1 files changed, 169 insertions, 0 deletions

diff --git a/tools/testing/selftests/pidfd/pidfd_open_test.c b/tools/testing/selftests/pidfd/pidfd_open_test.c
new file mode 100644
index 000000000000..0377133dd6dc
--- /dev/null
+++ b/tools/testing/selftests/pidfd/pidfd_open_test.c
@@ -0,0 +1,169 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <syscall.h>
+#include <sys/mount.h>
+#include <sys/prctl.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "pidfd.h"
+#include "../kselftest.h"
+
+static inline int sys_pidfd_open(pid_t pid, unsigned int flags)
+{
+        return syscall(__NR_pidfd_open, pid, flags);
+}
+
+static int safe_int(const char *numstr, int *converted)
+{
+        char *err = NULL;
+        long sli;
+
+        errno = 0;
+        sli = strtol(numstr, &err, 0);
+        if (errno == ERANGE && (sli == LONG_MAX || sli == LONG_MIN))
+                return -ERANGE;
+
+        if (errno != 0 && sli == 0)
+                return -EINVAL;
+
+        if (err == numstr || *err != '\0')
+                return -EINVAL;
+
+        if (sli > INT_MAX || sli < INT_MIN)
+                return -ERANGE;
+
+        *converted = (int)sli;
+        return 0;
+}
+
+static int char_left_gc(const char *buffer, size_t len)
+{
+        size_t i;
+
+        for (i = 0; i < len; i++) {
+                if (buffer[i] == ' ' ||
+                    buffer[i] == '\t')
+                        continue;
+
+                return i;
+        }
+
+        return 0;
+}
+
+static int char_right_gc(const char *buffer, size_t len)
+{
+        int i;
+
+        for (i = len - 1; i >= 0; i--) {
+                if (buffer[i] == ' '  ||
+                    buffer[i] == '\t' ||
+                    buffer[i] == '\n' ||
+                    buffer[i] == '\0')
+                        continue;
+
+                return i + 1;
+        }
+
+        return 0;
+}
+
+static char *trim_whitespace_in_place(char *buffer)
+{
+        buffer += char_left_gc(buffer, strlen(buffer));
+        buffer[char_right_gc(buffer, strlen(buffer))] = '\0';
+        return buffer;
+}
+
+static pid_t get_pid_from_fdinfo_file(int pidfd, const char *key, size_t keylen)
+{
+        int ret;
+        char path[512];
+        FILE *f;
+        size_t n = 0;
+        pid_t result = -1;
+        char *line = NULL;
+
+        snprintf(path, sizeof(path), "/proc/self/fdinfo/%d", pidfd);
+
+        f = fopen(path, "re");
+        if (!f)
+                return -1;
+
+        while (getline(&line, &n, f) != -1) {
+                char *numstr;
+
+                if (strncmp(line, key, keylen))
+                        continue;
+
+                numstr = trim_whitespace_in_place(line + 4);
+                ret = safe_int(numstr, &result);
+                if (ret < 0)
+                        goto out;
+
+                break;
+        }
+
+out:
+        free(line);
+        fclose(f);
+        return result;
+}
+
+int main(int argc, char **argv)
+{
+        int pidfd = -1, ret = 1;
+        pid_t pid;
+
+        ksft_set_plan(3);
+
+        pidfd = sys_pidfd_open(-1, 0);
+        if (pidfd >= 0) {
+                ksft_print_msg(
+                        "%s - succeeded to open pidfd for invalid pid -1\n",
+                        strerror(errno));
+                goto on_error;
+        }
+        ksft_test_result_pass("do not allow invalid pid test: passed\n");
+
+        pidfd = sys_pidfd_open(getpid(), 1);
+        if (pidfd >= 0) {
+                ksft_print_msg(
+                        "%s - succeeded to open pidfd with invalid flag value specified\n",
+                        strerror(errno));
+                goto on_error;
+        }
+        ksft_test_result_pass("do not allow invalid flag test: passed\n");
+
+        pidfd = sys_pidfd_open(getpid(), 0);
+        if (pidfd < 0) {
+                ksft_print_msg("%s - failed to open pidfd\n", strerror(errno));
+                goto on_error;
+        }
+        ksft_test_result_pass("open a new pidfd test: passed\n");
+
+        pid = get_pid_from_fdinfo_file(pidfd, "Pid:", sizeof("Pid:") - 1);
+        ksft_print_msg("pidfd %d refers to process with pid %d\n", pidfd, pid);
+
+        ret = 0;
+
+on_error:
+        if (pidfd >= 0)
+                close(pidfd);
+
+        return !ret ? ksft_exit_pass() : ksft_exit_fail();
+}