// SPDX-License-Identifier: GPL-2.0
#include <dirent.h>
#include <errno.h>
#include <limits.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include "string2.h"
#include "strlist.h"
#include <string.h>
#include <api/fs/fs.h>
#include <linux/string.h>
#include <linux/zalloc.h>
#include "asm/bug.h"
#include "thread_map.h"
#include "debug.h"
#include "event.h"

/* Skip "." and ".." directories */
static int filter(const struct dirent *dir)
{
        if (dir->d_name[0] == '.')
                return 0;
        else
                return 1;
}

static void thread_map__reset(struct thread_map *map, int start, int nr)
{
        size_t size = (nr - start) * sizeof(map->map[0]);

        memset(&map->map[start], 0, size);
        map->err_thread = -1;
}

static struct thread_map *thread_map__realloc(struct thread_map *map, int nr)
{
        size_t size = sizeof(*map) + sizeof(map->map[0]) * nr;
        int start = map ? map->nr : 0;

        map = realloc(map, size);
        /*
         * We only realloc to add more items, let's reset new items.
         */
        if (map)
                thread_map__reset(map, start, nr);

        return map;
}

#define thread_map__alloc(__nr) thread_map__realloc(NULL, __nr)

struct thread_map *thread_map__new_by_pid(pid_t pid)
{
        struct thread_map *threads;
        char name[256];
        int items;
        struct dirent **namelist = NULL;
        int i;

        sprintf(name, "/proc/%d/task", pid);
        items = scandir(name, &namelist, filter, NULL);
        if (items <= 0)
                return NULL;

        threads = thread_map__alloc(items);
        if (threads != NULL) {
                for (i = 0; i < items; i++)
                        thread_map__set_pid(threads, i, atoi(namelist[i]->d_name));
                threads->nr = items;
                refcount_set(&threads->refcnt, 1);
        }

        for (i=0; i<items; i++)
                zfree(&namelist[i]);
        free(namelist);

        return threads;
}

struct thread_map *thread_map__new_by_tid(pid_t tid)
{
        struct thread_map *threads = thread_map__alloc(1);

        if (threads != NULL) {
                thread_map__set_pid(threads, 0, tid);
                threads->nr = 1;
                refcount_set(&threads->refcnt, 1);
        }

        return threads;
}

static struct thread_map *__thread_map__new_all_cpus(uid_t uid)
{
        DIR *proc;
        int max_threads = 32, items, i;
        char path[NAME_MAX + 1 + 6];
        struct dirent *dirent, **namelist = NULL;
        struct thread_map *threads = thread_map__alloc(max_threads);

        if (threads == NULL)
                goto out;

        proc = opendir("/proc");
        if (proc == NULL)
                goto out_free_threads;

        threads->nr = 0;
        refcount_set(&threads->refcnt, 1);

        while ((dirent = readdir(proc)) != NULL) {
                char *end;
                bool grow = false;
                pid_t pid = strtol(dirent->d_name, &end, 10);

                if (*end) /* only interested in proper numerical dirents */
                        continue;

                snprintf(path, sizeof(path), "/proc/%s", dirent->d_name);

                if (uid != UINT_MAX) {
                        struct stat st;

                        if (stat(path, &st) != 0 || st.st_uid != uid)
                                continue;
                }

                snprintf(path, sizeof(path), "/proc/%d/task", pid);
                items = scandir(path, &namelist, filter, NULL);
                if (items <= 0)
                        goto out_free_closedir;

                while (threads->nr + items >= max_threads) {
                        max_threads *= 2;
                        grow = true;
                }

                if (grow) {
                        struct thread_map *tmp;

                        tmp = thread_map__realloc(threads, max_threads);
                        if (tmp == NULL)
                                goto out_free_namelist;

