Line data    Source code

       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:
      46           0 :   LineReader(int fd)
      47           0 :       : fd_(fd),
      48             :         hit_eof_(false),
      49           0 :         buf_used_(0) {
      50           0 :   }
      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.
      64           0 :   bool GetNextLine(const char **line, unsigned *len) {
      65             :     for (;;) {
      66           0 :       if (buf_used_ == 0 && hit_eof_)
      67           0 :         return false;
      68             : 
      69           0 :       for (unsigned i = 0; i < buf_used_; ++i) {
      70           0 :         if (buf_[i] == '\n' || buf_[i] == 0) {
      71           0 :           buf_[i] = 0;
      72           0 :           *len = i;
      73           0 :           *line = buf_;
      74           0 :           return true;
      75             :         }
      76             :       }
      77             : 
      78           0 :       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           0 :         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           0 :       if (hit_eof_) {
      87           0 :         assert(buf_used_);
      88             :         // There's room for the NUL because of the buf_used_ == sizeof(buf_)
      89             :         // check above.
      90           0 :         buf_[buf_used_] = 0;
      91           0 :         *len = buf_used_;
      92           0 :         buf_used_ += 1;  // since we appended the NUL.
      93           0 :         *line = buf_;
      94           0 :         return true;
      95             :       }
      96             : 
      97             :       // Otherwise, we should pull in more data from the file
      98           0 :       const ssize_t n = sys_read(fd_, buf_ + buf_used_,
      99           0 :                                  sizeof(buf_) - buf_used_);
     100           0 :       if (n < 0) {
     101           0 :         return false;
     102           0 :       } else if (n == 0) {
     103           0 :         hit_eof_ = true;
     104             :       } else {
     105           0 :         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           0 :     }
     111             :   }
     112             : 
     113           0 :   void PopLine(unsigned len) {
     114             :     // len doesn't include the NUL byte at the end.
     115             : 
     116           0 :     assert(buf_used_ >= len + 1);
     117           0 :     buf_used_ -= len + 1;
     118           0 :     my_memmove(buf_, buf_ + len + 1, buf_used_);
     119           0 :   }
     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_