1 // Copyright (c) 2009, Google Inc. 2 // All rights reserved. 3 // 4 // Redistribution and use in source and binary forms, with or without 5 // modification, are permitted provided that the following conditions are 6 // met: 7 // 8 // * Redistributions of source code must retain the above copyright 9 // notice, this list of conditions and the following disclaimer. 10 // * Redistributions in binary form must reproduce the above 11 // copyright notice, this list of conditions and the following disclaimer 12 // in the documentation and/or other materials provided with the 13 // distribution. 14 // * Neither the name of Google Inc. nor the names of its 15 // contributors may be used to endorse or promote products derived from 16 // this software without specific prior written permission. 17 // 18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 30 #ifndef CLIENT_LINUX_MINIDUMP_WRITER_LINE_READER_H_ 31 #define CLIENT_LINUX_MINIDUMP_WRITER_LINE_READER_H_ 32 33 #include <stdint.h> 34 #include <assert.h> 35 #include <string.h> 36 37 #include "common/linux/linux_libc_support.h" 38 #include "third_party/lss/linux_syscall_support.h" 39 40 namespace google_breakpad { 41 42 // A class for reading a file, line by line, without using fopen/fgets or other 43 // functions which may allocate memory. 44 class LineReader { 45 public: LineReader(int fd)46 LineReader(int fd) 47 : fd_(fd), 48 hit_eof_(false), 49 buf_used_(0) { 50 } 51 52 // The maximum length of a line. 53 static const size_t kMaxLineLen = 512; 54 55 // Return the next line from the file. 56 // line: (output) a pointer to the start of the line. The line is NUL 57 // terminated. 58 // len: (output) the length of the line (not inc the NUL byte) 59 // 60 // Returns true iff successful (false on EOF). 61 // 62 // One must call |PopLine| after this function, otherwise you'll continue to 63 // get the same line over and over. GetNextLine(const char ** line,unsigned * len)64 bool GetNextLine(const char **line, unsigned *len) { 65 for (;;) { 66 if (buf_used_ == 0 && hit_eof_) 67 return false; 68 69 for (unsigned i = 0; i < buf_used_; ++i) { 70 if (buf_[i] == '\n' || buf_[i] == 0) { 71 buf_[i] = 0; 72 *len = i; 73 *line = buf_; 74 return true; 75 } 76 } 77 78 if (buf_used_ == sizeof(buf_)) { 79 // we scanned the whole buffer and didn't find an end-of-line marker. 80 // This line is too long to process. 81 return false; 82 } 83 84 // We didn't find any end-of-line terminators in the buffer. However, if 85 // this is the last line in the file it might not have one: 86 if (hit_eof_) { 87 assert(buf_used_); 88 // There's room for the NUL because of the buf_used_ == sizeof(buf_) 89 // check above. 90 buf_[buf_used_] = 0; 91 *len = buf_used_; 92 buf_used_ += 1; // since we appended the NUL. 93 *line = buf_; 94 return true; 95 } 96 97 // Otherwise, we should pull in more data from the file 98 const ssize_t n = sys_read(fd_, buf_ + buf_used_, 99 sizeof(buf_) - buf_used_); 100 if (n < 0) { 101 return false; 102 } else if (n == 0) { 103 hit_eof_ = true; 104 } else { 105 buf_used_ += n; 106 } 107 108 // At this point, we have either set the hit_eof_ flag, or we have more 109 // data to process... 110 } 111 } 112 PopLine(unsigned len)113 void PopLine(unsigned len) { 114 // len doesn't include the NUL byte at the end. 115 116 assert(buf_used_ >= len + 1); 117 buf_used_ -= len + 1; 118 my_memmove(buf_, buf_ + len + 1, buf_used_); 119 } 120 121 private: 122 const int fd_; 123 124 bool hit_eof_; 125 unsigned buf_used_; 126 char buf_[kMaxLineLen]; 127 }; 128 129 } // namespace google_breakpad 130 131 #endif // CLIENT_LINUX_MINIDUMP_WRITER_LINE_READER_H_ 132