                        threads = tmp;
                }

                for (i = 0; i < items; i++) {
                        thread_map__set_pid(threads, threads->nr + i,
                                            atoi(namelist[i]->d_name));
                }

                for (i = 0; i < items; i++)
                        zfree(&namelist[i]);
                free(namelist);

                threads->nr += items;
        }

out_closedir:
        closedir(proc);
out:
        return threads;

out_free_threads:
        free(threads);
        return NULL;

out_free_namelist:
        for (i = 0; i < items; i++)
                zfree(&namelist[i]);
        free(namelist);

out_free_closedir:
        zfree(&threads);
        goto out_closedir;
}

struct thread_map *thread_map__new_all_cpus(void)
{
        return __thread_map__new_all_cpus(UINT_MAX);
}

struct thread_map *thread_map__new_by_uid(uid_t uid)
{
        return __thread_map__new_all_cpus(uid);
}

struct thread_map *thread_map__new(pid_t pid, pid_t tid, uid_t uid)
{
        if (pid != -1)
                return thread_map__new_by_pid(pid);

        if (tid == -1 && uid != UINT_MAX)
                return thread_map__new_by_uid(uid);

        return thread_map__new_by_tid(tid);
}

static struct thread_map *thread_map__new_by_pid_str(const char *pid_str)
{
        struct thread_map *threads = NULL, *nt;
        char name[256];
        int items, total_tasks = 0;
        struct dirent **namelist = NULL;
        int i, j = 0;
        pid_t pid, prev_pid = INT_MAX;
        char *end_ptr;
        struct str_node *pos;
        struct strlist_config slist_config = { .dont_dupstr = true, };
        struct strlist *slist = strlist__new(pid_str, &slist_config);

        if (!slist)
                return NULL;

        strlist__for_each_entry(pos, slist) {
                pid = strtol(pos->s, &end_ptr, 10);

                if (pid == INT_MIN || pid == INT_MAX ||
                    (*end_ptr != '\0' && *end_ptr != ','))
                        goto out_free_threads;

                if (pid == prev_pid)
                        continue;

                sprintf(name, "/proc/%d/task", pid);
                items = scandir(name, &namelist, filter, NULL);
                if (items <= 0)
                        goto out_free_threads;

                total_tasks += items;
                nt = thread_map__realloc(threads, total_tasks);
                if (nt == NULL)
                        goto out_free_namelist;

                threads = nt;

                for (i = 0; i < items; i++) {
                        thread_map__set_pid(threads, j++, atoi(namelist[i]->d_name));
                        zfree(&namelist[i]);
                }
                threads->nr = total_tasks;
                free(namelist);
        }

out:
        strlist__delete(slist);
        if (threads)
                refcount_set(&threads->refcnt, 1);
        return threads;

out_free_namelist:
        for (i = 0; i < items; i++)
                zfree(&namelist[i]);
        free(namelist);

out_free_threads:
        zfree(&threads);
        goto out;
}

struct thread_map *thread_map__new_dummy(void)
{
        struct thread_map *threads = thread_map__alloc(1);

        if (threads != NULL) {
                thread_map__set_pid(threads, 0, -1);
                threads->nr = 1;
                refcount_set(&threads->refcnt, 1);
        }
        return threads;
}

struct thread_map *thread_map__new_by_tid_str(const char *tid_str)
{
        struct thread_map *threads = NULL, *nt;
        int ntasks = 0;
        pid_t tid, prev_tid = INT_MAX;
        char *end_ptr;
        struct str_node *pos;
        struct strlist_config slist_config = { .dont_dupstr = true, };
        struct strlist *slist;

        /* perf-stat expects threads to be generated even if tid not given */
        if (!tid_str)
                return thread_map__new_dummy();

        slist = strlist__new(tid_str, &slist_config);
        if (!slist)
                return NULL;

        strlist__for_each_entry(pos, slist) {
                tid = strtol(pos->s, &end_ptr, 10);

                if (tid == INT_MIN || tid == INT_MAX ||
                    (*end_ptr != '\0' && *end_ptr != ','))
                        goto out_free_threads;

                if (tid == prev_tid)
                        continue;

                ntasks++;
                nt = thread_map__realloc(threads, ntasks);

                if (nt == NULL)
                        goto out_free_threads;

                threads = nt;
                thread_map__set_pid(threads, ntasks - 1, tid);
                threads->nr = ntasks;
        }
out:
        if (threads)
                refcount_set(&threads->refcnt, 1);
        return threads;

out_free_threads:
        zfree(&threads);
        strlist__delete(slist);
        goto out;
}

struct thread_map *thread_map__new_str(const char *pid, const char *tid,
                                       uid_t uid, bool all_threads)
{
        if (pid)
                return thread_map__new_by_pid_str(pid);

        if (!tid && uid != UINT_MAX)
                return thread_map__new_by_uid(uid);

        if (all_threads)
                return thread_map__new_all_cpus();

        return thread_map__new_by_tid_str(tid);
}

static void thread_map__delete(struct thread_map *threads)
{
        if (threads) {
                int i;

