Mercurial > hg > octave-nkf > gnulib-hg
changeset 12353:fd066c132b7d
utimens: work around older Linux failure with symlinks
Some Linux kernel versions support utimensat(,0) but not
utimensat(,AT_SYMLINK_NOFOLLOW), even for non-symlinks. Had the
fallback code for regular files been reached, it would have truncated
timestamps. But since glibc lutimes just wraps utimensat, and we
didn't expect ENOSYS from lutimes, the fallback wasn't even reached.
* lib/utimens.c (lutimensat_works_really): New variable.
(fdutimens, lutimens): Use it to manage kernels that support
nanosecond times on files, but not on symlinks.
Reported by Ondřej Vašík.
Signed-off-by: Eric Blake <ebb9@byu.net>
| author | Eric Blake <ebb9@byu.net> |
|---|---|
| date | Tue, 24 Nov 2009 10:07:57 -0700 |
| parents | a6f65d4b64bc |
| children | 8884d9d0fae4 |
| files | ChangeLog lib/utimens.c |
| diffstat | 2 files changed, 22 insertions(+), 8 deletions(-) [+] |
line wrap: on
line diff
--- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,11 @@ 2009-11-25 Eric Blake <ebb9@byu.net> + utimens: work around older Linux failure with symlinks + * lib/utimens.c (lutimensat_works_really): New variable. + (fdutimens, lutimens): Use it to manage kernels that support + nanosecond times on files, but not on symlinks. + Reported by Ondřej Vašík. + utimes: fix configure grammar * m4/utimes.m4 (gl_FUNC_UTIMES): Delete spurious word.
--- a/lib/utimens.c +++ b/lib/utimens.c @@ -54,10 +54,12 @@ #undef utimensat #if HAVE_UTIMENSAT || HAVE_FUTIMENS -/* Cache variable for whether syscall works; used to avoid calling the - syscall if we know it will just fail with ENOSYS. 0 = unknown, 1 = - yes, -1 = no. */ +/* Cache variables for whether the utimensat syscall works; used to + avoid calling the syscall if we know it will just fail with ENOSYS. + There are some Linux kernel versions where a flag of 0 passes, but + not AT_SYMLINK_NOFOLLOW. 0 = unknown, 1 = yes, -1 = no. */ static int utimensat_works_really; +static int lutimensat_works_really; #endif /* HAVE_UTIMENSAT || HAVE_UTIMENSAT */ /* Solaris 9 mistakenly succeeds when given a non-directory with a @@ -242,6 +244,7 @@ # endif /* HAVE_FUTIMENS */ } utimensat_works_really = -1; + lutimensat_works_really = -1; #endif /* HAVE_UTIMENSAT || HAVE_FUTIMENS */ /* The platform lacks an interface to set file timestamps with @@ -381,7 +384,7 @@ worry about bogus return values. */ #if HAVE_UTIMENSAT - if (0 <= utimensat_works_really) + if (0 <= lutimensat_works_really) { int result = utimensat (AT_FDCWD, file, ts, AT_SYMLINK_NOFOLLOW); # ifdef __linux__ @@ -398,10 +401,11 @@ if (result == 0 || errno != ENOSYS) { utimensat_works_really = 1; + lutimensat_works_really = 1; return result; } } - utimensat_works_really = -1; + lutimensat_works_really = -1; #endif /* HAVE_UTIMENSAT */ /* The platform lacks an interface to set file timestamps with @@ -416,7 +420,9 @@ return 0; } -#if HAVE_LUTIMES + /* On Linux, lutimes is a thin wrapper around utimensat, so there is + no point trying lutimes if utimensat failed with ENOSYS. */ +#if HAVE_LUTIMES && !HAVE_UTIMENSAT { struct timeval timeval[2]; struct timeval const *t; @@ -431,9 +437,11 @@ else t = NULL; - return lutimes (file, t); + result = lutimes (file, t); + if (result == 0 || errno != ENOSYS) + return result; } -#endif /* HAVE_LUTIMES */ +#endif /* HAVE_LUTIMES && !HAVE_UTIMENSAT */ /* Out of luck for symlinks, but we still handle regular files. */ if (!(adjustment_needed || REPLACE_FUNC_STAT_FILE) && lstat (file, &st))