1 files changed, 56 insertions, 0 deletions
diff --git a/sysdeps/posix/pread.c b/sysdeps/posix/pread.c
new file mode 100644
index 0000000000..300aabac65
--- /dev/null
+++ b/sysdeps/posix/pread.c
@@ -0,0 +1,56 @@
+/* Read block from given position in file without changing file pointer.
+   POSIX version.
+   Copyright (C) 1997 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 Library General Public License as
+   published by the Free Software Foundation; either version 2 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
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <errno.h>
+#include <unistd.h>
+
+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 = lseek (fd, 0, SEEK_CUR);
+  if (old_offset == (off_t) -1)
+    return -1;
+
+  /* Set to wanted position.  */
+  if (lseek (fd, offset, SEEK_SET) == (off_t) -1)
+    return -1;
+
+  /* Write out the data.  */
+  result = 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 (lseek (fd, old_offset, SEEK_SET) == (off_t) -1)
+    {
+      if (result == -1)
+	__set_errno (save_errno);
+      return -1;
+    }
+  __set_errno (save_errno);
+
+  return result;
+}