libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cc

   1 //===-- sanitizer_linux_libcdep.cc ----------------------------------------===//
   2 //
   3 // This file is distributed under the University of Illinois Open Source
   4 // License. See LICENSE.TXT for details.
   5 //
   6 //===----------------------------------------------------------------------===//
   7 //
   8 // This file is shared between AddressSanitizer and ThreadSanitizer
   9 // run-time libraries and implements linux-specific functions from
  10 // sanitizer_libc.h.
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "sanitizer_platform.h"
  14
  15 #if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD
  16
  17 #include "sanitizer_allocator_internal.h"
  18 #include "sanitizer_atomic.h"
  19 #include "sanitizer_common.h"
  20 #include "sanitizer_file.h"
  21 #include "sanitizer_flags.h"
  22 #include "sanitizer_freebsd.h"
  23 #include "sanitizer_linux.h"
  24 #include "sanitizer_placement_new.h"
  25 #include "sanitizer_procmaps.h"
  26 #include "sanitizer_stacktrace.h"
  27
  28 #include <dlfcn.h>  // for dlsym()
  29 #include <link.h>
  30 #include <pthread.h>
  31 #include <signal.h>
  32 #include <sys/resource.h>
  33 #include <syslog.h>
  34
  35 #if SANITIZER_FREEBSD
  36 #include <pthread_np.h>
  37 #include <osreldate.h>
  38 #define pthread_getattr_np pthread_attr_get_np
  39 #endif
  40
  41 #if SANITIZER_LINUX
  42 #include <sys/prctl.h>
  43 #endif
  44
  45 #if SANITIZER_ANDROID
  46 #include <android/api-level.h>
  47 #endif
  48
  49 #if SANITIZER_ANDROID && __ANDROID_API__ < 21
  50 #include <android/log.h>
  51 #endif
  52
  53 #if !SANITIZER_ANDROID
  54 #include <elf.h>
  55 #include <unistd.h>
  56 #endif
  57
  58 namespace __sanitizer {
  59
  60 SANITIZER_WEAK_ATTRIBUTE int
  61 real_sigaction(int signum, const void *act, void *oldact);
  62
  63 int internal_sigaction(int signum, const void *act, void *oldact) {
  64 #if !SANITIZER_GO
  65   if (&real_sigaction)
  66     return real_sigaction(signum, act, oldact);
  67 #endif
  68   return sigaction(signum, (const struct sigaction *)act,
  69                    (struct sigaction *)oldact);
  70 }
  71
  72 void GetThreadStackTopAndBottom(bool at_initialization, uptr *stack_top,
  73                                 uptr *stack_bottom) {
  74   CHECK(stack_top);
  75   CHECK(stack_bottom);
  76   if (at_initialization) {
  77     // This is the main thread. Libpthread may not be initialized yet.
  78     struct rlimit rl;
  79     CHECK_EQ(getrlimit(RLIMIT_STACK, &rl), 0);
  80
  81     // Find the mapping that contains a stack variable.
  82     MemoryMappingLayout proc_maps(/*cache_enabled*/true);
  83     MemoryMappedSegment segment;
  84     uptr prev_end = 0;
  85     while (proc_maps.Next(&segment)) {
  86       if ((uptr)&rl < segment.end) break;
  87       prev_end = segment.end;
  88     }
  89     CHECK((uptr)&rl >= segment.start && (uptr)&rl < segment.end);
  90
  91     // Get stacksize from rlimit, but clip it so that it does not overlap
  92     // with other mappings.
  93     uptr stacksize = rl.rlim_cur;
  94     if (stacksize > segment.end - prev_end) stacksize = segment.end - prev_end;
  95     // When running with unlimited stack size, we still want to set some limit.
  96     // The unlimited stack size is caused by 'ulimit -s unlimited'.
  97     // Also, for some reason, GNU make spawns subprocesses with unlimited stack.
