sysconf.cpp revision 72bbd423579bb971dc06cdd3c06201faf3fe95e6 
1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *  * Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 *  * Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in
12 *    the documentation and/or other materials provided with the
13 *    distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <ctype.h>
30#include <dirent.h>
31#include <errno.h>
32#include <fcntl.h>
33#include <limits.h>
34#include <pthread.h>
35#include <stdio.h>  // For FOPEN_MAX.
36#include <string.h>
37#include <sys/sysconf.h>
38#include <time.h>
39#include <unistd.h>
40
41#include "private/bionic_tls.h"
42#include "private/ScopedReaddir.h"
43
44/* seems to be the default on Linux, per the GLibc sources and my own digging */
45
46#define  SYSTEM_CLK_TCK         100
47#define  SYSTEM_IOV_MAX         1024
48#define  SYSTEM_DELAYTIMER_MAX  2147483647
49#define  SYSTEM_MQ_OPEN_MAX     8
50#define  SYSTEM_MQ_PRIO_MAX     32768
51#define  SYSTEM_SEM_NSEMS_MAX   256
52#define  SYSTEM_SEM_VALUE_MAX   0x3fffffff  /* see bionic/semaphore.c */
53#define  SYSTEM_SIGQUEUE_MAX    32
54#define  SYSTEM_TIMER_MAX       32
55#define  SYSTEM_LOGIN_NAME_MAX  256
56#define  SYSTEM_TTY_NAME_MAX    32
57
58/* the following depends on our implementation */
59#define  SYSTEM_ATEXIT_MAX          65536    /* our implementation is unlimited */
60#define  SYSTEM_THREAD_THREADS_MAX  2048     /* really unlimited */
61
62#define  SYSTEM_2_C_BIND     _POSIX_VERSION  /* Posix C binding version */
63#define  SYSTEM_2_C_VER      _POSIX2_C_VERSION
64#define  SYSTEM_2_C_DEV      -1       /* Posix C development tools unsupported on the device */
65#define  SYSTEM_2_FORT_DEV   -1       /* Fortran development unsupported */
66#define  SYSTEM_2_FORT_RUN   -1       /* Fortran runtime unsupported */
67#define  SYSTEM_2_SW_DEV     -1       /* posix software dev utilities unsupported */
68#define  SYSTEM_2_LOCALEDEF  -1       /* localedef() unimplemented */
69#define  SYSTEM_2_UPE        -1       /* No UPE for you ! (User Portability Utilities) */
70#define  SYSTEM_2_VERSION    -1       /* No posix command-line tools */
71
72static bool __matches_cpuN(const char* s) {
73  // The %c trick is to ensure that we have the anchored match "^cpu[0-9]+$".
74  unsigned cpu;
75  char dummy;
76  return (sscanf(s, "cpu%u%c", &cpu, &dummy) == 1);
77}
78
79static int __sysconf_nprocessors_conf() {
80  // On x86 kernels you can use /proc/cpuinfo for this, but on ARM kernels offline CPUs disappear
81  // from there. This method works on both.
82  ScopedReaddir reader("/sys/devices/system/cpu");
83  if (reader.IsBad()) {
84    return 1;
85  }
86
87  int result = 0;
88  dirent* entry;
89  while ((entry = reader.ReadEntry()) != NULL) {
90    if (entry->d_type == DT_DIR && __matches_cpuN(entry->d_name)) {
91      ++result;
92    }
93  }
94  return result;
95}
96
97static int __sysconf_nprocessors_onln() {
98  FILE* fp = fopen("/proc/stat", "r");
99  if (fp == NULL) {
100    return 1;
101  }
102
103  int result = 0;
104  char buf[256];
105  while (fgets(buf, sizeof(buf), fp) != NULL) {
106    // Extract just the first word from the line.
