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29
30#ifndef CLIENT_LINUX_MINIDUMP_WRITER_CPU_SET_H_
31#define CLIENT_LINUX_MINIDUMP_WRITER_CPU_SET_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// Helper class used to model a set of CPUs, as read from sysfs
43// files like /sys/devices/system/cpu/present
44// See See http://www.kernel.org/doc/Documentation/cputopology.txt
45class CpuSet {
46public:
47 // The maximum number of supported CPUs.
48 static const size_t kMaxCpus = 1024;
49
50 CpuSet() {
51 my_memset(mask_, 0, sizeof(mask_));
52 }
53
54 // Parse a sysfs file to extract the corresponding CPU set.
55 bool ParseSysFile(int fd) {
56 char buffer[512];
57 int ret = sys_read(fd, buffer, sizeof(buffer)-1);
58 if (ret < 0)
59 return false;
60
61 buffer[ret] = '\0';
62
63 // Expected format: comma-separated list of items, where each
64 // item can be a decimal integer, or two decimal integers separated
65 // by a dash.
66 // E.g.:
67 // 0
68 // 0,1,2,3
69 // 0-3
70 // 1,10-23
71 const char* p = buffer;
72 const char* p_end = p + ret;
73 while (p < p_end) {
74 // Skip leading space, if any
75 while (p < p_end && my_isspace(*p))
76 p++;
77
78 // Find start and size of current item.
79 const char* item = p;
80 size_t item_len = static_cast<size_t>(p_end - p);
81 const char* item_next =
82 static_cast<const char*>(my_memchr(p, ',', item_len));
83 if (item_next != NULL) {
84 p = item_next + 1;
85 item_len = static_cast<size_t>(item_next - item);
86 } else {
87 p = p_end;
88 item_next = p_end;
89 }
90
91 // Ignore trailing spaces.
92 while (item_next > item && my_isspace(item_next[-1]))
93 item_next--;
94
95 // skip empty items.
96 if (item_next == item)
97 continue;
98
99 // read first decimal value.
100 uintptr_t start = 0;
101 const char* next = my_read_decimal_ptr(&start, item);
102 uintptr_t end = start;
103 if (*next == '-')
104 my_read_decimal_ptr(&end, next+1);
105
106 while (start <= end)
107 SetBit(start++);
108 }
109 return true;
110 }
111
112 // Intersect this CPU set with another one.
113 void IntersectWith(const CpuSet& other) {
114 for (size_t nn = 0; nn < kMaskWordCount; ++nn)
115 mask_[nn] &= other.mask_[nn];
116 }
117
118 // Return the number of CPUs in this set.
119 int GetCount() {
120 int result = 0;
121 for (size_t nn = 0; nn < kMaskWordCount; ++nn) {
122 result += __builtin_popcount(mask_[nn]);
123 }
124 return result;
125 }
126
127private:
128 void SetBit(uintptr_t index) {
129 size_t nn = static_cast<size_t>(index);
130 if (nn < kMaxCpus)
131 mask_[nn / kMaskWordBits] |= (1U << (nn % kMaskWordBits));
132 }
133
134 typedef uint32_t MaskWordType;
135 static const size_t kMaskWordBits = 8*sizeof(MaskWordType);
136 static const size_t kMaskWordCount =
137 (kMaxCpus + kMaskWordBits - 1) / kMaskWordBits;
138
139 MaskWordType mask_[kMaskWordCount];
140};
141
142} // namespace google_breakpad
143
144#endif // CLIENT_LINUX_MINIDUMP_WRITER_CPU_SET_H_
145