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glibc  2.9
pread64.c
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00001 /* Copyright (C) 1997, 1998, 2000, 2002, 2003, 2004
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 #ifndef NO_SGIDEFS_H
00023 #include <sgidefs.h>
00024 #endif
00025 #include <unistd.h>
00026 #include <endian.h>
00027 
00028 #include <sysdep-cancel.h>
00029 #include <sys/syscall.h>
00030 #include <bp-checks.h>
00031 
00032 #include <kernel-features.h>
00033 
00034 #ifdef __NR_pread64             /* Newer kernels renamed but it's the same.  */
00035 # ifdef __NR_pread
00036 #  error "__NR_pread and __NR_pread64 both defined???"
00037 # endif
00038 # define __NR_pread __NR_pread64
00039 #endif
00040 
00041 #if defined __NR_pread || __ASSUME_PREAD_SYSCALL > 0
00042 
00043 # if __ASSUME_PREAD_SYSCALL == 0
00044 static ssize_t __emulate_pread64 (int fd, void *buf, size_t count,
00045                               off64_t offset) internal_function;
00046 # endif
00047 
00048 ssize_t
00049 __libc_pread64 (fd, buf, count, offset)
00050      int fd;
00051      void *buf;
00052      size_t count;
00053      off64_t offset;
00054 {
00055   ssize_t result;
00056 
00057 
00058   if (SINGLE_THREAD_P)
00059     {
00060      /* First try the syscall.  */
00061 #if _MIPS_SIM == _ABIN32 || _MIPS_SIM == _ABI64
00062       result = INLINE_SYSCALL (pread, 4, fd, CHECK_N (buf, count), count,
00063                             offset);
00064 #else
00065      result = INLINE_SYSCALL (pread, 6, fd, CHECK_N (buf, count), count, 0,
00066                            __LONG_LONG_PAIR ((off_t) (offset >> 32),
00067                            (off_t) (offset & 0xffffffff)));
00068 #endif
00069 # if __ASSUME_PREAD_SYSCALL == 0
00070      if (result == -1 && errno == ENOSYS)
00071      /* No system call available.  Use the emulation.  */
00072      result = __emulate_pread64 (fd, buf, count, offset);
00073 # endif
00074      return result;
00075     }
00076 
00077   int oldtype = LIBC_CANCEL_ASYNC ();
00078 
00079   /* First try the syscall.  */
00080 #if _MIPS_SIM == _ABIN32 || _MIPS_SIM == _ABI64
00081   result = INLINE_SYSCALL (pread, 4, fd, CHECK_N (buf, count), count, offset);
00082 #else
00083   result = INLINE_SYSCALL (pread, 6, fd, CHECK_N (buf, count), count, 0,
00084                         __LONG_LONG_PAIR ((off_t) (offset >> 32),
00085                                         (off_t) (offset & 0xffffffff)));
00086 #endif
00087 # if __ASSUME_PREAD_SYSCALL == 0
00088   if (result == -1 && errno == ENOSYS)
00089     /* No system call available.  Use the emulation.  */
00090     result = __emulate_pread64 (fd, buf, count, offset);
00091 # endif
00092 
00093   LIBC_CANCEL_RESET (oldtype);
00094 
00095   return result;
00096 }
00097 
00098 weak_alias (__libc_pread64, __pread64)
00099 weak_alias (__libc_pread64, pread64)
00100 
00101 # define __libc_pread64(fd, buf, count, offset) \
00102      static internal_function __emulate_pread64 (fd, buf, count, offset)
00103 #endif
00104 
00105 #if __ASSUME_PREAD_SYSCALL == 0
00106 # include <sysdeps/posix/pread64.c>
00107 #endif