text: /* Read block from given position in file without changing file pointer.
     POSIX version.
     Copyright (C) 1997-2016 Free Software Foundation, Inc.
     This file is part of the GNU C Library.
     Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
  
     The GNU C Library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Lesser General Public
     License as published by the Free Software Foundation; either
     version 2.1 of the License, or (at your option) any later version.
  
     The GNU C Library 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
     Lesser General Public License for more details.
  
     You should have received a copy of the GNU Lesser General Public
     License along with the GNU C Library; if not, see
     <http://www.gnu.org/licenses/>.  */
  
  #include <errno.h>
  #include <unistd.h>
  
  /* Note: This implementation of pread64 is not multithread-safe.  */
  
  ssize_t
  __libc_pread64 (int fd, void *buf, size_t nbyte, off64_t offset)
  {
    /* Since we must not change the file pointer preserve the value so that
       we can restore it later.  */
    int save_errno;
    ssize_t result;
    off64_t old_offset = __libc_lseek64 (fd, 0, SEEK_CUR);
    if (old_offset == (off64_t) -1)
      return -1;
  
    /* Set to wanted position.  */
    if (__libc_lseek64 (fd, offset, SEEK_SET) == (off64_t) -1)
      return -1;
  
    /* Write out the data.  */
    result = __libc_read (fd, buf, nbyte);
  
    /* Now we have to restore the position.  If this fails we have to
       return this as an error.  But if the writing also failed we
       return this error.  */
    save_errno = errno;
    if (__libc_lseek64 (fd, old_offset, SEEK_SET) == (off64_t) -1)
      {
        if (result == -1)
  	__set_errno (save_errno);
        return -1;
      }
    __set_errno (save_errno);
  
    return result;
  }
  
  #ifndef __libc_pread64
  weak_alias (__libc_pread64, __pread64)
  weak_alias (__libc_pread64, pread64)
  #endif
  