compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp

   1 //===-- sanitizer_linux.cpp -----------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file is shared between AddressSanitizer and ThreadSanitizer
  10 // run-time libraries and implements linux-specific functions from
  11 // sanitizer_libc.h.
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "sanitizer_platform.h"
  15
  16 #if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD || \
  17     SANITIZER_SOLARIS
  18
  19 #include "sanitizer_common.h"
  20 #include "sanitizer_flags.h"
  21 #include "sanitizer_getauxval.h"
  22 #include "sanitizer_internal_defs.h"
  23 #include "sanitizer_libc.h"
  24 #include "sanitizer_linux.h"
  25 #include "sanitizer_mutex.h"
  26 #include "sanitizer_placement_new.h"
  27 #include "sanitizer_procmaps.h"
  28
  29 #if SANITIZER_LINUX && !SANITIZER_GO
  30 #include <asm/param.h>
  31 #endif
  32
  33 // For mips64, syscall(__NR_stat) fills the buffer in the 'struct kernel_stat'
  34 // format. Struct kernel_stat is defined as 'struct stat' in asm/stat.h. To
  35 // access stat from asm/stat.h, without conflicting with definition in
  36 // sys/stat.h, we use this trick.
  37 #if defined(__mips64)
  38 #include <asm/unistd.h>
  39 #include <sys/types.h>
  40 #define stat kernel_stat
  41 #if SANITIZER_GO
  42 #undef st_atime
  43 #undef st_mtime
  44 #undef st_ctime
  45 #define st_atime st_atim
  46 #define st_mtime st_mtim
  47 #define st_ctime st_ctim
  48 #endif
  49 #include <asm/stat.h>
  50 #undef stat
  51 #endif
  52
  53 #include <dlfcn.h>
  54 #include <errno.h>
  55 #include <fcntl.h>
  56 #include <link.h>
  57 #include <pthread.h>
  58 #include <sched.h>
  59 #include <signal.h>
  60 #include <sys/mman.h>
  61 #include <sys/param.h>
  62 #if !SANITIZER_SOLARIS
  63 #include <sys/ptrace.h>
  64 #endif
  65 #include <sys/resource.h>
  66 #include <sys/stat.h>
  67 #include <sys/syscall.h>
  68 #include <sys/time.h>
  69 #include <sys/types.h>
  70 #include <ucontext.h>
  71 #include <unistd.h>
  72
  73 #if SANITIZER_LINUX
  74 #include <sys/utsname.h>
  75 #endif
  76
  77 #if SANITIZER_LINUX && !SANITIZER_ANDROID
  78 #include <sys/personality.h>
  79 #endif
  80
  81 #if SANITIZER_FREEBSD
  82 #include <sys/exec.h>
  83 #include <sys/procctl.h>
  84 #include <sys/sysctl.h>
  85 #include <machine/atomic.h>
  86 extern "C" {
  87 // <sys/umtx.h> must be included after <errno.h> and <sys/types.h> on
  88 // FreeBSD 9.2 and 10.0.
  89 #include <sys/umtx.h>
  90 }
  91 #include <sys/thr.h>
  92 #endif  // SANITIZER_FREEBSD
  93
  94 #if SANITIZER_NETBSD
  95 #include <limits.h>  // For NAME_MAX
  96 #include <sys/sysctl.h>
  97 #include <sys/exec.h>
  98 extern struct ps_strings *__ps_strings;
  99 #endif  // SANITIZER_NETBSD
 100
 101 #if SANITIZER_SOLARIS
 102 #include <stdlib.h>
 103 #include <thread.h>
 104 #define environ _environ
 105 #endif
 106
 107 extern char **environ;
 108
 109 #if SANITIZER_LINUX
 110 // <linux/time.h>
 111 struct kernel_timeval {
 112   long tv_sec;
 113   long tv_usec;
 114 };
 115
 116 // <linux/futex.h> is broken on some linux distributions.
 117 const int FUTEX_WAIT = 0;
 118 const int FUTEX_WAKE = 1;
 119 const int FUTEX_PRIVATE_FLAG = 128;
 120 const int FUTEX_WAIT_PRIVATE = FUTEX_WAIT | FUTEX_PRIVATE_FLAG;
 121 const int FUTEX_WAKE_PRIVATE = FUTEX_WAKE | FUTEX_PRIVATE_FLAG;
 122 #endif  // SANITIZER_LINUX
 123
 124 // Are we using 32-bit or 64-bit Linux syscalls?
 125 // x32 (which defines __x86_64__) has SANITIZER_WORDSIZE == 32
 126 // but it still needs to use 64-bit syscalls.
 127 #if SANITIZER_LINUX && (defined(__x86_64__) || defined(__powerpc64__) ||       \
 128                         SANITIZER_WORDSIZE == 64)
 129 # define SANITIZER_LINUX_USES_64BIT_SYSCALLS 1
 130 #else
 131 # define SANITIZER_LINUX_USES_64BIT_SYSCALLS 0
 132 #endif
 133
 134 // Note : FreeBSD had implemented both
 135 // Linux apis, available from
 136 // future 12.x version most likely
 137 #if SANITIZER_LINUX && defined(__NR_getrandom)
 138 # if !defined(GRND_NONBLOCK)
 139 #  define GRND_NONBLOCK 1
 140 # endif
 141 # define SANITIZER_USE_GETRANDOM 1
 142 #else
 143 # define SANITIZER_USE_GETRANDOM 0
 144 #endif  // SANITIZER_LINUX && defined(__NR_getrandom)
 145
 146 #if SANITIZER_FREEBSD && __FreeBSD_version >= 1200000
 147 #  define SANITIZER_USE_GETENTROPY 1
 148 #else
 149 #  define SANITIZER_USE_GETENTROPY 0
 150 #endif
 151
 152 namespace __sanitizer {
 153
 154 void SetSigProcMask(__sanitizer_sigset_t *set, __sanitizer_sigset_t *old) {
 155   CHECK_EQ(0, internal_sigprocmask(SIG_SETMASK, set, old));
 156 }
 157
 158 ScopedBlockSignals::ScopedBlockSignals(__sanitizer_sigset_t *copy) {
 159   __sanitizer_sigset_t set;
 160   internal_sigfillset(&set);
 161 #  if SANITIZER_LINUX && !SANITIZER_ANDROID
 162   // Glibc uses SIGSETXID signal during setuid call. If this signal is blocked
 163   // on any thread, setuid call hangs.
 164   // See test/sanitizer_common/TestCases/Linux/setuid.c.
 165   internal_sigdelset(&set, 33);
 166 #  endif
 167 #  if SANITIZER_LINUX
 168   // Seccomp-BPF-sandboxed processes rely on SIGSYS to handle trapped syscalls.
 169   // If this signal is blocked, such calls cannot be handled and the process may
 170   // hang.
 171   internal_sigdelset(&set, 31);
 172 #  endif
 173   SetSigProcMask(&set, &saved_);
 174   if (copy)
 175     internal_memcpy(copy, &saved_, sizeof(saved_));
 176 }
 177
 178 ScopedBlockSignals::~ScopedBlockSignals() { SetSigProcMask(&saved_, nullptr); }
 179
 180 #  if SANITIZER_LINUX && defined(__x86_64__)
 181 #    include "sanitizer_syscall_linux_x86_64.inc"
 182 #  elif SANITIZER_LINUX && SANITIZER_RISCV64
 183 #    include "sanitizer_syscall_linux_riscv64.inc"
 184 #  elif SANITIZER_LINUX && defined(__aarch64__)
 185 #    include "sanitizer_syscall_linux_aarch64.inc"
 186 #  elif SANITIZER_LINUX && defined(__arm__)
 187 #    include "sanitizer_syscall_linux_arm.inc"
 188 #  elif SANITIZER_LINUX && defined(__hexagon__)
 189 #    include "sanitizer_syscall_linux_hexagon.inc"
 190 #  else
 191 #    include "sanitizer_syscall_generic.inc"
 192 #  endif
 193
 194 // --------------- sanitizer_libc.h
 195 #if !SANITIZER_SOLARIS && !SANITIZER_NETBSD
 196 #if !SANITIZER_S390
 197 uptr internal_mmap(void *addr, uptr length, int prot, int flags, int fd,
 198                    u64 offset) {
 199 #if SANITIZER_FREEBSD || SANITIZER_LINUX_USES_64BIT_SYSCALLS
 200   return internal_syscall(SYSCALL(mmap), (uptr)addr, length, prot, flags, fd,
 201                           offset);
 202 #else
 203   // mmap2 specifies file offset in 4096-byte units.
 204   CHECK(IsAligned(offset, 4096));
 205   return internal_syscall(SYSCALL(mmap2), addr, length, prot, flags, fd,
 206                           offset / 4096);
 207 #endif
 208 }
 209 #endif // !SANITIZER_S390
 210
 211 uptr internal_munmap(void *addr, uptr length) {
 212   return internal_syscall(SYSCALL(munmap), (uptr)addr, length);
 213 }
 214
 215 #if SANITIZER_LINUX
 216 uptr internal_mremap(void *old_address, uptr old_size, uptr new_size, int flags,
 217                      void *new_address) {
 218   return internal_syscall(SYSCALL(mremap), (uptr)old_address, old_size,
 219                           new_size, flags, (uptr)new_address);
 220 }
 221 #endif
 222
 223 int internal_mprotect(void *addr, uptr length, int prot) {
 224   return internal_syscall(SYSCALL(mprotect), (uptr)addr, length, prot);
 225 }
 226
 227 int internal_madvise(uptr addr, uptr length, int advice) {
 228   return internal_syscall(SYSCALL(madvise), addr, length, advice);
 229 }
 230
 231 uptr internal_close(fd_t fd) {
 232   return internal_syscall(SYSCALL(close), fd);
 233 }
 234
 235 uptr internal_open(const char *filename, int flags) {
 236 #if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 237   return internal_syscall(SYSCALL(openat), AT_FDCWD, (uptr)filename, flags);
 238 #else
 239   return internal_syscall(SYSCALL(open), (uptr)filename, flags);
 240 #endif
 241 }
 242
 243 uptr internal_open(const char *filename, int flags, u32 mode) {
 244 #if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 245   return internal_syscall(SYSCALL(openat), AT_FDCWD, (uptr)filename, flags,
 246                           mode);
 247 #else
 248   return internal_syscall(SYSCALL(open), (uptr)filename, flags, mode);
 249 #endif
 250 }
 251
 252 uptr internal_read(fd_t fd, void *buf, uptr count) {
 253   sptr res;
 254   HANDLE_EINTR(res,
 255                (sptr)internal_syscall(SYSCALL(read), fd, (uptr)buf, count));
 256   return res;
 257 }
 258
 259 uptr internal_write(fd_t fd, const void *buf, uptr count) {
 260   sptr res;
 261   HANDLE_EINTR(res,
 262                (sptr)internal_syscall(SYSCALL(write), fd, (uptr)buf, count));
 263   return res;
 264 }
 265
 266 uptr internal_ftruncate(fd_t fd, uptr size) {
 267   sptr res;
 268   HANDLE_EINTR(res, (sptr)internal_syscall(SYSCALL(ftruncate), fd,
 269                (OFF_T)size));
 270   return res;
 271 }
 272
 273 #if !SANITIZER_LINUX_USES_64BIT_SYSCALLS && SANITIZER_LINUX
 274 static void stat64_to_stat(struct stat64 *in, struct stat *out) {
 275   internal_memset(out, 0, sizeof(*out));
 276   out->st_dev = in->st_dev;
 277   out->st_ino = in->st_ino;
 278   out->st_mode = in->st_mode;
 279   out->st_nlink = in->st_nlink;
 280   out->st_uid = in->st_uid;
 281   out->st_gid = in->st_gid;
 282   out->st_rdev = in->st_rdev;
 283   out->st_size = in->st_size;
 284   out->st_blksize = in->st_blksize;
 285   out->st_blocks = in->st_blocks;
 286   out->st_atime = in->st_atime;
 287   out->st_mtime = in->st_mtime;
 288   out->st_ctime = in->st_ctime;
 289 }
 290 #endif
 291
 292 #if defined(__mips64)
 293 // Undefine compatibility macros from <sys/stat.h>
 294 // so that they would not clash with the kernel_stat
 295 // st_[a|m|c]time fields
 296 #if !SANITIZER_GO
 297 #undef st_atime
 298 #undef st_mtime
 299 #undef st_ctime
 300 #endif
 301 #if defined(SANITIZER_ANDROID)
 302 // Bionic sys/stat.h defines additional macros
 303 // for compatibility with the old NDKs and
 304 // they clash with the kernel_stat structure
 305 // st_[a|m|c]time_nsec fields.
