Orthogonal approach to read()/write() that handles EINTR and counts > 2^31

[gnulib.git] / lib / full-read.c

diff --git a/lib/full-read.c b/lib/full-read.c
new file mode 100644 (file)
index 0000000..a328588
--- /dev/null
+++ b/lib/full-read.c
@@ -0,0 +1,65 @@
+/* An interface to read() that reads all it is asked to read.
+
+   Copyright (C) 1993, 1994, 1997, 1998, 1999, 2000, 2001, 2002 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 2, 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, read to the Free Software Foundation,
+   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+
+#if HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+/* Specification.  */
+#include "full-read.h"
+
+#include <errno.h>
+#ifndef errno
+extern int errno;
+#endif
+
+#include "safe-read.h"
+
+/* Read COUNT bytes at BUF to descriptor FD, retrying if interrupted
+   or if partial reads occur.  Return the number of bytes successfully
+   read, setting errno if that is less than COUNT.  errno = 0 means EOF.  */
+size_t
+full_read (int fd, void *buf, size_t count)
+{
+  size_t total_read = 0;
+
+  if (count > 0)
+    {
+      char *ptr = buf;
+
+      do
+       {
+         size_t nread = safe_read (fd, ptr, count);
+         if (nread == (size_t)-1)
+           break;
+         if (nread == 0)
+           {
+             /* EOF.  */
+             errno = 0;
+             break;
+           }
+         total_read += nread;
+         ptr += nread;
+         count -= nread;
+       }
+      while (count > 0);
+    }
+
+  return total_read;
+}