coreutils/lib/utime.c

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/* Copyright (C) 1998, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
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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 the
Free Software Foundation; either version 2, or (at your option) any
later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
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Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
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/* derived from a function in touch.c */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#undef utime
#include <sys/types.h>
#ifdef HAVE_UTIME_H
# include <utime.h>
#endif
#if !HAVE_UTIMES_NULL
# include <sys/stat.h>
# include <fcntl.h>
#endif
#include <unistd.h>
#include <errno.h>
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#include "full-write.h"
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#include "safe-read.h"
/* Some systems (even some that do have <utime.h>) don't declare this
structure anywhere. */
#ifndef HAVE_STRUCT_UTIMBUF
struct utimbuf
{
long actime;
long modtime;
};
#endif
/* Emulate utime (file, NULL) for systems (like 4.3BSD) that do not
interpret it to set the access and modification times of FILE to
the current time. Return 0 if successful, -1 if not. */
static int
utime_null (const char *file)
{
#if HAVE_UTIMES_NULL
return utimes (file, 0);
#else
int fd;
char c;
int status = 0;
struct stat st;
int saved_errno = 0;
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fd = open (file, O_RDWR);
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if (fd < 0
|| fstat (fd, &st) < 0
|| safe_read (fd, &c, sizeof c) == SAFE_READ_ERROR
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|| lseek (fd, (off_t) 0, SEEK_SET) < 0
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|| full_write (fd, &c, sizeof c) != sizeof c
/* Maybe do this -- it's necessary on SunOS 4.1.3 with some combination
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of patches, but that system doesn't use this code: it has utimes.
|| fsync (fd) < 0
*/
|| (st.st_size == 0 && ftruncate (fd, st.st_size) < 0))
{
saved_errno = errno;
status = -1;
}
if (0 <= fd)
{
if (close (fd) < 0)
status = -1;
/* If there was a prior failure, use the saved errno value.
But if the only failure was in the close, don't change errno. */
if (saved_errno)
errno = saved_errno;
}
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return status;
#endif
}
int
rpl_utime (const char *file, const struct utimbuf *times)
{
if (times)
return utime (file, times);
return utime_null (file);
}