 306 #undef st_atime_nsec
 307 #undef st_mtime_nsec
 308 #undef st_ctime_nsec
 309 #endif
 310 static void kernel_stat_to_stat(struct kernel_stat *in, struct stat *out) {
 311   internal_memset(out, 0, sizeof(*out));
 312   out->st_dev = in->st_dev;
 313   out->st_ino = in->st_ino;
 314   out->st_mode = in->st_mode;
 315   out->st_nlink = in->st_nlink;
 316   out->st_uid = in->st_uid;
 317   out->st_gid = in->st_gid;
 318   out->st_rdev = in->st_rdev;
 319   out->st_size = in->st_size;
 320   out->st_blksize = in->st_blksize;
 321   out->st_blocks = in->st_blocks;
 322 #if defined(__USE_MISC)     || \
 323     defined(__USE_XOPEN2K8) || \
 324     defined(SANITIZER_ANDROID)
 325   out->st_atim.tv_sec = in->st_atime;
 326   out->st_atim.tv_nsec = in->st_atime_nsec;
 327   out->st_mtim.tv_sec = in->st_mtime;
 328   out->st_mtim.tv_nsec = in->st_mtime_nsec;
 329   out->st_ctim.tv_sec = in->st_ctime;
 330   out->st_ctim.tv_nsec = in->st_ctime_nsec;
 331 #else
 332   out->st_atime = in->st_atime;
 333   out->st_atimensec = in->st_atime_nsec;
 334   out->st_mtime = in->st_mtime;
 335   out->st_mtimensec = in->st_mtime_nsec;
 336   out->st_ctime = in->st_ctime;
 337   out->st_atimensec = in->st_ctime_nsec;
 338 #endif
 339 }
 340 #endif
 341
 342 uptr internal_stat(const char *path, void *buf) {
 343 #if SANITIZER_FREEBSD
 344   return internal_syscall(SYSCALL(fstatat), AT_FDCWD, (uptr)path, (uptr)buf, 0);
 345 #elif SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 346   return internal_syscall(SYSCALL(newfstatat), AT_FDCWD, (uptr)path, (uptr)buf,
 347                           0);
 348 #elif SANITIZER_LINUX_USES_64BIT_SYSCALLS
 349 # if defined(__mips64)
 350   // For mips64, stat syscall fills buffer in the format of kernel_stat
 351   struct kernel_stat kbuf;
 352   int res = internal_syscall(SYSCALL(stat), path, &kbuf);
 353   kernel_stat_to_stat(&kbuf, (struct stat *)buf);
 354   return res;
 355 # else
 356   return internal_syscall(SYSCALL(stat), (uptr)path, (uptr)buf);
 357 # endif
 358 #else
 359   struct stat64 buf64;
 360   int res = internal_syscall(SYSCALL(stat64), path, &buf64);
 361   stat64_to_stat(&buf64, (struct stat *)buf);
 362   return res;
 363 #endif
 364 }
 365
 366 uptr internal_lstat(const char *path, void *buf) {
 367 #if SANITIZER_FREEBSD
 368   return internal_syscall(SYSCALL(fstatat), AT_FDCWD, (uptr)path, (uptr)buf,
 369                           AT_SYMLINK_NOFOLLOW);
 370 #elif SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 371   return internal_syscall(SYSCALL(newfstatat), AT_FDCWD, (uptr)path, (uptr)buf,
 372                           AT_SYMLINK_NOFOLLOW);
 373 #elif SANITIZER_LINUX_USES_64BIT_SYSCALLS
 374 # if SANITIZER_MIPS64
 375   // For mips64, lstat syscall fills buffer in the format of kernel_stat
 376   struct kernel_stat kbuf;
 377   int res = internal_syscall(SYSCALL(lstat), path, &kbuf);
 378   kernel_stat_to_stat(&kbuf, (struct stat *)buf);
 379   return res;
 380 # else
 381   return internal_syscall(SYSCALL(lstat), (uptr)path, (uptr)buf);
 382 # endif
 383 #else
 384   struct stat64 buf64;
 385   int res = internal_syscall(SYSCALL(lstat64), path, &buf64);
 386   stat64_to_stat(&buf64, (struct stat *)buf);
 387   return res;
 388 #endif
 389 }
 390
 391 uptr internal_fstat(fd_t fd, void *buf) {
 392 #if SANITIZER_FREEBSD || SANITIZER_LINUX_USES_64BIT_SYSCALLS
 393 #if SANITIZER_MIPS64
 394   // For mips64, fstat syscall fills buffer in the format of kernel_stat
 395   struct kernel_stat kbuf;
 396   int res = internal_syscall(SYSCALL(fstat), fd, &kbuf);
 397   kernel_stat_to_stat(&kbuf, (struct stat *)buf);
 398   return res;
 399 # else
 400   return internal_syscall(SYSCALL(fstat), fd, (uptr)buf);
 401 # endif
 402 #else
 403   struct stat64 buf64;
 404   int res = internal_syscall(SYSCALL(fstat64), fd, &buf64);
 405   stat64_to_stat(&buf64, (struct stat *)buf);
 406   return res;
 407 #endif
 408 }
 409
 410 uptr internal_filesize(fd_t fd) {
 411   struct stat st;
 412   if (internal_fstat(fd, &st))
 413     return -1;
 414   return (uptr)st.st_size;
 415 }
 416
 417 uptr internal_dup(int oldfd) {
 418   return internal_syscall(SYSCALL(dup), oldfd);
 419 }
 420
 421 uptr internal_dup2(int oldfd, int newfd) {
 422 #if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 423   return internal_syscall(SYSCALL(dup3), oldfd, newfd, 0);
 424 #else
 425   return internal_syscall(SYSCALL(dup2), oldfd, newfd);
 426 #endif
 427 }
 428
 429 uptr internal_readlink(const char *path, char *buf, uptr bufsize) {
 430 #if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 431   return internal_syscall(SYSCALL(readlinkat), AT_FDCWD, (uptr)path, (uptr)buf,
 432                           bufsize);
 433 #else
 434   return internal_syscall(SYSCALL(readlink), (uptr)path, (uptr)buf, bufsize);
 435 #endif
 436 }
 437
 438 uptr internal_unlink(const char *path) {
 439 #if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 440   return internal_syscall(SYSCALL(unlinkat), AT_FDCWD, (uptr)path, 0);
 441 #else
 442   return internal_syscall(SYSCALL(unlink), (uptr)path);
 443 #endif
 444 }
 445
 446 uptr internal_rename(const char *oldpath, const char *newpath) {
 447 #if defined(__riscv) && defined(__linux__)
 448   return internal_syscall(SYSCALL(renameat2), AT_FDCWD, (uptr)oldpath, AT_FDCWD,
 449                           (uptr)newpath, 0);
 450 #elif SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 451   return internal_syscall(SYSCALL(renameat), AT_FDCWD, (uptr)oldpath, AT_FDCWD,
 452                           (uptr)newpath);
 453 #else
 454   return internal_syscall(SYSCALL(rename), (uptr)oldpath, (uptr)newpath);
 455 #endif
 456 }
 457
 458 uptr internal_sched_yield() {
 459   return internal_syscall(SYSCALL(sched_yield));
 460 }
 461
 462 void internal_usleep(u64 useconds) {
 463   struct timespec ts;
 464   ts.tv_sec = useconds / 1000000;
 465   ts.tv_nsec = (useconds % 1000000) * 1000;
 466   internal_syscall(SYSCALL(nanosleep), &ts, &ts);
 467 }
 468
 469 uptr internal_execve(const char *filename, char *const argv[],
 470                      char *const envp[]) {
 471   return internal_syscall(SYSCALL(execve), (uptr)filename, (uptr)argv,
 472                           (uptr)envp);
 473 }
 474 #endif  // !SANITIZER_SOLARIS && !SANITIZER_NETBSD
 475
 476 #if !SANITIZER_NETBSD
 477 void internal__exit(int exitcode) {
 478 #if SANITIZER_FREEBSD || SANITIZER_SOLARIS
 479   internal_syscall(SYSCALL(exit), exitcode);
 480 #else
 481   internal_syscall(SYSCALL(exit_group), exitcode);
 482 #endif
 483   Die();  // Unreachable.
 484 }
 485 #endif  // !SANITIZER_NETBSD
 486
 487 // ----------------- sanitizer_common.h
 488 bool FileExists(const char *filename) {
 489   if (ShouldMockFailureToOpen(filename))
 490     return false;
 491   struct stat st;
 492 #if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 493   if (internal_syscall(SYSCALL(newfstatat), AT_FDCWD, filename, &st, 0))
 494 #else
 495   if (internal_stat(filename, &st))
 496 #endif
 497     return false;
 498   // Sanity check: filename is a regular file.
 499   return S_ISREG(st.st_mode);
 500 }
 501
 502 bool DirExists(const char *path) {
 503   struct stat st;
 504 #  if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 505   if (internal_syscall(SYSCALL(newfstatat), AT_FDCWD, path, &st, 0))
 506 #  else
 507   if (internal_stat(path, &st))
 508 #  endif
 509     return false;
 510   return S_ISDIR(st.st_mode);
 511 }
 512
 513 #  if !SANITIZER_NETBSD
 514 tid_t GetTid() {
 515 #if SANITIZER_FREEBSD
 516   long Tid;
 517   thr_self(&Tid);
 518   return Tid;
 519 #elif SANITIZER_SOLARIS
 520   return thr_self();
 521 #else
 522   return internal_syscall(SYSCALL(gettid));
 523 #endif
 524 }
 525
 526 int TgKill(pid_t pid, tid_t tid, int sig) {
 527 #if SANITIZER_LINUX
 528   return internal_syscall(SYSCALL(tgkill), pid, tid, sig);
 529 #elif SANITIZER_FREEBSD
 530   return internal_syscall(SYSCALL(thr_kill2), pid, tid, sig);
 531 #elif SANITIZER_SOLARIS
 532   (void)pid;
 533   return thr_kill(tid, sig);
 534 #endif
 535 }
 536 #endif
 537
 538 #if SANITIZER_GLIBC
 539 u64 NanoTime() {
 540   kernel_timeval tv;
 541   internal_memset(&tv, 0, sizeof(tv));
 542   internal_syscall(SYSCALL(gettimeofday), &tv, 0);
 543   return (u64)tv.tv_sec * 1000 * 1000 * 1000 + tv.tv_usec * 1000;
 544 }
 545 // Used by real_clock_gettime.
 546 uptr internal_clock_gettime(__sanitizer_clockid_t clk_id, void *tp) {
 547   return internal_syscall(SYSCALL(clock_gettime), clk_id, tp);
 548 }
 549 #elif !SANITIZER_SOLARIS && !SANITIZER_NETBSD
 550 u64 NanoTime() {
 551   struct timespec ts;
 552   clock_gettime(CLOCK_REALTIME, &ts);
 553   return (u64)ts.tv_sec * 1000 * 1000 * 1000 + ts.tv_nsec;
 554 }
 555 #endif
 556
 557 // Like getenv, but reads env directly from /proc (on Linux) or parses the
 558 // 'environ' array (on some others) and does not use libc. This function
 559 // should be called first inside __asan_init.
 560 const char *GetEnv(const char *name) {
 561 #if SANITIZER_FREEBSD || SANITIZER_NETBSD || SANITIZER_SOLARIS
 562   if (::environ != 0) {
 563     uptr NameLen = internal_strlen(name);
 564     for (char **Env = ::environ; *Env != 0; Env++) {
 565       if (internal_strncmp(*Env, name, NameLen) == 0 && (*Env)[NameLen] == '=')
 566         return (*Env) + NameLen + 1;
 567     }
 568   }
 569   return 0;  // Not found.
 570 #elif SANITIZER_LINUX
 571   static char *environ;
 572   static uptr len;
 573   static bool inited;
 574   if (!inited) {
 575     inited = true;
 576     uptr environ_size;
 577     if (!ReadFileToBuffer("/proc/self/environ", &environ, &environ_size, &len))
 578       environ = nullptr;
 579   }
 580   if (!environ || len == 0) return nullptr;
 581   uptr namelen = internal_strlen(name);
 582   const char *p = environ;
 583   while (*p != '\0') {  // will happen at the \0\0 that terminates the buffer
 584     // proc file has the format NAME=value\0NAME=value\0NAME=value\0...
 585     const char* endp =
 586         (char*)internal_memchr(p, '\0', len - (p - environ));
 587     if (!endp)  // this entry isn't NUL terminated
 588       return nullptr;
 589     else if (!internal_memcmp(p, name, namelen) && p[namelen] == '=')  // Match.
