1/* Determine various system internal values, Linux version.
2 Copyright (C) 1996-2020 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 <https://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_nocancel (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_nocancel (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_now ();
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_nocancel ("/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_nocancel_nostatus (fd);
184
185 if (result > 0)
186 goto out;
187 }
188
189 cp = buffer_end;
190 re = buffer_end;
191
192 /* Default to an SMP system in case we cannot obtain an accurate
193 number. */
194 result = 2;
195
196 /* The /proc/stat format is more uniform, use it by default. */
197 fd = __open_nocancel ("/proc/stat", flags);
198 if (fd != -1)
199 {
200 result = 0;
201
202 while ((l = next_line (fd, buffer, &cp, &re, buffer_end)) != NULL)
203 /* The current format of /proc/stat has all the cpu* entries
204 at the front. We assume here that stays this way. */
205 if (strncmp (l, "cpu", 3) != 0)
206 break;
207 else if (isdigit (l[3]))
208 ++result;
209
210 __close_nocancel_nostatus (fd);
211 }
212 else
213 {
214 fd = __open_nocancel ("/proc/cpuinfo", flags);
215 if (fd != -1)
216 {
217 GET_NPROCS_PARSER (fd, buffer, cp, re, buffer_end, result);
218 __close_nocancel_nostatus (fd);
219 }
220 }
221
222 out:
223 cached_result = result;
224 atomic_write_barrier ();
225 timestamp = now;
226
227 return result;
228}
229libc_hidden_def (__get_nprocs)
230weak_alias (__get_nprocs, get_nprocs)
231
232
233/* On some architectures it is possible to distinguish between configured
234 and active cpus. */
235int
236__get_nprocs_conf (void)
237{
238 /* XXX Here will come a test for the new system call. */
239
240 /* Try to use the sysfs filesystem. It has actual information about
241 online processors. */
242 DIR *dir = __opendir ("/sys/devices/system/cpu");
243 if (dir != NULL)
244 {
245 int count = 0;
246 struct dirent64 *d;
247
248 while ((d = __readdir64 (dir)) != NULL)
249 /* NB: the sysfs has d_type support. */
250 if (d->d_type == DT_DIR && strncmp (d->d_name, "cpu", 3) == 0)
251 {
252 char *endp;
253 unsigned long int nr = strtoul (d->d_name + 3, &endp, 10);
254 if (nr != ULONG_MAX && endp != d->d_name + 3 && *endp == '\0')
255 ++count;
256 }
257
258 __closedir (dir);
259
260 return count;
261 }
262
263 int result = 1;
264
265#ifdef GET_NPROCS_CONF_PARSER
266 /* If we haven't found an appropriate entry return 1. */
267 FILE *fp = fopen ("/proc/cpuinfo", "rce");
268 if (fp != NULL)
269 {
270 char buffer[8192];
271
272 /* No threads use this stream. */
273 __fsetlocking (fp, FSETLOCKING_BYCALLER);
274 GET_NPROCS_CONF_PARSER (fp, buffer, result);
275 fclose (fp);
276 }
277#else
278 result = __get_nprocs ();
279#endif
280
281 return result;
282}
283libc_hidden_def (__get_nprocs_conf)
284weak_alias (__get_nprocs_conf, get_nprocs_conf)
285
286
287/* Compute (num*mem_unit)/pagesize, but avoid overflowing long int.
288 In practice, mem_unit is never bigger than the page size, so after
289 the first loop it is 1. [In the kernel, it is initialized to
290 PAGE_SIZE in mm/page_alloc.c:si_meminfo(), and then in
291 kernel.sys.c:do_sysinfo() it is set to 1 if unsigned long can
292 represent all the sizes measured in bytes]. */
293static long int
294sysinfo_mempages (unsigned long int num, unsigned int mem_unit)
295{
296 unsigned long int ps = __getpagesize ();
297
298 while (mem_unit > 1 && ps > 1)
299 {
300 mem_unit >>= 1;
301 ps >>= 1;
302 }
303 num *= mem_unit;
304 while (ps > 1)
305 {
306 ps >>= 1;
307 num >>= 1;
308 }
309 return num;
310}
311
312/* Return the number of pages of total/available physical memory in
313 the system. This used to be done by parsing /proc/meminfo, but
314 that's unnecessarily expensive (and /proc is not always available).
315 The sysinfo syscall provides the same information, and has been
316 available at least since kernel 2.3.48. */
317long int
318__get_phys_pages (void)
319{
320 struct sysinfo info;
321
322 __sysinfo (&info);
323 return sysinfo_mempages (info.totalram, info.mem_unit);
324}
325libc_hidden_def (__get_phys_pages)
326weak_alias (__get_phys_pages, get_phys_pages)
327
328long int
329__get_avphys_pages (void)
330{
331 struct sysinfo info;
332
333 __sysinfo (&info);
334 return sysinfo_mempages (info.freeram, info.mem_unit);
335}
336libc_hidden_def (__get_avphys_pages)
337weak_alias (__get_avphys_pages, get_avphys_pages)
338