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glibc  2.9
pwrite.c
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00001 /* Copyright (C) 1997, 1998, 2000, 2002, 2003, 2004, 2006
00002    Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
00005 
00006    The GNU C Library is free software; you can redistribute it and/or
00007    modify it under the terms of the GNU Lesser General Public
00008    License as published by the Free Software Foundation; either
00009    version 2.1 of the License, or (at your option) any later version.
00010 
00011    The GNU C Library is distributed in the hope that it will be useful,
00012    but WITHOUT ANY WARRANTY; without even the implied warranty of
00013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00014    Lesser General Public License for more details.
00015 
00016    You should have received a copy of the GNU Lesser General Public
00017    License along with the GNU C Library; if not, write to the Free
00018    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00019    02111-1307 USA.  */
00020 
00021 #include <assert.h>
00022 #include <errno.h>
00023 #include <unistd.h>
00024 #include <endian.h>
00025 
00026 #include <sysdep-cancel.h>
00027 #include <sys/syscall.h>
00028 #include <bp-checks.h>
00029 
00030 #include <kernel-features.h>
00031 
00032 #ifdef __NR_pwrite64            /* Newer kernels renamed but it's the same.  */
00033 # ifdef __NR_pwrite
00034 #  error "__NR_pwrite and __NR_pwrite64 both defined???"
00035 # endif
00036 # define __NR_pwrite __NR_pwrite64
00037 #endif
00038 
00039 #if defined __NR_pwrite || __ASSUME_PWRITE_SYSCALL > 0
00040 
00041 # if __ASSUME_PWRITE_SYSCALL == 0
00042 static ssize_t __emulate_pwrite (int fd, const void *buf, size_t count,
00043                              off_t offset) internal_function;
00044 # endif
00045 
00046 ssize_t
00047 __libc_pwrite (fd, buf, count, offset)
00048      int fd;
00049      const void *buf;
00050      size_t count;
00051      off_t offset;
00052 {
00053   ssize_t result;
00054 
00055   if (SINGLE_THREAD_P)
00056     {
00057       /* First try the syscall.  */
00058       result = INLINE_SYSCALL (pwrite, 6, fd, CHECK_N (buf, count), count, 0,
00059                             __LONG_LONG_PAIR (offset >> 31, offset));
00060 # if __ASSUME_PWRITE_SYSCALL == 0
00061       if (result == -1 && errno == ENOSYS)
00062         /* No system call available.  Use the emulation.  */
00063         result = __emulate_pwrite (fd, buf, count, offset);
00064 # endif
00065       return result;
00066     }
00067 
00068   int oldtype = LIBC_CANCEL_ASYNC ();
00069 
00070   /* First try the syscall.  */
00071   result = INLINE_SYSCALL (pwrite, 6, fd, CHECK_N (buf, count), count, 0,
00072                         __LONG_LONG_PAIR (offset >> 31, offset));
00073 # if __ASSUME_PWRITE_SYSCALL == 0
00074   if (result == -1 && errno == ENOSYS)
00075     /* No system call available.  Use the emulation.  */
00076     result = __emulate_pwrite (fd, buf, count, offset);
00077 # endif
00078 
00079   LIBC_CANCEL_RESET (oldtype);
00080 
00081   return result;
00082 }
00083 
00084 strong_alias (__libc_pwrite, __pwrite)
00085 weak_alias (__libc_pwrite, pwrite)
00086 
00087 # define __libc_pwrite(fd, buf, count, offset) \
00088      static internal_function __emulate_pwrite (fd, buf, count, offset)
00089 #endif
00090 
00091 #if __ASSUME_PWRITE_SYSCALL == 0
00092 # include <sysdeps/posix/pwrite.c>
00093 #endif