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

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <linux/string.h>
#include <errno.h>
#include <unistd.h>
#include "fs.h"

#include "tracing_path.h"

static char tracing_path[PATH_MAX]        = "/sys/kernel/tracing";

static void __tracing_path_set(const char *tracing, const char *mountpoint)
{
        snprintf(tracing_path, sizeof(tracing_path), "%s/%s",
                 mountpoint, tracing);
}

static const char *tracing_path_tracefs_mount(void)
{
        const char *mnt;

        mnt = tracefs__mount();
        if (!mnt)
                return NULL;

        __tracing_path_set("", mnt);

        return tracing_path;
}

static const char *tracing_path_debugfs_mount(void)
{
        const char *mnt;

        mnt = debugfs__mount();
        if (!mnt)
                return NULL;

        __tracing_path_set("tracing/", mnt);

        return tracing_path;
}

const char *tracing_path_mount(void)
{
        const char *mnt;

        mnt = tracing_path_tracefs_mount();
        if (mnt)
                return mnt;

        mnt = tracing_path_debugfs_mount();

        return mnt;
}

void tracing_path_set(const char *mntpt)
{
        __tracing_path_set("tracing/", mntpt);
}

char *get_tracing_file(const char *name)
{
        char *file;

        if (asprintf(&file, "%s%s", tracing_path_mount(), name) < 0)
                return NULL;

        return file;
}

void put_tracing_file(char *file)
{
        free(file);
}

char *get_events_file(const char *name)
{
        char *file;

        if (asprintf(&file, "%s/events/%s", tracing_path_mount(), name) < 0)
                return NULL;

        return file;
}

void put_events_file(char *file)
{
        free(file);
}

DIR *tracing_events__opendir(void)
{
        DIR *dir = NULL;
        char *path = get_tracing_file("events");

        if (path) {
                dir = opendir(path);
                put_events_file(path);
        }

        return dir;
}

int tracing_events__scandir_alphasort(struct dirent ***namelist)
{
        char *path = get_tracing_file("events");
        int ret;

        if (!path) {
                *namelist = NULL;
                return 0;
        }

        ret = scandir(path, namelist, NULL, alphasort);
        put_events_file(path);

        return ret;
}

int tracing_path__strerror_open_tp(int err, char *buf, size_t size,
                                   const char *sys, const char *name)
{
        char sbuf[128];
        char filename[PATH_MAX];

        snprintf(filename, PATH_MAX, "%s/%s", sys, name ?: "*");

        switch (err) {
        case ENOENT:
                /*
                 * We will get here if we can't find the tracepoint, but one of
                 * debugfs or tracefs is configured, which means you probably
                 * want some tracepoint which wasn't compiled in your kernel.
                 * - jirka
                 */
                if (debugfs__configured() || tracefs__configured()) {
                        /* sdt markers */
                        if (!strncmp(filename, "sdt_", 4)) {
                                snprintf(buf, size,
                                        "Error:\tFile %s/events/%s not found.\n"
                                        "Hint:\tSDT event cannot be directly recorded on.\n"
                                        "\tPlease first use 'perf probe %s:%s' before recording it.\n",
                                        tracing_path, filename, sys, name);
                        } else {
                                snprintf(buf, size,
                                         "Error:\tFile %s/events/%s not found.\n"
                                         "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n",
                                         tracing_path, filename);
                        }
                        break;
                }
                snprintf(buf, size, "%s",
                         "Error:\tUnable to find debugfs/tracefs\n"
                         "Hint:\tWas your kernel compiled with debugfs/tracefs support?\n"
                         "Hint:\tIs the debugfs/tracefs filesystem mounted?\n"
                         "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
                break;
        case EACCES: {
                snprintf(buf, size,
                         "Error:\tNo permissions to read %s/events/%s\n"
                         "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
                         tracing_path, filename, tracing_path_mount());
        }
                break;
        default:
                snprintf(buf, size, "%s", str_error_r(err, sbuf, sizeof(sbuf)));
                break;
        }

        return 0;
}