 590       return p + namelen + 1;  // point after =
 591     p = endp + 1;
 592   }
 593   return nullptr;  // Not found.
 594 #else
 595 #error "Unsupported platform"
 596 #endif
 597 }
 598
 599 #if !SANITIZER_FREEBSD && !SANITIZER_NETBSD && !SANITIZER_GO
 600 extern "C" {
 601 SANITIZER_WEAK_ATTRIBUTE extern void *__libc_stack_end;
 602 }
 603 #endif
 604
 605 #if !SANITIZER_FREEBSD && !SANITIZER_NETBSD
 606 static void ReadNullSepFileToArray(const char *path, char ***arr,
 607                                    int arr_size) {
 608   char *buff;
 609   uptr buff_size;
 610   uptr buff_len;
 611   *arr = (char **)MmapOrDie(arr_size * sizeof(char *), "NullSepFileArray");
 612   if (!ReadFileToBuffer(path, &buff, &buff_size, &buff_len, 1024 * 1024)) {
 613     (*arr)[0] = nullptr;
 614     return;
 615   }
 616   (*arr)[0] = buff;
 617   int count, i;
 618   for (count = 1, i = 1; ; i++) {
 619     if (buff[i] == 0) {
 620       if (buff[i+1] == 0) break;
 621       (*arr)[count] = &buff[i+1];
 622       CHECK_LE(count, arr_size - 1);  // FIXME: make this more flexible.
 623       count++;
 624     }
 625   }
 626   (*arr)[count] = nullptr;
 627 }
 628 #endif
 629
 630 static void GetArgsAndEnv(char ***argv, char ***envp) {
 631 #if SANITIZER_FREEBSD
 632   // On FreeBSD, retrieving the argument and environment arrays is done via the
 633   // kern.ps_strings sysctl, which returns a pointer to a structure containing
 634   // this information. See also <sys/exec.h>.
 635   ps_strings *pss;
 636   uptr sz = sizeof(pss);
 637   if (internal_sysctlbyname("kern.ps_strings", &pss, &sz, NULL, 0) == -1) {
 638     Printf("sysctl kern.ps_strings failed\n");
 639     Die();
 640   }
 641   *argv = pss->ps_argvstr;
 642   *envp = pss->ps_envstr;
 643 #elif SANITIZER_NETBSD
 644   *argv = __ps_strings->ps_argvstr;
 645   *envp = __ps_strings->ps_envstr;
 646 #else // SANITIZER_FREEBSD
 647 #if !SANITIZER_GO
 648   if (&__libc_stack_end) {
 649     uptr* stack_end = (uptr*)__libc_stack_end;
 650     // Normally argc can be obtained from *stack_end, however, on ARM glibc's
 651     // _start clobbers it:
 652     // https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/arm/start.S;hb=refs/heads/release/2.31/master#l75
 653     // Do not special-case ARM and infer argc from argv everywhere.
 654     int argc = 0;
 655     while (stack_end[argc + 1]) argc++;
 656     *argv = (char**)(stack_end + 1);
 657     *envp = (char**)(stack_end + argc + 2);
 658   } else {
 659 #endif // !SANITIZER_GO
 660     static const int kMaxArgv = 2000, kMaxEnvp = 2000;
 661     ReadNullSepFileToArray("/proc/self/cmdline", argv, kMaxArgv);
 662     ReadNullSepFileToArray("/proc/self/environ", envp, kMaxEnvp);
 663 #if !SANITIZER_GO
 664   }
 665 #endif // !SANITIZER_GO
 666 #endif // SANITIZER_FREEBSD
 667 }
 668
 669 char **GetArgv() {
 670   char **argv, **envp;
 671   GetArgsAndEnv(&argv, &envp);
 672   return argv;
 673 }
 674
 675 char **GetEnviron() {
 676   char **argv, **envp;
 677   GetArgsAndEnv(&argv, &envp);
 678   return envp;
 679 }
 680
 681 #if !SANITIZER_SOLARIS
 682 void FutexWait(atomic_uint32_t *p, u32 cmp) {
 683 #    if SANITIZER_FREEBSD
 684   _umtx_op(p, UMTX_OP_WAIT_UINT, cmp, 0, 0);
 685 #    elif SANITIZER_NETBSD
 686   sched_yield();   /* No userspace futex-like synchronization */
 687 #    else
 688   internal_syscall(SYSCALL(futex), (uptr)p, FUTEX_WAIT_PRIVATE, cmp, 0, 0, 0);
 689 #    endif
 690 }
 691
 692 void FutexWake(atomic_uint32_t *p, u32 count) {
 693 #    if SANITIZER_FREEBSD
 694   _umtx_op(p, UMTX_OP_WAKE, count, 0, 0);
 695 #    elif SANITIZER_NETBSD
 696                    /* No userspace futex-like synchronization */
 697 #    else
 698   internal_syscall(SYSCALL(futex), (uptr)p, FUTEX_WAKE_PRIVATE, count, 0, 0, 0);
 699 #    endif
 700 }
 701
 702 #  endif  // !SANITIZER_SOLARIS
 703
 704 // ----------------- sanitizer_linux.h
 705 // The actual size of this structure is specified by d_reclen.
 706 // Note that getdents64 uses a different structure format. We only provide the
 707 // 32-bit syscall here.
 708 #if SANITIZER_NETBSD
 709 // Not used
 710 #else
 711 struct linux_dirent {
 712 #if SANITIZER_X32 || defined(__aarch64__) || SANITIZER_RISCV64
 713   u64 d_ino;
 714   u64 d_off;
 715 #else
 716   unsigned long      d_ino;
 717   unsigned long      d_off;
 718 #endif
 719   unsigned short     d_reclen;
 720 #if defined(__aarch64__) || SANITIZER_RISCV64
 721   unsigned char      d_type;
 722 #endif
 723   char               d_name[256];
 724 };
 725 #endif
 726
 727 #if !SANITIZER_SOLARIS && !SANITIZER_NETBSD
 728 // Syscall wrappers.
 729 uptr internal_ptrace(int request, int pid, void *addr, void *data) {
 730   return internal_syscall(SYSCALL(ptrace), request, pid, (uptr)addr,
 731                           (uptr)data);
 732 }
 733
 734 uptr internal_waitpid(int pid, int *status, int options) {
 735   return internal_syscall(SYSCALL(wait4), pid, (uptr)status, options,
 736                           0 /* rusage */);
 737 }
 738
 739 uptr internal_getpid() {
 740   return internal_syscall(SYSCALL(getpid));
 741 }
 742
 743 uptr internal_getppid() {
 744   return internal_syscall(SYSCALL(getppid));
 745 }
 746
 747 int internal_dlinfo(void *handle, int request, void *p) {
 748 #if SANITIZER_FREEBSD
 749   return dlinfo(handle, request, p);
 750 #else
 751   UNIMPLEMENTED();
 752 #endif
 753 }
 754
 755 uptr internal_getdents(fd_t fd, struct linux_dirent *dirp, unsigned int count) {
 756 #if SANITIZER_FREEBSD
 757   return internal_syscall(SYSCALL(getdirentries), fd, (uptr)dirp, count, NULL);
 758 #elif SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 759   return internal_syscall(SYSCALL(getdents64), fd, (uptr)dirp, count);
 760 #else
 761   return internal_syscall(SYSCALL(getdents), fd, (uptr)dirp, count);
 762 #endif
 763 }
 764
 765 uptr internal_lseek(fd_t fd, OFF_T offset, int whence) {
 766   return internal_syscall(SYSCALL(lseek), fd, offset, whence);
 767 }
 768
 769 #if SANITIZER_LINUX
 770 uptr internal_prctl(int option, uptr arg2, uptr arg3, uptr arg4, uptr arg5) {
 771   return internal_syscall(SYSCALL(prctl), option, arg2, arg3, arg4, arg5);
 772 }
 773 #endif
 774
 775 uptr internal_sigaltstack(const void *ss, void *oss) {
 776   return internal_syscall(SYSCALL(sigaltstack), (uptr)ss, (uptr)oss);
 777 }
 778
 779 int internal_fork() {
 780 #if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 781   return internal_syscall(SYSCALL(clone), SIGCHLD, 0);
 782 #else
 783   return internal_syscall(SYSCALL(fork));
 784 #endif
 785 }
 786
 787 #if SANITIZER_FREEBSD
 788 int internal_sysctl(const int *name, unsigned int namelen, void *oldp,
 789                     uptr *oldlenp, const void *newp, uptr newlen) {
 790   return internal_syscall(SYSCALL(__sysctl), name, namelen, oldp,
 791                           (size_t *)oldlenp, newp, (size_t)newlen);
 792 }
 793
 794 int internal_sysctlbyname(const char *sname, void *oldp, uptr *oldlenp,
 795                           const void *newp, uptr newlen) {
 796   // Note: this function can be called during startup, so we need to avoid
 797   // calling any interceptable functions. On FreeBSD >= 1300045 sysctlbyname()
 798   // is a real syscall, but for older versions it calls sysctlnametomib()
 799   // followed by sysctl(). To avoid calling the intercepted version and
 800   // asserting if this happens during startup, call the real sysctlnametomib()
 801   // followed by internal_sysctl() if the syscall is not available.
 802 #ifdef SYS___sysctlbyname
 803   return internal_syscall(SYSCALL(__sysctlbyname), sname,
 804                           internal_strlen(sname), oldp, (size_t *)oldlenp, newp,
 805                           (size_t)newlen);
 806 #else
 807   static decltype(sysctlnametomib) *real_sysctlnametomib = nullptr;
 808   if (!real_sysctlnametomib)
 809     real_sysctlnametomib =
 810         (decltype(sysctlnametomib) *)dlsym(RTLD_NEXT, "sysctlnametomib");
 811   CHECK(real_sysctlnametomib);
 812
 813   int oid[CTL_MAXNAME];
 814   size_t len = CTL_MAXNAME;
 815   if (real_sysctlnametomib(sname, oid, &len) == -1)
 816     return (-1);
 817   return internal_sysctl(oid, len, oldp, oldlenp, newp, newlen);
 818 #endif
 819 }
 820 #endif
 821
 822 #if SANITIZER_LINUX
 823 #define SA_RESTORER 0x04000000
 824 // Doesn't set sa_restorer if the caller did not set it, so use with caution
 825 //(see below).
 826 int internal_sigaction_norestorer(int signum, const void *act, void *oldact) {
 827   __sanitizer_kernel_sigaction_t k_act, k_oldact;
 828   internal_memset(&k_act, 0, sizeof(__sanitizer_kernel_sigaction_t));
 829   internal_memset(&k_oldact, 0, sizeof(__sanitizer_kernel_sigaction_t));
 830   const __sanitizer_sigaction *u_act = (const __sanitizer_sigaction *)act;
 831   __sanitizer_sigaction *u_oldact = (__sanitizer_sigaction *)oldact;
 832   if (u_act) {
 833     k_act.handler = u_act->handler;
 834     k_act.sigaction = u_act->sigaction;
 835     internal_memcpy(&k_act.sa_mask, &u_act->sa_mask,
 836                     sizeof(__sanitizer_kernel_sigset_t));
 837     // Without SA_RESTORER kernel ignores the calls (probably returns EINVAL).
 838     k_act.sa_flags = u_act->sa_flags | SA_RESTORER;
 839     // FIXME: most often sa_restorer is unset, however the kernel requires it
 840     // to point to a valid signal restorer that calls the rt_sigreturn syscall.
 841     // If sa_restorer passed to the kernel is NULL, the program may crash upon
 842     // signal delivery or fail to unwind the stack in the signal handler.
 843     // libc implementation of sigaction() passes its own restorer to
 844     // rt_sigaction, so we need to do the same (we'll need to reimplement the
 845     // restorers; for x86_64 the restorer address can be obtained from
 846     // oldact->sa_restorer upon a call to sigaction(xxx, NULL, oldact).
