// SPDX-License-Identifier: GPL-2.0
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <linux/kernel.h>
#include <linux/zalloc.h>
#include "dso.h"
#include "session.h"
#include "thread.h"
#include "thread-stack.h"
#include "debug.h"
#include "namespaces.h"
#include "comm.h"
#include "map.h"
#include "symbol.h"
#include "unwind.h"
#include "callchain.h"

#include <api/fs/fs.h>

int thread__init_maps(struct thread *thread, struct machine *machine)
{
        pid_t pid = thread->pid_;

        if (pid == thread->tid || pid == -1) {
                thread->maps = maps__new(machine);
        } else {
                struct thread *leader = __machine__findnew_thread(machine, pid, pid);
                if (leader) {
                        thread->maps = maps__get(leader->maps);
                        thread__put(leader);
                }
        }

        return thread->maps ? 0 : -1;
}

struct thread *thread__new(pid_t pid, pid_t tid)
{
        char *comm_str;
        struct comm *comm;
        struct thread *thread = zalloc(sizeof(*thread));

        if (thread != NULL) {
                thread->pid_ = pid;
                thread->tid = tid;
                thread->ppid = -1;
                thread->cpu = -1;
                thread->lbr_stitch_enable = false;
                INIT_LIST_HEAD(&thread->namespaces_list);
                INIT_LIST_HEAD(&thread->comm_list);
                init_rwsem(&thread->namespaces_lock);
                init_rwsem(&thread->comm_lock);

                comm_str = malloc(32);
                if (!comm_str)
                        goto err_thread;

                snprintf(comm_str, 32, ":%d", tid);
                comm = comm__new(comm_str, 0, false);
                free(comm_str);
                if (!comm)
                        goto err_thread;

                list_add(&comm->list, &thread->comm_list);
                refcount_set(&thread->refcnt, 1);
                RB_CLEAR_NODE(&thread->rb_node);
                /* Thread holds first ref to nsdata. */
                thread->nsinfo = nsinfo__new(pid);
                srccode_state_init(&thread->srccode_state);
        }

        return thread;

err_thread:
        free(thread);
        return NULL;
}

void thread__delete(struct thread *thread)
{
        struct namespaces *namespaces, *tmp_namespaces;
        struct comm *comm, *tmp_comm;

        BUG_ON(!RB_EMPTY_NODE(&thread->rb_node));

        thread_stack__free(thread);

        if (thread->maps) {
                maps__put(thread->maps);
                thread->maps = NULL;
        }
        down_write(&thread->namespaces_lock);
        list_for_each_entry_safe(namespaces, tmp_namespaces,
                                 &thread->namespaces_list, list) {
                list_del_init(&namespaces->list);
                namespaces__free(namespaces);
        }
        up_write(&thread->namespaces_lock);

        down_write(&thread->comm_lock);
        list_for_each_entry_safe(comm, tmp_comm, &thread->comm_list, list) {
                list_del_init(&comm->list);
                comm__free(comm);
        }
        up_write(&thread->comm_lock);

        nsinfo__zput(thread->nsinfo);
        srccode_state_free(&thread->srccode_state);

        exit_rwsem(&thread->namespaces_lock);
        exit_rwsem(&thread->comm_lock);
        thread__free_stitch_list(thread);
        free(thread);
}

struct thread *thread__get(struct thread *thread)
{
        if (thread)
                refcount_inc(&thread->refcnt);
        return thread;
}

void thread__put(struct thread *thread)
{
        if (thread && refcount_dec_and_test(&thread->refcnt)) {
                /*
                 * Remove it from the dead threads list, as last reference is
                 * gone, if it is in a dead threads list.
                 *
                 * We may not be there anymore if say, the machine where it was
                 * stored was already deleted, so we already removed it from
                 * the dead threads and some other piece of code still keeps a
                 * reference.
                 *
                 * This is what 'perf sched' does and finally drops it in
                 * perf_sched__lat(), where it calls perf_sched__read_events(),
                 * that processes the events by creating a session and deleting
                 * it, which ends up destroying the list heads for the dead
                 * threads, but before it does that it removes all threads from
                 * it using list_del_init().
                 *
                 * So we need to check here if it is in a dead threads list and
                 * if so, remove it before finally deleting the thread, to avoid
                 * an use after free situation.
                 */
                if (!list_empty(&thread->node))
                        list_del_init(&thread->node);
                thread__delete(thread);
        }
}

