On Mon, 25 Aug 2003 11:27:31 +0300
Gavrie Philipson <[EMAIL PROTECTED]> wrote:
> I'll be able to do that tomorrow, hopefully. I'll also do some more
> tests with another NFS server.
Can you please try running the attached test case? It contains an
extract of the relevant code in standalone form. Just run with
./mmaptest /disksites/scratchfile
Thanks,
--
Martin
/*
* Copyright abandoned 2003 by Martin Pool. Share and enjoy.
*
* Test case for mmap failures on NFS, reported to be causing problems
* in distcc and ccache in August 2003.
*
* This is an extracted form of the code in dcc_r_bulk_plain() in
* distcc 2.10.1.
*
* It ought to be valid to just mmap(), truncate, write some data in
* and then munmap(). This seems correct according to the manuals and
* the source of other programs, such as tdb.
*
* However, on NFS in Red Hat 9, this seems to give a file full of
* NULLs. Perhaps the buffer is discarded by the kernel before it
* gets sent to the NFS server.
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <sys/time.h>
#include <sys/mman.h>
int main(int argc, char *argv[])
{
int fd, check_fd;
unsigned char *map_buf, *check_buf;
const size_t data_len = 100<<10;
int i;
unsigned char fill_val = 'a';
if (argc != 2) {
fprintf(stderr, "usage: mmaptest FILE\n"
"FILE is replaced with scratch data!\n"
"Try a file on NFS to check for bugs.\n");
return 1;
}
if ((fd = open(argv[1], O_CREAT|O_EXCL|O_RDWR, 0600)) == -1) {
perror("open");
return 1;
}
map_buf = mmap(NULL, /* anywhere */
data_len,
PROT_READ|PROT_WRITE,
MAP_SHARED,
fd,
0); /* offset */
if (map_buf == MAP_FAILED) {
perror("mmap");
return 1;
}
if (ftruncate(fd, data_len) == -1) {
perror("ftruncate");
return 1;
}
memset(map_buf, fill_val, data_len);
if (munmap(map_buf, data_len) == -1) {
perror("munmap");
return 1;
}
if (close(fd) == -1) {
perror("close");
return 1;
}
/* now open the file, re-read and check it */
if ((check_fd = open(argv[1], O_RDONLY, 0)) == -1) {
perror("open");
return 1;
}
if (!(check_buf = malloc(data_len))) {
perror("malloc");
return 1;
}
if (read(check_fd, check_buf, data_len) != data_len) {
perror("read");
return 1;
}
for (i = 0; i < data_len; i++) {
if (check_buf[i] != fill_val) {
fprintf(stderr,
"mismatch at %d! %#x != %#x\n",
i, (int) check_buf[i], (int) fill_val);
return 1;
}
}
if (close(check_fd) == -1) {
perror("close");
return 1;
}
return 0;
}
/*
* Local variables:
* c-file-style: "linux"
* compile-command: "gcc -Wall -static -o mmaptest mmaptest.c"
* End:
*/
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