1// Copyright (c) 2013, Google Inc.
2// All rights reserved.
3//
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17//
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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