static struct namespaces *__thread__namespaces(const struct thread *thread)
{
        if (list_empty(&thread->namespaces_list))
                return NULL;

        return list_first_entry(&thread->namespaces_list, struct namespaces, list);
}

struct namespaces *thread__namespaces(struct thread *thread)
{
        struct namespaces *ns;

        down_read(&thread->namespaces_lock);
        ns = __thread__namespaces(thread);
        up_read(&thread->namespaces_lock);

        return ns;
}

static int __thread__set_namespaces(struct thread *thread, u64 timestamp,
                                    struct perf_record_namespaces *event)
{
        struct namespaces *new, *curr = __thread__namespaces(thread);

        new = namespaces__new(event);
        if (!new)
                return -ENOMEM;

        list_add(&new->list, &thread->namespaces_list);

        if (timestamp && curr) {
                /*
                 * setns syscall must have changed few or all the namespaces
                 * of this thread. Update end time for the namespaces
                 * previously used.
                 */
                curr = list_next_entry(new, list);
                curr->end_time = timestamp;
        }

        return 0;
}

int thread__set_namespaces(struct thread *thread, u64 timestamp,
                           struct perf_record_namespaces *event)
{
        int ret;

        down_write(&thread->namespaces_lock);
        ret = __thread__set_namespaces(thread, timestamp, event);
        up_write(&thread->namespaces_lock);
        return ret;
}

struct comm *thread__comm(const struct thread *thread)
{
        if (list_empty(&thread->comm_list))
                return NULL;

        return list_first_entry(&thread->comm_list, struct comm, list);
}

struct comm *thread__exec_comm(const struct thread *thread)
{
        struct comm *comm, *last = NULL, *second_last = NULL;

        list_for_each_entry(comm, &thread->comm_list, list) {
                if (comm->exec)
                        return comm;
                second_last = last;
                last = comm;
        }

        /*
         * 'last' with no start time might be the parent's comm of a synthesized
         * thread (created by processing a synthesized fork event). For a main
         * thread, that is very probably wrong. Prefer a later comm to avoid
         * that case.
         */
        if (second_last && !last->start && thread->pid_ == thread->tid)
                return second_last;

        return last;
}

static int ____thread__set_comm(struct thread *thread, const char *str,
                                u64 timestamp, bool exec)
{
        struct comm *new, *curr = thread__comm(thread);

        /* Override the default :tid entry */
        if (!thread->comm_set) {
                int err = comm__override(curr, str, timestamp, exec);
                if (err)
                        return err;
        } else {
                new = comm__new(str, timestamp, exec);
                if (!new)
                        return -ENOMEM;
                list_add(&new->list, &thread->comm_list);

                if (exec)
                        unwind__flush_access(thread->maps);
        }

        thread->comm_set = true;

        return 0;
}

int __thread__set_comm(struct thread *thread, const char *str, u64 timestamp,
                       bool exec)
{
        int ret;

        down_write(&thread->comm_lock);
        ret = ____thread__set_comm(thread, str, timestamp, exec);
        up_write(&thread->comm_lock);
        return ret;
}

int thread__set_comm_from_proc(struct thread *thread)
{
        char path[64];
        char *comm = NULL;
        size_t sz;
        int err = -1;

        if (!(snprintf(path, sizeof(path), "%d/task/%d/comm",
                       thread->pid_, thread->tid) >= (int)sizeof(path)) &&
            procfs__read_str(path, &comm, &sz) == 0) {
                comm[sz - 1] = '\0';
                err = thread__set_comm(thread, comm, 0);
        }

        return err;
}

static const char *__thread__comm_str(const struct thread *thread)
{
        const struct comm *comm = thread__comm(thread);

        if (!comm)
                return NULL;

        return comm__str(comm);
}

const char *thread__comm_str(struct thread *thread)
{
        const char *str;

        down_read(&thread->comm_lock);
        str = __thread__comm_str(thread);
        up_read(&thread->comm_lock);

        return str;
}

/* CHECKME: it should probably better return the max comm len from its comm list */
int thread__comm_len(struct thread *thread)
{
        if (!thread->comm_len) {
                const char *comm = thread__comm_str(thread);
                if (!comm)
                        return 0;
                thread->comm_len = strlen(comm);
        }

