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coreutils fix for dd blocksizes >= 2**31 bytes
From: |
Paul Eggert |
Subject: |
coreutils fix for dd blocksizes >= 2**31 bytes |
Date: |
Mon, 02 Aug 2004 00:13:27 -0700 |
User-agent: |
Gnus/5.1006 (Gnus v5.10.6) Emacs/21.3 (gnu/linux) |
GNU coreutils dd currently mishandles I/O blocksizes of 2**31 bytes or
greater, due to a workaround for a Tru64 5.1 bug with these
blocksizes. I installed the following patch, which I tested on a
64-bit Solaris host.
2004-08-01 Paul Eggert <address@hidden>
* safe-read.c (errno): Remove decl; we now assume C89 or better.
(safe_rw): Don't work around Tru64 bug unless the bug symptoms
manifest themselves. This allows us to do proper reads and writes
on other hosts, e.g., "dd" with a block size greater than 2**31.
Index: safe-read.c
===================================================================
RCS file: /home/eggert/coreutils/cu/lib/safe-read.c,v
retrieving revision 1.22
retrieving revision 1.23
diff -p -u -r1.22 -r1.23
--- safe-read.c 18 Aug 2003 09:44:49 -0000 1.22
+++ safe-read.c 2 Aug 2004 05:55:54 -0000 1.23
@@ -1,5 +1,7 @@
/* 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
@@ -33,9 +35,6 @@
#endif
#include <errno.h>
-#ifndef errno
-extern int errno;
-#endif
#ifdef EINTR
# define IS_EINTR(x) ((x) == EINTR)
@@ -61,22 +60,23 @@ extern int errno;
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;
+ }
}
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