libcorkscrew/map_info.c

/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#define LOG_TAG "Corkscrew"
//#define LOG_NDEBUG 0

#include <corkscrew/map_info.h>

#include <ctype.h>
#include <stdio.h>
#include <string.h>
#include <limits.h>
#include <pthread.h>
#include <unistd.h>
#include <cutils/log.h>

// 6f000000-6f01e000 rwxp 00000000 00:0c 16389419   /system/lib/libcomposer.so\n
// 012345678901234567890123456789012345678901234567890123456789
// 0         1         2         3         4         5
static map_info_t* parse_maps_line(const char* line)
{
    unsigned long int start;
    unsigned long int end;
    char permissions[5];
    int name_pos;
    if (sscanf(line, "%lx-%lx %4s %*x %*x:%*x %*d%n", &start, &end,
            permissions, &name_pos) != 3) {
        return NULL;
    }

    while (isspace(line[name_pos])) {
        name_pos += 1;
    }
    const char* name = line + name_pos;
    size_t name_len = strlen(name);
    if (name_len && name[name_len - 1] == '\n') {
        name_len -= 1;
    }

    map_info_t* mi = calloc(1, sizeof(map_info_t) + name_len + 1);
    if (mi) {
        mi->start = start;
        mi->end = end;
        mi->is_executable = strlen(permissions) == 4 && permissions[2] == 'x';
        mi->data = NULL;
        memcpy(mi->name, name, name_len);
        mi->name[name_len] = '\0';
    }
    return mi;
}

map_info_t* load_map_info_list(pid_t tid) {
    char path[PATH_MAX];
    char line[1024];
    FILE* fp;
    map_info_t* milist = NULL;

    snprintf(path, PATH_MAX, "/proc/%d/maps", tid);
    fp = fopen(path, "r");
    if (fp) {
        while(fgets(line, sizeof(line), fp)) {
            map_info_t* mi = parse_maps_line(line);
            if (mi) {
                mi->next = milist;
                milist = mi;
            }
        }
        fclose(fp);
    }
    return milist;
}

void free_map_info_list(map_info_t* milist) {
    while (milist) {
        map_info_t* next = milist->next;
        free(milist);
        milist = next;
    }
}

const map_info_t* find_map_info(const map_info_t* milist, uintptr_t addr) {
    const map_info_t* mi = milist;
    while (mi && !(addr >= mi->start && addr < mi->end)) {
        mi = mi->next;
    }
    return mi;
}

static pthread_once_t g_my_milist_once = PTHREAD_ONCE_INIT;
static map_info_t* g_my_milist = NULL;

static void init_my_milist_once() {
    g_my_milist = load_map_info_list(getpid());
}

const map_info_t* my_map_info_list() {
    pthread_once(&g_my_milist_once, init_my_milist_once);
    return g_my_milist;
}