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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
40namespace 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.
44class LineReader {
45 public:
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.
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
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