trace-event-info.c

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/*
 * Copyright (C) 2008,2009, Steven Rostedt <srostedt@redhat.com>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License (not later!)
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */
#include "util.h"
#include <dirent.h>
#include <mntent.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <stdbool.h>
#include <linux/list.h>
#include <linux/kernel.h>

#include "../perf.h"
#include "trace-event.h"
#include <api/fs/tracing_path.h>
#include "evsel.h"
#include "debug.h"

#define VERSION "0.6"

static int output_fd;


int bigendian(void)
{
    unsigned char str[] = { 0x1, 0x2, 0x3, 0x4, 0x0, 0x0, 0x0, 0x0};
    unsigned int *ptr;

    ptr = (unsigned int *)(void *)str;
    return *ptr == 0x01020304;
}

/* unfortunately, you can not stat debugfs or proc files for size */
static int record_file(const char *file, ssize_t hdr_sz)
{
    unsigned long long size = 0;
    char buf[BUFSIZ], *sizep;
    off_t hdr_pos = lseek(output_fd, 0, SEEK_CUR);
    int r, fd;
    int err = -EIO;

    fd = open(file, O_RDONLY);
    if (fd < 0) {
        pr_debug("Can't read '%s'", file);
        return -errno;
    }

    /* put in zeros for file size, then fill true size later */
    if (hdr_sz) {
        if (write(output_fd, &size, hdr_sz) != hdr_sz)
            goto out;
    }

    do {
        r = read(fd, buf, BUFSIZ);
        if (r > 0) {
            size += r;
            if (write(output_fd, buf, r) != r)
                goto out;
        }
    } while (r > 0);

    /* ugh, handle big-endian hdr_size == 4 */
    sizep = (char*)&size;
    if (bigendian())
        sizep += sizeof(u64) - hdr_sz;

    if (hdr_sz && pwrite(output_fd, sizep, hdr_sz, hdr_pos) < 0) {
        pr_debug("writing file size failed\n");
        goto out;
    }

    err = 0;
out:
    close(fd);
    return err;
}

static int record_header_files(void)
{
    char *path = get_events_file("header_page");
    struct stat st;
    int err = -EIO;

    if (!path) {
        pr_debug("can't get tracing/events/header_page");
        return -ENOMEM;
    }

    if (stat(path, &st) < 0) {
        pr_debug("can't read '%s'", path);
        goto out;
    }

    if (write(output_fd, "header_page", 12) != 12) {
        pr_debug("can't write header_page\n");
        goto out;
    }

    if (record_file(path, 8) < 0) {
        pr_debug("can't record header_page file\n");
        goto out;
    }

    put_events_file(path);

    path = get_events_file("header_event");
    if (!path) {
        pr_debug("can't get tracing/events/header_event");
        err = -ENOMEM;
        goto out;
    }

    if (stat(path, &st) < 0) {
        pr_debug("can't read '%s'", path);
        goto out;
    }

    if (write(output_fd, "header_event", 13) != 13) {
        pr_debug("can't write header_event\n");
        goto out;
    }

    if (record_file(path, 8) < 0) {
        pr_debug("can't record header_event file\n");
        goto out;
    }

    err = 0;
out:
    put_events_file(path);
    return err;
}

static bool name_in_tp_list(char *sys, struct tracepoint_path *tps)
{
    while (tps) {
        if (!strcmp(sys, tps->name))
            return true;
        tps = tps->next;
    }

    return false;
}

#define for_each_event(dir, dent, tps)              \
    while ((dent = readdir(dir)))               \
        if (dent->d_type == DT_DIR &&           \
            (strcmp(dent->d_name, ".")) &&      \
            (strcmp(dent->d_name, "..")))       \

static int copy_event_system(const char *sys, struct tracepoint_path *tps)
{
    struct dirent *dent;
    struct stat st;
    char *format;
    DIR *dir;
    int count = 0;
    int ret;
    int err;

    dir = opendir(sys);
    if (!dir) {
        pr_debug("can't read directory '%s'", sys);
        return -errno;
    }

    for_each_event(dir, dent, tps) {
        if (!name_in_tp_list(dent->d_name, tps))
            continue;

        if (asprintf(&format, "%s/%s/format", sys, dent->d_name) < 0) {
            err = -ENOMEM;
            goto out;
        }
        ret = stat(format, &st);
        free(format);
        if (ret < 0)
            continue;
        count++;
    }

    if (write(output_fd, &count, 4) != 4) {
        err = -EIO;
        pr_debug("can't write count\n");
        goto out;
    }

