call pretty buffer

We don't need callers to manage string storage for each pretty_sizes()
call.  We can use a macro to have per-thread and per-call static storage
so that pretty_sizes() can be used as many times as needed in printf()
arguments without requiring a bunch of supporting variables.

This lets us have a natural interface at the cost of requiring __thread
and TLS from gcc and a small amount of static storage.  This seems
better than the current code or doing something with illegible format
specifier macros.

Signed-off-by: Zach Brown <zab@redhat.com>
Acked-by: Wang Shilong <wangs.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/utils.h b/utils.h
index 3c17e14b..36fb591a 100644
--- a/utils.h
+++ b/utils.h
@@ -44,7 +44,15 @@ int check_mounted_where(int fd, const char *file, char *where, int size,
 			struct btrfs_fs_devices **fs_devices_mnt);
 int btrfs_device_already_in_root(struct btrfs_root *root, int fd,
 				 int super_offset);
-char *pretty_sizes(u64 size);
+
+void pretty_size_snprintf(u64 size, char *str, size_t str_bytes);
+#define pretty_size(size) 						\
+	({								\
+		static __thread char _str[24];				\
+		pretty_size_snprintf((size), _str, sizeof(_str));	\
+		_str;							\
+	})
+
 int get_mountpt(char *dev, char *mntpt, size_t size);
 int btrfs_scan_block_devices(int run_ioctl);
 u64 parse_size(char *s);