/* An interface to read and write that retries after interrupts.
- Copyright (C) 1993, 1994, 1998, 2002-2003 Free Software Foundation, Inc.
+
+ Copyright (C) 1993, 1994, 1998, 2002, 2003, 2004 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
#endif
#include <errno.h>
-#ifndef errno
-extern int errno;
-#endif
#ifdef EINTR
# define IS_EINTR(x) ((x) == EINTR)
size_t
safe_rw (int fd, void const *buf, size_t count)
{
- ssize_t result;
-
- /* POSIX limits COUNT to SSIZE_MAX, but we limit it further, requiring
- that COUNT <= INT_MAX, to avoid triggering a bug in Tru64 5.1.
- When decreasing COUNT, keep the file pointer block-aligned.
- Note that in any case, read(write) may succeed, yet read(write)
- fewer than COUNT bytes, so the caller must be prepared to handle
- partial results. */
- if (count > INT_MAX)
- count = INT_MAX & ~8191;
+ /* 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 };
- do
+ for (;;)
{
- result = rw (fd, buf, count);
- }
- while (result < 0 && IS_EINTR (errno));
+ ssize_t result = rw (fd, buf, count);
- return (size_t) result;
+ 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;
+ }
}