  98     if (stacksize > kMaxThreadStackSize)
  99       stacksize = kMaxThreadStackSize;
 100     *stack_top = segment.end;
 101     *stack_bottom = segment.end - stacksize;
 102     return;
 103   }
 104   pthread_attr_t attr;
 105   pthread_attr_init(&attr);
 106   CHECK_EQ(pthread_getattr_np(pthread_self(), &attr), 0);
 107   uptr stacksize = 0;
 108   void *stackaddr = nullptr;
 109   my_pthread_attr_getstack(&attr, &stackaddr, &stacksize);
 110   pthread_attr_destroy(&attr);
 111
 112   *stack_top = (uptr)stackaddr + stacksize;
 113   *stack_bottom = (uptr)stackaddr;
 114 }
 115
 116 #if !SANITIZER_GO
 117 bool SetEnv(const char *name, const char *value) {
 118   void *f = dlsym(RTLD_NEXT, "setenv");
 119   if (!f)
 120     return false;
 121   typedef int(*setenv_ft)(const char *name, const char *value, int overwrite);
 122   setenv_ft setenv_f;
 123   CHECK_EQ(sizeof(setenv_f), sizeof(f));
 124   internal_memcpy(&setenv_f, &f, sizeof(f));
 125   return setenv_f(name, value, 1) == 0;
 126 }
 127 #endif
 128
 129 bool SanitizerSetThreadName(const char *name) {
 130 #ifdef PR_SET_NAME
 131   return 0 == prctl(PR_SET_NAME, (unsigned long)name, 0, 0, 0);  // NOLINT
 132 #else
 133   return false;
 134 #endif
 135 }
 136
 137 bool SanitizerGetThreadName(char *name, int max_len) {
 138 #ifdef PR_GET_NAME
 139   char buff[17];
 140   if (prctl(PR_GET_NAME, (unsigned long)buff, 0, 0, 0))  // NOLINT
 141     return false;
 142   internal_strncpy(name, buff, max_len);
 143   name[max_len] = 0;
 144   return true;
 145 #else
 146   return false;
 147 #endif
 148 }
 149
 150 #ifndef __GLIBC_PREREQ
 151 #define __GLIBC_PREREQ(x, y) 0
 152 #endif
 153
 154 #if !SANITIZER_FREEBSD && !SANITIZER_ANDROID && !SANITIZER_GO && \
 155     !SANITIZER_NETBSD
 156 static uptr g_tls_size;
 157
 158 void InitTlsSize() {
 159 // all current supported platforms have 16 bytes stack alignment
 160   const size_t kStackAlign = 16;
 161   size_t tls_size = 0;
 162   size_t tls_align = 0;
 163   void *get_tls_static_info_ptr = dlsym(RTLD_NEXT, "_dl_get_tls_static_info");
 164 #if defined(__i386__) && !__GLIBC_PREREQ(2, 27)
 165   /* On i?86, _dl_get_tls_static_info used to be internal_function, i.e.
