Two possibly independent bugs found by 'stress-ng --lockf ...':
1) lockf() may abort the process with api_fatal() if the new range
partly overlaps with two ranges previously locked by the same process.
2) lockf() prints a warning on too many locks and returns success. It
should not print a warning and fail with ENOLCK instead.
Testcase for both:
$ uname -r
3.5.4-1.x86_64
$ cat locktest.c
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
static int lock_at(int fd, int off, int size)
{
if (lseek(fd, off, SEEK_SET) < 0) {
perror("lseek"); return -1;
}
printf("\rlock %d-%d\n", off, off + size - 1); fflush(stdout);
if (lockf(fd, F_LOCK, size) < 0) {
perror("lock"); return -1;
}
return 0;
}
int main(int argc, char **argv)
{
int fd = open("locktest.tmp", O_RDWR|O_CREAT, 0666);
if (fd < 0) {
perror("open"); return 1;
}
if (argc == 1) {
lock_at(fd, 0, 2);
lock_at(fd, 2, 2);
lock_at(fd, 1, 2);
}
else {
for (int i = 0; i < 914; i++)
if (lock_at(fd, i, 1))
return 1;
}
printf("\rdone\n");
return 0;
}
$ gcc -o locktest locktest.c
$ ./locktest
lock 0-1
lock 2-3
lock 1-2
1 [main] locktest 44864 C:\cygwin64\tmp\locktest.exe: \
*** fatal error - NtCreateEvent(lock): 0xC0000035\
Hangup
$ ./locktest loop
lock 0-0
lock 1-1
lock 2-2
lock 3-3
...
lock 909-909
lock 910-910
lock 911-911
0 [main] locktest 44865 inode_t::get_all_locks_list: \
Warning, can't handle more than 910 locks per file.
lock 912-912
727 [main] locktest 44865 inode_t::get_all_locks_list: \
Warning, can't handle more than 910 locks per file.
lock 913-913
1329 [main] locktest 44865 inode_t::get_all_locks_list: \
Warning, can't handle more than 910 locks per file.
done
There is possibly also an off-by-one error as the 912'th lockf() prints
the first warning.
--
Regards,
Christian
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