1 | /* |
2 | * Copyright 2013-present Facebook, Inc. |
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 <folly/experimental/symbolizer/LineReader.h> |
18 | |
19 | #include <cstring> |
20 | |
21 | #include <folly/FileUtil.h> |
22 | |
23 | namespace folly { |
24 | namespace symbolizer { |
25 | |
26 | LineReader::LineReader(int fd, char* buf, size_t bufSize) |
27 | : fd_(fd), |
28 | buf_(buf), |
29 | bufEnd_(buf_ + bufSize), |
30 | bol_(buf), |
31 | eol_(buf), |
32 | end_(buf), |
33 | state_(kReading) {} |
34 | |
35 | LineReader::State LineReader::readLine(StringPiece& line) { |
36 | bol_ = eol_; // Start past what we already returned |
37 | for (;;) { |
38 | // Search for newline |
39 | char* newline = static_cast<char*>(memchr(eol_, '\n', end_ - eol_)); |
40 | if (newline) { |
41 | eol_ = newline + 1; |
42 | break; |
43 | } else if (state_ != kReading || (bol_ == buf_ && end_ == bufEnd_)) { |
44 | // If the buffer is full with one line (line too long), or we're |
45 | // at the end of the file, return what we have. |
46 | eol_ = end_; |
47 | break; |
48 | } |
49 | |
50 | // We don't have a full line in the buffer, but we have room to read. |
51 | // Move to the beginning of the buffer. |
52 | memmove(buf_, eol_, end_ - eol_); |
53 | end_ -= (eol_ - buf_); |
54 | bol_ = buf_; |
55 | eol_ = end_; |
56 | |
57 | // Refill |
58 | ssize_t available = bufEnd_ - end_; |
59 | ssize_t n = readFull(fd_, end_, available); |
60 | if (n < 0) { |
61 | state_ = kError; |
62 | n = 0; |
63 | } else if (n < available) { |
64 | state_ = kEof; |
65 | } |
66 | end_ += n; |
67 | } |
68 | |
69 | line.assign(bol_, eol_); |
70 | return eol_ != bol_ ? kReading : state_; |
71 | } |
72 | } // namespace symbolizer |
73 | } // namespace folly |
74 | |