 847 #if !SANITIZER_ANDROID || !SANITIZER_MIPS32
 848     k_act.sa_restorer = u_act->sa_restorer;
 849 #endif
 850   }
 851
 852   uptr result = internal_syscall(SYSCALL(rt_sigaction), (uptr)signum,
 853       (uptr)(u_act ? &k_act : nullptr),
 854       (uptr)(u_oldact ? &k_oldact : nullptr),
 855       (uptr)sizeof(__sanitizer_kernel_sigset_t));
 856
 857   if ((result == 0) && u_oldact) {
 858     u_oldact->handler = k_oldact.handler;
 859     u_oldact->sigaction = k_oldact.sigaction;
 860     internal_memcpy(&u_oldact->sa_mask, &k_oldact.sa_mask,
 861                     sizeof(__sanitizer_kernel_sigset_t));
 862     u_oldact->sa_flags = k_oldact.sa_flags;
 863 #if !SANITIZER_ANDROID || !SANITIZER_MIPS32
 864     u_oldact->sa_restorer = k_oldact.sa_restorer;
 865 #endif
 866   }
 867   return result;
 868 }
 869 #endif  // SANITIZER_LINUX
 870
 871 uptr internal_sigprocmask(int how, __sanitizer_sigset_t *set,
 872                           __sanitizer_sigset_t *oldset) {
 873 #if SANITIZER_FREEBSD
 874   return internal_syscall(SYSCALL(sigprocmask), how, set, oldset);
 875 #else
 876   __sanitizer_kernel_sigset_t *k_set = (__sanitizer_kernel_sigset_t *)set;
 877   __sanitizer_kernel_sigset_t *k_oldset = (__sanitizer_kernel_sigset_t *)oldset;
 878   return internal_syscall(SYSCALL(rt_sigprocmask), (uptr)how, (uptr)k_set,
 879                           (uptr)k_oldset, sizeof(__sanitizer_kernel_sigset_t));
 880 #endif
 881 }
 882
 883 void internal_sigfillset(__sanitizer_sigset_t *set) {
 884   internal_memset(set, 0xff, sizeof(*set));
 885 }
 886
 887 void internal_sigemptyset(__sanitizer_sigset_t *set) {
 888   internal_memset(set, 0, sizeof(*set));
 889 }
 890
 891 #if SANITIZER_LINUX
 892 void internal_sigdelset(__sanitizer_sigset_t *set, int signum) {
 893   signum -= 1;
 894   CHECK_GE(signum, 0);
 895   CHECK_LT(signum, sizeof(*set) * 8);
 896   __sanitizer_kernel_sigset_t *k_set = (__sanitizer_kernel_sigset_t *)set;
 897   const uptr idx = signum / (sizeof(k_set->sig[0]) * 8);
 898   const uptr bit = signum % (sizeof(k_set->sig[0]) * 8);
 899   k_set->sig[idx] &= ~((uptr)1 << bit);
 900 }
 901
 902 bool internal_sigismember(__sanitizer_sigset_t *set, int signum) {
 903   signum -= 1;
 904   CHECK_GE(signum, 0);
 905   CHECK_LT(signum, sizeof(*set) * 8);
 906   __sanitizer_kernel_sigset_t *k_set = (__sanitizer_kernel_sigset_t *)set;
 907   const uptr idx = signum / (sizeof(k_set->sig[0]) * 8);
 908   const uptr bit = signum % (sizeof(k_set->sig[0]) * 8);
 909   return k_set->sig[idx] & ((uptr)1 << bit);
 910 }
 911 #elif SANITIZER_FREEBSD
 912 void internal_sigdelset(__sanitizer_sigset_t *set, int signum) {
 913   sigset_t *rset = reinterpret_cast<sigset_t *>(set);
 914   sigdelset(rset, signum);
 915 }
 916
 917 bool internal_sigismember(__sanitizer_sigset_t *set, int signum) {
 918   sigset_t *rset = reinterpret_cast<sigset_t *>(set);
 919   return sigismember(rset, signum);
 920 }
 921 #endif
 922 #endif // !SANITIZER_SOLARIS
 923
 924 #if !SANITIZER_NETBSD
 925 // ThreadLister implementation.
 926 ThreadLister::ThreadLister(pid_t pid) : pid_(pid), buffer_(4096) {
 927   char task_directory_path[80];
 928   internal_snprintf(task_directory_path, sizeof(task_directory_path),
 929                     "/proc/%d/task/", pid);
 930   descriptor_ = internal_open(task_directory_path, O_RDONLY | O_DIRECTORY);
 931   if (internal_iserror(descriptor_)) {
 932     Report("Can't open /proc/%d/task for reading.\n", pid);
 933   }
 934 }
 935
 936 ThreadLister::Result ThreadLister::ListThreads(
 937     InternalMmapVector<tid_t> *threads) {
 938   if (internal_iserror(descriptor_))
 939     return Error;
 940   internal_lseek(descriptor_, 0, SEEK_SET);
 941   threads->clear();
 942
 943   Result result = Ok;
 944   for (bool first_read = true;; first_read = false) {
 945     // Resize to max capacity if it was downsized by IsAlive.
 946     buffer_.resize(buffer_.capacity());
 947     CHECK_GE(buffer_.size(), 4096);
 948     uptr read = internal_getdents(
 949         descriptor_, (struct linux_dirent *)buffer_.data(), buffer_.size());
 950     if (!read)
 951       return result;
 952     if (internal_iserror(read)) {
 953       Report("Can't read directory entries from /proc/%d/task.\n", pid_);
 954       return Error;
 955     }
 956
 957     for (uptr begin = (uptr)buffer_.data(), end = begin + read; begin < end;) {
 958       struct linux_dirent *entry = (struct linux_dirent *)begin;
 959       begin += entry->d_reclen;
 960       if (entry->d_ino == 1) {
 961         // Inode 1 is for bad blocks and also can be a reason for early return.
 962         // Should be emitted if kernel tried to output terminating thread.
 963         // See proc_task_readdir implementation in Linux.
 964         result = Incomplete;
 965       }
 966       if (entry->d_ino && *entry->d_name >= '0' && *entry->d_name <= '9')
 967         threads->push_back(internal_atoll(entry->d_name));
 968     }
 969
 970     // Now we are going to detect short-read or early EOF. In such cases Linux
 971     // can return inconsistent list with missing alive threads.
 972     // Code will just remember that the list can be incomplete but it will
 973     // continue reads to return as much as possible.
 974     if (!first_read) {
 975       // The first one was a short-read by definition.
 976       result = Incomplete;
 977     } else if (read > buffer_.size() - 1024) {
 978       // Read was close to the buffer size. So double the size and assume the
 979       // worst.
 980       buffer_.resize(buffer_.size() * 2);
 981       result = Incomplete;
 982     } else if (!threads->empty() && !IsAlive(threads->back())) {
 983       // Maybe Linux early returned from read on terminated thread (!pid_alive)
 984       // and failed to restore read position.
 985       // See next_tid and proc_task_instantiate in Linux.
 986       result = Incomplete;
 987     }
 988   }
 989 }
 990
 991 bool ThreadLister::IsAlive(int tid) {
 992   // /proc/%d/task/%d/status uses same call to detect alive threads as
 993   // proc_task_readdir. See task_state implementation in Linux.
 994   char path[80];
 995   internal_snprintf(path, sizeof(path), "/proc/%d/task/%d/status", pid_, tid);
 996   if (!ReadFileToVector(path, &buffer_) || buffer_.empty())
 997     return false;
 998   buffer_.push_back(0);
 999   static const char kPrefix[] = "\nPPid:";
1000   const char *field = internal_strstr(buffer_.data(), kPrefix);
1001   if (!field)
1002     return false;
1003   field += internal_strlen(kPrefix);
1004   return (int)internal_atoll(field) != 0;
1005 }
1006
1007 ThreadLister::~ThreadLister() {
1008   if (!internal_iserror(descriptor_))
1009     internal_close(descriptor_);
1010 }
1011 #endif
1012
1013 #if SANITIZER_WORDSIZE == 32
1014 // Take care of unusable kernel area in top gigabyte.
1015 static uptr GetKernelAreaSize() {
1016 #if SANITIZER_LINUX && !SANITIZER_X32
1017   const uptr gbyte = 1UL << 30;
1018
1019   // Firstly check if there are writable segments
1020   // mapped to top gigabyte (e.g. stack).
1021   MemoryMappingLayout proc_maps(/*cache_enabled*/true);
1022   if (proc_maps.Error())
1023     return 0;
1024   MemoryMappedSegment segment;
1025   while (proc_maps.Next(&segment)) {
1026     if ((segment.end >= 3 * gbyte) && segment.IsWritable()) return 0;
1027   }
1028
1029 #if !SANITIZER_ANDROID
1030   // Even if nothing is mapped, top Gb may still be accessible
1031   // if we are running on 64-bit kernel.
1032   // Uname may report misleading results if personality type
1033   // is modified (e.g. under schroot) so check this as well.
1034   struct utsname uname_info;
1035   int pers = personality(0xffffffffUL);
1036   if (!(pers & PER_MASK) && internal_uname(&uname_info) == 0 &&
1037       internal_strstr(uname_info.machine, "64"))
1038     return 0;
1039 #endif  // SANITIZER_ANDROID
1040
1041   // Top gigabyte is reserved for kernel.
1042   return gbyte;
1043 #else
1044   return 0;
1045 #endif  // SANITIZER_LINUX && !SANITIZER_X32
1046 }
1047 #endif  // SANITIZER_WORDSIZE == 32
1048
1049 uptr GetMaxVirtualAddress() {
1050 #if SANITIZER_NETBSD && defined(__x86_64__)
1051   return 0x7f7ffffff000ULL;  // (0x00007f8000000000 - PAGE_SIZE)
1052 #elif SANITIZER_WORDSIZE == 64
1053 # if defined(__powerpc64__) || defined(__aarch64__)
1054   // On PowerPC64 we have two different address space layouts: 44- and 46-bit.
1055   // We somehow need to figure out which one we are using now and choose
1056   // one of 0x00000fffffffffffUL and 0x00003fffffffffffUL.
1057   // Note that with 'ulimit -s unlimited' the stack is moved away from the top
1058   // of the address space, so simply checking the stack address is not enough.
1059   // This should (does) work for both PowerPC64 Endian modes.
1060   // Similarly, aarch64 has multiple address space layouts: 39, 42 and 47-bit.
1061   return (1ULL << (MostSignificantSetBitIndex(GET_CURRENT_FRAME()) + 1)) - 1;
1062 #elif SANITIZER_RISCV64
1063   return (1ULL << 38) - 1;
1064 # elif defined(__mips64)
1065   return (1ULL << 40) - 1;  // 0x000000ffffffffffUL;
1066 # elif defined(__s390x__)
1067   return (1ULL << 53) - 1;  // 0x001fffffffffffffUL;
1068 #elif defined(__sparc__)
1069   return ~(uptr)0;
1070 # else
1071   return (1ULL << 47) - 1;  // 0x00007fffffffffffUL;
1072 # endif
1073 #else  // SANITIZER_WORDSIZE == 32
1074 # if defined(__s390__)
1075   return (1ULL << 31) - 1;  // 0x7fffffff;
1076 # else
1077   return (1ULL << 32) - 1;  // 0xffffffff;
1078 # endif
1079 #endif  // SANITIZER_WORDSIZE
1080 }
1081
1082 uptr GetMaxUserVirtualAddress() {
1083   uptr addr = GetMaxVirtualAddress();
1084 #if SANITIZER_WORDSIZE == 32 && !defined(__s390__)
1085   if (!common_flags()->full_address_space)
1086     addr -= GetKernelAreaSize();
1087   CHECK_LT(reinterpret_cast<uptr>(&addr), addr);
1088 #endif
1089   return addr;
1090 }
1091
1092 #if !SANITIZER_ANDROID
1093 uptr GetPageSize() {
1094 #if SANITIZER_LINUX && (defined(__x86_64__) || defined(__i386__)) && \
1095     defined(EXEC_PAGESIZE)
1096   return EXEC_PAGESIZE;
1097 #elif SANITIZER_FREEBSD || SANITIZER_NETBSD
1098 // Use sysctl as sysconf can trigger interceptors internally.
1099   int pz = 0;
1100   uptr pzl = sizeof(pz);
1101   int mib[2] = {CTL_HW, HW_PAGESIZE};
1102   int rv = internal_sysctl(mib, 2, &pz, &pzl, nullptr, 0);
1103   CHECK_EQ(rv, 0);
1104   return (uptr)pz;
1105 #elif SANITIZER_USE_GETAUXVAL
1106   return getauxval(AT_PAGESZ);
1107 #else
1108   return sysconf(_SC_PAGESIZE);  // EXEC_PAGESIZE may not be trustworthy.
