Mail Archives: cygwin/2006/08/16/16:36:02
On Aug 16 11:43, Donna Jecha wrote:
> In the function msync in the file src/winsup/cygwin/mmap.cc, the declaration for pagesize goes out of its way to invoke either getsystempagesize -or- getpagesize():
>
>
> 1366 size_t pagesize = wincap.has_mmap_alignment_bug () ?
> 1367 getsystempagesize () : getpagesize ();
>
>
> Later in this same function, however, only getpagesize() is called:
>
>
> 1393 for (DWORD i = getpagesize (); i < len; i += getpagesize ())
>
>
> Shouldn't the getpagesize invocation at line 1383 also be conditional as to which gets called as is done on line 1367???
Maybe, I have to have another look into that. But that can't be the
reason for the ENOMEM problem since getpagesize is definitely correct
for NT systems as you're using. getsystempagesize is only the right
choice for systems with the mmap alignment bug, which are 95/98/Me.
I'm not overly concerned by that since 9x support is phased out anyway.
> fsx is a file system exerciser program. It has proven to be a good test case for finding corruption problems. The fsx program works on cygwin 1.5.18, but not on cygwin 1.5.19. On cygwin 1.5.19, msync always returns a status of -1 and sets errno to ENOMEM. Here's the code snippet:
>
> 673 pg_offset = offset & page_mask;
> 674 map_size = pg_offset + size;
> 675
> 676 if ((p = (char *)mmap(0, map_size, PROT_READ | PROT_WRITE,
> 677 MAP_FILE | MAP_SHARED, fd,
> 678 (off_t)(offset - pg_offset))) == (char *)-1) {
> 679 prterr("domapwrite: mmap");
> 680 report_failure(202);
> 681 }
> 682 memcpy(p + pg_offset, good_buf + offset, size); // status of memcpy is not checked ... yet
> 683 if (msync(p, map_size, 0) != 0) {
> 684 prterr("domapwrite: msync");
> 685 report_failure(203);
> 686 }
> 687
> 688 check_eofpage("Write", offset, p, size);
> 689
> 690 if (munmap(p, map_size) != 0) {
> 691 prterr("domapwrite: munmap");
> 692 report_failure(204);
> 693 }
Would you mind to create a self-contained, *minimal* testcase from that?
The snippet alone seems correct but I'm missing a few parameters like,
for instance the values of offset and page_mask, etc. If you could
create a tiny testcase which builds out of the box and reproduces the
problem, that would be enourmeously helpful.
Thanks in advance,
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Project Co-Leader cygwin AT cygwin DOT com
Red Hat
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