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 <errno.h>
30 #include <fcntl.h>
31 #include <limits.h>
32 #include <pthread.h>
33 #include <stdio.h> // For FOPEN_MAX.
34 #include <sys/auxv.h>
35 #include <sys/param.h>
36 #include <sys/resource.h>
37 #include <sys/sysinfo.h>
38 #include <time.h>
39 #include <unistd.h>
40
41 #include "private/bionic_tls.h"
42
__sysconf_rlimit(int resource)43 static long __sysconf_rlimit(int resource) {
44 rlimit rl;
45 getrlimit(resource, &rl);
46 return rl.rlim_cur;
47 }
48
sysconf(int name)49 long sysconf(int name) {
50 switch (name) {
51 //
52 // Things we actually have to calculate...
53 //
54 case _SC_ARG_MAX:
55 // You might think that just returning a constant 128KiB (ARG_MAX) would
56 // make sense, as this guy did:
57 //
58 // https://lkml.org/lkml/2017/11/15/813...
59 //
60 // I suspect a 128kB sysconf(_SC_ARG_MAX) is the sanest bet, simply
61 // because of that "conservative is better than aggressive".
62 //
63 // Especially since _technically_ we're still limiting things to that
64 // 128kB due to the single-string limit.
65 //
66 // Linus
67 //
68 // In practice that caused us trouble with toybox tests for xargs edge
69 // cases. The tests assume that they can at least reach the kernel's
70 // "minimum maximum" of 128KiB, but if we report 128KiB for _SC_ARG_MAX
71 // and xargs starts subtracting the environment space and so on from that,
72 // then xargs will think it's run out of space when given 128KiB of data,
73 // which should always work. See this thread for more:
74 //
75 // http://lists.landley.net/pipermail/toybox-landley.net/2019-November/011229.html
76 //
77 // So let's resign ourselves to tracking what the kernel actually does.
78 // Right now (2019, Linux 5.3) that amounts to:
79 return MAX(MIN(__sysconf_rlimit(RLIMIT_STACK) / 4, 3 * _STK_LIM / 4), ARG_MAX);
80
81 case _SC_AVPHYS_PAGES: return get_avphys_pages();
82 case _SC_CHILD_MAX: return __sysconf_rlimit(RLIMIT_NPROC);
83 case _SC_CLK_TCK: return static_cast<long>(getauxval(AT_CLKTCK));
84 case _SC_NPROCESSORS_CONF: return get_nprocs_conf();
85 case _SC_NPROCESSORS_ONLN: return get_nprocs();
86 case _SC_OPEN_MAX: return __sysconf_rlimit(RLIMIT_NOFILE);
87
88 case _SC_PAGESIZE:
89 case _SC_PAGE_SIZE:
90 // _SC_PAGESIZE and _SC_PAGE_SIZE are distinct, but return the same value.
91 return static_cast<long>(getauxval(AT_PAGESZ));
92
93 case _SC_PHYS_PAGES: return get_phys_pages();
94
95 //
96 // Constants...
97 //
98 case _SC_BC_BASE_MAX: return _POSIX2_BC_BASE_MAX; // Minimum requirement.
99 case _SC_BC_DIM_MAX: return _POSIX2_BC_DIM_MAX; // Minimum requirement.
100 case _SC_BC_SCALE_MAX: return _POSIX2_BC_SCALE_MAX; // Minimum requirement.
101 case _SC_BC_STRING_MAX: return _POSIX2_BC_STRING_MAX; // Minimum requirement.
102 case _SC_COLL_WEIGHTS_MAX: return _POSIX2_COLL_WEIGHTS_MAX; // Minimum requirement.
103 case _SC_EXPR_NEST_MAX: return _POSIX2_EXPR_NEST_MAX; // Minimum requirement.
104 case _SC_LINE_MAX: return _POSIX2_LINE_MAX; // Minimum requirement.
