1// Copyright (c) 2013, 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
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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.
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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
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22// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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24// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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28// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29
30#ifndef CLIENT_LINUX_MINIDUMP_WRITER_PROC_CPUINFO_READER_H_
31#define CLIENT_LINUX_MINIDUMP_WRITER_PROC_CPUINFO_READER_H_
32
33#include <stdint.h>
34#include <assert.h>
35#include <string.h>
36
37#include "client/linux/minidump_writer/line_reader.h"
38#include "common/linux/linux_libc_support.h"
39#include "third_party/lss/linux_syscall_support.h"
40
41namespace google_breakpad {
42
43// A class for reading /proc/cpuinfo without using fopen/fgets or other
44// functions which may allocate memory.
45class ProcCpuInfoReader {
46public:
47  ProcCpuInfoReader(int fd)
48    : line_reader_(fd), pop_count_(-1) {
49  }
50
51  // Return the next field name, or NULL in case of EOF.
52  // field: (output) Pointer to zero-terminated field name.
53  // Returns true on success, or false on EOF or error (line too long).
54  bool GetNextField(const char** field) {
55    for (;;) {
56      const char* line;
57      unsigned line_len;
58
59      // Try to read next line.
60      if (pop_count_ >= 0) {
61        line_reader_.PopLine(pop_count_);
62        pop_count_ = -1;
63      }
64
65      if (!line_reader_.GetNextLine(&line, &line_len))
66        return false;
67
68      pop_count_ = static_cast<int>(line_len);
69
70      const char* line_end = line + line_len;
71
72      // Expected format: <field-name> <space>+ ':' <space> <value>
73      // Note that:
74      //   - empty lines happen.
75      //   - <field-name> can contain spaces.
76      //   - some fields have an empty <value>
77      char* sep = static_cast<char*>(my_memchr(line, ':', line_len));
78      if (sep == NULL)
79        continue;
80
81      // Record the value. Skip leading space after the column to get
82      // its start.
83      const char* val = sep+1;
84      while (val < line_end && my_isspace(*val))
85        val++;
86
87      value_ = val;
88      value_len_ = static_cast<size_t>(line_end - val);
89
90      // Remove trailing spaces before the column to properly 0-terminate
91      // the field name.
92      while (sep > line && my_isspace(sep[-1]))
93        sep--;
94
95      if (sep == line)
96        continue;
97
98      // zero-terminate field name.
99      *sep = '\0';
100
101      *field = line;
102      return true;
103    }
104  }
105
106  // Return the field value. This must be called after a succesful
107  // call to GetNextField().
108  const char* GetValue() {
109    assert(value_);
110    return value_;
111  }
112
113  // Same as GetValue(), but also returns the length in characters of
114  // the value.
115  const char* GetValueAndLen(size_t* length) {
116    assert(value_);
117    *length = value_len_;
118    return value_;
119  }
120
121private:
122  LineReader line_reader_;
123  int pop_count_;
124  const char* value_;
125  size_t value_len_;
126};
127
128}  // namespace google_breakpad
129
130#endif  // CLIENT_LINUX_MINIDUMP_WRITER_PROC_CPUINFO_READER_H_
131