 166      __attribute__((regparm(3), stdcall)) before glibc 2.27 and is normal
 167      function in 2.27 and later.  */
 168   if (!dlvsym(RTLD_NEXT, "glob", "GLIBC_2.27")) {
 169     typedef void (*get_tls_func)(size_t*, size_t*)
 170       __attribute__((regparm(3), stdcall));
 171     get_tls_func get_tls;
 172     CHECK_EQ(sizeof(get_tls), sizeof(get_tls_static_info_ptr));
 173     internal_memcpy(&get_tls, &get_tls_static_info_ptr,
 174                     sizeof(get_tls_static_info_ptr));
 175     CHECK_NE(get_tls, 0);
 176     get_tls(&tls_size, &tls_align);
 177   } else
 178 #endif
 179   {
 180     typedef void (*get_tls_func)(size_t*, size_t*);
 181     get_tls_func get_tls;
 182     CHECK_EQ(sizeof(get_tls), sizeof(get_tls_static_info_ptr));
 183     internal_memcpy(&get_tls, &get_tls_static_info_ptr,
 184                     sizeof(get_tls_static_info_ptr));
 185     CHECK_NE(get_tls, 0);
 186     get_tls(&tls_size, &tls_align);
 187   }
 188   if (tls_align < kStackAlign)
 189     tls_align = kStackAlign;
 190   g_tls_size = RoundUpTo(tls_size, tls_align);
 191 }
 192 #else
 193 void InitTlsSize() { }
 194 #endif  // !SANITIZER_FREEBSD && !SANITIZER_ANDROID && !SANITIZER_GO &&
 195         // !SANITIZER_NETBSD
 196
 197 #if (defined(__x86_64__) || defined(__i386__) || defined(__mips__) \
 198     || defined(__aarch64__) || defined(__powerpc64__) || defined(__s390__) \
 199     || defined(__arm__)) && SANITIZER_LINUX && !SANITIZER_ANDROID
 200 // sizeof(struct pthread) from glibc.
 201 static atomic_uintptr_t kThreadDescriptorSize;
 202
 203 uptr ThreadDescriptorSize() {
 204   uptr val = atomic_load(&kThreadDescriptorSize, memory_order_relaxed);
 205   if (val)
 206     return val;
 207 #if defined(__x86_64__) || defined(__i386__) || defined(__arm__)
 208 #ifdef _CS_GNU_LIBC_VERSION
 209   char buf[64];
 210   uptr len = confstr(_CS_GNU_LIBC_VERSION, buf, sizeof(buf));
 211   if (len < sizeof(buf) && internal_strncmp(buf, "glibc 2.", 8) == 0) {
 212     char *end;
 213     int minor = internal_simple_strtoll(buf + 8, &end, 10);
 214     if (end != buf + 8 && (*end == '\0' || *end == '.' || *end == '-')) {
 215       int patch = 0;
 216       if (*end == '.')
 217         // strtoll will return 0 if no valid conversion could be performed
 218         patch = internal_simple_strtoll(end + 1, nullptr, 10);
 219
 220       /* sizeof(struct pthread) values from various glibc versions.  */
 221       if (SANITIZER_X32)
 222         val = 1728;  // Assume only one particular version for x32.
 223       // For ARM sizeof(struct pthread) changed in Glibc 2.23.
 224       else if (SANITIZER_ARM)
 225         val = minor <= 22 ? 1120 : 1216;
 226       else if (minor <= 3)
 227         val = FIRST_32_SECOND_64(1104, 1696);
 228       else if (minor == 4)
 229         val = FIRST_32_SECOND_64(1120, 1728);
 230       else if (minor == 5)
 231         val = FIRST_32_SECOND_64(1136, 1728);
 232       else if (minor <= 9)
 233         val = FIRST_32_SECOND_64(1136, 1712);
 234       else if (minor == 10)
 235         val = FIRST_32_SECOND_64(1168, 1776);
 236       else if (minor == 11 || (minor == 12 && patch == 1))
 237         val = FIRST_32_SECOND_64(1168, 2288);
 238       else if (minor <= 14)
 239         val = FIRST_32_SECOND_64(1168, 2304);
 240       else
 241         val = FIRST_32_SECOND_64(1216, 2304);
 242     }
 243     if (val)
 244       atomic_store(&kThreadDescriptorSize, val, memory_order_relaxed);
 245     return val;
 246   }
 247 #endif
 248 #elif defined(__mips__)
 249   // TODO(sagarthakur): add more values as per different glibc versions.
 250   val = FIRST_32_SECOND_64(1152, 1776);
 251   if (val)
 252     atomic_store(&kThreadDescriptorSize, val, memory_order_relaxed);
 253   return val;
 254 #elif defined(__aarch64__)
 255   // The sizeof (struct pthread) is the same from GLIBC 2.17 to 2.22.
