libsanitizer/sanitizer_common/sanitizer_linux.cc

   1 //===-- sanitizer_linux.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 #if SANITIZER_FREEBSD || SANITIZER_LINUX
  15
  16 #include "sanitizer_common.h"
  17 #include "sanitizer_flags.h"
  18 #include "sanitizer_internal_defs.h"
  19 #include "sanitizer_libc.h"
  20 #include "sanitizer_linux.h"
  21 #include "sanitizer_mutex.h"
  22 #include "sanitizer_placement_new.h"
  23 #include "sanitizer_procmaps.h"
  24 #include "sanitizer_stacktrace.h"
  25 #include "sanitizer_symbolizer.h"
  26
  27 #if !SANITIZER_FREEBSD
  28 #include <asm/param.h>
  29 #endif
  30
  31 #include <dlfcn.h>
  32 #include <errno.h>
  33 #include <fcntl.h>
  34 #if !SANITIZER_ANDROID
  35 #include <link.h>
  36 #endif
  37 #include <pthread.h>
  38 #include <sched.h>
  39 #include <sys/mman.h>
  40 #include <sys/ptrace.h>
  41 #include <sys/resource.h>
  42 #include <sys/stat.h>
  43 #include <sys/syscall.h>
  44 #include <sys/time.h>
  45 #include <sys/types.h>
  46 #include <unistd.h>
  47 #include <unwind.h>
  48
  49 #if SANITIZER_FREEBSD
  50 #include <machine/atomic.h>
  51 extern "C" {
  52 // <sys/umtx.h> must be included after <errno.h> and <sys/types.h> on
  53 // FreeBSD 9.2 and 10.0.
  54 #include <sys/umtx.h>
  55 }
  56 #endif  // SANITIZER_FREEBSD
  57
  58 #if !SANITIZER_ANDROID
  59 #include <sys/signal.h>
  60 #endif
  61
  62 #if SANITIZER_ANDROID
  63 #include <android/log.h>
  64 #include <sys/system_properties.h>
  65 #endif
  66
  67 #if SANITIZER_LINUX
  68 // <linux/time.h>
  69 struct kernel_timeval {
  70   long tv_sec;
  71   long tv_usec;
  72 };
  73
  74 // <linux/futex.h> is broken on some linux distributions.
  75 const int FUTEX_WAIT = 0;
  76 const int FUTEX_WAKE = 1;
  77 #endif  // SANITIZER_LINUX
  78
  79 // Are we using 32-bit or 64-bit Linux syscalls?
  80 // x32 (which defines __x86_64__) has SANITIZER_WORDSIZE == 32
  81 // but it still needs to use 64-bit syscalls.
  82 #if SANITIZER_LINUX && (defined(__x86_64__) || SANITIZER_WORDSIZE == 64)
  83 # define SANITIZER_LINUX_USES_64BIT_SYSCALLS 1
  84 #else
  85 # define SANITIZER_LINUX_USES_64BIT_SYSCALLS 0
  86 #endif
  87
  88 namespace __sanitizer {
  89
  90 #if SANITIZER_LINUX && defined(__x86_64__)
  91 #include "sanitizer_syscall_linux_x86_64.inc"
  92 #else
  93 #include "sanitizer_syscall_generic.inc"
  94 #endif
  95
  96 // --------------- sanitizer_libc.h
  97 uptr internal_mmap(void *addr, uptr length, int prot, int flags,
  98                     int fd, u64 offset) {
  99 #if SANITIZER_FREEBSD || SANITIZER_LINUX_USES_64BIT_SYSCALLS
 100   return internal_syscall(SYSCALL(mmap), (uptr)addr, length, prot, flags, fd,
 101                           offset);
 102 #else
 103   return internal_syscall(SYSCALL(mmap2), addr, length, prot, flags, fd,
 104                           offset);
 105 #endif
 106 }
 107
 108 uptr internal_munmap(void *addr, uptr length) {
 109   return internal_syscall(SYSCALL(munmap), (uptr)addr, length);
 110 }
 111
 112 uptr internal_close(fd_t fd) {
 113   return internal_syscall(SYSCALL(close), fd);
 114 }
 115
 116 uptr internal_open(const char *filename, int flags) {
 117 #if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 118   return internal_syscall(SYSCALL(openat), AT_FDCWD, (uptr)filename, flags);
 119 #else
 120   return internal_syscall(SYSCALL(open), (uptr)filename, flags);
 121 #endif
 122 }
 123
 124 uptr internal_open(const char *filename, int flags, u32 mode) {
