gettimeofday: port recent C++ fix to Emacs

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

diff --git a/lib/full-write.c b/lib/full-write.c
index f21e479..beb5bf9 100644 (file)
--- a/lib/full-write.c
+++ b/lib/full-write.c
@@ -1,12 +1,11 @@
-/* An interface to write() that writes all it is asked to write.
+/* An interface to read and write that retries (if necessary) until complete.
 
-   Copyright (C) 1993, 1994, 1997, 1998, 1999, 2000, 2001, 2002 Free Software
-   Foundation, Inc.
+   Copyright (C) 1993-1994, 1997-2006, 2009-2013 Free Software Foundation, Inc.
 
-   This program is free software; you can redistribute it and/or modify
+   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.
+   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
@@ -14,53 +13,67 @@
    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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-#if HAVE_CONFIG_H
-# include <config.h>
-#endif
+#include <config.h>
 
 /* Specification.  */
-#include "full-write.h"
+#ifdef FULL_READ
+# include "full-read.h"
+#else
+# include "full-write.h"
+#endif
 
 #include <errno.h>
-#ifndef errno
-extern int errno;
+
+#ifdef FULL_READ
+# include "safe-read.h"
+# define safe_rw safe_read
+# define full_rw full_read
+# undef const
+# define const /* empty */
+#else
+# include "safe-write.h"
+# define safe_rw safe_write
+# define full_rw full_write
 #endif
 
-#include "safe-write.h"
+#ifdef FULL_READ
+/* Set errno to zero upon EOF.  */
+# define ZERO_BYTE_TRANSFER_ERRNO 0
+#else
+/* Some buggy drivers return 0 when one tries to write beyond
+   a device's end.  (Example: Linux 1.2.13 on /dev/fd0.)
+   Set errno to ENOSPC so they get a sensible diagnostic.  */
+# define ZERO_BYTE_TRANSFER_ERRNO ENOSPC
+#endif
 
-/* 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.  */
+/* Write(read) COUNT bytes at BUF to(from) descriptor FD, retrying if
+   interrupted or if a partial write(read) occurs.  Return the number
+   of bytes transferred.
+   When writing, set errno if fewer than COUNT bytes are written.
+   When reading, if fewer than COUNT bytes are read, you must examine
+   errno to distinguish failure from EOF (errno == 0).  */
 size_t
-full_write (int fd, const void *buf, size_t count)
+full_rw (int fd, const void *buf, size_t count)
 {
-  size_t total_written = 0;
+  size_t total = 0;
+  const char *ptr = (const char *) buf;
 
-  if (count > 0)
+  while (count > 0)
     {
-      const char *ptr = buf;
-
-      do
-       {
-         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;
-       }
-      while (count > 0);
+      size_t n_rw = safe_rw (fd, ptr, count);
+      if (n_rw == (size_t) -1)
+        break;
+      if (n_rw == 0)
+        {
+          errno = ZERO_BYTE_TRANSFER_ERRNO;
+          break;
+        }
+      total += n_rw;
+      ptr += n_rw;
+      count -= n_rw;
     }
 
-  return total_written;
+  return total;
 }