105 case _SC_NGROUPS_MAX: return NGROUPS_MAX;
106 case _SC_PASS_MAX: return PASS_MAX;
107 case _SC_2_C_BIND: return _POSIX2_C_BIND;
108 case _SC_2_C_DEV: return _POSIX2_C_DEV;
109 case _SC_2_CHAR_TERM: return _POSIX2_CHAR_TERM;
110 case _SC_2_FORT_DEV: return -1;
111 case _SC_2_FORT_RUN: return -1;
112 case _SC_2_LOCALEDEF: return _POSIX2_LOCALEDEF;
113 case _SC_2_SW_DEV: return _POSIX2_SW_DEV;
114 case _SC_2_UPE: return _POSIX2_UPE;
115 case _SC_2_VERSION: return _POSIX2_VERSION;
116 case _SC_JOB_CONTROL: return _POSIX_JOB_CONTROL;
117 case _SC_SAVED_IDS: return _POSIX_SAVED_IDS;
118 case _SC_VERSION: return _POSIX_VERSION;
119 case _SC_RE_DUP_MAX: return _POSIX_RE_DUP_MAX; // Minimum requirement.
120 case _SC_STREAM_MAX: return FOPEN_MAX;
121 case _SC_TZNAME_MAX: return _POSIX_TZNAME_MAX; // Minimum requirement.
122 case _SC_XOPEN_CRYPT: return _XOPEN_CRYPT;
123 case _SC_XOPEN_ENH_I18N: return _XOPEN_ENH_I18N;
124 case _SC_XOPEN_SHM: return _XOPEN_SHM;
125 case _SC_XOPEN_VERSION: return _XOPEN_VERSION;
126 case _SC_XOPEN_REALTIME: return _XOPEN_REALTIME;
127 case _SC_XOPEN_REALTIME_THREADS: return _XOPEN_REALTIME_THREADS;
128 case _SC_XOPEN_LEGACY: return _XOPEN_LEGACY;
129 case _SC_ATEXIT_MAX: return LONG_MAX; // Unlimited.
130 case _SC_IOV_MAX: return IOV_MAX;
131
132 case _SC_XOPEN_UNIX: return _XOPEN_UNIX;
133 case _SC_AIO_LISTIO_MAX: return _POSIX_AIO_LISTIO_MAX; // Minimum requirement.
134 case _SC_AIO_MAX: return _POSIX_AIO_MAX; // Minimum requirement.
135 case _SC_AIO_PRIO_DELTA_MAX:return 0; // Minimum requirement.
136 case _SC_DELAYTIMER_MAX: return INT_MAX;
137 case _SC_MQ_OPEN_MAX: return _POSIX_MQ_OPEN_MAX; // Minimum requirement.
138 case _SC_MQ_PRIO_MAX: return _POSIX_MQ_PRIO_MAX; // Minimum requirement.
139 case _SC_RTSIG_MAX: return RTSIG_MAX;
140 case _SC_SEM_NSEMS_MAX: return _POSIX_SEM_NSEMS_MAX; // Minimum requirement.
141 case _SC_SEM_VALUE_MAX: return SEM_VALUE_MAX;
142 case _SC_SIGQUEUE_MAX: return _POSIX_SIGQUEUE_MAX; // Minimum requirement.
143 case _SC_TIMER_MAX: return _POSIX_TIMER_MAX; // Minimum requirement.
