Jeffrey Hutzelman wrote:
On Friday, March 09, 2007 03:51:32 PM -0600 "Douglas E. Engert"
<[EMAIL PROTECTED]> wrote:
Derrick J Brashear wrote:
On Fri, 9 Mar 2007, Douglas E. Engert wrote:
It was not clear if this was a name made up by AFS, or a
name that is defined on some OS. If its an AFS made up name than
I agree.
The idea was to use the OS' definition, if they defined it. However, the
question then is whether OFFSET_MAX(fd) is portable, or whether this is
just inherently a non-portable macro and we have to do something ugly.
If I understand the comments in the code in that area, you are trying
to detect if the af->l_len is the max value for an offset, or if Java
may have passed in a 32 bit 0x7ffffffe, as this is what Java thinks is
the max. And why would java use the -1?
The comment is mostly useless. Please see the earlier mailing list
thread in which the author of that patch points out that his original
reference to 0x7ffffffe is in error, and the correct value is in fact
0x7ffffffffffffffe. The comments about -1 and 32 bits are merely an
attempt at explaining why some java implementations erroneously request
whole-file locks using that offset, but the explanation is irrelevant -
the important thing is that the bug exists, and this works around it.
If so, the use of 0x7fffffff in line 547 for non UNIX machines
is not right as it assumes a 32 bit offset. It really needs to look
at the max for an offset. The code after the comment about Java and 32
bit offset -1 does not make sense when using a OFFSET_MAX which is 64
bits.
Only the code after the comment is new. The code before it is correct -
I don't believe it is. It may be on Linux,
Here is the Solars 10 cc -E output of MODLOAD64/afs_vnop_flock*
27252 # 539
27253
27254 # 547
27255 if (af->l_len == 0x7fffffff)
27256 af->l_len = 0;
27257 # 554
27258
27259 # 559
27260 if (af->l_len == OFFSET_MAX -1)
27261 # 561
27262 af->l_len = 0;
27263
on AFS_LINUX24_ENV, we use OFFSET_MAX; on other platforms we use
0x7fffffff always, and, on 64-bit-kernel platforms, _also_ LONG_MAX
(0x7fffffffffffffff).
lines:
549 #ifdef AFS_LINUX_64BIT_KERNEL
550 if (af->l_len == LONG_MAX)
551 af->l_len = 0; /* since some systems indicate it as EOF */
552 #endif
Are not processed, as Solaris is not a "LINUX" system.
But LONG_MAX is defined in ./sys/types.h as
#if defined(_LP64)
#define LONG_MAX 9223372036854775807L
...
#else /* _ILP32 */
#define LONG_MAX 2147483647L
...
This has nothing whatsoever to do with the Java
issue; it is simply detecting cases where user-land or the OS depicts a
whole-file lock using the maximum possible offset instead of 0. It's
also not new.
-- Jeff
--
Douglas E. Engert <[EMAIL PROTECTED]>
Argonne National Laboratory
9700 South Cass Avenue
Argonne, Illinois 60439
(630) 252-5444
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