1109 #endif
1110 }
1111 #endif // !SANITIZER_ANDROID
1112
1113 uptr ReadBinaryName(/*out*/char *buf, uptr buf_len) {
1114 #if SANITIZER_SOLARIS
1115   const char *default_module_name = getexecname();
1116   CHECK_NE(default_module_name, NULL);
1117   return internal_snprintf(buf, buf_len, "%s", default_module_name);
1118 #else
1119 #if SANITIZER_FREEBSD || SANITIZER_NETBSD
1120 #if SANITIZER_FREEBSD
1121   const int Mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
1122 #else
1123   const int Mib[4] = {CTL_KERN, KERN_PROC_ARGS, -1, KERN_PROC_PATHNAME};
1124 #endif
1125   const char *default_module_name = "kern.proc.pathname";
1126   uptr Size = buf_len;
1127   bool IsErr =
1128       (internal_sysctl(Mib, ARRAY_SIZE(Mib), buf, &Size, NULL, 0) != 0);
1129   int readlink_error = IsErr ? errno : 0;
1130   uptr module_name_len = Size;
1131 #else
1132   const char *default_module_name = "/proc/self/exe";
1133   uptr module_name_len = internal_readlink(
1134       default_module_name, buf, buf_len);
1135   int readlink_error;
1136   bool IsErr = internal_iserror(module_name_len, &readlink_error);
1137 #endif  // SANITIZER_SOLARIS
1138   if (IsErr) {
1139     // We can't read binary name for some reason, assume it's unknown.
1140     Report("WARNING: reading executable name failed with errno %d, "
1141            "some stack frames may not be symbolized\n", readlink_error);
1142     module_name_len = internal_snprintf(buf, buf_len, "%s",
1143                                         default_module_name);
1144     CHECK_LT(module_name_len, buf_len);
1145   }
1146   return module_name_len;
1147 #endif
1148 }
1149
1150 uptr ReadLongProcessName(/*out*/ char *buf, uptr buf_len) {
1151 #if SANITIZER_LINUX
1152   char *tmpbuf;
1153   uptr tmpsize;
1154   uptr tmplen;
1155   if (ReadFileToBuffer("/proc/self/cmdline", &tmpbuf, &tmpsize, &tmplen,
1156                        1024 * 1024)) {
1157     internal_strncpy(buf, tmpbuf, buf_len);
1158     UnmapOrDie(tmpbuf, tmpsize);
1159     return internal_strlen(buf);
1160   }
1161 #endif
1162   return ReadBinaryName(buf, buf_len);
1163 }
1164
1165 // Match full names of the form /path/to/base_name{-,.}*
1166 bool LibraryNameIs(const char *full_name, const char *base_name) {
1167   const char *name = full_name;
1168   // Strip path.
1169   while (*name != '\0') name++;
1170   while (name > full_name && *name != '/') name--;
1171   if (*name == '/') name++;
1172   uptr base_name_length = internal_strlen(base_name);
1173   if (internal_strncmp(name, base_name, base_name_length)) return false;
1174   return (name[base_name_length] == '-' || name[base_name_length] == '.');
1175 }
1176
1177 #if !SANITIZER_ANDROID
1178 // Call cb for each region mapped by map.
1179 void ForEachMappedRegion(link_map *map, void (*cb)(const void *, uptr)) {
1180   CHECK_NE(map, nullptr);
1181 #if !SANITIZER_FREEBSD
1182   typedef ElfW(Phdr) Elf_Phdr;
1183   typedef ElfW(Ehdr) Elf_Ehdr;
1184 #endif // !SANITIZER_FREEBSD
1185   char *base = (char *)map->l_addr;
1186   Elf_Ehdr *ehdr = (Elf_Ehdr *)base;
1187   char *phdrs = base + ehdr->e_phoff;
1188   char *phdrs_end = phdrs + ehdr->e_phnum * ehdr->e_phentsize;
1189
1190   // Find the segment with the minimum base so we can "relocate" the p_vaddr
1191   // fields.  Typically ET_DYN objects (DSOs) have base of zero and ET_EXEC
1192   // objects have a non-zero base.
1193   uptr preferred_base = (uptr)-1;
1194   for (char *iter = phdrs; iter != phdrs_end; iter += ehdr->e_phentsize) {
1195     Elf_Phdr *phdr = (Elf_Phdr *)iter;
1196     if (phdr->p_type == PT_LOAD && preferred_base > (uptr)phdr->p_vaddr)
1197       preferred_base = (uptr)phdr->p_vaddr;
1198   }
1199
1200   // Compute the delta from the real base to get a relocation delta.
1201   sptr delta = (uptr)base - preferred_base;
1202   // Now we can figure out what the loader really mapped.
1203   for (char *iter = phdrs; iter != phdrs_end; iter += ehdr->e_phentsize) {
1204     Elf_Phdr *phdr = (Elf_Phdr *)iter;
1205     if (phdr->p_type == PT_LOAD) {
1206       uptr seg_start = phdr->p_vaddr + delta;
1207       uptr seg_end = seg_start + phdr->p_memsz;
1208       // None of these values are aligned.  We consider the ragged edges of the
1209       // load command as defined, since they are mapped from the file.
1210       seg_start = RoundDownTo(seg_start, GetPageSizeCached());
1211       seg_end = RoundUpTo(seg_end, GetPageSizeCached());
1212       cb((void *)seg_start, seg_end - seg_start);
1213     }
1214   }
1215 }
1216 #endif
1217
1218 #if SANITIZER_LINUX
1219 #if defined(__x86_64__)
1220 // We cannot use glibc's clone wrapper, because it messes with the child
1221 // task's TLS. It writes the PID and TID of the child task to its thread
1222 // descriptor, but in our case the child task shares the thread descriptor with
1223 // the parent (because we don't know how to allocate a new thread
1224 // descriptor to keep glibc happy). So the stock version of clone(), when
1225 // used with CLONE_VM, would end up corrupting the parent's thread descriptor.
1226 uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg,
1227                     int *parent_tidptr, void *newtls, int *child_tidptr) {
1228   long long res;
1229   if (!fn || !child_stack)
1230     return -EINVAL;
1231   CHECK_EQ(0, (uptr)child_stack % 16);
1232   child_stack = (char *)child_stack - 2 * sizeof(unsigned long long);
1233   ((unsigned long long *)child_stack)[0] = (uptr)fn;
1234   ((unsigned long long *)child_stack)[1] = (uptr)arg;
1235   register void *r8 __asm__("r8") = newtls;
1236   register int *r10 __asm__("r10") = child_tidptr;
1237   __asm__ __volatile__(
1238                        /* %rax = syscall(%rax = SYSCALL(clone),
1239                         *                %rdi = flags,
1240                         *                %rsi = child_stack,
1241                         *                %rdx = parent_tidptr,
1242                         *                %r8  = new_tls,
1243                         *                %r10 = child_tidptr)
1244                         */
1245                        "syscall\n"
1246
1247                        /* if (%rax != 0)
1248                         *   return;
1249                         */
1250                        "testq  %%rax,%%rax\n"
1251                        "jnz    1f\n"
1252
1253                        /* In the child. Terminate unwind chain. */
1254                        // XXX: We should also terminate the CFI unwind chain
1255                        // here. Unfortunately clang 3.2 doesn't support the
1256                        // necessary CFI directives, so we skip that part.
1257                        "xorq   %%rbp,%%rbp\n"
1258
1259                        /* Call "fn(arg)". */
1260                        "popq   %%rax\n"
1261                        "popq   %%rdi\n"
1262                        "call   *%%rax\n"
1263
1264                        /* Call _exit(%rax). */
1265                        "movq   %%rax,%%rdi\n"
1266                        "movq   %2,%%rax\n"
1267                        "syscall\n"
1268
1269                        /* Return to parent. */
1270                      "1:\n"
1271                        : "=a" (res)
1272                        : "a"(SYSCALL(clone)), "i"(SYSCALL(exit)),
1273                          "S"(child_stack),
1274                          "D"(flags),
1275                          "d"(parent_tidptr),
1276                          "r"(r8),
1277                          "r"(r10)
1278                        : "memory", "r11", "rcx");
1279   return res;
1280 }
1281 #elif defined(__mips__)
1282 uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg,
1283                     int *parent_tidptr, void *newtls, int *child_tidptr) {
1284   long long res;
1285   if (!fn || !child_stack)
1286     return -EINVAL;
1287   CHECK_EQ(0, (uptr)child_stack % 16);
1288   child_stack = (char *)child_stack - 2 * sizeof(unsigned long long);
1289   ((unsigned long long *)child_stack)[0] = (uptr)fn;
1290   ((unsigned long long *)child_stack)[1] = (uptr)arg;
1291   register void *a3 __asm__("$7") = newtls;
1292   register int *a4 __asm__("$8") = child_tidptr;
1293   // We don't have proper CFI directives here because it requires alot of code
1294   // for very marginal benefits.
1295   __asm__ __volatile__(
1296                        /* $v0 = syscall($v0 = __NR_clone,
1297                         * $a0 = flags,
1298                         * $a1 = child_stack,
1299                         * $a2 = parent_tidptr,
1300                         * $a3 = new_tls,
1301                         * $a4 = child_tidptr)
1302                         */
1303                        ".cprestore 16;\n"
1304                        "move $4,%1;\n"
1305                        "move $5,%2;\n"
1306                        "move $6,%3;\n"
1307                        "move $7,%4;\n"
1308                        /* Store the fifth argument on stack
1309                         * if we are using 32-bit abi.
1310                         */
1311 #if SANITIZER_WORDSIZE == 32
1312                        "lw %5,16($29);\n"
1313 #else
1314                        "move $8,%5;\n"
1315 #endif
1316                        "li $2,%6;\n"
1317                        "syscall;\n"
1318
1319                        /* if ($v0 != 0)
1320                         * return;
1321                         */
1322                        "bnez $2,1f;\n"
1323
1324                        /* Call "fn(arg)". */
1325 #if SANITIZER_WORDSIZE == 32
1326 #ifdef __BIG_ENDIAN__
1327                        "lw $25,4($29);\n"
1328                        "lw $4,12($29);\n"
1329 #else
1330                        "lw $25,0($29);\n"
1331                        "lw $4,8($29);\n"
1332 #endif
1333 #else
1334                        "ld $25,0($29);\n"
1335                        "ld $4,8($29);\n"
1336 #endif
1337                        "jal $25;\n"
1338
1339                        /* Call _exit($v0). */
1340                        "move $4,$2;\n"
1341                        "li $2,%7;\n"
1342                        "syscall;\n"
1343
1344                        /* Return to parent. */
1345                      "1:\n"
1346                        : "=r" (res)
1347                        : "r"(flags),
1348                          "r"(child_stack),
1349                          "r"(parent_tidptr),
1350                          "r"(a3),
1351                          "r"(a4),
1352                          "i"(__NR_clone),
1353                          "i"(__NR_exit)
1354                        : "memory", "$29" );
1355   return res;
1356 }
1357 #elif SANITIZER_RISCV64
1358 uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg,
1359                     int *parent_tidptr, void *newtls, int *child_tidptr) {
1360   if (!fn || !child_stack)
1361     return -EINVAL;
1362
1363   CHECK_EQ(0, (uptr)child_stack % 16);
1364
1365   register int res __asm__("a0");
1366   register int __flags __asm__("a0") = flags;
1367   register void *__stack __asm__("a1") = child_stack;
1368   register int *__ptid __asm__("a2") = parent_tidptr;
1369   register void *__tls __asm__("a3") = newtls;
1370   register int *__ctid __asm__("a4") = child_tidptr;
1371   register int (*__fn)(void *) __asm__("a5") = fn;
1372   register void *__arg __asm__("a6") = arg;
1373   register int nr_clone __asm__("a7") = __NR_clone;
1374
1375   __asm__ __volatile__(
1376       "ecall\n"
1377
1378       /* if (a0 != 0)
1379        *   return a0;
1380        */
1381       "bnez a0, 1f\n"
1382
1383       // In the child, now. Call "fn(arg)".
1384       "mv a0, a6\n"
1385       "jalr a5\n"
1386
1387       // Call _exit(a0).