        return thread->comm_len;
}

size_t thread__fprintf(struct thread *thread, FILE *fp)
{
        return fprintf(fp, "Thread %d %s\n", thread->tid, thread__comm_str(thread)) +
               maps__fprintf(thread->maps, fp);
}

int thread__insert_map(struct thread *thread, struct map *map)
{
        int ret;

        ret = unwind__prepare_access(thread->maps, map, NULL);
        if (ret)
                return ret;

        maps__fixup_overlappings(thread->maps, map, stderr);
        maps__insert(thread->maps, map);

        return 0;
}

static int __thread__prepare_access(struct thread *thread)
{
        bool initialized = false;
        int err = 0;
        struct maps *maps = thread->maps;
        struct map *map;

        down_read(&maps->lock);

        maps__for_each_entry(maps, map) {
                err = unwind__prepare_access(thread->maps, map, &initialized);
                if (err || initialized)
                        break;
        }

        up_read(&maps->lock);

        return err;
}

static int thread__prepare_access(struct thread *thread)
{
        int err = 0;

        if (dwarf_callchain_users)
                err = __thread__prepare_access(thread);

        return err;
}

static int thread__clone_maps(struct thread *thread, struct thread *parent, bool do_maps_clone)
{
        /* This is new thread, we share map groups for process. */
        if (thread->pid_ == parent->pid_)
                return thread__prepare_access(thread);

        if (thread->maps == parent->maps) {
                pr_debug("broken map groups on thread %d/%d parent %d/%d\n",
                         thread->pid_, thread->tid, parent->pid_, parent->tid);
                return 0;
        }
        /* But this one is new process, copy maps. */
        return do_maps_clone ? maps__clone(thread, parent->maps) : 0;
}

int thread__fork(struct thread *thread, struct thread *parent, u64 timestamp, bool do_maps_clone)
{
        if (parent->comm_set) {
                const char *comm = thread__comm_str(parent);
                int err;
                if (!comm)
                        return -ENOMEM;
                err = thread__set_comm(thread, comm, timestamp);
                if (err)
                        return err;
        }

        thread->ppid = parent->tid;
        return thread__clone_maps(thread, parent, do_maps_clone);
}

void thread__find_cpumode_addr_location(struct thread *thread, u64 addr,
                                        struct addr_location *al)
{
        size_t i;
        const u8 cpumodes[] = {
                PERF_RECORD_MISC_USER,
                PERF_RECORD_MISC_KERNEL,
                PERF_RECORD_MISC_GUEST_USER,
                PERF_RECORD_MISC_GUEST_KERNEL
        };

        for (i = 0; i < ARRAY_SIZE(cpumodes); i++) {
                thread__find_symbol(thread, cpumodes[i], addr, al);
                if (al->map)
                        break;
        }
}

struct thread *thread__main_thread(struct machine *machine, struct thread *thread)
{
        if (thread->pid_ == thread->tid)
                return thread__get(thread);

        if (thread->pid_ == -1)
                return NULL;

        return machine__find_thread(machine, thread->pid_, thread->pid_);
}

int thread__memcpy(struct thread *thread, struct machine *machine,
                   void *buf, u64 ip, int len, bool *is64bit)
{
       u8 cpumode = PERF_RECORD_MISC_USER;
       struct addr_location al;
       long offset;

       if (machine__kernel_ip(machine, ip))
               cpumode = PERF_RECORD_MISC_KERNEL;

       if (!thread__find_map(thread, cpumode, ip, &al) || !al.map->dso ||
           al.map->dso->data.status == DSO_DATA_STATUS_ERROR ||
           map__load(al.map) < 0)
               return -1;

       offset = al.map->map_ip(al.map, ip);
       if (is64bit)
               *is64bit = al.map->dso->is_64_bit;

       return dso__data_read_offset(al.map->dso, machine, offset, buf, len);
}

void thread__free_stitch_list(struct thread *thread)
{
        struct lbr_stitch *lbr_stitch = thread->lbr_stitch;
        struct stitch_list *pos, *tmp;

        if (!lbr_stitch)
                return;

        list_for_each_entry_safe(pos, tmp, &lbr_stitch->lists, node) {
                list_del_init(&pos->node);
                free(pos);
        }

        list_for_each_entry_safe(pos, tmp, &lbr_stitch->free_lists, node) {
                list_del_init(&pos->node);
                free(pos);
        }

        zfree(&lbr_stitch->prev_lbr_cursor);
        zfree(&thread->lbr_stitch);
}