    rewinddir(dir);
    for_each_event(dir, dent, tps) {
        if (!name_in_tp_list(dent->d_name, tps))
            continue;

        if (asprintf(&format, "%s/%s/format", sys, dent->d_name) < 0) {
            err = -ENOMEM;
            goto out;
        }
        ret = stat(format, &st);

        if (ret >= 0) {
            err = record_file(format, 8);
            if (err) {
                free(format);
                goto out;
            }
        }
        free(format);
    }
    err = 0;
out:
    closedir(dir);
    return err;
}

static int record_ftrace_files(struct tracepoint_path *tps)
{
    char *path;
    int ret;

    path = get_events_file("ftrace");
    if (!path) {
        pr_debug("can't get tracing/events/ftrace");
        return -ENOMEM;
    }

    ret = copy_event_system(path, tps);

    put_tracing_file(path);

    return ret;
}

static bool system_in_tp_list(char *sys, struct tracepoint_path *tps)
{
    while (tps) {
        if (!strcmp(sys, tps->system))
            return true;
        tps = tps->next;
    }

    return false;
}

static int record_event_files(struct tracepoint_path *tps)
{
    struct dirent *dent;
    struct stat st;
    char *path;
    char *sys;
    DIR *dir;
    int count = 0;
    int ret;
    int err;

    path = get_tracing_file("events");
    if (!path) {
        pr_debug("can't get tracing/events");
        return -ENOMEM;
    }

    dir = opendir(path);
    if (!dir) {
        err = -errno;
        pr_debug("can't read directory '%s'", path);
        goto out;
    }

    for_each_event(dir, dent, tps) {
        if (strcmp(dent->d_name, "ftrace") == 0 ||
            !system_in_tp_list(dent->d_name, tps))
            continue;

        count++;
    }

    if (write(output_fd, &count, 4) != 4) {
        err = -EIO;
        pr_debug("can't write count\n");
        goto out;
    }

    rewinddir(dir);
    for_each_event(dir, dent, tps) {
        if (strcmp(dent->d_name, "ftrace") == 0 ||
            !system_in_tp_list(dent->d_name, tps))
            continue;

        if (asprintf(&sys, "%s/%s", path, dent->d_name) < 0) {
            err = -ENOMEM;
            goto out;
        }
        ret = stat(sys, &st);
        if (ret >= 0) {
            ssize_t size = strlen(dent->d_name) + 1;

            if (write(output_fd, dent->d_name, size) != size ||
                copy_event_system(sys, tps) < 0) {
                err = -EIO;
                free(sys);
                goto out;
            }
        }
        free(sys);
    }
    err = 0;
out:
    closedir(dir);
    put_tracing_file(path);

    return err;
}

static int record_proc_kallsyms(void)
{
    unsigned long long size = 0;
    /*
     * Just to keep older perf.data file parsers happy, record a zero
     * sized kallsyms file, i.e. do the same thing that was done when
     * /proc/kallsyms (or something specified via --kallsyms, in a
     * different path) couldn't be read.
     */
    return write(output_fd, &size, 4) != 4 ? -EIO : 0;
}

static int record_ftrace_printk(void)
{
    unsigned int size;
    char *path;
    struct stat st;
    int ret, err = 0;

    path = get_tracing_file("printk_formats");
    if (!path) {
        pr_debug("can't get tracing/printk_formats");
        return -ENOMEM;
    }

    ret = stat(path, &st);
    if (ret < 0) {
        /* not found */
        size = 0;
        if (write(output_fd, &size, 4) != 4)
            err = -EIO;
        goto out;
    }
    err = record_file(path, 4);

out:
    put_tracing_file(path);
    return err;
}

static int record_saved_cmdline(void)
{
    unsigned int size;
    char *path;
    struct stat st;
    int ret, err = 0;

    path = get_tracing_file("saved_cmdlines");
    if (!path) {
        pr_debug("can't get tracing/saved_cmdline");
        return -ENOMEM;
    }

    ret = stat(path, &st);
    if (ret < 0) {
        /* not found */
        size = 0;
        if (write(output_fd, &size, 8) != 8)
            err = -EIO;
        goto out;
    }
    err = record_file(path, 8);

out:
    put_tracing_file(path);
    return err;
}

static void
put_tracepoints_path(struct tracepoint_path *tps)
{
    while (tps) {
        struct tracepoint_path *t = tps;

        tps = tps->next;
        zfree(&t->name);
        zfree(&t->system);
        free(t);
    }
}