                WARN_ONCE(refcount_read(&threads->refcnt) != 0,
                          "thread map refcnt unbalanced\n");
                for (i = 0; i < threads->nr; i++)
                        free(thread_map__comm(threads, i));
                free(threads);
        }
}

struct thread_map *thread_map__get(struct thread_map *map)
{
        if (map)
                refcount_inc(&map->refcnt);
        return map;
}

void thread_map__put(struct thread_map *map)
{
        if (map && refcount_dec_and_test(&map->refcnt))
                thread_map__delete(map);
}

size_t thread_map__fprintf(struct thread_map *threads, FILE *fp)
{
        int i;
        size_t printed = fprintf(fp, "%d thread%s: ",
                                 threads->nr, threads->nr > 1 ? "s" : "");
        for (i = 0; i < threads->nr; ++i)
                printed += fprintf(fp, "%s%d", i ? ", " : "", thread_map__pid(threads, i));

        return printed + fprintf(fp, "\n");
}

static int get_comm(char **comm, pid_t pid)
{
        char *path;
        size_t size;
        int err;

        if (asprintf(&path, "%s/%d/comm", procfs__mountpoint(), pid) == -1)
                return -ENOMEM;

        err = filename__read_str(path, comm, &size);
        if (!err) {
                /*
                 * We're reading 16 bytes, while filename__read_str
                 * allocates data per BUFSIZ bytes, so we can safely
                 * mark the end of the string.
                 */
                (*comm)[size] = 0;
                strim(*comm);
        }

        free(path);
        return err;
}

static void comm_init(struct thread_map *map, int i)
{
        pid_t pid = thread_map__pid(map, i);
        char *comm = NULL;

        /* dummy pid comm initialization */
        if (pid == -1) {
                map->map[i].comm = strdup("dummy");
                return;
        }

        /*
         * The comm name is like extra bonus ;-),
         * so just warn if we fail for any reason.
         */
        if (get_comm(&comm, pid))
                pr_warning("Couldn't resolve comm name for pid %d\n", pid);

        map->map[i].comm = comm;
}

void thread_map__read_comms(struct thread_map *threads)
{
        int i;

        for (i = 0; i < threads->nr; ++i)
                comm_init(threads, i);
}

static void thread_map__copy_event(struct thread_map *threads,
                                   struct thread_map_event *event)
{
        unsigned i;

        threads->nr = (int) event->nr;

        for (i = 0; i < event->nr; i++) {
                thread_map__set_pid(threads, i, (pid_t) event->entries[i].pid);
                threads->map[i].comm = strndup(event->entries[i].comm, 16);
        }

        refcount_set(&threads->refcnt, 1);
}

struct thread_map *thread_map__new_event(struct thread_map_event *event)
{
        struct thread_map *threads;

        threads = thread_map__alloc(event->nr);
        if (threads)
                thread_map__copy_event(threads, event);

        return threads;
}

bool thread_map__has(struct thread_map *threads, pid_t pid)
{
        int i;

        for (i = 0; i < threads->nr; ++i) {
                if (threads->map[i].pid == pid)
                        return true;
        }

        return false;
}

int thread_map__remove(struct thread_map *threads, int idx)
{
        int i;

        if (threads->nr < 1)
                return -EINVAL;

        if (idx >= threads->nr)
                return -EINVAL;

        /*
         * Free the 'idx' item and shift the rest up.
         */
        zfree(&threads->map[idx].comm);

        for (i = idx; i < threads->nr - 1; i++)
                threads->map[i] = threads->map[i + 1];

        threads->nr--;
        return 0;
}