Fixed the bug with checking physically the same file; for example: 'mount --bind parent parent/child' command makes 'parent' mount point which physically is 'parent/child'; If we are trying to 'diff parent parent/child' we must get '0' because files (dirs) are physically the same; That means we need to check stats of files and return '0' in this case.
There is the comment in diff-utils: src/system.h which is describing why isn't comparing only st_dev and st_ino sufficient: /* Do struct stat *S, *T have the same file attributes? POSIX says that two files are identical if st_ino and st_dev are the same, but many file systems incorrectly assign the same (device, inode) pair to two distinct files, including: GNU/Linux NFS servers that export all local file systems as a single NFS file system, if a local device number (st_dev) exceeds 255, or if a local inode number (st_ino) exceeds 16777215. ... It's ppossible for two distinct files on a buggy file system to have the same attributes, but it's not worth slowing down all implementations (or complicating the configuration) to cater to these rare cases in buggy implementations. */ Signed-off-by: Roman Borisov <[email protected]> --- editors/diff.c | 15 +++++++++++++++ 1 files changed, 15 insertions(+), 0 deletions(-) diff --git a/editors/diff.c b/editors/diff.c index ca4a4ea..ba8cd64 100644 --- a/editors/diff.c +++ b/editors/diff.c @@ -952,6 +952,21 @@ int diff_main(int argc UNUSED_PARAM, char **argv) if (gotstdin && (S_ISDIR(stb[0].st_mode) || S_ISDIR(stb[1].st_mode))) bb_error_msg_and_die("can't compare stdin to a directory"); + /* Compare stats to check if the files are the same physically; + See diffutils: src/system.h for full description */ + if (stb[0].st_ino == stb[1].st_ino && + stb[0].st_dev == stb[1].st_dev && + stb[0].st_mode == stb[1].st_mode && + stb[0].st_nlink == stb[1].st_nlink && + stb[0].st_uid == stb[1].st_uid && + stb[0].st_gid == stb[1].st_gid && + stb[0].st_size == stb[1].st_size && + stb[0].st_mtime == stb[1].st_mtime && + stb[0].st_ctime == stb[1].st_ctime) { + /* files are physically the same; no need to compare them */ + return STATUS_SAME; + } + if (S_ISDIR(stb[0].st_mode) && S_ISDIR(stb[1].st_mode)) { #if ENABLE_FEATURE_DIFF_DIR diffdir(file, s_start); -- 1.7.0.4 _______________________________________________ busybox mailing list [email protected] http://lists.busybox.net/mailman/listinfo/busybox
