Mercurial > hg > octave-lojdl > gnulib-hg
changeset 12159:0ae159ba1adf
utimecmp: support symlink timestamps
Update this module to reflect POSIX 2008:
With pathconf, we can avoid calling utimens.
With utimensat, the system resolution can be 1.
With lutimens, we can determine resolution on symlinks.
* lib/utimecmp.c (utimecmp): Use new interface. Skip effort of
hashing when possible. Use pathconf when available.
(SYSCALL_RESOLUTION): Recognize tighter resolution.
* modules/utimecmp (Depends-on): Add lstat.
Signed-off-by: Eric Blake <ebb9@byu.net>
| author | Eric Blake <ebb9@byu.net> |
|---|---|
| date | Wed, 07 Oct 2009 22:06:49 -0600 |
| parents | 899dd13e9f8b |
| children | d0732ed2dd55 |
| files | ChangeLog lib/utimecmp.c modules/utimecmp |
| diffstat | 3 files changed, 55 insertions(+), 15 deletions(-) [+] |
line wrap: on
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--- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,11 @@ 2009-10-10 Eric Blake <ebb9@byu.net> + utimecmp: support symlink timestamps + * lib/utimecmp.c (utimecmp): Use new interface. Skip effort of + hashing when possible. Use pathconf when available. + (SYSCALL_RESOLUTION): Recognize tighter resolution. + * modules/utimecmp (Depends-on): Add lstat. + utimens: add lutimens interface * lib/utimens.c (lutimens): New function. * m4/utimens.m4 (gl_UTIMENS): Check for lutimes.
--- a/lib/utimecmp.c +++ b/lib/utimecmp.c @@ -1,6 +1,7 @@ /* utimecmp.c -- compare file time stamps - Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc. + Copyright (C) 2004, 2005, 2006, 2007, 2009 Free Software + Foundation, Inc. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -26,6 +27,8 @@ #include <stdint.h> #include <stdlib.h> #include <time.h> +#include <unistd.h> + #include "hash.h" #include "intprops.h" #include "stat-time.h" @@ -42,12 +45,14 @@ /* Best possible resolution that utimens can set and stat can return, due to system-call limitations. It must be a power of 10 that is no greater than 1 billion. */ -#if (HAVE_WORKING_UTIMES \ - && (defined HAVE_STRUCT_STAT_ST_ATIM_TV_NSEC \ - || defined HAVE_STRUCT_STAT_ST_ATIMESPEC_TV_NSEC \ - || defined HAVE_STRUCT_STAT_ST_ATIMENSEC \ - || defined HAVE_STRUCT_STAT_ST_ATIM_ST__TIM_TV_NSEC \ - || defined HAVE_STRUCT_STAT_ST_SPARE1)) +#if HAVE_UTIMENSAT +enum { SYSCALL_RESOLUTION = 1 }; +#elif ((HAVE_FUTIMESAT || HAVE_WORKING_UTIMES) \ + && (defined HAVE_STRUCT_STAT_ST_ATIM_TV_NSEC \ + || defined HAVE_STRUCT_STAT_ST_ATIMESPEC_TV_NSEC \ + || defined HAVE_STRUCT_STAT_ST_ATIMENSEC \ + || defined HAVE_STRUCT_STAT_ST_ATIM_ST__TIM_TV_NSEC \ + || defined HAVE_STRUCT_STAT_ST_SPARE1)) enum { SYSCALL_RESOLUTION = 1000 }; #else enum { SYSCALL_RESOLUTION = BILLION }; @@ -100,6 +105,8 @@ DST_NAME and status DST_STAT) is older than SRC_STAT, the same age as SRC_STAT, or newer than SRC_STAT, respectively. + DST_NAME may be NULL if OPTIONS is 0. + If OPTIONS & UTIMECMP_TRUNCATE_SOURCE, do the comparison after SRC is converted to the destination's timestamp resolution as filtered through utimens. In this case, return -2 if the exact answer cannot be @@ -147,6 +154,16 @@ /* Time stamp resolution in nanoseconds. */ int res; + /* Quick exit, if possible. Since the worst resolution is 2 + seconds, anything that differs by more than that does not + needs source truncation. */ + if (dst_s == src_s && dst_ns == src_ns) + return 0; + if (dst_s <= src_s - 2) + return -1; + if (src_s <= dst_s - 2) + return 1; + if (! ht) ht = hash_initialize (16, NULL, dev_info_hash, dev_info_compare, free); if (! new_dst_res) @@ -169,6 +186,19 @@ res = dst_res->resolution; +#ifdef _PC_TIMESTAMP_RESOLUTION + /* If the system will tell us the resolution, we're set! */ + if (! dst_res->exact) + { + res = pathconf (dst_name, _PC_TIMESTAMP_RESOLUTION); + if (0 < res) + { + dst_res->resolution = res; + dst_res->exact = true; + } + } +#endif + if (! dst_res->exact) { /* This file system's resolution is not known exactly. @@ -258,16 +288,16 @@ /* Set the modification time. But don't try to set the modification time of symbolic links; on many hosts this sets the time of the pointed-to file. */ - if (S_ISLNK (dst_stat->st_mode) - || utimens (dst_name, timespec) != 0) + if ((S_ISLNK (dst_stat->st_mode) + ? lutimens (dst_name, timespec) + : utimens (dst_name, timespec)) != 0) return -2; - /* Read the modification time that was set. It's safe to call - 'stat' here instead of worrying about 'lstat'; either the - caller used 'stat', or the caller used 'lstat' and found - something other than a symbolic link. */ + /* Read the modification time that was set. */ { - int stat_result = stat (dst_name, &dst_status); + int stat_result = (S_ISLNK (dst_stat->st_mode) + ? lstat (dst_name, &dst_status) + : stat (dst_name, &dst_status)); if (stat_result | (dst_status.st_mtime ^ dst_m_s) @@ -277,7 +307,10 @@ it changed. Change it back as best we can. */ timespec[1].tv_sec = dst_m_s; timespec[1].tv_nsec = dst_m_ns; - utimens (dst_name, timespec); + if (S_ISLNK (dst_stat->st_mode)) + lutimens (dst_name, timespec); + else + utimens (dst_name, timespec); } if (stat_result != 0)