144 case _SC_ASYNCHRONOUS_IO: return _POSIX_ASYNCHRONOUS_IO;
145 case _SC_FSYNC: return _POSIX_FSYNC;
146 case _SC_MAPPED_FILES: return _POSIX_MAPPED_FILES;
147 case _SC_MEMLOCK: return _POSIX_MEMLOCK;
148 case _SC_MEMLOCK_RANGE: return _POSIX_MEMLOCK_RANGE;
149 case _SC_MEMORY_PROTECTION: return _POSIX_MEMORY_PROTECTION;
150 case _SC_MESSAGE_PASSING: return _POSIX_MESSAGE_PASSING;
151 case _SC_PRIORITIZED_IO: return _POSIX_PRIORITIZED_IO;
152 case _SC_PRIORITY_SCHEDULING: return _POSIX_PRIORITY_SCHEDULING;
153 case _SC_REALTIME_SIGNALS: return _POSIX_REALTIME_SIGNALS;
154 case _SC_SEMAPHORES: return _POSIX_SEMAPHORES;
155 case _SC_SHARED_MEMORY_OBJECTS: return _POSIX_SHARED_MEMORY_OBJECTS;
156 case _SC_SYNCHRONIZED_IO: return _POSIX_SYNCHRONIZED_IO;
157 case _SC_TIMERS: return _POSIX_TIMERS;
158 case _SC_GETGR_R_SIZE_MAX: return 1024;
159 case _SC_GETPW_R_SIZE_MAX: return 1024;
160 case _SC_LOGIN_NAME_MAX: return LOGIN_NAME_MAX;
161 case _SC_THREAD_DESTRUCTOR_ITERATIONS: return PTHREAD_DESTRUCTOR_ITERATIONS;
162 case _SC_THREAD_KEYS_MAX: return PTHREAD_KEYS_MAX;
163 case _SC_THREAD_STACK_MIN: return PTHREAD_STACK_MIN;
164 case _SC_THREAD_THREADS_MAX: return -1; // No specific limit.
165 case _SC_TTY_NAME_MAX: return TTY_NAME_MAX;
166 case _SC_THREADS: return _POSIX_THREADS;
167 case _SC_THREAD_ATTR_STACKADDR: return _POSIX_THREAD_ATTR_STACKADDR;
168 case _SC_THREAD_ATTR_STACKSIZE: return _POSIX_THREAD_ATTR_STACKSIZE;
169 case _SC_THREAD_PRIORITY_SCHEDULING: return _POSIX_THREAD_PRIORITY_SCHEDULING;
170 case _SC_THREAD_PRIO_INHERIT: return _POSIX_THREAD_PRIO_INHERIT;
171 case _SC_THREAD_PRIO_PROTECT: return _POSIX_THREAD_PRIO_PROTECT;
172 case _SC_THREAD_SAFE_FUNCTIONS: return _POSIX_THREAD_SAFE_FUNCTIONS;
173 case _SC_MONOTONIC_CLOCK: return _POSIX_MONOTONIC_CLOCK;
174
175 case _SC_2_PBS: return -1; // Obsolescent in POSIX.1-2008.
176 case _SC_2_PBS_ACCOUNTING: return -1; // Obsolescent in POSIX.1-2008.
177 case _SC_2_PBS_CHECKPOINT: return -1; // Obsolescent in POSIX.1-2008.
178 case _SC_2_PBS_LOCATE: return -1; // Obsolescent in POSIX.1-2008.
179 case _SC_2_PBS_MESSAGE: return -1; // Obsolescent in POSIX.1-2008.
180 case _SC_2_PBS_TRACK: return -1; // Obsolescent in POSIX.1-2008.
181 case _SC_ADVISORY_INFO: return _POSIX_ADVISORY_INFO;
182 case _SC_BARRIERS: return _POSIX_BARRIERS;
183 case _SC_CLOCK_SELECTION: return _POSIX_CLOCK_SELECTION;
184 case _SC_CPUTIME: return _POSIX_CPUTIME;
185
186 case _SC_HOST_NAME_MAX: return _POSIX_HOST_NAME_MAX; // Minimum requirement.