 256   val = 1776;
 257   atomic_store(&kThreadDescriptorSize, val, memory_order_relaxed);
 258   return val;
 259 #elif defined(__powerpc64__)
 260   val = 1776; // from glibc.ppc64le 2.20-8.fc21
 261   atomic_store(&kThreadDescriptorSize, val, memory_order_relaxed);
 262   return val;
 263 #elif defined(__s390__)
 264   val = FIRST_32_SECOND_64(1152, 1776); // valid for glibc 2.22
 265   atomic_store(&kThreadDescriptorSize, val, memory_order_relaxed);
 266 #endif
 267   return 0;
 268 }
 269
 270 // The offset at which pointer to self is located in the thread descriptor.
 271 const uptr kThreadSelfOffset = FIRST_32_SECOND_64(8, 16);
 272
 273 uptr ThreadSelfOffset() {
 274   return kThreadSelfOffset;
 275 }
 276
 277 #if defined(__mips__) || defined(__powerpc64__)
 278 // TlsPreTcbSize includes size of struct pthread_descr and size of tcb
 279 // head structure. It lies before the static tls blocks.
 280 static uptr TlsPreTcbSize() {
 281 # if defined(__mips__)
 282   const uptr kTcbHead = 16; // sizeof (tcbhead_t)
 283 # elif defined(__powerpc64__)
 284   const uptr kTcbHead = 88; // sizeof (tcbhead_t)
 285 # endif
 286   const uptr kTlsAlign = 16;
 287   const uptr kTlsPreTcbSize =
 288       RoundUpTo(ThreadDescriptorSize() + kTcbHead, kTlsAlign);
 289   return kTlsPreTcbSize;
 290 }
 291 #endif
 292
 293 uptr ThreadSelf() {
 294   uptr descr_addr;
 295 # if defined(__i386__)
 296   asm("mov %%gs:%c1,%0" : "=r"(descr_addr) : "i"(kThreadSelfOffset));
 297 # elif defined(__x86_64__)
 298   asm("mov %%fs:%c1,%0" : "=r"(descr_addr) : "i"(kThreadSelfOffset));
 299 # elif defined(__mips__)
 300   // MIPS uses TLS variant I. The thread pointer (in hardware register $29)
 301   // points to the end of the TCB + 0x7000. The pthread_descr structure is
 302   // immediately in front of the TCB. TlsPreTcbSize() includes the size of the
 303   // TCB and the size of pthread_descr.
 304   const uptr kTlsTcbOffset = 0x7000;
 305   uptr thread_pointer;
 306   asm volatile(".set push;\
 307                 .set mips64r2;\
 308                 rdhwr %0,$29;\
 309                 .set pop" : "=r" (thread_pointer));
 310   descr_addr = thread_pointer - kTlsTcbOffset - TlsPreTcbSize();
 311 # elif defined(__aarch64__) || defined(__arm__)
 312   descr_addr = reinterpret_cast<uptr>(__builtin_thread_pointer()) -
 313                                       ThreadDescriptorSize();
 314 # elif defined(__s390__)
 315   descr_addr = reinterpret_cast<uptr>(__builtin_thread_pointer());
 316 # elif defined(__powerpc64__)
 317   // PPC64LE uses TLS variant I. The thread pointer (in GPR 13)
 318   // points to the end of the TCB + 0x7000. The pthread_descr structure is
 319   // immediately in front of the TCB. TlsPreTcbSize() includes the size of the
 320   // TCB and the size of pthread_descr.
