Hi Petr,
Thanks very much for reply.
On Mon, Mar 31, 2025 at 08:32:27PM +0200, Petr Vorel wrote:
Hi all,
Set maximum file descriptor number limit by rlimit.rlim_max than nr_open(hard limit). Hard limit may cause dup2 fail.
It actually changes from failure:
# ./unshare_test TAP version 13 1..1 # Starting 1 tests from 1 test cases. # RUN global.unshare_EMFILE ... # unshare_test.c:60:unshare_EMFILE:Expected dup2(2, nr_open + 64) (-1) >= 0 (0) # unshare_EMFILE: Test failed # FAIL global.unshare_EMFILE not ok 1 global.unshare_EMFILE # FAILED: 0 / 1 tests passed. # Totals: pass:0 fail:1 xfail:0 xpass:0 skip:0 error:0
to pass:
TAP version 13 1..1 # Starting 1 tests from 1 test cases. # RUN global.unshare_EMFILE ... # OK global.unshare_EMFILE ok 1 global.unshare_EMFILE # PASSED: 1 / 1 tests passed. # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
Signed-off-by: lufei lufei@uniontech.com
tools/testing/selftests/core/unshare_test.c | 28 +++++++++++++-------- 1 file changed, 18 insertions(+), 10 deletions(-)
diff --git a/tools/testing/selftests/core/unshare_test.c b/tools/testing/selftests/core/unshare_test.c index 7fec9dfb1b0e..2c4e7104b0d9 100644 --- a/tools/testing/selftests/core/unshare_test.c +++ b/tools/testing/selftests/core/unshare_test.c @@ -26,10 +26,11 @@ TEST(unshare_EMFILE) .exit_signal = SIGCHLD, }; int fd;
- ssize_t n, n2;
- static char buf[512], buf2[512];
- ssize_t n, n2, n3;
- static char buf[512], buf2[512], buf3[512]; struct rlimit rlimit; int nr_open;
- int rlimit_max;
fd = open("/proc/sys/fs/nr_open", O_RDWR); ASSERT_GE(fd, 0); @@ -42,22 +43,24 @@ TEST(unshare_EMFILE)
ASSERT_EQ(0, getrlimit(RLIMIT_NOFILE, &rlimit));
- /* bump fs.nr_open */
- n2 = sprintf(buf2, "%d\n", nr_open + 1024);
- rlimit_max = rlimit.rlim_max;
- /* bump rlimit.rlim_max */
- n2 = sprintf(buf2, "%d\n", rlimit_max + 1024); lseek(fd, 0, SEEK_SET); write(fd, buf2, n2);
/* bump ulimit -n */
- rlimit.rlim_cur = nr_open + 1024;
- rlimit.rlim_max = nr_open + 1024;
- rlimit.rlim_cur = rlimit_max + 1024;
- rlimit.rlim_max = rlimit_max + 1024; EXPECT_EQ(0, setrlimit(RLIMIT_NOFILE, &rlimit)) { lseek(fd, 0, SEEK_SET); write(fd, buf, n); exit(EXIT_FAILURE); }
- /* get a descriptor past the old fs.nr_open */
- EXPECT_GE(dup2(2, nr_open + 64), 0) {
- /* get a descriptor past the old rlimit.rlim_max */
- EXPECT_GE(dup2(2, rlimit_max + 64), 0) { lseek(fd, 0, SEEK_SET); write(fd, buf, n); exit(EXIT_FAILURE);
@@ -74,15 +77,20 @@ TEST(unshare_EMFILE) if (pid == 0) { int err;
/* restore fs.nr_open */
n3 = sprintf(buf3, "%d\n", rlimit_max);
write(fd, buf, n);
write(fd, buf3, n3);nit: do we really need buf3? Can't we reuse buf2? Or do I miss something obvious?
Reuse buf2 is better. I'll make change.
Reviewed-by: Petr Vorel pvorel@suse.cz
Kind regards, Petr
- /* ... and now unshare(CLONE_FILES) must fail with EMFILE */ err = unshare(CLONE_FILES); EXPECT_EQ(err, -1) exit(EXIT_FAILURE); EXPECT_EQ(errno, EMFILE) exit(EXIT_FAILURE);
/* restore fs.nr_open */lseek(fd, 0, SEEK_SET);write(fd, buf, n);