maint: update copyright

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

diff --git a/lib/full-write.c b/lib/full-write.c
index 1feb2f7..b803677 100644 (file)
--- a/lib/full-write.c
+++ b/lib/full-write.c
@@ -1,10 +1,11 @@
-/* full-write.c -- an interface to write that retries after interrupts
-   Copyright (C) 1993, 1994, 1997, 1998, 2000 Free Software Foundation, Inc.
+/* An interface to read and write that retries (if necessary) until complete.
 
-   This program is free software; you can redistribute it and/or modify
+   Copyright (C) 1993-1994, 1997-2006, 2009-2014 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.
+   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
@@ -12,55 +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/>.  */
 
-   Copied largely from GNU C's cccp.c.
-   */
+#include <config.h>
 
-#if HAVE_CONFIG_H
-# include <config.h>
+/* Specification.  */
+#ifdef FULL_READ
+# include "full-read.h"
+#else
+# include "full-write.h"
 #endif
 
-#include <sys/types.h>
+#include <errno.h>
 
-#if HAVE_UNISTD_H
-# include <unistd.h>
+#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 <errno.h>
-#ifndef errno
-extern int errno;
+#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 LEN bytes at PTR to descriptor DESC, retrying if interrupted.
-   Return LEN upon success, write's (negative) error code otherwise.  */
-
-int
-full_write (int desc, const char *ptr, size_t len)
+/* 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_rw (int fd, const void *buf, size_t count)
 {
-  int total_written;
+  size_t total = 0;
+  const char *ptr = (const char *) buf;
 
-  total_written = 0;
-  while (len > 0)
+  while (count > 0)
     {
-      int written = write (desc, ptr, len);
-      /* write on an old Slackware Linux 1.2.13 returns zero when
-        I try to write more data than there is room on a floppy disk.
-        This puts dd into an infinite loop.  Reproduce with
-        dd if=/dev/zero of=/dev/fd0.  If you have this problem,
-        consider upgrading to a newer kernel.  */
-      if (written < 0)
-       {
-#ifdef EINTR
-         if (errno == EINTR)
-           continue;
-#endif
-         return written;
-       }
-      total_written += written;
-      ptr += written;
-      len -= written;
+      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;
 }