-/* safe-read.c -- an interface to read that retries after interrupts
- Copyright (C) 1993, 1994 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, 2009-2010 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., 675 Mass Ave, Cambridge, MA 02139, USA.
- */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
-#ifdef 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>
-
-#ifdef HAVE_UNISTD_H
#include <unistd.h>
-#endif
#include <errno.h>
-#ifndef STDC_HEADERS
-extern int errno;
+
+#ifdef EINTR
+# define IS_EINTR(x) ((x) == EINTR)
+#else
+# define IS_EINTR(x) 0
#endif
-/* Read LEN bytes at PTR from descriptor DESC, for file FILENAME,
- retrying if necessary. Return a negative value if an error occurs,
- otherwise return the actual number of bytes read,
- which must be LEN unless end-of-file was reached. */
+#include <limits.h>
- The canonical source for this function is in the gcc distribution
- in file cccp.c. So don't make any changes here. */
+#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
-static int
-safe_read (desc, ptr, len)
- int desc;
- char *ptr;
- int 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)
{
- int left = len;
- while (left > 0) {
- int nchars = read (desc, ptr, left);
- if (nchars < 0)
- {
-#ifdef EINTR
- if (errno == EINTR)
- continue;
-#endif
- return nchars;
- }
- if (nchars == 0)
- break;
- ptr += nchars;
- left -= nchars;
- }
- return len - left;
+ /* 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 };
+
+ for (;;)
+ {
+ ssize_t result = rw (fd, buf, count);
+
+ 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;
+ }
}