187 case _SC_IPV6: return _POSIX_IPV6;
188 case _SC_RAW_SOCKETS: return _POSIX_RAW_SOCKETS;
189 case _SC_READER_WRITER_LOCKS: return _POSIX_READER_WRITER_LOCKS;
190 case _SC_REGEXP: return _POSIX_REGEXP;
191 case _SC_SHELL: return _POSIX_SHELL;
192 case _SC_SPAWN: return _POSIX_SPAWN;
193 case _SC_SPIN_LOCKS: return _POSIX_SPIN_LOCKS;
194 case _SC_SPORADIC_SERVER: return _POSIX_SPORADIC_SERVER;
195 case _SC_SS_REPL_MAX: return -1;
196 case _SC_SYMLOOP_MAX: return _POSIX_SYMLOOP_MAX; // Minimum requirement.
197 case _SC_THREAD_CPUTIME: return _POSIX_THREAD_CPUTIME;
198
199 case _SC_THREAD_PROCESS_SHARED: return _POSIX_THREAD_PROCESS_SHARED;
200 case _SC_THREAD_ROBUST_PRIO_INHERIT: return _POSIX_THREAD_ROBUST_PRIO_INHERIT;
201 case _SC_THREAD_ROBUST_PRIO_PROTECT: return _POSIX_THREAD_ROBUST_PRIO_PROTECT;
202 case _SC_THREAD_SPORADIC_SERVER: return _POSIX_THREAD_SPORADIC_SERVER;
203 case _SC_TIMEOUTS: return _POSIX_TIMEOUTS;
204 case _SC_TRACE: return -1; // Obsolescent in POSIX.1-2008.
205 case _SC_TRACE_EVENT_FILTER: return -1; // Obsolescent in POSIX.1-2008.
206 case _SC_TRACE_EVENT_NAME_MAX: return -1;
207 case _SC_TRACE_INHERIT: return -1; // Obsolescent in POSIX.1-2008.
208 case _SC_TRACE_LOG: return -1; // Obsolescent in POSIX.1-2008.
209 case _SC_TRACE_NAME_MAX: return -1;
210 case _SC_TRACE_SYS_MAX: return -1;
211 case _SC_TRACE_USER_EVENT_MAX: return -1;
212 case _SC_TYPED_MEMORY_OBJECTS: return _POSIX_TYPED_MEMORY_OBJECTS;
213 case _SC_V7_ILP32_OFF32: return _POSIX_V7_ILP32_OFF32;
214 case _SC_V7_ILP32_OFFBIG: return _POSIX_V7_ILP32_OFFBIG;
215 case _SC_V7_LP64_OFF64: return _POSIX_V7_LP64_OFF64;
216 case _SC_V7_LPBIG_OFFBIG: return _POSIX_V7_LPBIG_OFFBIG;
217 case _SC_XOPEN_STREAMS: return -1; // Obsolescent in POSIX.1-2008.
218 case _SC_XOPEN_UUCP: return -1;
219
220 // We do not have actual implementations for cache queries.
221 // It's valid to return 0 as the result is unknown.
222 case _SC_LEVEL1_ICACHE_SIZE: return 0;
223 case _SC_LEVEL1_ICACHE_ASSOC: return 0;
224 case _SC_LEVEL1_ICACHE_LINESIZE: return 0;
225 case _SC_LEVEL1_DCACHE_SIZE: return 0;
226 case _SC_LEVEL1_DCACHE_ASSOC: return 0;
227 case _SC_LEVEL1_DCACHE_LINESIZE: return 0;
228 case _SC_LEVEL2_CACHE_SIZE: return 0;
229 case _SC_LEVEL2_CACHE_ASSOC: return 0;
230 case _SC_LEVEL2_CACHE_LINESIZE: return 0;
231 case _SC_LEVEL3_CACHE_SIZE: return 0;
232 case _SC_LEVEL3_CACHE_ASSOC: return 0;
233 case _SC_LEVEL3_CACHE_LINESIZE: return 0;
234 case _SC_LEVEL4_CACHE_SIZE: return 0;
235 case _SC_LEVEL4_CACHE_ASSOC: return 0;
236 case _SC_LEVEL4_CACHE_LINESIZE: return 0;
237
238 default:
239 errno = EINVAL;
240 return -1;
241 }
242 }
243