 321   const uptr kTlsTcbOffset = 0x7000;
 322   uptr thread_pointer;
 323   asm("addi %0,13,%1" : "=r"(thread_pointer) : "I"(-kTlsTcbOffset));
 324   descr_addr = thread_pointer - TlsPreTcbSize();
 325 # else
 326 #  error "unsupported CPU arch"
 327 # endif
 328   return descr_addr;
 329 }
 330 #endif  // (x86_64 || i386 || MIPS) && SANITIZER_LINUX
 331
 332 #if SANITIZER_FREEBSD
 333 static void **ThreadSelfSegbase() {
 334   void **segbase = 0;
 335 # if defined(__i386__)
 336   // sysarch(I386_GET_GSBASE, segbase);
 337   __asm __volatile("mov %%gs:0, %0" : "=r" (segbase));
 338 # elif defined(__x86_64__)
 339   // sysarch(AMD64_GET_FSBASE, segbase);
 340   __asm __volatile("movq %%fs:0, %0" : "=r" (segbase));
 341 # else
 342 #  error "unsupported CPU arch for FreeBSD platform"
 343 # endif
 344   return segbase;
 345 }
 346
 347 uptr ThreadSelf() {
 348   return (uptr)ThreadSelfSegbase()[2];
 349 }
 350 #elif SANITIZER_NETBSD
 351 uptr ThreadSelf() { return (uptr)pthread_self(); }
 352 #endif  // SANITIZER_NETBSD
 353
 354 #if !SANITIZER_GO
 355 static void GetTls(uptr *addr, uptr *size) {
 356 #if SANITIZER_LINUX && !SANITIZER_ANDROID
 357 # if defined(__x86_64__) || defined(__i386__) || defined(__s390__)
 358   *addr = ThreadSelf();
 359   *size = GetTlsSize();
 360   *addr -= *size;
 361   *addr += ThreadDescriptorSize();
 362 # elif defined(__mips__) || defined(__aarch64__) || defined(__powerpc64__) \
 363     || defined(__arm__)
 364   *addr = ThreadSelf();
 365   *size = GetTlsSize();
 366 # else
 367   *addr = 0;
 368   *size = 0;
 369 # endif
 370 #elif SANITIZER_FREEBSD
 371   void** segbase = ThreadSelfSegbase();
 372   *addr = 0;
 373   *size = 0;
 374   if (segbase != 0) {
 375     // tcbalign = 16
 376     // tls_size = round(tls_static_space, tcbalign);
 377     // dtv = segbase[1];
 378     // dtv[2] = segbase - tls_static_space;
 379     void **dtv = (void**) segbase[1];
 380     *addr = (uptr) dtv[2];
 381     *size = (*addr == 0) ? 0 : ((uptr) segbase[0] - (uptr) dtv[2]);
 382   }
 383 #elif SANITIZER_ANDROID || SANITIZER_NETBSD
 384   *addr = 0;
 385   *size = 0;
 386 #else
 387 # error "Unknown OS"
 388 #endif
 389 }
 390 #endif
 391
 392 #if !SANITIZER_GO
 393 uptr GetTlsSize() {
 394 #if SANITIZER_FREEBSD || SANITIZER_ANDROID || SANITIZER_NETBSD
 395   uptr addr, size;
 396   GetTls(&addr, &size);
 397   return size;
 398 #elif defined(__mips__) || defined(__powerpc64__)
 399   return RoundUpTo(g_tls_size + TlsPreTcbSize(), 16);
 400 #else
 401   return g_tls_size;
 402 #endif
 403 }
 404 #endif
 405
 406 void GetThreadStackAndTls(bool main, uptr *stk_addr, uptr *stk_size,
 407                           uptr *tls_addr, uptr *tls_size) {
 408 #if SANITIZER_GO
 409   // Stub implementation for Go.
 410   *stk_addr = *stk_size = *tls_addr = *tls_size = 0;
 411 #else
 412   GetTls(tls_addr, tls_size);
 413
 414   uptr stack_top, stack_bottom;
 415   GetThreadStackTopAndBottom(main, &stack_top, &stack_bottom);
 416   *stk_addr = stack_bottom;
 417   *stk_size = stack_top - stack_bottom;
 418
 419   if (!main) {
 420     // If stack and tls intersect, make them non-intersecting.
