[PATCH v3 2/2] selftests: core: add tests for CLOSE_RANGE_CLOEXEC

From: Giuseppe Scrivano
Date: Wed Nov 18 2020 - 05:48:33 EST


check that close_range(initial_fd, last_fd, CLOSE_RANGE_CLOEXEC)
correctly sets the close-on-exec bit for the specified file
descriptors.

Open 100 file descriptors and set the close-on-exec flag for a subset
of them first, then set it for every file descriptor above 2. Make
sure RLIMIT_NOFILE doesn't affect the result.

Signed-off-by: Giuseppe Scrivano <gscrivan@xxxxxxxxxx>
---
.../testing/selftests/core/close_range_test.c | 74 +++++++++++++++++++
1 file changed, 74 insertions(+)

diff --git a/tools/testing/selftests/core/close_range_test.c b/tools/testing/selftests/core/close_range_test.c
index c99b98b0d461..18992c383852 100644
--- a/tools/testing/selftests/core/close_range_test.c
+++ b/tools/testing/selftests/core/close_range_test.c
@@ -11,6 +11,7 @@
#include <string.h>
#include <syscall.h>
#include <unistd.h>
+#include <sys/resource.h>

#include "../kselftest_harness.h"
#include "../clone3/clone3_selftests.h"
@@ -23,6 +24,10 @@
#define CLOSE_RANGE_UNSHARE (1U << 1)
#endif

+#ifndef CLOSE_RANGE_CLOEXEC
+#define CLOSE_RANGE_CLOEXEC (1U << 2)
+#endif
+
static inline int sys_close_range(unsigned int fd, unsigned int max_fd,
unsigned int flags)
{
@@ -224,4 +229,73 @@ TEST(close_range_unshare_capped)
EXPECT_EQ(0, WEXITSTATUS(status));
}

+TEST(close_range_cloexec)
+{
+ int i, ret;
+ int open_fds[101];
+ struct rlimit rlimit;
+
+ for (i = 0; i < ARRAY_SIZE(open_fds); i++) {
+ int fd;
+
+ fd = open("/dev/null", O_RDONLY);
+ ASSERT_GE(fd, 0) {
+ if (errno == ENOENT)
+ XFAIL(return, "Skipping test since /dev/null does not exist");
+ }
+
+ open_fds[i] = fd;
+ }
+
+ ret = sys_close_range(1000, 1000, CLOSE_RANGE_CLOEXEC);
+ if (ret < 0) {
+ if (errno == ENOSYS)
+ XFAIL(return, "close_range() syscall not supported");
+ if (errno == EINVAL)
+ XFAIL(return, "close_range() doesn't support CLOSE_RANGE_CLOEXEC");
+ }
+
+ /* Ensure the FD_CLOEXEC bit is set also with a resource limit in place. */
+ ASSERT_EQ(0, getrlimit(RLIMIT_NOFILE, &rlimit));
+ rlimit.rlim_cur = 25;
+ ASSERT_EQ(0, setrlimit(RLIMIT_NOFILE, &rlimit));
+
+ /* Set close-on-exec for two ranges: [0-50] and [75-100]. */
+ ret = sys_close_range(open_fds[0], open_fds[50], CLOSE_RANGE_CLOEXEC);
+ ASSERT_EQ(0, ret);
+ ret = sys_close_range(open_fds[75], open_fds[100], CLOSE_RANGE_CLOEXEC);
+ ASSERT_EQ(0, ret);
+
+ for (i = 0; i <= 50; i++) {
+ int flags = fcntl(open_fds[i], F_GETFD);
+
+ EXPECT_GT(flags, -1);
+ EXPECT_EQ(flags & FD_CLOEXEC, FD_CLOEXEC);
+ }
+
+ for (i = 51; i <= 74; i++) {
+ int flags = fcntl(open_fds[i], F_GETFD);
+
+ EXPECT_GT(flags, -1);
+ EXPECT_EQ(flags & FD_CLOEXEC, 0);
+ }
+
+ for (i = 75; i <= 100; i++) {
+ int flags = fcntl(open_fds[i], F_GETFD);
+
+ EXPECT_GT(flags, -1);
+ EXPECT_EQ(flags & FD_CLOEXEC, FD_CLOEXEC);
+ }
+
+ /* Test a common pattern. */
+ ret = sys_close_range(3, UINT_MAX, CLOSE_RANGE_CLOEXEC);
+ for (i = 0; i <= 100; i++) {
+ int flags = fcntl(open_fds[i], F_GETFD);
+
+ EXPECT_GT(flags, -1);
+ EXPECT_EQ(flags & FD_CLOEXEC, FD_CLOEXEC);
+ }
+}
+
+
TEST_HARNESS_MAIN
--
2.28.0