107    // 'cpu0 7976751 1364388 3116842 469770388 8629405 0 49047 0 0 0'
108    char* p = strchr(buf, ' ');
109    if (p != NULL) {
110      *p = 0;
111    }
112    if (__matches_cpuN(buf)) {
113      ++result;
114    }
115  }
116  fclose(fp);
117  return result;
118}
119
120static int __get_meminfo(const char* pattern) {
121  FILE* fp = fopen("/proc/meminfo", "r");
122  if (fp == NULL) {
123    return -1;
124  }
125
126  int result = -1;
127  char buf[256];
128  while (fgets(buf, sizeof(buf), fp) != NULL) {
129    long total;
130    if (sscanf(buf, pattern, &total) == 1) {
131      result = (int) (total / (PAGE_SIZE/1024));
132      break;
133    }
134  }
135  fclose(fp);
136  return result;
137}
138
139static int __sysconf_phys_pages() {
140  return __get_meminfo("MemTotal: %ld kB");
141}
142
143static int __sysconf_avphys_pages() {
144  return __get_meminfo("MemFree: %ld kB");
145}
146
147static int __sysconf_monotonic_clock() {
148  timespec t;
149  int rc = clock_getres(CLOCK_MONOTONIC, &t);
150  return (rc == -1) ? -1 : _POSIX_VERSION;
151}
152
153int sysconf(int name) {
154    switch (name) {
155#ifdef _POSIX_ARG_MAX
156    case _SC_ARG_MAX:           return _POSIX_ARG_MAX;
157#endif
158#ifdef _POSIX2_BC_BASE_MAX
159    case _SC_BC_BASE_MAX:       return _POSIX2_BC_BASE_MAX;
160#endif
161#ifdef _POSIX2_BC_DIM_MAX
162    case _SC_BC_DIM_MAX:        return _POSIX2_BC_DIM_MAX;
163#endif
164#ifdef _POSIX2_BC_SCALE_MAX
165    case _SC_BC_SCALE_MAX:      return _POSIX2_BC_SCALE_MAX;
166#endif
167#ifdef _POSIX2_BC_STRING_MAX
168    case _SC_BC_STRING_MAX:     return _POSIX2_BC_STRING_MAX;
169#endif
170    case _SC_CHILD_MAX:         return CHILD_MAX;
171    case _SC_CLK_TCK:           return SYSTEM_CLK_TCK;
172#ifdef _POSIX2_COLL_WEIGHTS_MASK
173    case _SC_COLL_WEIGHTS_MAX:  return _POSIX2_COLL_WEIGHTS_MASK;
174#endif
175#ifdef _POSIX2_EXPR_NEST_MAX
176    case _SC_EXPR_NEST_MAX:    return _POSIX2_EXPR_NEST_MAX;
177#endif
178#ifdef _POSIX2_LINE_MAX
179    case _SC_LINE_MAX:          return _POSIX2_LINE_MAX;
180#endif
181    case _SC_NGROUPS_MAX:       return NGROUPS_MAX;
182    case _SC_OPEN_MAX:          return OPEN_MAX;
183    //case _SC_PASS_MAX:          return PASS_MAX;
184    case _SC_2_C_BIND:          return SYSTEM_2_C_BIND;
185    case _SC_2_C_DEV:           return SYSTEM_2_C_DEV;
186    case _SC_2_C_VERSION:       return SYSTEM_2_C_VER;
187    //case _SC_2_CHAR_TERM:         return ;
188    case _SC_2_FORT_DEV:        return SYSTEM_2_FORT_DEV;
189    case _SC_2_FORT_RUN:        return SYSTEM_2_FORT_RUN;
190    case _SC_2_LOCALEDEF:       return SYSTEM_2_LOCALEDEF;
191    case _SC_2_SW_DEV:          return SYSTEM_2_SW_DEV;
192    case _SC_2_UPE:             return SYSTEM_2_UPE;
193    case _SC_2_VERSION:         return SYSTEM_2_VERSION;
194#ifdef _POSIX_JOB_CONTROL
