// SPDX-License-Identifier: GPL-2.0
#include <subcmd/parse-options.h>
#include "evsel.h"
#include "cgroup.h"
#include "evlist.h"
#include "rblist.h"
#include "metricgroup.h"
#include "stat.h"
#include <linux/zalloc.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/statfs.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <api/fs/fs.h>
#include <ftw.h>
#include <regex.h>

int nr_cgroups;
bool cgrp_event_expanded;

/* used to match cgroup name with patterns */
struct cgroup_name {
        struct list_head list;
        bool used;
        char name[];
};
static LIST_HEAD(cgroup_list);

static int open_cgroup(const char *name)
{
        char path[PATH_MAX + 1];
        char mnt[PATH_MAX + 1];
        int fd;


        if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1, "perf_event"))
                return -1;

        scnprintf(path, PATH_MAX, "%s/%s", mnt, name);

        fd = open(path, O_RDONLY);
        if (fd == -1)
                fprintf(stderr, "no access to cgroup %s\n", path);

        return fd;
}

#ifdef HAVE_FILE_HANDLE
static u64 __read_cgroup_id(const char *path)
{
        struct {
                struct file_handle fh;
                uint64_t cgroup_id;
        } handle;
        int mount_id;

        handle.fh.handle_bytes = sizeof(handle.cgroup_id);
        if (name_to_handle_at(AT_FDCWD, path, &handle.fh, &mount_id, 0) < 0)
                return -1ULL;

        return handle.cgroup_id;
}

int read_cgroup_id(struct cgroup *cgrp)
{
        char path[PATH_MAX + 1];
        char mnt[PATH_MAX + 1];

        if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1, "perf_event"))
                return -1;

        scnprintf(path, PATH_MAX, "%s/%s", mnt, cgrp->name);

        cgrp->id = __read_cgroup_id(path);
        return 0;
}
#else
static inline u64 __read_cgroup_id(const char *path __maybe_unused) { return -1ULL; }
#endif  /* HAVE_FILE_HANDLE */

#ifndef CGROUP2_SUPER_MAGIC
#define CGROUP2_SUPER_MAGIC  0x63677270
#endif

int cgroup_is_v2(const char *subsys)
{
        char mnt[PATH_MAX + 1];
        struct statfs stbuf;

        if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1, subsys))
                return -1;

        if (statfs(mnt, &stbuf) < 0)
                return -1;

        return (stbuf.f_type == CGROUP2_SUPER_MAGIC);
}

static struct cgroup *evlist__find_cgroup(struct evlist *evlist, const char *str)
{
        struct evsel *counter;
        /*
         * check if cgrp is already defined, if so we reuse it
         */
        evlist__for_each_entry(evlist, counter) {
                if (!counter->cgrp)
                        continue;
                if (!strcmp(counter->cgrp->name, str))
                        return cgroup__get(counter->cgrp);
        }

        return NULL;
}

struct cgroup *cgroup__new(const char *name, bool do_open)
{
        struct cgroup *cgroup = zalloc(sizeof(*cgroup));

        if (cgroup != NULL) {
                refcount_set(&cgroup->refcnt, 1);

                cgroup->name = strdup(name);
                if (!cgroup->name)
                        goto out_err;

                if (do_open) {
                        cgroup->fd = open_cgroup(name);
                        if (cgroup->fd == -1)
                                goto out_free_name;
                } else {
                        cgroup->fd = -1;
                }
        }

        return cgroup;

out_free_name:
        zfree(&cgroup->name);
out_err:
        free(cgroup);
        return NULL;
}

struct cgroup *evlist__findnew_cgroup(struct evlist *evlist, const char *name)
{
        struct cgroup *cgroup = evlist__find_cgroup(evlist, name);

        return cgroup ?: cgroup__new(name, true);
}

static int add_cgroup(struct evlist *evlist, const char *str)
{
        struct evsel *counter;
        struct cgroup *cgrp = evlist__findnew_cgroup(evlist, str);
        int n;

        if (!cgrp)
                return -1;
        /*
         * find corresponding event
         * if add cgroup N, then need to find event N
         */
        n = 0;
        evlist__for_each_entry(evlist, counter) {
                if (n == nr_cgroups)
                        goto found;
                n++;
        }

