Mercurial > gnulib
view doc/posix-functions/utimensat.texi @ 39550:9c066f6340ed
timespec: fix resolution confusion
In normal usage, clock resolution is given in seconds, but the
code was mistakenly using inverse seconds and calling it
“resolution”. Fix this, partly by renaming two identifiers.
The old names will be kept for a bit, to ease transition.
* lib/timespec.h (TIMESPEC_HZ, LOG10_TIMESPEC_HZ):
New constants, replacing TIMESPEC_RESOLUTION and
LOG10_TIMESPEC_RESOLUTION, which are now obsolescent.
All uses changed.
author | Paul Eggert <eggert@cs.ucla.edu> |
---|---|
date | Mon, 10 Sep 2018 18:42:25 -0700 |
parents | 870603b7c7b5 |
children |
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@node utimensat @section @code{utimensat} @findex utimensat POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/utimensat.html} Gnulib module: utimensat Portability problems fixed by Gnulib: @itemize @item This function is missing on some platforms: glibc 2.3.6, Mac OS X 10.5, FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 10, Cygwin 1.5.x, mingw, MSVC 14, Interix 3.5, BeOS, Android 3.0. However, the replacement function may end up truncating timestamps to worse resolution than supported by the file system. Furthermore, the replacement function is not safe to be used in libraries and is not multithread-safe. @item This function returns a bogus value instead of failing with @code{ENOSYS} on some platforms: Linux kernel 2.6.21. @item This function fails with @code{ENOSYS} if passed the flag @code{AT_SYMLINK_NOFOLLOW} on a regular file: Linux kernel 2.6.22. @item When using @code{UTIME_OMIT} or @code{UTIME_NOW}, some systems require the @code{tv_sec} argument to be 0, and don't necessarily handle all file permissions in the manner required by POSIX: Linux kernel 2.6.25. @item When using @code{UTIME_OMIT} for the modification time, but specifying an access time, some systems fail to update the change time: Linux kernel 2.6.32, Solaris 11.1. @item Out-of-range values of @code{tv_nsec} do not lead to a failure on some platforms: Linux kernel 2.6.22.19 on hppa. @end itemize Portability problems not fixed by Gnulib: @itemize @item On some platforms, timestamps of symbolic links cannot be modified, so the replacement fails with @code{ENOSYS} if passed the flag @code{AT_SYMLINK_NOFOLLOW} on a symlink. @item The mere act of using @code{lstat} modifies the access time of symlinks on some platforms, so @code{utimensat} with @code{AT_SYMLINK_NOFOLLOW} can only effectively change modification time: Cygwin. @item The mere act of using @code{stat} modifies the access time of directories on some platforms, so @code{utimensat} can only effectively change directory modification time: Cygwin 1.5.x. @end itemize The gnulib module @code{fdutimensat} provides a similar interface.