dup2(2, nr_open+64) may cause ENOMEM error, change to dup2(2, bits_per_long +1) and set nr_open to bits_per_long to avoid ENOMEM.
Signed-off-by: lufei <[email protected]> --- tools/testing/selftests/core/unshare_test.c | 32 +++++++-------------- 1 file changed, 11 insertions(+), 21 deletions(-) diff --git a/tools/testing/selftests/core/unshare_test.c b/tools/testing/selftests/core/unshare_test.c index 7fec9dfb1b0e..ea4caa7ec28d 100644 --- a/tools/testing/selftests/core/unshare_test.c +++ b/tools/testing/selftests/core/unshare_test.c @@ -28,8 +28,8 @@ TEST(unshare_EMFILE) int fd; ssize_t n, n2; static char buf[512], buf2[512]; - struct rlimit rlimit; int nr_open; + int bits_per_long = sizeof(long) * 8; fd = open("/proc/sys/fs/nr_open", O_RDWR); ASSERT_GE(fd, 0); @@ -40,24 +40,8 @@ TEST(unshare_EMFILE) ASSERT_EQ(sscanf(buf, "%d", &nr_open), 1); - ASSERT_EQ(0, getrlimit(RLIMIT_NOFILE, &rlimit)); - - /* bump fs.nr_open */ - n2 = sprintf(buf2, "%d\n", nr_open + 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; - 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 >= bits_per_long */ + EXPECT_GE(dup2(2, bits_per_long+1), 0) { lseek(fd, 0, SEEK_SET); write(fd, buf, n); exit(EXIT_FAILURE); @@ -74,15 +58,21 @@ TEST(unshare_EMFILE) if (pid == 0) { int err; - /* restore fs.nr_open */ + /* set nr_open == bits_per_long */ + n2 = sprintf(buf2, "%d\n", bits_per_long); lseek(fd, 0, SEEK_SET); - write(fd, buf, n); + write(fd, buf2, n2); + /* ... 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); exit(EXIT_SUCCESS); } -- 2.39.3
