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Subject[PATCH v2 2/5] test: verify fdinfo for pidfd of reaped process
Date
Test that the fdinfo field of a pidfd referring to a dead process
correctly shows Pid: -1 and NSpid: -1.

Cc: Christian Kellner <christian@kellner.me>
Reviewed-by: Christian Kellner <christian@kellner.me>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
/* v1 */
Link: https://lore.kernel.org/r/20191015141332.4055-2-christian.brauner@ubuntu.com

/* v2 */
unchanged
---
.../selftests/pidfd/pidfd_fdinfo_test.c | 59 ++++++++++++++-----
1 file changed, 45 insertions(+), 14 deletions(-)

diff --git a/tools/testing/selftests/pidfd/pidfd_fdinfo_test.c b/tools/testing/selftests/pidfd/pidfd_fdinfo_test.c
index 3721be994abd..22558524f71c 100644
--- a/tools/testing/selftests/pidfd/pidfd_fdinfo_test.c
+++ b/tools/testing/selftests/pidfd/pidfd_fdinfo_test.c
@@ -113,11 +113,15 @@ static struct child clone_newns(int (*fn)(void *), void *args,
return ret;
}

+static inline void child_close(struct child *child)
+{
+ close(child->fd);
+}
+
static inline int child_join(struct child *child, struct error *err)
{
int r;

- (void)close(child->fd);
r = wait_for_pid(child->pid);
if (r < 0)
error_set(err, PIDFD_ERROR, "waitpid failed (ret %d, errno %d)",
@@ -128,6 +132,12 @@ static inline int child_join(struct child *child, struct error *err)
return r;
}

+static inline int child_join_close(struct child *child, struct error *err)
+{
+ child_close(child);
+ return child_join(child, err);
+}
+
static inline void trim_newline(char *str)
{
char *pos = strrchr(str, '\n');
@@ -136,8 +146,8 @@ static inline void trim_newline(char *str)
*pos = '\0';
}

-static int verify_fdinfo_nspid(int pidfd, struct error *err,
- const char *expect, ...)
+static int verify_fdinfo(int pidfd, struct error *err, const char *prefix,
+ size_t prefix_len, const char *expect, ...)
{
char buffer[512] = {0, };
char path[512] = {0, };
@@ -160,17 +170,20 @@ static int verify_fdinfo_nspid(int pidfd, struct error *err,
pidfd);

while (getline(&line, &n, f) != -1) {
- if (strncmp(line, "NSpid:", 6))
+ char *val;
+
+ if (strncmp(line, prefix, prefix_len))
continue;

found = 1;

- r = strcmp(line + 6, buffer);
+ val = line + prefix_len;
+ r = strcmp(val, buffer);
if (r != 0) {
trim_newline(line);
trim_newline(buffer);
- error_set(err, PIDFD_FAIL, "NSpid: '%s' != '%s'",
- line + 6, buffer);
+ error_set(err, PIDFD_FAIL, "%s '%s' != '%s'",
+ prefix, val, buffer);
}
break;
}
@@ -179,8 +192,8 @@ static int verify_fdinfo_nspid(int pidfd, struct error *err,
fclose(f);

if (found == 0)
- return error_set(err, PIDFD_FAIL, "NSpid not found for fd %d",
- pidfd);
+ return error_set(err, PIDFD_FAIL, "%s not found for fd %d",
+ prefix, pidfd);

return PIDFD_PASS;
}
@@ -213,7 +226,7 @@ static int child_fdinfo_nspid_test(void *args)
}

pidfd = *(int *)args;
- r = verify_fdinfo_nspid(pidfd, &err, "\t0\n");
+ r = verify_fdinfo(pidfd, &err, "NSpid:", 6, "\t0\n");

if (r != PIDFD_PASS)
ksft_print_msg("NSpid fdinfo check failed: %s\n", err.msg);
@@ -242,24 +255,42 @@ static void test_pidfd_fdinfo_nspid(void)
/* The children will have pid 1 in the new pid namespace,
* so the line must be 'NSPid:\t<pid>\t1'.
*/
- verify_fdinfo_nspid(a.fd, &err, "\t%d\t%d\n", a.pid, 1);
- verify_fdinfo_nspid(b.fd, &err, "\t%d\t%d\n", b.pid, 1);
+ verify_fdinfo(a.fd, &err, "NSpid:", 6, "\t%d\t%d\n", a.pid, 1);
+ verify_fdinfo(b.fd, &err, "NSpid:", 6, "\t%d\t%d\n", b.pid, 1);

/* wait for the process, check the exit status and set
* 'err' accordingly, if it is not already set.
*/
+ child_join_close(&a, &err);
+ child_join_close(&b, &err);
+
+ error_report(&err, test_name);
+}
+
+static void test_pidfd_dead_fdinfo(void)
+{
+ struct child a;
+ struct error err = {0, };
+ const char *test_name = "pidfd check fdinfo for dead process";
+
+ /* Create a new child in a new pid and mount namespace */
+ a = clone_newns(child_fdinfo_nspid_test, NULL, &err);
+ error_check(&err, test_name);
child_join(&a, &err);
- child_join(&b, &err);

+ verify_fdinfo(a.fd, &err, "Pid:", 4, "\t-1\n");
+ verify_fdinfo(a.fd, &err, "NSpid:", 6, "\t-1\n");
+ child_close(&a);
error_report(&err, test_name);
}

int main(int argc, char **argv)
{
ksft_print_header();
- ksft_set_plan(1);
+ ksft_set_plan(2);

test_pidfd_fdinfo_nspid();
+ test_pidfd_dead_fdinfo();

return ksft_exit_pass();
}
--
2.23.0
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