 421     if (*tls_addr > *stk_addr && *tls_addr < *stk_addr + *stk_size) {
 422       CHECK_GT(*tls_addr + *tls_size, *stk_addr);
 423       CHECK_LE(*tls_addr + *tls_size, *stk_addr + *stk_size);
 424       *stk_size -= *tls_size;
 425       *tls_addr = *stk_addr + *stk_size;
 426     }
 427   }
 428 #endif
 429 }
 430
 431 # if !SANITIZER_FREEBSD
 432 typedef ElfW(Phdr) Elf_Phdr;
 433 # elif SANITIZER_WORDSIZE == 32 && __FreeBSD_version <= 902001  // v9.2
 434 #  define Elf_Phdr XElf32_Phdr
 435 #  define dl_phdr_info xdl_phdr_info
 436 #  define dl_iterate_phdr(c, b) xdl_iterate_phdr((c), (b))
 437 # endif
 438
 439 struct DlIteratePhdrData {
 440   InternalMmapVectorNoCtor<LoadedModule> *modules;
 441   bool first;
 442 };
 443
 444 static int dl_iterate_phdr_cb(dl_phdr_info *info, size_t size, void *arg) {
 445   DlIteratePhdrData *data = (DlIteratePhdrData*)arg;
 446   InternalScopedString module_name(kMaxPathLength);
 447   if (data->first) {
 448     data->first = false;
 449     // First module is the binary itself.
 450     ReadBinaryNameCached(module_name.data(), module_name.size());
 451   } else if (info->dlpi_name) {
 452     module_name.append("%s", info->dlpi_name);
 453   }
 454   if (module_name[0] == '\0')
 455     return 0;
 456   LoadedModule cur_module;
 457   cur_module.set(module_name.data(), info->dlpi_addr);
 458   for (int i = 0; i < info->dlpi_phnum; i++) {
 459     const Elf_Phdr *phdr = &info->dlpi_phdr[i];
 460     if (phdr->p_type == PT_LOAD) {
 461       uptr cur_beg = info->dlpi_addr + phdr->p_vaddr;
 462       uptr cur_end = cur_beg + phdr->p_memsz;
 463       bool executable = phdr->p_flags & PF_X;
 464       bool writable = phdr->p_flags & PF_W;
 465       cur_module.addAddressRange(cur_beg, cur_end, executable,
 466                                  writable);
 467     }
 468   }
 469   data->modules->push_back(cur_module);
 470   return 0;
 471 }
 472
 473 #if SANITIZER_ANDROID && __ANDROID_API__ < 21
 474 extern "C" __attribute__((weak)) int dl_iterate_phdr(
 475     int (*)(struct dl_phdr_info *, size_t, void *), void *);
 476 #endif
 477
 478 static bool requiresProcmaps() {
 479 #if SANITIZER_ANDROID && __ANDROID_API__ <= 22
 480   // Fall back to /proc/maps if dl_iterate_phdr is unavailable or broken.
 481   // The runtime check allows the same library to work with
 482   // both K and L (and future) Android releases.
 483   return AndroidGetApiLevel() <= ANDROID_LOLLIPOP_MR1;
 484 #else
 485   return false;
 486 #endif
 487 }
 488
 489 static void procmapsInit(InternalMmapVectorNoCtor<LoadedModule> *modules) {
 490   MemoryMappingLayout memory_mapping(/*cache_enabled*/true);
 491   memory_mapping.DumpListOfModules(modules);
 492 }
 493
 494 void ListOfModules::init() {
 495   clearOrInit();
 496   if (requiresProcmaps()) {
 497     procmapsInit(&modules_);
 498   } else {
 499     DlIteratePhdrData data = {&modules_, true};
 500     dl_iterate_phdr(dl_iterate_phdr_cb, &data);
 501   }
 502 }
 503
 504 // When a custom loader is used, dl_iterate_phdr may not contain the full
 505 // list of modules. Allow callers to fall back to using procmaps.
