// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE

#include <errno.h>
#include <linux/limits.h>
#include <signal.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

#include "kselftest.h"
#include "cgroup_util.h"

static int run_success(const char *cgroup, void *arg)
{
        return 0;
}

static int run_pause(const char *cgroup, void *arg)
{
        return pause();
}

/*
 * This test checks that pids.max prevents forking new children above the
 * specified limit in the cgroup.
 */
static int test_pids_max(const char *root)
{
        int ret = KSFT_FAIL;
        char *cg_pids;
        int pid;

        cg_pids = cg_name(root, "pids_test");
        if (!cg_pids)
                goto cleanup;

        if (cg_create(cg_pids))
                goto cleanup;

        if (cg_read_strcmp(cg_pids, "pids.max", "max\n"))
                goto cleanup;

        if (cg_write(cg_pids, "pids.max", "2"))
                goto cleanup;

        if (cg_enter_current(cg_pids))
                goto cleanup;

        pid = cg_run_nowait(cg_pids, run_pause, NULL);
        if (pid < 0)
                goto cleanup;

        if (cg_run_nowait(cg_pids, run_success, NULL) != -1 || errno != EAGAIN)
                goto cleanup;

        if (kill(pid, SIGINT))
                goto cleanup;

        ret = KSFT_PASS;

cleanup:
        cg_enter_current(root);
        cg_destroy(cg_pids);
        free(cg_pids);

        return ret;
}

/*
 * This test checks that pids.events are counted in cgroup associated with pids.max
 */
static int test_pids_events(const char *root)
{
        int ret = KSFT_FAIL;
        char *cg_parent = NULL, *cg_child = NULL;
        int pid;

        if (cgroup_feature("pids_localevents") <= 0)
                return KSFT_SKIP;

        cg_parent = cg_name(root, "pids_parent");
        cg_child = cg_name(cg_parent, "pids_child");
        if (!cg_parent || !cg_child)
                goto cleanup;

        if (cg_create(cg_parent))
                goto cleanup;
        if (cg_write(cg_parent, "cgroup.subtree_control", "+pids"))
                goto cleanup;
        if (cg_create(cg_child))
                goto cleanup;

        if (cg_write(cg_parent, "pids.max", "2"))
                goto cleanup;

        if (cg_read_strcmp(cg_child, "pids.max", "max\n"))
                goto cleanup;

        if (cg_enter_current(cg_child))
                goto cleanup;

        pid = cg_run_nowait(cg_child, run_pause, NULL);
        if (pid < 0)
                goto cleanup;

        if (cg_run_nowait(cg_child, run_success, NULL) != -1 || errno != EAGAIN)
                goto cleanup;

        if (kill(pid, SIGINT))
                goto cleanup;

        if (cg_read_key_long(cg_child, "pids.events", "max ") != 0)
                goto cleanup;
        if (cg_read_key_long(cg_parent, "pids.events", "max ") != 1)
                goto cleanup;


        ret = KSFT_PASS;

cleanup:
        cg_enter_current(root);
        if (cg_child)
                cg_destroy(cg_child);
        if (cg_parent)
                cg_destroy(cg_parent);
        free(cg_child);
        free(cg_parent);

        return ret;
}



#define T(x) { x, #x }
struct pids_test {
        int (*fn)(const char *root);
        const char *name;
} tests[] = {
        T(test_pids_max),
        T(test_pids_events),
};
#undef T

int main(int argc, char **argv)
{
        char root[PATH_MAX];

        ksft_print_header();
        ksft_set_plan(ARRAY_SIZE(tests));
        if (cg_find_unified_root(root, sizeof(root), NULL))
                ksft_exit_skip("cgroup v2 isn't mounted\n");

        /*
         * Check that pids controller is available:
         * pids is listed in cgroup.controllers
         */
        if (cg_read_strstr(root, "cgroup.controllers", "pids"))
                ksft_exit_skip("pids controller isn't available\n");

        if (cg_read_strstr(root, "cgroup.subtree_control", "pids"))
                if (cg_write(root, "cgroup.subtree_control", "+pids"))
                        ksft_exit_skip("Failed to set pids controller\n");

        for (int i = 0; i < ARRAY_SIZE(tests); i++) {
                switch (tests[i].fn(root)) {
                case KSFT_PASS:
                        ksft_test_result_pass("%s\n", tests[i].name);
                        break;
                case KSFT_SKIP:
                        ksft_test_result_skip("%s\n", tests[i].name);
                        break;
                default:
                        ksft_test_result_fail("%s\n", tests[i].name);
                        break;
                }
        }

        ksft_finished();
}