        cgroup__put(cgrp);
        return -1;
found:
        counter->cgrp = cgrp;
        return 0;
}

static void cgroup__delete(struct cgroup *cgroup)
{
        if (cgroup->fd >= 0)
                close(cgroup->fd);
        zfree(&cgroup->name);
        free(cgroup);
}

void cgroup__put(struct cgroup *cgrp)
{
        if (cgrp && refcount_dec_and_test(&cgrp->refcnt)) {
                cgroup__delete(cgrp);
        }
}

struct cgroup *cgroup__get(struct cgroup *cgroup)
{
       if (cgroup)
                refcount_inc(&cgroup->refcnt);
       return cgroup;
}

static void evsel__set_default_cgroup(struct evsel *evsel, struct cgroup *cgroup)
{
        if (evsel->cgrp == NULL)
                evsel->cgrp = cgroup__get(cgroup);
}

void evlist__set_default_cgroup(struct evlist *evlist, struct cgroup *cgroup)
{
        struct evsel *evsel;

        evlist__for_each_entry(evlist, evsel)
                evsel__set_default_cgroup(evsel, cgroup);
}

/* helper function for ftw() in match_cgroups and list_cgroups */
static int add_cgroup_name(const char *fpath, const struct stat *sb __maybe_unused,
                           int typeflag, struct FTW *ftwbuf __maybe_unused)
{
        struct cgroup_name *cn;

        if (typeflag != FTW_D)
                return 0;

        cn = malloc(sizeof(*cn) + strlen(fpath) + 1);
        if (cn == NULL)
                return -1;

        cn->used = false;
        strcpy(cn->name, fpath);

        list_add_tail(&cn->list, &cgroup_list);
        return 0;
}

static int check_and_add_cgroup_name(const char *fpath)
{
        struct cgroup_name *cn;

        list_for_each_entry(cn, &cgroup_list, list) {
                if (!strcmp(cn->name, fpath))
                        return 0;
        }

        /* pretend if it's added by ftw() */
        return add_cgroup_name(fpath, NULL, FTW_D, NULL);
}

static void release_cgroup_list(void)
{
        struct cgroup_name *cn;

        while (!list_empty(&cgroup_list)) {
                cn = list_first_entry(&cgroup_list, struct cgroup_name, list);
                list_del(&cn->list);
                free(cn);
        }
}

/* collect given cgroups only */
static int list_cgroups(const char *str)
{
        const char *p, *e, *eos = str + strlen(str);
        struct cgroup_name *cn;
        char *s;

        /* use given name as is when no regex is given */
        for (;;) {
                p = strchr(str, ',');
                e = p ? p : eos;

                if (e - str) {
                        int ret;

                        s = strndup(str, e - str);
                        if (!s)
                                return -1;

                        ret = check_and_add_cgroup_name(s);
                        free(s);
                        if (ret < 0)
                                return -1;
                } else {
                        if (check_and_add_cgroup_name("/") < 0)
                                return -1;
                }

                if (!p)
                        break;
                str = p+1;
        }

        /* these groups will be used */
        list_for_each_entry(cn, &cgroup_list, list)
                cn->used = true;

        return 0;
}

/* collect all cgroups first and then match with the pattern */
static int match_cgroups(const char *str)
{
        char mnt[PATH_MAX];
        const char *p, *e, *eos = str + strlen(str);
        struct cgroup_name *cn;
        regex_t reg;
        int prefix_len;
        char *s;

        if (cgroupfs_find_mountpoint(mnt, sizeof(mnt), "perf_event"))
                return -1;

        /* cgroup_name will have a full path, skip the root directory */
        prefix_len = strlen(mnt);

        /* collect all cgroups in the cgroup_list */
        if (nftw(mnt, add_cgroup_name, 20, 0) < 0)
                return -1;

        for (;;) {
                p = strchr(str, ',');
                e = p ? p : eos;

                /* allow empty cgroups, i.e., skip */
                if (e - str) {
                        /* termination added */
                        s = strndup(str, e - str);
                        if (!s)
                                return -1;
                        if (regcomp(&reg, s, REG_NOSUB)) {
                                free(s);
                                return -1;
                        }