1388       "addi a7, zero, %9\n"
1389       "ecall\n"
1390       "1:\n"
1391
1392       : "=r"(res)
1393       : "0"(__flags), "r"(__stack), "r"(__ptid), "r"(__tls), "r"(__ctid),
1394         "r"(__fn), "r"(__arg), "r"(nr_clone), "i"(__NR_exit)
1395       : "memory");
1396   return res;
1397 }
1398 #elif defined(__aarch64__)
1399 uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg,
1400                     int *parent_tidptr, void *newtls, int *child_tidptr) {
1401   register long long res __asm__("x0");
1402   if (!fn || !child_stack)
1403     return -EINVAL;
1404   CHECK_EQ(0, (uptr)child_stack % 16);
1405   child_stack = (char *)child_stack - 2 * sizeof(unsigned long long);
1406   ((unsigned long long *)child_stack)[0] = (uptr)fn;
1407   ((unsigned long long *)child_stack)[1] = (uptr)arg;
1408
1409   register int (*__fn)(void *)  __asm__("x0") = fn;
1410   register void *__stack __asm__("x1") = child_stack;
1411   register int   __flags __asm__("x2") = flags;
1412   register void *__arg   __asm__("x3") = arg;
1413   register int  *__ptid  __asm__("x4") = parent_tidptr;
1414   register void *__tls   __asm__("x5") = newtls;
1415   register int  *__ctid  __asm__("x6") = child_tidptr;
1416
1417   __asm__ __volatile__(
1418                        "mov x0,x2\n" /* flags  */
1419                        "mov x2,x4\n" /* ptid  */
1420                        "mov x3,x5\n" /* tls  */
1421                        "mov x4,x6\n" /* ctid  */
1422                        "mov x8,%9\n" /* clone  */
1423
1424                        "svc 0x0\n"
1425
1426                        /* if (%r0 != 0)
1427                         *   return %r0;
1428                         */
1429                        "cmp x0, #0\n"
1430                        "bne 1f\n"
1431
1432                        /* In the child, now. Call "fn(arg)". */
1433                        "ldp x1, x0, [sp], #16\n"
1434                        "blr x1\n"
1435
1436                        /* Call _exit(%r0).  */
1437                        "mov x8, %10\n"
1438                        "svc 0x0\n"
1439                      "1:\n"
1440
1441                        : "=r" (res)
1442                        : "i"(-EINVAL),
1443                          "r"(__fn), "r"(__stack), "r"(__flags), "r"(__arg),
1444                          "r"(__ptid), "r"(__tls), "r"(__ctid),
1445                          "i"(__NR_clone), "i"(__NR_exit)
1446                        : "x30", "memory");
1447   return res;
1448 }
1449 #elif defined(__powerpc64__)
1450 uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg,
1451                    int *parent_tidptr, void *newtls, int *child_tidptr) {
1452   long long res;
1453 // Stack frame structure.
1454 #if SANITIZER_PPC64V1
1455 //   Back chain == 0        (SP + 112)
1456 // Frame (112 bytes):
1457 //   Parameter save area    (SP + 48), 8 doublewords
1458 //   TOC save area          (SP + 40)
1459 //   Link editor doubleword (SP + 32)
1460 //   Compiler doubleword    (SP + 24)
1461 //   LR save area           (SP + 16)
1462 //   CR save area           (SP + 8)
1463 //   Back chain             (SP + 0)
1464 # define FRAME_SIZE 112
1465 # define FRAME_TOC_SAVE_OFFSET 40
1466 #elif SANITIZER_PPC64V2
1467 //   Back chain == 0        (SP + 32)
1468 // Frame (32 bytes):
1469 //   TOC save area          (SP + 24)
1470 //   LR save area           (SP + 16)
1471 //   CR save area           (SP + 8)
1472 //   Back chain             (SP + 0)
1473 # define FRAME_SIZE 32
1474 # define FRAME_TOC_SAVE_OFFSET 24
1475 #else
1476 # error "Unsupported PPC64 ABI"
1477 #endif
1478   if (!fn || !child_stack)
1479     return -EINVAL;
1480   CHECK_EQ(0, (uptr)child_stack % 16);
1481
1482   register int (*__fn)(void *) __asm__("r3") = fn;
1483   register void *__cstack      __asm__("r4") = child_stack;
1484   register int __flags         __asm__("r5") = flags;
1485   register void *__arg         __asm__("r6") = arg;
1486   register int *__ptidptr      __asm__("r7") = parent_tidptr;
1487   register void *__newtls      __asm__("r8") = newtls;
1488   register int *__ctidptr      __asm__("r9") = child_tidptr;
1489
1490  __asm__ __volatile__(
1491            /* fn and arg are saved across the syscall */
1492            "mr 28, %5\n\t"
1493            "mr 27, %8\n\t"
1494
1495            /* syscall
1496              r0 == __NR_clone
1497              r3 == flags
1498              r4 == child_stack
1499              r5 == parent_tidptr
1500              r6 == newtls
1501              r7 == child_tidptr */
1502            "mr 3, %7\n\t"
1503            "mr 5, %9\n\t"
1504            "mr 6, %10\n\t"
1505            "mr 7, %11\n\t"
1506            "li 0, %3\n\t"
1507            "sc\n\t"
1508
1509            /* Test if syscall was successful */
1510            "cmpdi  cr1, 3, 0\n\t"
1511            "crandc cr1*4+eq, cr1*4+eq, cr0*4+so\n\t"
1512            "bne-   cr1, 1f\n\t"
1513
1514            /* Set up stack frame */
1515            "li    29, 0\n\t"
1516            "stdu  29, -8(1)\n\t"
1517            "stdu  1, -%12(1)\n\t"
1518            /* Do the function call */
1519            "std   2, %13(1)\n\t"
1520 #if SANITIZER_PPC64V1
1521            "ld    0, 0(28)\n\t"
1522            "ld    2, 8(28)\n\t"
1523            "mtctr 0\n\t"
1524 #elif SANITIZER_PPC64V2
1525            "mr    12, 28\n\t"
1526            "mtctr 12\n\t"
1527 #else
1528 # error "Unsupported PPC64 ABI"
1529 #endif
1530            "mr    3, 27\n\t"
1531            "bctrl\n\t"
1532            "ld    2, %13(1)\n\t"
1533
1534            /* Call _exit(r3) */
1535            "li 0, %4\n\t"
1536            "sc\n\t"
1537
1538            /* Return to parent */
1539            "1:\n\t"
1540            "mr %0, 3\n\t"
1541              : "=r" (res)
1542              : "0" (-1),
1543                "i" (EINVAL),
1544                "i" (__NR_clone),
1545                "i" (__NR_exit),
1546                "r" (__fn),
1547                "r" (__cstack),
1548                "r" (__flags),
1549                "r" (__arg),
1550                "r" (__ptidptr),
1551                "r" (__newtls),
1552                "r" (__ctidptr),
1553                "i" (FRAME_SIZE),
1554                "i" (FRAME_TOC_SAVE_OFFSET)
1555              : "cr0", "cr1", "memory", "ctr", "r0", "r27", "r28", "r29");
1556   return res;
1557 }
1558 #elif defined(__i386__)
1559 uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg,
1560                     int *parent_tidptr, void *newtls, int *child_tidptr) {
1561   int res;
1562   if (!fn || !child_stack)
1563     return -EINVAL;
1564   CHECK_EQ(0, (uptr)child_stack % 16);
1565   child_stack = (char *)child_stack - 7 * sizeof(unsigned int);
1566   ((unsigned int *)child_stack)[0] = (uptr)flags;
1567   ((unsigned int *)child_stack)[1] = (uptr)0;
1568   ((unsigned int *)child_stack)[2] = (uptr)fn;
1569   ((unsigned int *)child_stack)[3] = (uptr)arg;
1570   __asm__ __volatile__(
1571                        /* %eax = syscall(%eax = SYSCALL(clone),
1572                         *                %ebx = flags,
1573                         *                %ecx = child_stack,
1574                         *                %edx = parent_tidptr,
1575                         *                %esi  = new_tls,
1576                         *                %edi = child_tidptr)
1577                         */
1578
1579                         /* Obtain flags */
1580                         "movl    (%%ecx), %%ebx\n"
1581                         /* Do the system call */
1582                         "pushl   %%ebx\n"
1583                         "pushl   %%esi\n"
1584                         "pushl   %%edi\n"
1585                         /* Remember the flag value.  */
1586                         "movl    %%ebx, (%%ecx)\n"
1587                         "int     $0x80\n"
1588                         "popl    %%edi\n"
1589                         "popl    %%esi\n"
1590                         "popl    %%ebx\n"
1591
1592                         /* if (%eax != 0)
1593                          *   return;
1594                          */
1595
1596                         "test    %%eax,%%eax\n"
1597                         "jnz    1f\n"
1598
1599                         /* terminate the stack frame */
1600                         "xorl   %%ebp,%%ebp\n"
1601                         /* Call FN. */
1602                         "call    *%%ebx\n"
1603 #ifdef PIC
1604                         "call    here\n"
1605                         "here:\n"
1606                         "popl    %%ebx\n"
1607                         "addl    $_GLOBAL_OFFSET_TABLE_+[.-here], %%ebx\n"
1608 #endif
1609                         /* Call exit */
1610                         "movl    %%eax, %%ebx\n"
1611                         "movl    %2, %%eax\n"
1612                         "int     $0x80\n"
1613                         "1:\n"
1614                        : "=a" (res)
1615                        : "a"(SYSCALL(clone)), "i"(SYSCALL(exit)),
1616                          "c"(child_stack),
1617                          "d"(parent_tidptr),
1618                          "S"(newtls),
1619                          "D"(child_tidptr)
1620                        : "memory");
1621   return res;
1622 }
1623 #elif defined(__arm__)
1624 uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg,
1625                     int *parent_tidptr, void *newtls, int *child_tidptr) {
1626   unsigned int res;
1627   if (!fn || !child_stack)
1628     return -EINVAL;
1629   child_stack = (char *)child_stack - 2 * sizeof(unsigned int);
1630   ((unsigned int *)child_stack)[0] = (uptr)fn;
1631   ((unsigned int *)child_stack)[1] = (uptr)arg;
1632   register int r0 __asm__("r0") = flags;
1633   register void *r1 __asm__("r1") = child_stack;
1634   register int *r2 __asm__("r2") = parent_tidptr;
1635   register void *r3 __asm__("r3") = newtls;
1636   register int *r4 __asm__("r4") = child_tidptr;
1637   register int r7 __asm__("r7") = __NR_clone;
1638
1639 #if __ARM_ARCH > 4 || defined (__ARM_ARCH_4T__)
1640 # define ARCH_HAS_BX
1641 #endif
1642 #if __ARM_ARCH > 4
1643 # define ARCH_HAS_BLX
1644 #endif
1645
1646 #ifdef ARCH_HAS_BX
1647 # ifdef ARCH_HAS_BLX
1648 #  define BLX(R) "blx "  #R "\n"
1649 # else
1650 #  define BLX(R) "mov lr, pc; bx " #R "\n"
1651 # endif
1652 #else
1653 # define BLX(R)  "mov lr, pc; mov pc," #R "\n"
1654 #endif
1655
1656   __asm__ __volatile__(
1657                        /* %r0 = syscall(%r7 = SYSCALL(clone),
1658                         *               %r0 = flags,
1659                         *               %r1 = child_stack,
1660                         *               %r2 = parent_tidptr,
1661                         *               %r3  = new_tls,
1662                         *               %r4 = child_tidptr)
1663                         */
1664
1665                        /* Do the system call */
1666                        "swi 0x0\n"
1667
1668                        /* if (%r0 != 0)
1669                         *   return %r0;
1670                         */
1671                        "cmp r0, #0\n"
1672                        "bne 1f\n"
1673
1674                        /* In the child, now. Call "fn(arg)". */
1675                        "ldr r0, [sp, #4]\n"
1676                        "ldr ip, [sp], #8\n"
1677                        BLX(ip)
1678                        /* Call _exit(%r0). */
1679                        "mov r7, %7\n"
1680                        "swi 0x0\n"
1681                        "1:\n"
1682                        "mov %0, r0\n"
1683                        : "=r"(res)
1684                        : "r"(r0), "r"(r1), "r"(r2), "r"(r3), "r"(r4), "r"(r7),
1685                          "i"(__NR_exit)
1686                        : "memory");
1687   return res;
1688 }
1689 #endif
1690 #endif  // SANITIZER_LINUX
1691
1692 #if SANITIZER_LINUX
1693 int internal_uname(struct utsname *buf) {
1694   return internal_syscall(SYSCALL(uname), buf);
1695 }
1696 #endif
1697
1698 #if SANITIZER_ANDROID
1699 #if __ANDROID_API__ < 21
1700 extern "C" __attribute__((weak)) int dl_iterate_phdr(
1701     int (*)(struct dl_phdr_info *, size_t, void *), void *);
1702 #endif
1703
1704 static int dl_iterate_phdr_test_cb(struct dl_phdr_info *info, size_t size,
1705                                    void *data) {
1706   // Any name starting with "lib" indicates a bug in L where library base names
1707   // are returned instead of paths.