 125 #if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 126   return internal_syscall(SYSCALL(openat), AT_FDCWD, (uptr)filename, flags,
 127                           mode);
 128 #else
 129   return internal_syscall(SYSCALL(open), (uptr)filename, flags, mode);
 130 #endif
 131 }
 132
 133 uptr OpenFile(const char *filename, bool write) {
 134   return internal_open(filename,
 135       write ? O_WRONLY | O_CREAT /*| O_CLOEXEC*/ : O_RDONLY, 0660);
 136 }
 137
 138 uptr internal_read(fd_t fd, void *buf, uptr count) {
 139   sptr res;
 140   HANDLE_EINTR(res, (sptr)internal_syscall(SYSCALL(read), fd, (uptr)buf,
 141                count));
 142   return res;
 143 }
 144
 145 uptr internal_write(fd_t fd, const void *buf, uptr count) {
 146   sptr res;
 147   HANDLE_EINTR(res, (sptr)internal_syscall(SYSCALL(write), fd, (uptr)buf,
 148                count));
 149   return res;
 150 }
 151
 152 #if !SANITIZER_LINUX_USES_64BIT_SYSCALLS && !SANITIZER_FREEBSD
 153 static void stat64_to_stat(struct stat64 *in, struct stat *out) {
 154   internal_memset(out, 0, sizeof(*out));
 155   out->st_dev = in->st_dev;
 156   out->st_ino = in->st_ino;
 157   out->st_mode = in->st_mode;
 158   out->st_nlink = in->st_nlink;
 159   out->st_uid = in->st_uid;
 160   out->st_gid = in->st_gid;
 161   out->st_rdev = in->st_rdev;
 162   out->st_size = in->st_size;
 163   out->st_blksize = in->st_blksize;
 164   out->st_blocks = in->st_blocks;
 165   out->st_atime = in->st_atime;
 166   out->st_mtime = in->st_mtime;
 167   out->st_ctime = in->st_ctime;
 168   out->st_ino = in->st_ino;
 169 }
 170 #endif
 171
 172 uptr internal_stat(const char *path, void *buf) {
 173 #if SANITIZER_FREEBSD
 174   return internal_syscall(SYSCALL(stat), path, buf);
 175 #elif SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 176   return internal_syscall(SYSCALL(newfstatat), AT_FDCWD, (uptr)path,
 177                           (uptr)buf, 0);
 178 #elif SANITIZER_LINUX_USES_64BIT_SYSCALLS
 179   return internal_syscall(SYSCALL(stat), (uptr)path, (uptr)buf);
 180 #else
 181   struct stat64 buf64;
 182   int res = internal_syscall(SYSCALL(stat64), path, &buf64);
 183   stat64_to_stat(&buf64, (struct stat *)buf);
 184   return res;
 185 #endif
 186 }
 187
 188 uptr internal_lstat(const char *path, void *buf) {
 189 #if SANITIZER_FREEBSD
 190   return internal_syscall(SYSCALL(lstat), path, buf);
 191 #elif SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 192   return internal_syscall(SYSCALL(newfstatat), AT_FDCWD, (uptr)path,
 193                          (uptr)buf, AT_SYMLINK_NOFOLLOW);
 194 #elif SANITIZER_LINUX_USES_64BIT_SYSCALLS
 195   return internal_syscall(SYSCALL(lstat), (uptr)path, (uptr)buf);
 196 #else
 197   struct stat64 buf64;
 198   int res = internal_syscall(SYSCALL(lstat64), path, &buf64);
 199   stat64_to_stat(&buf64, (struct stat *)buf);
 200   return res;
 201 #endif
 202 }
 203
 204 uptr internal_fstat(fd_t fd, void *buf) {
 205 #if SANITIZER_FREEBSD || SANITIZER_LINUX_USES_64BIT_SYSCALLS
 206   return internal_syscall(SYSCALL(fstat), fd, (uptr)buf);
 207 #else
 208   struct stat64 buf64;
 209   int res = internal_syscall(SYSCALL(fstat64), fd, &buf64);
 210   stat64_to_stat(&buf64, (struct stat *)buf);
 211   return res;
 212 #endif
 213 }
 214
 215 uptr internal_filesize(fd_t fd) {
 216   struct stat st;
 217   if (internal_fstat(fd, &st))
 218     return -1;
 219   return (uptr)st.st_size;
 220 }
 221
 222 uptr internal_dup2(int oldfd, int newfd) {