                        /* check cgroup name with the pattern */
                        list_for_each_entry(cn, &cgroup_list, list) {
                                char *name = cn->name + prefix_len;

                                if (name[0] == '/' && name[1])
                                        name++;
                                if (!regexec(&reg, name, 0, NULL, 0))
                                        cn->used = true;
                        }
                        regfree(&reg);
                        free(s);
                } else {
                        /* first entry to root cgroup */
                        cn = list_first_entry(&cgroup_list, struct cgroup_name,
                                              list);
                        cn->used = true;
                }

                if (!p)
                        break;
                str = p+1;
        }
        return prefix_len;
}

int parse_cgroups(const struct option *opt, const char *str,
                  int unset __maybe_unused)
{
        struct evlist *evlist = *(struct evlist **)opt->value;
        struct evsel *counter;
        struct cgroup *cgrp = NULL;
        const char *p, *e, *eos = str + strlen(str);
        char *s;
        int ret, i;

        if (list_empty(&evlist->core.entries)) {
                fprintf(stderr, "must define events before cgroups\n");
                return -1;
        }

        for (;;) {
                p = strchr(str, ',');
                e = p ? p : eos;

                /* allow empty cgroups, i.e., skip */
                if (e - str) {
                        /* termination added */
                        s = strndup(str, e - str);
                        if (!s)
                                return -1;
                        ret = add_cgroup(evlist, s);
                        free(s);
                        if (ret)
                                return -1;
                }
                /* nr_cgroups is increased een for empty cgroups */
                nr_cgroups++;
                if (!p)
                        break;
                str = p+1;
        }
        /* for the case one cgroup combine to multiple events */
        i = 0;
        if (nr_cgroups == 1) {
                evlist__for_each_entry(evlist, counter) {
                        if (i == 0)
                                cgrp = counter->cgrp;
                        else {
                                counter->cgrp = cgrp;
                                refcount_inc(&cgrp->refcnt);
                        }
                        i++;
                }
        }
        return 0;
}

static bool has_pattern_string(const char *str)
{
        return !!strpbrk(str, "{}[]()|*+?^$");
}

int evlist__expand_cgroup(struct evlist *evlist, const char *str, bool open_cgroup)
{
        struct evlist *orig_list, *tmp_list;
        struct evsel *pos, *evsel, *leader;
        struct rblist orig_metric_events;
        struct cgroup *cgrp = NULL;
        struct cgroup_name *cn;
        int ret = -1;
        int prefix_len;

        if (evlist->core.nr_entries == 0) {
                fprintf(stderr, "must define events before cgroups\n");
                return -EINVAL;
        }

        orig_list = evlist__new();
        tmp_list = evlist__new();
        if (orig_list == NULL || tmp_list == NULL) {
                fprintf(stderr, "memory allocation failed\n");
                return -ENOMEM;
        }

        /* save original events and init evlist */
        evlist__splice_list_tail(orig_list, &evlist->core.entries);
        evlist->core.nr_entries = 0;

        orig_metric_events = evlist->metric_events;
        metricgroup__rblist_init(&evlist->metric_events);

        if (has_pattern_string(str))
                prefix_len = match_cgroups(str);
        else
                prefix_len = list_cgroups(str);

        if (prefix_len < 0)
                goto out_err;

        list_for_each_entry(cn, &cgroup_list, list) {
                char *name;

                if (!cn->used)
                        continue;

                /* cgroup_name might have a full path, skip the prefix */
                name = cn->name + prefix_len;
                if (name[0] == '/' && name[1])
                        name++;

                /* the cgroup can go away in the meantime */
                cgrp = cgroup__new(name, open_cgroup);
                if (cgrp == NULL)
                        continue;

                leader = NULL;
                evlist__for_each_entry(orig_list, pos) {
                        evsel = evsel__clone(/*dest=*/NULL, pos);
                        if (evsel == NULL)
                                goto out_err;

                        cgroup__put(evsel->cgrp);
                        evsel->cgrp = cgroup__get(cgrp);

                        if (evsel__is_group_leader(pos))
                                leader = evsel;
                        evsel__set_leader(evsel, leader);