1708   if (info->dlpi_name && info->dlpi_name[0] == 'l' &&
1709       info->dlpi_name[1] == 'i' && info->dlpi_name[2] == 'b') {
1710     *(bool *)data = true;
1711     return 1;
1712   }
1713   return 0;
1714 }
1715
1716 static atomic_uint32_t android_api_level;
1717
1718 static AndroidApiLevel AndroidDetectApiLevelStatic() {
1719 #if __ANDROID_API__ <= 19
1720   return ANDROID_KITKAT;
1721 #elif __ANDROID_API__ <= 22
1722   return ANDROID_LOLLIPOP_MR1;
1723 #else
1724   return ANDROID_POST_LOLLIPOP;
1725 #endif
1726 }
1727
1728 static AndroidApiLevel AndroidDetectApiLevel() {
1729   if (!&dl_iterate_phdr)
1730     return ANDROID_KITKAT; // K or lower
1731   bool base_name_seen = false;
1732   dl_iterate_phdr(dl_iterate_phdr_test_cb, &base_name_seen);
1733   if (base_name_seen)
1734     return ANDROID_LOLLIPOP_MR1; // L MR1
1735   return ANDROID_POST_LOLLIPOP;   // post-L
1736   // Plain L (API level 21) is completely broken wrt ASan and not very
1737   // interesting to detect.
1738 }
1739
1740 extern "C" __attribute__((weak)) void* _DYNAMIC;
1741
1742 AndroidApiLevel AndroidGetApiLevel() {
1743   AndroidApiLevel level =
1744       (AndroidApiLevel)atomic_load(&android_api_level, memory_order_relaxed);
1745   if (level) return level;
1746   level = &_DYNAMIC == nullptr ? AndroidDetectApiLevelStatic()
1747                                : AndroidDetectApiLevel();
1748   atomic_store(&android_api_level, level, memory_order_relaxed);
1749   return level;
1750 }
1751
1752 #endif
1753
1754 static HandleSignalMode GetHandleSignalModeImpl(int signum) {
1755   switch (signum) {
1756     case SIGABRT:
1757       return common_flags()->handle_abort;
1758     case SIGILL:
1759       return common_flags()->handle_sigill;
1760     case SIGTRAP:
1761       return common_flags()->handle_sigtrap;
1762     case SIGFPE:
1763       return common_flags()->handle_sigfpe;
1764     case SIGSEGV:
1765       return common_flags()->handle_segv;
1766     case SIGBUS:
1767       return common_flags()->handle_sigbus;
1768   }
1769   return kHandleSignalNo;
1770 }
1771
1772 HandleSignalMode GetHandleSignalMode(int signum) {
1773   HandleSignalMode result = GetHandleSignalModeImpl(signum);
1774   if (result == kHandleSignalYes && !common_flags()->allow_user_segv_handler)
1775     return kHandleSignalExclusive;
1776   return result;
1777 }
1778
1779 #if !SANITIZER_GO
1780 void *internal_start_thread(void *(*func)(void *arg), void *arg) {
1781   if (&real_pthread_create == 0)
1782     return nullptr;
1783   // Start the thread with signals blocked, otherwise it can steal user signals.
1784   ScopedBlockSignals block(nullptr);
1785   void *th;
1786   real_pthread_create(&th, nullptr, func, arg);
1787   return th;
1788 }
1789
1790 void internal_join_thread(void *th) {
1791   if (&real_pthread_join)
1792     real_pthread_join(th, nullptr);
1793 }
1794 #else
1795 void *internal_start_thread(void *(*func)(void *), void *arg) { return 0; }
1796
1797 void internal_join_thread(void *th) {}
1798 #endif
1799
1800 #if defined(__aarch64__)
1801 // Android headers in the older NDK releases miss this definition.
1802 struct __sanitizer_esr_context {
1803   struct _aarch64_ctx head;
1804   uint64_t esr;
1805 };
1806
1807 static bool Aarch64GetESR(ucontext_t *ucontext, u64 *esr) {
1808   static const u32 kEsrMagic = 0x45535201;
1809   u8 *aux = reinterpret_cast<u8 *>(ucontext->uc_mcontext.__reserved);
1810   while (true) {
1811     _aarch64_ctx *ctx = (_aarch64_ctx *)aux;
1812     if (ctx->size == 0) break;
1813     if (ctx->magic == kEsrMagic) {
1814       *esr = ((__sanitizer_esr_context *)ctx)->esr;
1815       return true;
1816     }
1817     aux += ctx->size;
1818   }
1819   return false;
1820 }
1821 #endif
1822
1823 using Context = ucontext_t;
1824
1825 SignalContext::WriteFlag SignalContext::GetWriteFlag() const {
1826   Context *ucontext = (Context *)context;
1827 #if defined(__x86_64__) || defined(__i386__)
1828   static const uptr PF_WRITE = 1U << 1;
1829 #if SANITIZER_FREEBSD
1830   uptr err = ucontext->uc_mcontext.mc_err;
1831 #elif SANITIZER_NETBSD
1832   uptr err = ucontext->uc_mcontext.__gregs[_REG_ERR];
1833 #elif SANITIZER_SOLARIS && defined(__i386__)
1834   const int Err = 13;
1835   uptr err = ucontext->uc_mcontext.gregs[Err];
1836 #else
1837   uptr err = ucontext->uc_mcontext.gregs[REG_ERR];
1838 #endif // SANITIZER_FREEBSD
1839   return err & PF_WRITE ? Write : Read;
1840 #elif defined(__mips__)
1841   uint32_t *exception_source;
1842   uint32_t faulty_instruction;
1843   uint32_t op_code;
1844
1845   exception_source = (uint32_t *)ucontext->uc_mcontext.pc;
1846   faulty_instruction = (uint32_t)(*exception_source);
1847
1848   op_code = (faulty_instruction >> 26) & 0x3f;
1849
1850   // FIXME: Add support for FPU, microMIPS, DSP, MSA memory instructions.
1851   switch (op_code) {
1852     case 0x28:  // sb
1853     case 0x29:  // sh
1854     case 0x2b:  // sw
1855     case 0x3f:  // sd
1856 #if __mips_isa_rev < 6
1857     case 0x2c:  // sdl
1858     case 0x2d:  // sdr
1859     case 0x2a:  // swl
1860     case 0x2e:  // swr
1861 #endif
1862       return SignalContext::Write;
1863
1864     case 0x20:  // lb
1865     case 0x24:  // lbu
1866     case 0x21:  // lh
1867     case 0x25:  // lhu
1868     case 0x23:  // lw
1869     case 0x27:  // lwu
1870     case 0x37:  // ld
1871 #if __mips_isa_rev < 6
1872     case 0x1a:  // ldl
1873     case 0x1b:  // ldr
1874     case 0x22:  // lwl
1875     case 0x26:  // lwr
1876 #endif
1877       return SignalContext::Read;
1878 #if __mips_isa_rev == 6
1879     case 0x3b:  // pcrel
1880       op_code = (faulty_instruction >> 19) & 0x3;
1881       switch (op_code) {
1882         case 0x1:  // lwpc
1883         case 0x2:  // lwupc
1884           return SignalContext::Read;
1885       }
1886 #endif
1887   }
1888   return SignalContext::Unknown;
1889 #elif defined(__arm__)
1890   static const uptr FSR_WRITE = 1U << 11;
1891   uptr fsr = ucontext->uc_mcontext.error_code;
1892   return fsr & FSR_WRITE ? Write : Read;
1893 #elif defined(__aarch64__)
1894   static const u64 ESR_ELx_WNR = 1U << 6;
1895   u64 esr;
1896   if (!Aarch64GetESR(ucontext, &esr)) return Unknown;
1897   return esr & ESR_ELx_WNR ? Write : Read;
1898 #elif defined(__sparc__)
1899   // Decode the instruction to determine the access type.
1900   // From OpenSolaris $SRC/uts/sun4/os/trap.c (get_accesstype).
1901 #if SANITIZER_SOLARIS
1902   uptr pc = ucontext->uc_mcontext.gregs[REG_PC];
1903 #else
1904   // Historical BSDism here.
1905   struct sigcontext *scontext = (struct sigcontext *)context;
1906 #if defined(__arch64__)
1907   uptr pc = scontext->sigc_regs.tpc;
1908 #else
1909   uptr pc = scontext->si_regs.pc;
1910 #endif
1911 #endif
1912   u32 instr = *(u32 *)pc;
1913   return (instr >> 21) & 1 ? Write: Read;
1914 #elif defined(__riscv)
1915 #if SANITIZER_FREEBSD
1916   unsigned long pc = ucontext->uc_mcontext.mc_gpregs.gp_sepc;
1917 #else
1918   unsigned long pc = ucontext->uc_mcontext.__gregs[REG_PC];
1919 #endif
1920   unsigned faulty_instruction = *(uint16_t *)pc;
1921
1922 #if defined(__riscv_compressed)
1923   if ((faulty_instruction & 0x3) != 0x3) {  // it's a compressed instruction
1924     // set op_bits to the instruction bits [1, 0, 15, 14, 13]
1925     unsigned op_bits =
1926         ((faulty_instruction & 0x3) << 3) | (faulty_instruction >> 13);
1927     unsigned rd = faulty_instruction & 0xF80;  // bits 7-11, inclusive
1928     switch (op_bits) {
1929       case 0b10'010:  // c.lwsp (rd != x0)
1930 #if __riscv_xlen == 64
1931       case 0b10'011:  // c.ldsp (rd != x0)
1932 #endif
1933         return rd ? SignalContext::Read : SignalContext::Unknown;
1934       case 0b00'010:  // c.lw
1935 #if __riscv_flen >= 32 && __riscv_xlen == 32
1936       case 0b10'011:  // c.flwsp
1937 #endif
1938 #if __riscv_flen >= 32 || __riscv_xlen == 64
1939       case 0b00'011:  // c.flw / c.ld
1940 #endif
1941 #if __riscv_flen == 64
1942       case 0b00'001:  // c.fld
1943       case 0b10'001:  // c.fldsp
1944 #endif
1945         return SignalContext::Read;
1946       case 0b00'110:  // c.sw
1947       case 0b10'110:  // c.swsp
1948 #if __riscv_flen >= 32 || __riscv_xlen == 64
1949       case 0b00'111:  // c.fsw / c.sd
1950       case 0b10'111:  // c.fswsp / c.sdsp
1951 #endif
1952 #if __riscv_flen == 64
1953       case 0b00'101:  // c.fsd
1954       case 0b10'101:  // c.fsdsp
1955 #endif
1956         return SignalContext::Write;
1957       default:
1958         return SignalContext::Unknown;
1959     }
1960   }
1961 #endif
1962
1963   unsigned opcode = faulty_instruction & 0x7f;         // lower 7 bits
1964   unsigned funct3 = (faulty_instruction >> 12) & 0x7;  // bits 12-14, inclusive
1965   switch (opcode) {
1966     case 0b0000011:  // loads
1967       switch (funct3) {
1968         case 0b000:  // lb
1969         case 0b001:  // lh
1970         case 0b010:  // lw
1971 #if __riscv_xlen == 64
1972         case 0b011:  // ld
1973 #endif
1974         case 0b100:  // lbu
1975         case 0b101:  // lhu
1976           return SignalContext::Read;
1977         default:
1978           return SignalContext::Unknown;
1979       }
1980     case 0b0100011:  // stores
1981       switch (funct3) {
1982         case 0b000:  // sb
1983         case 0b001:  // sh
1984         case 0b010:  // sw
1985 #if __riscv_xlen == 64
1986         case 0b011:  // sd
1987 #endif
1988           return SignalContext::Write;
1989         default:
1990           return SignalContext::Unknown;
1991       }
1992 #if __riscv_flen >= 32
1993     case 0b0000111:  // floating-point loads
1994       switch (funct3) {
1995         case 0b010:  // flw
1996 #if __riscv_flen == 64
1997         case 0b011:  // fld
1998 #endif
1999           return SignalContext::Read;
2000         default:
2001           return SignalContext::Unknown;
2002       }
2003     case 0b0100111:  // floating-point stores
2004       switch (funct3) {
2005         case 0b010:  // fsw
2006 #if __riscv_flen == 64
2007         case 0b011:  // fsd
2008 #endif
2009           return SignalContext::Write;
2010         default:
2011           return SignalContext::Unknown;
2012       }
2013 #endif
2014     default:
2015       return SignalContext::Unknown;
2016   }
2017 #else
2018   (void)ucontext;
2019   return Unknown;  // FIXME: Implement.
2020 #endif
2021 }
2022
2023 bool SignalContext::IsTrueFaultingAddress() const {
2024   auto si = static_cast<const siginfo_t *>(siginfo);
2025   // SIGSEGV signals without a true fault address have si_code set to 128.
2026   return si->si_signo == SIGSEGV && si->si_code != 128;
2027 }
2028
2029 void SignalContext::DumpAllRegisters(void *context) {
2030   // FIXME: Implement this.