static struct tracepoint_path *
get_tracepoints_path(struct list_head *pattrs)
{
    struct tracepoint_path path, *ppath = &path;
    struct perf_evsel *pos;
    int nr_tracepoints = 0;

    list_for_each_entry(pos, pattrs, node) {
        if (pos->attr.type != PERF_TYPE_TRACEPOINT)
            continue;
        ++nr_tracepoints;

        if (pos->name) {
            ppath->next = tracepoint_name_to_path(pos->name);
            if (ppath->next)
                goto next;

            if (strchr(pos->name, ':') == NULL)
                goto try_id;

            goto error;
        }

try_id:
        ppath->next = tracepoint_id_to_path(pos->attr.config);
        if (!ppath->next) {
error:
            pr_debug("No memory to alloc tracepoints list\n");
            put_tracepoints_path(&path);
            return NULL;
        }
next:
        ppath = ppath->next;
    }

    return nr_tracepoints > 0 ? path.next : NULL;
}

bool have_tracepoints(struct list_head *pattrs)
{
    struct perf_evsel *pos;

    list_for_each_entry(pos, pattrs, node)
        if (pos->attr.type == PERF_TYPE_TRACEPOINT)
            return true;

    return false;
}

static int tracing_data_header(void)
{
    char buf[20];
    ssize_t size;

    /* just guessing this is someone's birthday.. ;) */
    buf[0] = 23;
    buf[1] = 8;
    buf[2] = 68;
    memcpy(buf + 3, "tracing", 7);

    if (write(output_fd, buf, 10) != 10)
        return -1;

    size = strlen(VERSION) + 1;
    if (write(output_fd, VERSION, size) != size)
        return -1;

    /* save endian */
    if (bigendian())
        buf[0] = 1;
    else
        buf[0] = 0;

    if (write(output_fd, buf, 1) != 1)
        return -1;

    /* save size of long */
    buf[0] = sizeof(long);
    if (write(output_fd, buf, 1) != 1)
        return -1;

    /* save page_size */
    if (write(output_fd, &page_size, 4) != 4)
        return -1;

    return 0;
}

struct tracing_data *tracing_data_get(struct list_head *pattrs,
                      int fd, bool temp)
{
    struct tracepoint_path *tps;
    struct tracing_data *tdata;
    int err;

    output_fd = fd;

    tps = get_tracepoints_path(pattrs);
    if (!tps)
        return NULL;

    tdata = malloc(sizeof(*tdata));
    if (!tdata)
        return NULL;

    tdata->temp = temp;
    tdata->size = 0;

    if (temp) {
        int temp_fd;

        snprintf(tdata->temp_file, sizeof(tdata->temp_file),
             "/tmp/perf-XXXXXX");
        if (!mkstemp(tdata->temp_file)) {
            pr_debug("Can't make temp file");
            return NULL;
        }

        temp_fd = open(tdata->temp_file, O_RDWR);
        if (temp_fd < 0) {
            pr_debug("Can't read '%s'", tdata->temp_file);
            return NULL;
        }

        /*
         * Set the temp file the default output, so all the
         * tracing data are stored into it.
         */
        output_fd = temp_fd;
    }

    err = tracing_data_header();
    if (err)
        goto out;
    err = record_header_files();
    if (err)
        goto out;
    err = record_ftrace_files(tps);
    if (err)
        goto out;
    err = record_event_files(tps);
    if (err)
        goto out;
    err = record_proc_kallsyms();
    if (err)
        goto out;
    err = record_ftrace_printk();
    if (err)
        goto out;
    err = record_saved_cmdline();

out:
    /*
     * All tracing data are stored by now, we can restore
     * the default output file in case we used temp file.
     */
    if (temp) {
        tdata->size = lseek(output_fd, 0, SEEK_CUR);
        close(output_fd);
        output_fd = fd;
    }

    if (err)
        zfree(&tdata);

    put_tracepoints_path(tps);
    return tdata;
}

int tracing_data_put(struct tracing_data *tdata)
{
    int err = 0;

    if (tdata->temp) {
        err = record_file(tdata->temp_file, 0);
        unlink(tdata->temp_file);
    }

    free(tdata);
    return err;
}

int read_tracing_data(int fd, struct list_head *pattrs)
{
    int err;
    struct tracing_data *tdata;

    /*
     * We work over the real file, so we can write data
     * directly, no temp file is needed.
     */
    tdata = tracing_data_get(pattrs, fd, false);
    if (!tdata)
        return -ENOMEM;

    err = tracing_data_put(tdata);
    return err;
}