+
−/* replacement pread function
+
−   Copyright (C) 2009-2013 Free Software Foundation, Inc.
+
−
+
−   This program is free software: you can redistribute it and/or modify
+
−   it under the terms of the GNU General Public License as published by
+
−   the Free Software Foundation; either version 3 of the License, or
+
−   (at your option) any later version.
+
−
+
−   This program 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 General Public License for more details.
+
−
+
−   You should have received a copy of the GNU General Public License
+
−   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
−
+
−#include <config.h>
+
−
+
−/* Specification.  */
+
−#include <unistd.h>
+
−
+
−#include <errno.h>
+
−
+
−#define __libc_lseek(f,o,w) lseek (f, o, w)
+
−#define __set_errno(Val) errno = (Val)
+
−#define __libc_read(f,b,n) read (f, b, n)
+
−
+
−/* pread substitute for systems that the function, such as mingw32 and BeOS.  */
+
−/* The following is identical to the function from glibc's
+
−   sysdeps/posix/pread.c */
+
−
+
−/* Note: This implementation of pread is not multithread-safe.  */
+
−
+
−ssize_t
+
−pread (int fd, void *buf, size_t nbyte, off_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;
+
−  off_t old_offset = __libc_lseek (fd, 0, SEEK_CUR);
+
−  if (old_offset == (off_t) -1)
+
−    return -1;
+
−
+
−  /* Set to wanted position.  */
+
−  if (__libc_lseek (fd, offset, SEEK_SET) == (off_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_lseek (fd, old_offset, SEEK_SET) == (off_t) -1)
+
−    {
+
−      if (result == -1)
+
−        __set_errno (save_errno);
+
−      return -1;
+
−    }
+
−  __set_errno (save_errno);
+
−
+
−  return result;
+
−}