 506 void ListOfModules::fallbackInit() {
 507   if (!requiresProcmaps()) {
 508     clearOrInit();
 509     procmapsInit(&modules_);
 510   } else {
 511     clear();
 512   }
 513 }
 514
 515 // getrusage does not give us the current RSS, only the max RSS.
 516 // Still, this is better than nothing if /proc/self/statm is not available
 517 // for some reason, e.g. due to a sandbox.
 518 static uptr GetRSSFromGetrusage() {
 519   struct rusage usage;
 520   if (getrusage(RUSAGE_SELF, &usage))  // Failed, probably due to a sandbox.
 521     return 0;
 522   return usage.ru_maxrss << 10;  // ru_maxrss is in Kb.
 523 }
 524
 525 uptr GetRSS() {
 526   if (!common_flags()->can_use_proc_maps_statm)
 527     return GetRSSFromGetrusage();
 528   fd_t fd = OpenFile("/proc/self/statm", RdOnly);
 529   if (fd == kInvalidFd)
 530     return GetRSSFromGetrusage();
 531   char buf[64];
 532   uptr len = internal_read(fd, buf, sizeof(buf) - 1);
 533   internal_close(fd);
 534   if ((sptr)len <= 0)
 535     return 0;
 536   buf[len] = 0;
 537   // The format of the file is:
 538   // 1084 89 69 11 0 79 0
 539   // We need the second number which is RSS in pages.
 540   char *pos = buf;
 541   // Skip the first number.
 542   while (*pos >= '0' && *pos <= '9')
 543     pos++;
 544   // Skip whitespaces.
 545   while (!(*pos >= '0' && *pos <= '9') && *pos != 0)
 546     pos++;
 547   // Read the number.
 548   uptr rss = 0;
 549   while (*pos >= '0' && *pos <= '9')
 550     rss = rss * 10 + *pos++ - '0';
 551   return rss * GetPageSizeCached();
 552 }
 553
 554 // 64-bit Android targets don't provide the deprecated __android_log_write.
 555 // Starting with the L release, syslog() works and is preferable to
 556 // __android_log_write.
 557 #if SANITIZER_LINUX
 558
 559 #if SANITIZER_ANDROID
 560 static atomic_uint8_t android_log_initialized;
 561
 562 void AndroidLogInit() {
 563   openlog(GetProcessName(), 0, LOG_USER);
 564   atomic_store(&android_log_initialized, 1, memory_order_release);
 565 }
 566
 567 static bool ShouldLogAfterPrintf() {
 568   return atomic_load(&android_log_initialized, memory_order_acquire);
 569 }
 570 #else
 571 void AndroidLogInit() {}
 572
 573 static bool ShouldLogAfterPrintf() { return true; }
 574 #endif  // SANITIZER_ANDROID
 575
 576 void WriteOneLineToSyslog(const char *s) {
 577 #if SANITIZER_ANDROID &&__ANDROID_API__ < 21
 578   __android_log_write(ANDROID_LOG_INFO, NULL, s);
 579 #else
 580   syslog(LOG_INFO, "%s", s);
 581 #endif
 582 }
 583
 584 void LogMessageOnPrintf(const char *str) {
 585   if (common_flags()->log_to_syslog && ShouldLogAfterPrintf())
 586     WriteToSyslog(str);
 587 }
 588
 589 #if SANITIZER_ANDROID
 590 extern "C" __attribute__((weak)) void android_set_abort_message(const char *);
 591 void SetAbortMessage(const char *str) {
 592   if (&android_set_abort_message) android_set_abort_message(str);
 593 }
 594 #else
 595 void SetAbortMessage(const char *str) {}
 596 #endif
 597
 598 #endif // SANITIZER_LINUX
 599
 600 } // namespace __sanitizer
 601
 602 #endif // SANITIZER_FREEBSD || SANITIZER_LINUX