2031 }
2032
2033 static void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp) {
2034 #if SANITIZER_NETBSD
2035   // This covers all NetBSD architectures
2036   ucontext_t *ucontext = (ucontext_t *)context;
2037   *pc = _UC_MACHINE_PC(ucontext);
2038   *bp = _UC_MACHINE_FP(ucontext);
2039   *sp = _UC_MACHINE_SP(ucontext);
2040 #elif defined(__arm__)
2041   ucontext_t *ucontext = (ucontext_t*)context;
2042   *pc = ucontext->uc_mcontext.arm_pc;
2043   *bp = ucontext->uc_mcontext.arm_fp;
2044   *sp = ucontext->uc_mcontext.arm_sp;
2045 #elif defined(__aarch64__)
2046   ucontext_t *ucontext = (ucontext_t*)context;
2047   *pc = ucontext->uc_mcontext.pc;
2048   *bp = ucontext->uc_mcontext.regs[29];
2049   *sp = ucontext->uc_mcontext.sp;
2050 #elif defined(__hppa__)
2051   ucontext_t *ucontext = (ucontext_t*)context;
2052   *pc = ucontext->uc_mcontext.sc_iaoq[0];
2053   /* GCC uses %r3 whenever a frame pointer is needed.  */
2054   *bp = ucontext->uc_mcontext.sc_gr[3];
2055   *sp = ucontext->uc_mcontext.sc_gr[30];
2056 #elif defined(__x86_64__)
2057 # if SANITIZER_FREEBSD
2058   ucontext_t *ucontext = (ucontext_t*)context;
2059   *pc = ucontext->uc_mcontext.mc_rip;
2060   *bp = ucontext->uc_mcontext.mc_rbp;
2061   *sp = ucontext->uc_mcontext.mc_rsp;
2062 # else
2063   ucontext_t *ucontext = (ucontext_t*)context;
2064   *pc = ucontext->uc_mcontext.gregs[REG_RIP];
2065   *bp = ucontext->uc_mcontext.gregs[REG_RBP];
2066   *sp = ucontext->uc_mcontext.gregs[REG_RSP];
2067 # endif
2068 #elif defined(__i386__)
2069 # if SANITIZER_FREEBSD
2070   ucontext_t *ucontext = (ucontext_t*)context;
2071   *pc = ucontext->uc_mcontext.mc_eip;
2072   *bp = ucontext->uc_mcontext.mc_ebp;
2073   *sp = ucontext->uc_mcontext.mc_esp;
2074 # else
2075   ucontext_t *ucontext = (ucontext_t*)context;
2076 # if SANITIZER_SOLARIS
2077   /* Use the numeric values: the symbolic ones are undefined by llvm
2078      include/llvm/Support/Solaris.h.  */
2079 # ifndef REG_EIP
2080 #  define REG_EIP 14 // REG_PC
2081 # endif
2082 # ifndef REG_EBP
2083 #  define REG_EBP  6 // REG_FP
2084 # endif
2085 # ifndef REG_UESP
2086 #  define REG_UESP 17 // REG_SP
2087 # endif
2088 # endif
2089   *pc = ucontext->uc_mcontext.gregs[REG_EIP];
2090   *bp = ucontext->uc_mcontext.gregs[REG_EBP];
2091   *sp = ucontext->uc_mcontext.gregs[REG_UESP];
2092 # endif
2093 #elif defined(__powerpc__) || defined(__powerpc64__)
2094   ucontext_t *ucontext = (ucontext_t*)context;
2095   *pc = ucontext->uc_mcontext.regs->nip;
2096   *sp = ucontext->uc_mcontext.regs->gpr[PT_R1];
2097   // The powerpc{,64}-linux ABIs do not specify r31 as the frame
2098   // pointer, but GCC always uses r31 when we need a frame pointer.
2099   *bp = ucontext->uc_mcontext.regs->gpr[PT_R31];
2100 #elif defined(__sparc__)
2101 #if defined(__arch64__) || defined(__sparcv9)
2102 #define STACK_BIAS 2047
2103 #else
2104 #define STACK_BIAS 0
2105 # endif
2106 # if SANITIZER_SOLARIS
2107   ucontext_t *ucontext = (ucontext_t *)context;
2108   *pc = ucontext->uc_mcontext.gregs[REG_PC];
2109   *sp = ucontext->uc_mcontext.gregs[REG_O6] + STACK_BIAS;
2110 #else
2111   // Historical BSDism here.
2112   struct sigcontext *scontext = (struct sigcontext *)context;
2113 #if defined(__arch64__)
2114   *pc = scontext->sigc_regs.tpc;
2115   *sp = scontext->sigc_regs.u_regs[14] + STACK_BIAS;
2116 #else
2117   *pc = scontext->si_regs.pc;
2118   *sp = scontext->si_regs.u_regs[14];
2119 #endif
2120 # endif
2121   *bp = (uptr)((uhwptr *)*sp)[14] + STACK_BIAS;
2122 #elif defined(__mips__)
2123   ucontext_t *ucontext = (ucontext_t*)context;
2124   *pc = ucontext->uc_mcontext.pc;
2125   *bp = ucontext->uc_mcontext.gregs[30];
2126   *sp = ucontext->uc_mcontext.gregs[29];
2127 #elif defined(__s390__)
2128   ucontext_t *ucontext = (ucontext_t*)context;
2129 # if defined(__s390x__)
2130   *pc = ucontext->uc_mcontext.psw.addr;
2131 # else
2132   *pc = ucontext->uc_mcontext.psw.addr & 0x7fffffff;
2133 # endif
2134   *bp = ucontext->uc_mcontext.gregs[11];
2135   *sp = ucontext->uc_mcontext.gregs[15];
2136 #elif defined(__riscv)
2137   ucontext_t *ucontext = (ucontext_t*)context;
2138 #    if SANITIZER_FREEBSD
2139   *pc = ucontext->uc_mcontext.mc_gpregs.gp_sepc;
2140   *bp = ucontext->uc_mcontext.mc_gpregs.gp_s[0];
2141   *sp = ucontext->uc_mcontext.mc_gpregs.gp_sp;
2142 #    else
2143   *pc = ucontext->uc_mcontext.__gregs[REG_PC];
2144   *bp = ucontext->uc_mcontext.__gregs[REG_S0];
2145   *sp = ucontext->uc_mcontext.__gregs[REG_SP];
2146 #    endif
2147 #  elif defined(__hexagon__)
2148   ucontext_t *ucontext = (ucontext_t *)context;
2149   *pc = ucontext->uc_mcontext.pc;
2150   *bp = ucontext->uc_mcontext.r30;
2151   *sp = ucontext->uc_mcontext.r29;
2152 #  else
2153 #    error "Unsupported arch"
2154 #  endif
2155 }
2156
2157 void SignalContext::InitPcSpBp() { GetPcSpBp(context, &pc, &sp, &bp); }
2158
2159 void InitializePlatformEarly() {
2160   // Do nothing.
2161 }
2162
2163 void MaybeReexec() {
2164   // No need to re-exec on Linux.
2165 }
2166
2167 void CheckASLR() {
2168 #if SANITIZER_NETBSD
2169   int mib[3];
2170   int paxflags;
2171   uptr len = sizeof(paxflags);
2172
2173   mib[0] = CTL_PROC;
2174   mib[1] = internal_getpid();
2175   mib[2] = PROC_PID_PAXFLAGS;
2176
2177   if (UNLIKELY(internal_sysctl(mib, 3, &paxflags, &len, NULL, 0) == -1)) {
2178     Printf("sysctl failed\n");
2179     Die();
2180   }
2181
2182   if (UNLIKELY(paxflags & CTL_PROC_PAXFLAGS_ASLR)) {
2183     Printf("This sanitizer is not compatible with enabled ASLR.\n"
2184            "To disable ASLR, please run \"paxctl +a %s\" and try again.\n",
2185            GetArgv()[0]);
2186     Die();
2187   }
2188 #elif SANITIZER_PPC64V2
2189   // Disable ASLR for Linux PPC64LE.
2190   int old_personality = personality(0xffffffff);
2191   if (old_personality != -1 && (old_personality & ADDR_NO_RANDOMIZE) == 0) {
2192     VReport(1, "WARNING: Program is being run with address space layout "
2193                "randomization (ASLR) enabled which prevents the thread and "
2194                "memory sanitizers from working on powerpc64le.\n"
2195                "ASLR will be disabled and the program re-executed.\n");
2196     CHECK_NE(personality(old_personality | ADDR_NO_RANDOMIZE), -1);
2197     ReExec();
2198   }
2199 #elif SANITIZER_FREEBSD
2200   int aslr_status;
2201   if (UNLIKELY(procctl(P_PID, 0, PROC_ASLR_STATUS, &aslr_status) == -1)) {
2202     // We're making things less 'dramatic' here since
2203     // the cmd is not necessarily guaranteed to be here
2204     // just yet regarding FreeBSD release
2205     return;
2206   }
2207   if ((aslr_status & PROC_ASLR_ACTIVE) != 0) {
2208     Printf("This sanitizer is not compatible with enabled ASLR "
2209            "and binaries compiled with PIE\n");
2210     Die();
2211   }
2212 #else
2213   // Do nothing
2214 #endif
2215 }
2216
2217 void CheckMPROTECT() {
2218 #if SANITIZER_NETBSD
2219   int mib[3];
2220   int paxflags;
2221   uptr len = sizeof(paxflags);
2222
2223   mib[0] = CTL_PROC;
2224   mib[1] = internal_getpid();
2225   mib[2] = PROC_PID_PAXFLAGS;
2226
2227   if (UNLIKELY(internal_sysctl(mib, 3, &paxflags, &len, NULL, 0) == -1)) {
2228     Printf("sysctl failed\n");
2229     Die();
2230   }
2231
2232   if (UNLIKELY(paxflags & CTL_PROC_PAXFLAGS_MPROTECT)) {
2233     Printf("This sanitizer is not compatible with enabled MPROTECT\n");
2234     Die();
2235   }
2236 #else
2237   // Do nothing
2238 #endif
2239 }
2240
2241 void CheckNoDeepBind(const char *filename, int flag) {
2242 #ifdef RTLD_DEEPBIND
2243   if (flag & RTLD_DEEPBIND) {
2244     Report(
2245         "You are trying to dlopen a %s shared library with RTLD_DEEPBIND flag"
2246         " which is incompatible with sanitizer runtime "
2247         "(see https://github.com/google/sanitizers/issues/611 for details"
2248         "). If you want to run %s library under sanitizers please remove "
2249         "RTLD_DEEPBIND from dlopen flags.\n",
2250         filename, filename);
2251     Die();
2252   }
2253 #endif
2254 }
2255
2256 uptr FindAvailableMemoryRange(uptr size, uptr alignment, uptr left_padding,
2257                               uptr *largest_gap_found,
2258                               uptr *max_occupied_addr) {
2259   UNREACHABLE("FindAvailableMemoryRange is not available");
2260   return 0;
2261 }
2262
2263 bool GetRandom(void *buffer, uptr length, bool blocking) {
2264   if (!buffer || !length || length > 256)
2265     return false;
2266 #if SANITIZER_USE_GETENTROPY
2267   uptr rnd = getentropy(buffer, length);
2268   int rverrno = 0;
2269   if (internal_iserror(rnd, &rverrno) && rverrno == EFAULT)
2270     return false;
2271   else if (rnd == 0)
2272     return true;
2273 #endif // SANITIZER_USE_GETENTROPY
2274
2275 #if SANITIZER_USE_GETRANDOM
2276   static atomic_uint8_t skip_getrandom_syscall;
2277   if (!atomic_load_relaxed(&skip_getrandom_syscall)) {
2278     // Up to 256 bytes, getrandom will not be interrupted.
2279     uptr res = internal_syscall(SYSCALL(getrandom), buffer, length,
2280                                 blocking ? 0 : GRND_NONBLOCK);
2281     int rverrno = 0;
2282     if (internal_iserror(res, &rverrno) && rverrno == ENOSYS)
2283       atomic_store_relaxed(&skip_getrandom_syscall, 1);
2284     else if (res == length)
2285       return true;
2286   }
2287 #endif // SANITIZER_USE_GETRANDOM
2288   // Up to 256 bytes, a read off /dev/urandom will not be interrupted.
2289   // blocking is moot here, O_NONBLOCK has no effect when opening /dev/urandom.
2290   uptr fd = internal_open("/dev/urandom", O_RDONLY);
2291   if (internal_iserror(fd))
2292     return false;
2293   uptr res = internal_read(fd, buffer, length);
2294   if (internal_iserror(res))
2295     return false;
2296   internal_close(fd);
2297   return true;
2298 }
2299
2300 } // namespace __sanitizer
2301
2302 #endif