about summary refs log tree commit diff
path: root/sysdeps/unix/sysv/linux/getsysstats.c
blob: dce568c417f2be116d2348d38b8a4a6f1179cb2a (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
/* Determine various system internal values, Linux version.
   Copyright (C) 1996, 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <alloca.h>
#include <assert.h>
#include <errno.h>
#include <mntent.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/sysinfo.h>

#include <atomicity.h>


/* The default value for the /proc filesystem mount point.  */
static const char path_proc[] = "/proc";

/* Actual mount point of /proc filesystem.  */
static char *mount_proc;

/* Determine the path to the /proc filesystem if available.  */
static const char *
internal_function
get_proc_path (char *buffer, size_t bufsize)
{
  struct mntent mount_point;
  struct mntent *entry;
  char *result = NULL;
  char *copy_result;
  FILE *fp;

  /* First find the mount point of the proc filesystem.  */
  fp = __setmntent (_PATH_MOUNTED, "r");
  if (fp == NULL)
    fp = __setmntent (_PATH_MNTTAB, "r");
  if (fp != NULL)
    {
      while ((entry = __getmntent_r (fp, &mount_point, buffer, bufsize))
	     != NULL)
	if (strcmp (mount_point.mnt_type, "proc") == 0)
	  {
	    result = mount_point.mnt_dir;
	    break;
	  }
      __endmntent (fp);
    }

  /* If we haven't found anything this is generally a bad sign but we
     handle it gracefully.  We return what is hopefully the right
     answer (/proc) but we don't remember this.  This will enable
     programs which started before the system is fully running to
     adjust themselves.  */
  if (result == NULL)
    return path_proc;

  /* Make a copy we can keep around.  */
  copy_result = __strdup (result);
  if (copy_result == NULL)
    return result;

  /* Now store the copied value.  But do it atomically.  */
  assert (sizeof (long int) == sizeof (void *__unbounded));
  if (compare_and_swap ((long int *) &mount_proc, (long int) 0,
			(long int) copy_result) == 0)
    /* Replacing the value failed.  This means another thread was
       faster and we don't need the copy anymore.  */
    free (copy_result);

  return mount_proc;
}


/* How we can determine the number of available processors depends on
   the configuration.  There is currently (as of version 2.0.21) no
   system call to determine the number.  It is planned for the 2.1.x
   series to add this, though.

   One possibility to implement it for systems using Linux 2.0 is to
   examine the pseudo file /proc/cpuinfo.  Here we have one entry for
   each processor.

   But not all systems have support for the /proc filesystem.  If it
   is not available we simply return 1 since there is no way.  */

/* Other architectures use different formats for /proc/cpuinfo.  This
   provides a hook for alternative parsers.  */
#ifndef GET_NPROCS_PARSER
# define GET_NPROCS_PARSER(FP, BUFFER, RESULT)				\
  do									\
    {									\
      (RESULT) = 0;							\
      /* Read all lines and count the lines starting with the string	\
	 "processor".  We don't have to fear extremely long lines since	\
	 the kernel will not generate them.  8192 bytes are really	\
	 enough.  */							\
      while (fgets_unlocked (BUFFER, sizeof (BUFFER), FP) != NULL)	\
	if (strncmp (BUFFER, "processor", 9) == 0)			\
	  ++(RESULT);							\
    }									\
  while (0)
#endif

int
__get_nprocs ()
{
  FILE *fp;
  char buffer[8192];
  const char *proc_path;
  int result = 1;

  /* XXX Here will come a test for the new system call.  */

  /* Get mount point of proc filesystem.  */
  proc_path = get_proc_path (buffer, sizeof buffer);

  /* If we haven't found an appropriate entry return 1.  */
  if (proc_path != NULL)
    {
      char *proc_cpuinfo = alloca (strlen (proc_path) + sizeof ("/cpuinfo"));
      __stpcpy (__stpcpy (proc_cpuinfo, proc_path), "/cpuinfo");

      fp = fopen (proc_cpuinfo, "r");
      if (fp != NULL)
	{
	  GET_NPROCS_PARSER (fp, buffer, result);
	  fclose (fp);
	}
    }

  return result;
}
weak_alias (__get_nprocs, get_nprocs)


