Re: changes for openat, mkdir-p, lchmod

[Jim Meyering]

It looks like I've subverted things a little: the lib/ChangeLog entry for
fts.c and openat.[ch] below correspond to a change I haven't yet committed.
I think it's complete, but it's rather ambitious, and requires changes
(albeit small) in every program that uses fts.  So I'm taking my time.

I committed it (only the ChangeLog entry) by mistake when I made the
version-etc.c change.  I'll back it out of coreutils and gnulib now.
Sorry about that.

Paul Eggert <address@hidden> wrote:
> I installed this to sync gnulib from coreutils.  This is the biggest
> change hunk; the changes all tend to depend on each other.  It's still
> mutating but I think this snapshot will work with other programs (it
> works with GNU tar, anyway).
>
> The lchmod business is a bit tricky, since it uses chmod as a
> substitute for lchmod.  Callers are supposed to check that files are
> not symbolic links before using lchmod, which obviously leads to race
> conditions, but that's the best we can do on hosts that lack lchmod.
>
> 2006-01-09  Paul Eggert  <address@hidden>
...
> 2006-01-09  Jim Meyering  <address@hidden>
>
>       Sync from coreutils.
>
>       Rewrite fts.c not to change the current working directory,
>       by using openat, fstatat, fdopendir, etc..
>
>       * lib/fts.c [! _LIBC]: Include "openat.h", "unistd--.h", and 
> "fcntl--.h".
>       [_LIBC] (fchdir): Don't undef or define; no longer used.
>       (FCHDIR): Define in terms of cwd_advance_fd rather than fchdir.
>       Now, this `function' always succeeds, and consumes its file descriptor
>       parameter -- so callers must not close such FDs.  Update callers.
>       (diropen_fd, opendirat, cwd_advance_fd): New functions.
>       (diropen): Add parameter, SP.  Adjust all callers.
>       Implement using diropen_fd, rather than open.
>       (fts_open): Initialize new member, fts_cwd_fd.
>       Remove fts_rft-setting code.
>       (fts_close): Close fts_cwd_fd, if necessary.
>       (__opendir2): Define in terms of opendir or opendirat,
>       depending on whether the FST_NOCHDIR flag is set.
>       (fts_build): Since fts_safe_changedir consumes its FD, and since
>       this code must do `closedir(dirp)', dup the dirfd(dirp) argument,
>       and close the dup'd file descriptor upon failure.
>       (fts_stat): Use fstatat(...AT_SYMLINK_NOFOLLOW) in place of lstat.
>       (fts_safe_changedir): Tweak semantics to reflect that this function
>       now calls cwd_advance_fd and hence consumes its FD argument.
>       * lib/fts_.h [struct FTS] (fts_cwd_fd): New member.
>       (fts_rft): Remove now-unused member.
>
>       * lib/openat.c (fchownat): New function.
>       * lib/openat.h (fchmodat, fchownat): Declare.
>       (chmodat, lchmodat): Define convenience functions.
>       (chownat, lchownat): Likewise.
...