1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "LocalArray.h"
18#include "readlink.h"
19
20#include <string>
21#include <unistd.h>
22
23bool readlink(const char* path, std::string& result) {
24    // We can't know how big a buffer readlink(2) will need, so we need to
25    // loop until it says "that fit".
26    size_t bufSize = 512;
27    while (true) {
28        LocalArray<512> buf(bufSize);
29        ssize_t len = readlink(path, &buf[0], buf.size());
30        if (len == -1) {
31            // An error occurred.
32            return false;
33        }
34        if (static_cast<size_t>(len) < buf.size()) {
35            // The buffer was big enough.
36            result.assign(&buf[0], len);
37            return true;
38        }
39        // Try again with a bigger buffer.
40        bufSize *= 2;
41    }
42}
43