1 /*
2 * Copyright (C) 2018 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 <sys/stat.h>
18
19 #include "perfetto/base/file_utils.h"
20
21 #include "perfetto/base/logging.h"
22 #include "perfetto/base/scoped_file.h"
23
24 namespace perfetto {
25 namespace base {
26 namespace {
27 constexpr size_t kBufSize = 2048;
28 }
29
ReadFile(const std::string & path,std::string * out)30 bool ReadFile(const std::string& path, std::string* out) {
31 // Do not override existing data in string.
32 size_t i = out->size();
33
34 base::ScopedFile fd = base::OpenFile(path.c_str(), O_RDONLY);
35 if (!fd)
36 return false;
37
38 struct stat buf {};
39 if (fstat(*fd, &buf) != -1) {
40 if (buf.st_size > 0)
41 out->resize(i + static_cast<size_t>(buf.st_size));
42 }
43
44 ssize_t bytes_read;
45 for (;;) {
46 if (out->size() < i + kBufSize)
47 out->resize(out->size() + kBufSize);
48
49 bytes_read = PERFETTO_EINTR(read(fd.get(), &((*out)[i]), kBufSize));
50 if (bytes_read > 0) {
51 i += static_cast<size_t>(bytes_read);
52 } else {
53 out->resize(i);
54 return bytes_read == 0;
55 }
56 }
57 }
58
59 } // namespace base
60 } // namespace perfetto
61