#ifdef GET_NPROCS_CONF_PARSER
/* On some architectures it is possible to distinguish between configured
   and active cpus.  */
int
__get_nprocs_conf ()
{
  FILE *fp;
  char buffer[8192];
  const char *proc_path;
  int result = 1;

  /* XXX Here will come a test for the new system call.  */

  /* Get mount point of proc filesystem.  */
  proc_path = get_proc_path (buffer, sizeof buffer);

  /* If we haven't found an appropriate entry return 1.  */
  if (proc_path != NULL)
    {
      char *proc_cpuinfo = alloca (strlen (proc_path) + sizeof ("/cpuinfo"));
      __stpcpy (__stpcpy (proc_cpuinfo, proc_path), "/cpuinfo");

      fp = fopen (proc_cpuinfo, "r");
      if (fp != NULL)
	{
	  GET_NPROCS_CONF_PARSER (fp, buffer, result);
	  fclose (fp);
	}
    }

  return result;
}
#else
/* As far as I know Linux has no separate numbers for configured and
   available processors.  So make the `get_nprocs_conf' function an
   alias.  */
strong_alias (__get_nprocs, __get_nprocs_conf)
#endif
weak_alias (__get_nprocs_conf, get_nprocs_conf)

/* General function to get information about memory status from proc
   filesystem.  */
static int
internal_function
phys_pages_info (const char *format)
{
  FILE *fp;
  char buffer[8192];
  const char *proc_path;
  int result = -1;

  /* Get mount point of proc filesystem.  */
  proc_path = get_proc_path (buffer, sizeof buffer);

  /* If we haven't found an appropriate entry return 1.  */
  if (proc_path != NULL)
    {
      char *proc_meminfo = alloca (strlen (proc_path) + sizeof ("/meminfo"));
      __stpcpy (__stpcpy (proc_meminfo, proc_path), "/meminfo");

      fp = fopen (proc_meminfo, "r");
      if (fp != NULL)
	{
	  result = 0;
	  /* Read all lines and count the lines starting with the
	     string "processor".  We don't have to fear extremely long
	     lines since the kernel will not generate them.  8192
	     bytes are really enough.  */
	  while (fgets_unlocked (buffer, sizeof buffer, fp) != NULL)
	    if (sscanf (buffer, format, &result) == 1)
	      {
		result /= (__getpagesize () / 1024);
		break;
	      }

	  fclose (fp);
	}
    }

  if (result == -1)
    /* We cannot get the needed value: signal an error.  */
    __set_errno (ENOSYS);

  return result;
}


/* Return the number of pages of physical memory in the system.  There
   is currently (as of version 2.0.21) no system call to determine the
   number.  It is planned for the 2.1.x series to add this, though.

   One possibility to implement it for systems using Linux 2.0 is to
   examine the pseudo file /proc/cpuinfo.  Here we have one entry for
   each processor.

   But not all systems have support for the /proc filesystem.  If it
   is not available we return -1 as an error signal.  */
int
__get_phys_pages ()
{
  /* XXX Here will come a test for the new system call.  */

  return phys_pages_info ("MemTotal: %d kB");
}
weak_alias (__get_phys_pages, get_phys_pages)


/* Return the number of available pages of physical memory in the
   system.  There is currently (as of version 2.0.21) no system call
   to determine the number.  It is planned for the 2.1.x series to add
   this, though.

   One possibility to implement it for systems using Linux 2.0 is to
   examine the pseudo file /proc/cpuinfo.  Here we have one entry for
   each processor.

   But not all systems have support for the /proc filesystem.  If it
   is not available we return -1 as an error signal.  */
int
__get_avphys_pages ()
{
  /* XXX Here will come a test for the new system call.  */

  return phys_pages_info ("MemFree: %d kB");
}
weak_alias (__get_avphys_pages, get_avphys_pages)


static void
free_mem (void)
{
  free (mount_proc);
}
text_set_element (__libc_subfreeres, free_mem);