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

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

diff --git a/lib/full-write.c b/lib/full-write.c
index cce5f0f..f21e479 100644 (file)
--- a/lib/full-write.c
+++ b/lib/full-write.c
@@ -1,5 +1,7 @@
-/* full-write.c -- an interface to write that retries after interrupts
-   Copyright (C) 1993 Free Software Foundation, Inc.
+/* An interface to write() that writes all it is asked to write.
+
+   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
@@ -12,60 +14,53 @@
    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, write to the Free Software
-   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
-
-   Copied largely from GNU C's cccp.c.
-   */
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
 
-#ifdef HAVE_CONFIG_H
-#if defined (CONFIG_BROKETS)
-/* We use <config.h> instead of "config.h" so that a compilation
-   using -I. -I$srcdir will use ./config.h rather than $srcdir/config.h
-   (which it would do because it found this file in $srcdir).  */
-#include <config.h>
-#else
-#include "config.h"
+#if HAVE_CONFIG_H
+# include <config.h>
 #endif
-#endif
-
-#include <sys/types.h>
 
-#ifdef HAVE_UNISTD_H
-#include <unistd.h>
-#endif
+/* Specification.  */
+#include "full-write.h"
 
 #include <errno.h>
-#ifndef STDC_HEADERS
+#ifndef errno
 extern int errno;
 #endif
 
-/* Write LEN bytes at PTR to descriptor DESC, retrying if interrupted.
-   Return LEN upon success, write's (negative) error code otherwise.  */
+#include "safe-write.h"
 
-int
-full_write (desc, ptr, len)
-     int desc;
-     char *ptr;
-     int len;
+/* Write COUNT bytes at BUF to descriptor FD, retrying if interrupted
+   or if partial writes occur.  Return the number of bytes successfully
+   written, setting errno if that is less than COUNT.  */
+size_t
+full_write (int fd, const void *buf, size_t count)
 {
-  int total_written;
+  size_t total_written = 0;
 
-  total_written = 0;
-  while (len > 0)
+  if (count > 0)
     {
-      int written = write (desc, ptr, len);
-      if (written < 0)
+      const char *ptr = buf;
+
+      do
        {
-#ifdef EINTR
-         if (errno == EINTR)
-           continue;
-#endif
-         return written;
+         size_t written = safe_write (fd, ptr, count);
+         if (written == (size_t)-1)
+           break;
+         if (written == 0)
+           {
+             /* Some buggy drivers return 0 when you fall off a device's
+                end.  (Example: Linux 1.2.13 on /dev/fd0.)  */
+             errno = ENOSPC;
+             break;
+           }
+         total_written += written;
+         ptr += written;
+         count -= written;
        }
-      total_written += written;
-      ptr += written;
-      len -= written;
+      while (count > 0);
     }
+
   return total_written;
 }