1/* Determine various system internal values, Linux version.
2 Copyright (C) 1996-2016 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <http://www.gnu.org/licenses/>. */
19
20#include <alloca.h>
21#include <assert.h>
22#include <ctype.h>
23#include <dirent.h>
24#include <errno.h>
25#include <fcntl.h>
26#include <mntent.h>
27#include <paths.h>
28#include <stdio.h>
29#include <stdio_ext.h>
30#include <stdlib.h>
31#include <string.h>
32#include <unistd.h>
33#include <sys/sysinfo.h>
34
35#include <atomic.h>
36#include <not-cancel.h>
37
38
39/* How we can determine the number of available processors depends on
40 the configuration. There is currently (as of version 2.0.21) no
41 system call to determine the number. It is planned for the 2.1.x
42 series to add this, though.
43
44 One possibility to implement it for systems using Linux 2.0 is to
45 examine the pseudo file /proc/cpuinfo. Here we have one entry for
46 each processor.
47
48 But not all systems have support for the /proc filesystem. If it
49 is not available we simply return 1 since there is no way. */
50
51
52/* Other architectures use different formats for /proc/cpuinfo. This
53 provides a hook for alternative parsers. */
54#ifndef GET_NPROCS_PARSER
55# define GET_NPROCS_PARSER(FD, BUFFER, CP, RE, BUFFER_END, RESULT) \
56 do \
57 { \
58 (RESULT) = 0; \
59 /* Read all lines and count the lines starting with the string \
60 "processor". We don't have to fear extremely long lines since \
61 the kernel will not generate them. 8192 bytes are really \
62 enough. */ \
63 char *l; \
64 while ((l = next_line (FD, BUFFER, &CP, &RE, BUFFER_END)) != NULL) \
65 if (strncmp (l, "processor", 9) == 0) \
66 ++(RESULT); \
67 } \
68 while (0)
69#endif
70
71
72static char *
73next_line (int fd, char *const buffer, char **cp, char **re,
74 char *const buffer_end)
75{
76 char *res = *cp;
77 char *nl = memchr (*cp, '\n', *re - *cp);
78 if (nl == NULL)
79 {
80 if (*cp != buffer)
81 {
82 if (*re == buffer_end)
83 {
84 memmove (buffer, *cp, *re - *cp);
85 *re = buffer + (*re - *cp);
86 *cp = buffer;
87
88 ssize_t n = read_not_cancel (fd, *re, buffer_end - *re);
89 if (n < 0)
90 return NULL;
91
92 *re += n;
93
94 nl = memchr (*cp, '\n', *re - *cp);
95 while (nl == NULL && *re == buffer_end)
96 {
97 /* Truncate too long lines. */
98 *re = buffer + 3 * (buffer_end - buffer) / 4;
99 n = read_not_cancel (fd, *re, buffer_end - *re);
100 if (n < 0)
101 return NULL;
102
103 nl = memchr (*re, '\n', n);
104 **re = '\n';
105 *re += n;
106 }
107 }
108 else
109 nl = memchr (*cp, '\n', *re - *cp);
110
111 res = *cp;
112 }
113
114 if (nl == NULL)
115 nl = *re - 1;
116 }
117
118 *cp = nl + 1;
119 assert (*cp <= *re);
120
121 return res == *re ? NULL : res;
122}
123
124
125int
126__get_nprocs (void)
127{
128 static int cached_result = -1;
129 static time_t timestamp;
130
131 time_t now = time (NULL);
132 time_t prev = timestamp;
133 atomic_read_barrier ();
134 if (now == prev && cached_result > -1)
135 return cached_result;
136
137 /* XXX Here will come a test for the new system call. */
138
139 const size_t buffer_size = __libc_use_alloca (8192) ? 8192 : 512;
140 char *buffer = alloca (buffer_size);
141 char *buffer_end = buffer + buffer_size;
142 char *cp = buffer_end;
143 char *re = buffer_end;
144
145 const int flags = O_RDONLY | O_CLOEXEC;
146 int fd = open_not_cancel_2 ("/sys/devices/system/cpu/online", flags);
147 char *l;
148 int result = 0;
149 if (fd != -1)
150 {
151 l = next_line (fd, buffer, &cp, &re, buffer_end);
152 if (l != NULL)
153 do
154 {
155 char *endp;
156 unsigned long int n = strtoul (l, &endp, 10);
157 if (l == endp)
158 {
159 result = 0;
160 break;
161 }
162
163 unsigned long int m = n;
164 if (*endp == '-')
165 {
166 l = endp + 1;
167 m = strtoul (l, &endp, 10);
168 if (l == endp)
169 {
170 result = 0;
171 break;
172 }
173 }
174
175 result += m - n + 1;
176
177 l = endp;