195    case _SC_JOB_CONTROL:       return _POSIX_JOB_CONTROL;
196#endif
197#ifdef _POSIX_SAVED_IDS
198    case _SC_SAVED_IDS:         return _POSIX_SAVED_IDS;
199#endif
200#ifdef _POSIX_VERSION
201    case _SC_VERSION:           return _POSIX_VERSION;
202#endif
203    //case _SC_RE_DUP_<AX:        return ;
204    case _SC_STREAM_MAX:        return FOPEN_MAX;
205    //case _SC_TZNAME_MAX:        return ;
206#if _XOPEN_CRYPT
207    case _SC_XOPEN_CRYPT:       return _XOPEN_CRYPT;
208#endif
209#ifdef _XOPEN_ENH_I18N
210    case _SC_XOPEN_ENH_I18N:    return _XOPEN_ENH_I18N;
211#endif
212#ifdef _XOPEN_SHM
213    case _SC_XOPEN_SHM:         return _XOPEN_SHM;
214#endif
215#ifdef _XOPEN_VERSION
216    case _SC_XOPEN_VERSION:     return _XOPEN_VERSION;
217#endif
218#ifdef _XOPEN_XCU_VERSION
219    case _SC_XOPEN_XCU_VERSION: return _XOPEN_XCU_VERSION;
220#endif
221#ifdef _XOPEN_REALTIME
222    case _SC_XOPEN_REALTIME:    return _XOPEN_REALTIME;
223#endif
224#ifdef _XOPEN_REALTIME_THREADS
225    case _SC_XOPEN_REALTIME_THREADS: return _XOPEN_REALTIME_THREADS;
226#endif
227#ifdef _XOPEN_LEGACY
228    case _SC_XOPEN_LEGACY:      return _XOPEN_LEGACY;
229#endif
230    case _SC_ATEXIT_MAX:        return SYSTEM_ATEXIT_MAX;
231    case _SC_IOV_MAX:           return SYSTEM_IOV_MAX;
232
233    case _SC_PAGESIZE:
234    case _SC_PAGE_SIZE:
235        return PAGE_SIZE;
236
237#ifdef _XOPEN_UNIX
238    case _SC_XOPEN_UNIX:        return _XOPEN_UNIX;
239#endif
240
241    // XXX: TODO: XBS5 nonsense
242
243#ifdef AIO_LISTIO_MAX
244    case _SC_AIO_LISTIO_MAX:       return AIO_LISTIO_MAX;
245#endif
246#ifdef AIO_MAX
247    case _SC_AIO_MAX:              return AIO_MAX;
248#endif
249#ifdef AIO_PRIO_DELTA_MAX
250    case _SC_AIO_PRIO_DELTA_MAX:   return AIO_PRIO_DELTA_MAX;
251#endif
252    case _SC_DELAYTIMER_MAX:    return SYSTEM_DELAYTIMER_MAX;
253    case _SC_MQ_OPEN_MAX:       return SYSTEM_MQ_OPEN_MAX;
254    case _SC_MQ_PRIO_MAX:       return SYSTEM_MQ_PRIO_MAX;
255    case _SC_RTSIG_MAX:         return RTSIG_MAX;
256    case _SC_SEM_NSEMS_MAX:     return SYSTEM_SEM_NSEMS_MAX;
257    case _SC_SEM_VALUE_MAX:     return SYSTEM_SEM_VALUE_MAX;
258    case _SC_SIGQUEUE_MAX:      return SYSTEM_SIGQUEUE_MAX;
259    case _SC_TIMER_MAX:         return SYSTEM_TIMER_MAX;
260#ifdef _POSIX_ASYNCHRONOUS_IO
261    case _SC_ASYNCHRONOUS_IO:   return _POSIX_ASYNCHRONOUS_IO;
262#endif
263#ifdef _POSIX_FSYNC
264    case _SC_FSYNC:             return _POSIX_FSYNC;
265#endif
266#ifdef _POSIX_MAPPED_FILES
267    case _SC_MAPPED_FILES:      return _POSIX_MAPPED_FILES;
268#endif
269#ifdef _POSIX_MEMLOCK
270    case _SC_MEMLOCK:           return _POSIX_MEMLOCK;
271#endif
272#ifdef _POSIX_MEMLOCK_RANGE
273    case _SC_MEMLOCK_RANGE:     return _POSIX_MEMLOCK_RANGE
274#endif
275#ifdef _POSIX_MEMORY_PROTECTION
