// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2024 Google */

#include <test_progs.h>
#include <bpf/libbpf.h>
#include <bpf/btf.h>
#include "kmem_cache_iter.skel.h"

#define SLAB_NAME_MAX  32

struct kmem_cache_result {
        char name[SLAB_NAME_MAX];
        long obj_size;
};

static void subtest_kmem_cache_iter_check_task_struct(struct kmem_cache_iter *skel)
{
        LIBBPF_OPTS(bpf_test_run_opts, opts,
                .flags = 0,  /* Run it with the current task */
        );
        int prog_fd = bpf_program__fd(skel->progs.check_task_struct);

        /* Get task_struct and check it if's from a slab cache */
        ASSERT_OK(bpf_prog_test_run_opts(prog_fd, &opts), "prog_test_run");

        /* The BPF program should set 'found' variable */
        ASSERT_EQ(skel->bss->task_struct_found, 1, "task_struct_found");
}

static void subtest_kmem_cache_iter_check_slabinfo(struct kmem_cache_iter *skel)
{
        FILE *fp;
        int map_fd;
        char name[SLAB_NAME_MAX];
        unsigned long objsize;
        char rest_of_line[1000];
        struct kmem_cache_result r;
        int seen = 0;

        fp = fopen("/proc/slabinfo", "r");
        if (fp == NULL) {
                /* CONFIG_SLUB_DEBUG is not enabled */
                return;
        }

        map_fd = bpf_map__fd(skel->maps.slab_result);

        /* Ignore first two lines for header */
        fscanf(fp, "slabinfo - version: %*d.%*d\n");
        fscanf(fp, "# %*s %*s %*s %*s %*s %*s : %[^\n]\n", rest_of_line);

        /* Compare name and objsize only - others can be changes frequently */
        while (fscanf(fp, "%s %*u %*u %lu %*u %*u : %[^\n]\n",
                      name, &objsize, rest_of_line) == 3) {
                int ret = bpf_map_lookup_elem(map_fd, &seen, &r);

                if (!ASSERT_OK(ret, "kmem_cache_lookup"))
                        break;

                ASSERT_STRNEQ(r.name, name, sizeof(r.name) - 1,
                              "kmem_cache_name");
                ASSERT_EQ(r.obj_size, objsize, "kmem_cache_objsize");

                seen++;
        }

        ASSERT_EQ(skel->bss->kmem_cache_seen, seen, "kmem_cache_seen_eq");

        fclose(fp);
}

static void subtest_kmem_cache_iter_open_coded(struct kmem_cache_iter *skel)
{
        LIBBPF_OPTS(bpf_test_run_opts, topts);
        int err, fd;

        /* No need to attach it, just run it directly */
        fd = bpf_program__fd(skel->progs.open_coded_iter);

        err = bpf_prog_test_run_opts(fd, &topts);
        if (!ASSERT_OK(err, "test_run_opts err"))
                return;
        if (!ASSERT_OK(topts.retval, "test_run_opts retval"))
                return;

        /* It should be same as we've seen from the explicit iterator */
        ASSERT_EQ(skel->bss->open_coded_seen, skel->bss->kmem_cache_seen, "open_code_seen_eq");
}

void test_kmem_cache_iter(void)
{
        struct kmem_cache_iter *skel = NULL;
        char buf[256];
        int iter_fd;

        skel = kmem_cache_iter__open_and_load();
        if (!ASSERT_OK_PTR(skel, "kmem_cache_iter__open_and_load"))
                return;

        if (!ASSERT_OK(kmem_cache_iter__attach(skel), "skel_attach"))
                goto destroy;

        iter_fd = bpf_iter_create(bpf_link__fd(skel->links.slab_info_collector));
        if (!ASSERT_GE(iter_fd, 0, "iter_create"))
                goto destroy;

        while (read(iter_fd, buf, sizeof(buf)) > 0)
                ; /* Read out all contents */

        /* Next reads should return 0 */
        ASSERT_EQ(read(iter_fd, buf, sizeof(buf)), 0, "read");

        if (test__start_subtest("check_task_struct"))
                subtest_kmem_cache_iter_check_task_struct(skel);
        if (test__start_subtest("check_slabinfo"))
                subtest_kmem_cache_iter_check_slabinfo(skel);
        if (test__start_subtest("open_coded_iter"))
                subtest_kmem_cache_iter_open_coded(skel);

        close(iter_fd);

destroy:
        kmem_cache_iter__destroy(skel);
}