178 while (l < re && isspace (*l))
179 ++l;
180 }
181 while (l < re);
182
183 close_not_cancel_no_status (fd);
184
185 if (result > 0)
186 goto out;
187 }
188
189 cp = buffer_end;
190 re = buffer_end;
191 result = 1;
192
193 /* The /proc/stat format is more uniform, use it by default. */
194 fd = open_not_cancel_2 ("/proc/stat", flags);
195 if (fd != -1)
196 {
197 result = 0;
198
199 while ((l = next_line (fd, buffer, &cp, &re, buffer_end)) != NULL)
200 /* The current format of /proc/stat has all the cpu* entries
201 at the front. We assume here that stays this way. */
202 if (strncmp (l, "cpu", 3) != 0)
203 break;
204 else if (isdigit (l[3]))
205 ++result;
206
207 close_not_cancel_no_status (fd);
208 }
209 else
210 {
211 fd = open_not_cancel_2 ("/proc/cpuinfo", flags);
212 if (fd != -1)
213 {
214 GET_NPROCS_PARSER (fd, buffer, cp, re, buffer_end, result);
215 close_not_cancel_no_status (fd);
216 }
217 }
218
219 out:
220 cached_result = result;
221 atomic_write_barrier ();
222 timestamp = now;
223
224 return result;
225}
226weak_alias (__get_nprocs, get_nprocs)
227
228
229/* On some architectures it is possible to distinguish between configured
230 and active cpus. */
231int
232__get_nprocs_conf (void)
233{
234 /* XXX Here will come a test for the new system call. */
235
236 /* Try to use the sysfs filesystem. It has actual information about
237 online processors. */
238 DIR *dir = __opendir ("/sys/devices/system/cpu");
239 if (dir != NULL)
240 {
241 int count = 0;
242 struct dirent64 *d;
243
244 while ((d = __readdir64 (dir)) != NULL)
245 /* NB: the sysfs has d_type support. */
246 if (d->d_type == DT_DIR && strncmp (d->d_name, "cpu", 3) == 0)
247 {
248 char *endp;
249 unsigned long int nr = strtoul (d->d_name + 3, &endp, 10);
250 if (nr != ULONG_MAX && endp != d->d_name + 3 && *endp == '\0')
251 ++count;
252 }
253
254 __closedir (dir);
255
256 return count;
257 }
258
259 int result = 1;
260
261#ifdef GET_NPROCS_CONF_PARSER
262 /* If we haven't found an appropriate entry return 1. */
263 FILE *fp = fopen ("/proc/cpuinfo", "rce");
264 if (fp != NULL)
265 {
266 char buffer[8192];
267
268 /* No threads use this stream. */
269 __fsetlocking (fp, FSETLOCKING_BYCALLER);
270 GET_NPROCS_CONF_PARSER (fp, buffer, result);
271 fclose (fp);
272 }
273#else
274 result = __get_nprocs ();
275#endif
276
277 return result;
278}
279weak_alias (__get_nprocs_conf, get_nprocs_conf)
280
281
282/* Compute (num*mem_unit)/pagesize, but avoid overflowing long int.
283 In practice, mem_unit is never bigger than the page size, so after
284 the first loop it is 1. [In the kernel, it is initialized to
285 PAGE_SIZE in mm/page_alloc.c:si_meminfo(), and then in
286 kernel.sys.c:do_sysinfo() it is set to 1 if unsigned long can
287 represent all the sizes measured in bytes]. */
288static long int
289sysinfo_mempages (unsigned long int num, unsigned int mem_unit)
290{
291 unsigned long int ps = __getpagesize ();
292
293 while (mem_unit > 1 && ps > 1)
294 {
295 mem_unit >>= 1;
296 ps >>= 1;
297 }
298 num *= mem_unit;
299 while (ps > 1)
300 {
301 ps >>= 1;
302 num >>= 1;
303 }
304 return num;
305}
306
307/* Return the number of pages of total/available physical memory in
308 the system. This used to be done by parsing /proc/meminfo, but
309 that's unnecessarily expensive (and /proc is not always available).
310 The sysinfo syscall provides the same information, and has been
311 available at least since kernel 2.3.48. */
312long int
313__get_phys_pages (void)
314{
315 struct sysinfo info;
316
317 __sysinfo (&info);
318 return sysinfo_mempages (info.totalram, info.mem_unit);
319}
320weak_alias (__get_phys_pages, get_phys_pages)
321
322long int
323__get_avphys_pages (void)
324{
325 struct sysinfo info;
326
327 __sysinfo (&info);
328 return sysinfo_mempages (info.freeram, info.mem_unit);
329}
330weak_alias (__get_avphys_pages, get_avphys_pages)
331