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glibc  2.9
pread64.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 <unistd.h>
00023 
00024 #include <sysdep-cancel.h>
00025 #include <sys/syscall.h>
00026 #include <bp-checks.h>
00027 
00028 #include <kernel-features.h>
00029 
00030 #if defined __NR_pread || __ASSUME_PREAD_SYSCALL > 0
00031 
00032 # if __ASSUME_PREAD_SYSCALL == 0
00033 static ssize_t __emulate_pread64 (int fd, void *buf, size_t count,
00034                               off64_t offset) internal_function;
00035 # endif
00036 
00037 
00038 ssize_t
00039 __libc_pread64 (fd, buf, count, offset)
00040      int fd;
00041      void *buf;
00042      size_t count;
00043      off64_t offset;
00044 {
00045   ssize_t result;
00046 
00047   if (SINGLE_THREAD_P)
00048     {
00049       result = INLINE_SYSCALL (pread, 4, fd, CHECK_N (buf, count), count,
00050                                 offset);
00051 # if __ASSUME_PREAD_SYSCALL == 0
00052       if (result == -1 && errno == ENOSYS)
00053        /* No system call available.  Use the emulation.  */
00054        result = __emulate_pread64 (fd, buf, count, offset);
00055 # endif
00056 
00057       return result;
00058     }
00059 
00060   int oldtype = LIBC_CANCEL_ASYNC ();
00061 
00062    result = INLINE_SYSCALL (pread, 4, fd, CHECK_N (buf, count), count,
00063                             offset);
00064 # if __ASSUME_PREAD_SYSCALL == 0
00065   if (result == -1 && errno == ENOSYS)
00066     /* No system call available.  Use the emulation.  */
00067     result = __emulate_pread64 (fd, buf, count, offset);
00068 # endif
00069 
00070   LIBC_CANCEL_RESET (oldtype);
00071 
00072   return result;
00073 }
00074 
00075 weak_alias (__libc_pread64, __pread64)
00076 weak_alias (__libc_pread64, pread64)
00077 
00078 # define __libc_pread64(fd, buf, count, offset) \
00079      static internal_function __emulate_pread64 (fd, buf, count, offset)
00080 #endif
00081 
00082 # if __ASSUME_PREAD_SYSCALL == 0
00083 # include <sysdeps/posix/pread64.c>
00084 #endif