-/* safe-read.c -- an interface to read that retries after interrupts
- Copyright (C) 1993, 1994, 1998, 2000 Free Software Foundation, Inc.
+/* An interface to read and write that retries after interrupts.
- This program is free software; you can redistribute it and/or modify
+ Copyright (C) 1993-1994, 1998, 2002-2006, 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
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/>. */
+
+#include <config.h>
-#if HAVE_CONFIG_H
-# include <config.h>
+/* Specification. */
+#ifdef SAFE_WRITE
+# include "safe-write.h"
+#else
+# include "safe-read.h"
#endif
+/* Get ssize_t. */
#include <sys/types.h>
-
-#if HAVE_UNISTD_H
-# include <unistd.h>
-#endif
+#include <unistd.h>
#include <errno.h>
-#ifndef errno
-extern int errno;
+
+#ifdef EINTR
+# define IS_EINTR(x) ((x) == EINTR)
+#else
+# define IS_EINTR(x) 0
#endif
-#include "safe-read.h"
+#include <limits.h>
-/* Read LEN bytes at PTR from descriptor DESC, retrying if interrupted.
- Return the actual number of bytes read, zero for EOF, or negative
- for an error. */
+#ifdef SAFE_WRITE
+# define safe_rw safe_write
+# define rw write
+#else
+# define safe_rw safe_read
+# define rw read
+# undef const
+# define const /* empty */
+#endif
-ssize_t
-safe_read (int desc, void *ptr, size_t len)
+/* Read(write) up to COUNT bytes at BUF from(to) descriptor FD, retrying if
+ interrupted. Return the actual number of bytes read(written), zero for EOF,
+ or SAFE_READ_ERROR(SAFE_WRITE_ERROR) upon error. */
+size_t
+safe_rw (int fd, void const *buf, size_t count)
{
- ssize_t n_chars;
+ /* Work around a bug in Tru64 5.1. Attempting to read more than
+ INT_MAX bytes fails with errno == EINVAL. See
+ <http://lists.gnu.org/archive/html/bug-gnu-utils/2002-04/msg00010.html>.
+ When decreasing COUNT, keep it block-aligned. */
+ enum { BUGGY_READ_MAXIMUM = INT_MAX & ~8191 };
- if (len <= 0)
- return len;
-
-#ifdef EINTR
- do
+ for (;;)
{
- n_chars = read (desc, ptr, len);
- }
- while (n_chars < 0 && errno == EINTR);
-#else
- n_chars = read (desc, ptr, len);
-#endif
+ ssize_t result = rw (fd, buf, count);
- return n_chars;
+ if (0 <= result)
+ return result;
+ else if (IS_EINTR (errno))
+ continue;
+ else if (errno == EINVAL && BUGGY_READ_MAXIMUM < count)
+ count = BUGGY_READ_MAXIMUM;
+ else
+ return result;
+ }
}