                        evlist__add(tmp_list, evsel);
                }
                /* cgroup__new() has a refcount, release it here */
                cgroup__put(cgrp);
                nr_cgroups++;

                if (metricgroup__copy_metric_events(tmp_list, cgrp,
                                                    &evlist->metric_events,
                                                    &orig_metric_events) < 0)
                        goto out_err;

                evlist__splice_list_tail(evlist, &tmp_list->core.entries);
                tmp_list->core.nr_entries = 0;
        }

        if (list_empty(&evlist->core.entries)) {
                fprintf(stderr, "no cgroup matched: %s\n", str);
                goto out_err;
        }

        ret = 0;
        cgrp_event_expanded = true;

out_err:
        evlist__delete(orig_list);
        evlist__delete(tmp_list);
        metricgroup__rblist_exit(&orig_metric_events);
        release_cgroup_list();

        return ret;
}

static struct cgroup *__cgroup__findnew(struct rb_root *root, uint64_t id,
                                        bool create, const char *path)
{
        struct rb_node **p = &root->rb_node;
        struct rb_node *parent = NULL;
        struct cgroup *cgrp;

        while (*p != NULL) {
                parent = *p;
                cgrp = rb_entry(parent, struct cgroup, node);

                if (cgrp->id == id)
                        return cgrp;

                if (cgrp->id < id)
                        p = &(*p)->rb_left;
                else
                        p = &(*p)->rb_right;
        }

        if (!create)
                return NULL;

        cgrp = malloc(sizeof(*cgrp));
        if (cgrp == NULL)
                return NULL;

        cgrp->name = strdup(path);
        if (cgrp->name == NULL) {
                free(cgrp);
                return NULL;
        }

        cgrp->fd = -1;
        cgrp->id = id;
        refcount_set(&cgrp->refcnt, 1);

        rb_link_node(&cgrp->node, parent, p);
        rb_insert_color(&cgrp->node, root);

        return cgrp;
}

struct cgroup *cgroup__findnew(struct perf_env *env, uint64_t id,
                               const char *path)
{
        struct cgroup *cgrp;

        down_write(&env->cgroups.lock);
        cgrp = __cgroup__findnew(&env->cgroups.tree, id, true, path);
        up_write(&env->cgroups.lock);
        return cgrp;
}

struct cgroup *__cgroup__find(struct rb_root *root, uint64_t id)
{
        return __cgroup__findnew(root, id, /*create=*/false, /*path=*/NULL);
}

struct cgroup *cgroup__find(struct perf_env *env, uint64_t id)
{
        struct cgroup *cgrp;

        down_read(&env->cgroups.lock);
        cgrp = __cgroup__findnew(&env->cgroups.tree, id, false, NULL);
        up_read(&env->cgroups.lock);
        return cgrp;
}

void perf_env__purge_cgroups(struct perf_env *env)
{
        struct rb_node *node;
        struct cgroup *cgrp;

        down_write(&env->cgroups.lock);
        while (!RB_EMPTY_ROOT(&env->cgroups.tree)) {
                node = rb_first(&env->cgroups.tree);
                cgrp = rb_entry(node, struct cgroup, node);

                rb_erase(node, &env->cgroups.tree);
                cgroup__put(cgrp);
        }
        up_write(&env->cgroups.lock);
}

void read_all_cgroups(struct rb_root *root)
{
        char mnt[PATH_MAX];
        struct cgroup_name *cn;
        int prefix_len;

        if (cgroupfs_find_mountpoint(mnt, sizeof(mnt), "perf_event"))
                return;

        /* cgroup_name will have a full path, skip the root directory */
        prefix_len = strlen(mnt);

        /* collect all cgroups in the cgroup_list */
        if (nftw(mnt, add_cgroup_name, 20, 0) < 0)
                return;

        list_for_each_entry(cn, &cgroup_list, list) {
                const char *name;
                u64 cgrp_id;

                /* cgroup_name might have a full path, skip the prefix */
                name = cn->name + prefix_len;
                if (name[0] == '\0')
                        name = "/";

                cgrp_id = __read_cgroup_id(cn->name);
                __cgroup__findnew(root, cgrp_id, /*create=*/true, name);
        }

        release_cgroup_list();
}