276    case _SC_MEMORY_PROTECTION: return _POSIX_MEMORY_PROTECTION;
277#endif
278#ifdef _POSIX_MESSAGE_PASSING
279    case _SC_MESSAGE_PASSING:   return _POSIX_MESSAGE_PASSING;
280#endif
281#ifdef _POSIX_PRIORITIZED_IO
282    case _SC_PRIORITIZED_IO:    return _POSIX_PRIORITIZED_IO;
283#endif
284#ifdef _POSIX_PRIORITY_SCHEDULING
285    case _SC_PRIORITY_SCHEDULING:  return _POSIX_PRIORITY_SCHEDULING;
286#endif
287#ifdef _POSIX_REALTIME_SIGNALS
288    case _SC_REALTIME_SIGNALS:  return _POSIX_REALTIME_SIGNALS;
289#endif
290#ifdef _POSIX_SEMAPHORES
291    case _SC_SEMAPHORES:        return _POSIX_SEMAPHORES;
292#endif
293#ifdef _POSIX_SHARED_MEMORY_OBJECTS
294    case _SC_SHARED_MEMORY_OBJECTS:  return _POSIX_SHARED_MEMORY_OBJECTS;
295#endif
296#ifdef _POSIX_SYNCHRONIZED_IO
297    case _SC_SYNCHRONIZED_IO:   return _POSIX_SYNCHRONIZED_IO;
298#endif
299#ifdef _POSIX_TIMERS
300    case _SC_TIMERS:            return _POSIX_TIMERS;
301#endif
302
303    case _SC_GETGR_R_SIZE_MAX: return 1024;
304    case _SC_GETPW_R_SIZE_MAX: return 1024;
305
306    case _SC_LOGIN_NAME_MAX:    return SYSTEM_LOGIN_NAME_MAX;
307
308    case _SC_THREAD_DESTRUCTOR_ITERATIONS:
309      return _POSIX_THREAD_DESTRUCTOR_ITERATIONS;
310
311    case _SC_THREAD_KEYS_MAX:
312      return (BIONIC_TLS_SLOTS - TLS_SLOT_FIRST_USER_SLOT - BIONIC_TLS_RESERVED_SLOTS);
313
314    case _SC_THREAD_STACK_MIN:    return PTHREAD_STACK_MIN;
315    case _SC_THREAD_THREADS_MAX:  return SYSTEM_THREAD_THREADS_MAX;
316    case _SC_TTY_NAME_MAX:        return SYSTEM_TTY_NAME_MAX;
317#ifdef _POSIX_THREADS
318    case _SC_THREADS:             return _POSIX_THREADS;
319#endif
320
321    case _SC_THREAD_ATTR_STACKADDR:   return -1; // Removed in POSIX 2008
322    case _SC_THREAD_ATTR_STACKSIZE:   return -1; // Removed in POSIX 2008
323
324#ifdef _POSIX_THREAD_PRIORITY_SCHEDULING
325    case _SC_THREAD_PRIORITY_SCHEDULING:  return _POSIX_THREAD_PRIORITY_SCHEDULING;
326#endif
327#ifdef _POSIX_THREAD_PRIO_INHERIT
328    case _SC_THREAD_PRIO_INHERIT:         return _POSIX_THREAD_PRIO_INHERIT;
329#endif
330#ifdef _POSIX_THREAD_PRIO_PROTECT
331    case _SC_THREAD_PRIO_PROTECT: return _POSIX_THREAD_PRIO_PROTECT;
332#endif
333#ifdef _POSIX_THREAD_SAFE_FUNCTIONS
334    case _SC_THREAD_SAFE_FUNCTIONS:  return _POSIX_THREAD_SAFE_FUNCTIONS
335#endif
336
337    case _SC_MONOTONIC_CLOCK:   return __sysconf_monotonic_clock();
338    case _SC_NPROCESSORS_CONF:  return __sysconf_nprocessors_conf();
339    case _SC_NPROCESSORS_ONLN:  return __sysconf_nprocessors_onln();
340    case _SC_PHYS_PAGES:        return __sysconf_phys_pages();
341    case _SC_AVPHYS_PAGES:      return __sysconf_avphys_pages();
342
343    default:
344       /* Posix says EINVAL is the only error that shall be returned,
345        * but GLibc uses ENOSYS */
346        errno = ENOSYS;
347        return -1;
348    }
349}
350