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glibc  2.9
pwrite64.c
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00001 /* Copyright (C) 1997,1998,1999,2000,2002,2003,2006
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 <errno.h>
00022 #include <endian.h>
00023 #include <unistd.h>
00024 
00025 #include <sysdep-cancel.h>
00026 #include <sys/syscall.h>
00027 #include <bp-checks.h>
00028 
00029 #include <kernel-features.h>
00030 
00031 #ifdef __NR_pwrite64        /* Newer kernels renamed but it's the same.  */
00032 # ifdef __NR_pwrite
00033 #  error "__NR_pwrite and __NR_pwrite64 both defined???"
00034 # endif
00035 # define __NR_pwrite __NR_pwrite64
00036 #endif
00037 
00038 #if defined __NR_pwrite || __ASSUME_PWRITE_SYSCALL > 0
00039 
00040 # if __ASSUME_PWRITE_SYSCALL == 0
00041 static ssize_t __emulate_pwrite64 (int fd, const void *buf, size_t count,
00042                                off64_t offset) internal_function;
00043 # endif
00044 
00045 
00046 static ssize_t
00047 do_pwrite64 (int fd, const void *buf, size_t count, off64_t offset)
00048 {
00049   ssize_t result;
00050 
00051   /* First try the syscall.  */
00052   result = INLINE_SYSCALL (pwrite, 5, fd, CHECK_N (buf, count), count,
00053                         __LONG_LONG_PAIR ((off_t) (offset >> 32),
00054                                         (off_t) (offset & 0xffffffff)));
00055 # if __ASSUME_PWRITE_SYSCALL == 0
00056   if (result == -1 && errno == ENOSYS)
00057     /* No system call available.  Use the emulation.  */
00058     result = __emulate_pwrite64 (fd, buf, count, offset);
00059 # endif
00060 
00061   return result;
00062 }
00063 
00064 
00065 ssize_t
00066 __libc_pwrite64 (fd, buf, count, offset)
00067      int fd;
00068      const void *buf;
00069      size_t count;
00070      off64_t offset;
00071 {
00072   if (SINGLE_THREAD_P)
00073     return do_pwrite64 (fd, buf, count, offset);
00074 
00075   int oldtype = LIBC_CANCEL_ASYNC ();
00076 
00077   ssize_t result = do_pwrite64 (fd, buf, count, offset);
00078 
00079   LIBC_CANCEL_RESET (oldtype);
00080 
00081   return result;
00082 }
00083 
00084 weak_alias (__libc_pwrite64, __pwrite64)
00085 libc_hidden_weak (__pwrite64)
00086 weak_alias (__libc_pwrite64, pwrite64)
00087 
00088 # define __libc_pwrite64(fd, buf, count, offset) \
00089      static internal_function __emulate_pwrite64 (fd, buf, count, offset)
00090 #endif
00091 
00092 #if __ASSUME_PWRITE_SYSCALL == 0
00093 # include <sysdeps/posix/pwrite64.c>
00094 #endif