 223 #if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 224   return internal_syscall(SYSCALL(dup3), oldfd, newfd, 0);
 225 #else
 226   return internal_syscall(SYSCALL(dup2), oldfd, newfd);
 227 #endif
 228 }
 229
 230 uptr internal_readlink(const char *path, char *buf, uptr bufsize) {
 231 #if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 232   return internal_syscall(SYSCALL(readlinkat), AT_FDCWD,
 233                           (uptr)path, (uptr)buf, bufsize);
 234 #else
 235   return internal_syscall(SYSCALL(readlink), (uptr)path, (uptr)buf, bufsize);
 236 #endif
 237 }
 238
 239 uptr internal_unlink(const char *path) {
 240 #if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 241   return internal_syscall(SYSCALL(unlinkat), AT_FDCWD, (uptr)path, 0);
 242 #else
 243   return internal_syscall(SYSCALL(unlink), (uptr)path);
 244 #endif
 245 }
 246
 247 uptr internal_sched_yield() {
 248   return internal_syscall(SYSCALL(sched_yield));
 249 }
 250
 251 void internal__exit(int exitcode) {
 252 #if SANITIZER_FREEBSD
 253   internal_syscall(SYSCALL(exit), exitcode);
 254 #else
 255   internal_syscall(SYSCALL(exit_group), exitcode);
 256 #endif
 257   Die();  // Unreachable.
 258 }
 259
 260 uptr internal_execve(const char *filename, char *const argv[],
 261                      char *const envp[]) {
 262   return internal_syscall(SYSCALL(execve), (uptr)filename, (uptr)argv,
 263                           (uptr)envp);
 264 }
 265
 266 // ----------------- sanitizer_common.h
 267 bool FileExists(const char *filename) {
 268 #if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 269   struct stat st;
 270   if (internal_syscall(SYSCALL(newfstatat), AT_FDCWD, filename, &st, 0))
 271     return false;
 272 #else
 273   struct stat st;
 274   if (internal_stat(filename, &st))
 275     return false;
 276   // Sanity check: filename is a regular file.
 277   return S_ISREG(st.st_mode);
 278 #endif
 279 }
 280
 281 uptr GetTid() {
 282 #if SANITIZER_FREEBSD
 283   return (uptr)pthread_self();
 284 #else
 285   return internal_syscall(SYSCALL(gettid));
 286 #endif
 287 }
 288
 289 u64 NanoTime() {
 290 #if SANITIZER_FREEBSD
 291   timeval tv;
 292 #else
 293   kernel_timeval tv;
 294 #endif
 295   internal_memset(&tv, 0, sizeof(tv));
 296   internal_syscall(SYSCALL(gettimeofday), (uptr)&tv, 0);
 297   return (u64)tv.tv_sec * 1000*1000*1000 + tv.tv_usec * 1000;
 298 }
 299
 300 // Like getenv, but reads env directly from /proc and does not use libc.
 301 // This function should be called first inside __asan_init.
 302 const char *GetEnv(const char *name) {
 303   static char *environ;
 304   static uptr len;
 305   static bool inited;
 306   if (!inited) {
 307     inited = true;
 308     uptr environ_size;
 309     len = ReadFileToBuffer("/proc/self/environ",
 310                            &environ, &environ_size, 1 << 26);
 311   }
 312   if (!environ || len == 0) return 0;
 313   uptr namelen = internal_strlen(name);
 314   const char *p = environ;
 315   while (*p != '\0') {  // will happen at the \0\0 that terminates the buffer
 316     // proc file has the format NAME=value\0NAME=value\0NAME=value\0...
 317     const char* endp =
 318         (char*)internal_memchr(p, '\0', len - (p - environ));
 319     if (endp == 0)  // this entry isn't NUL terminated
 320       return 0;
 321     else if (!internal_memcmp(p, name, namelen) && p[namelen] == '=')  // Match.
 322       return p + namelen + 1;  // point after =
 323     p = endp + 1;
 324   }
 325   return 0;  // Not found.
 326 }
 327
 328 extern "C" {
 329   SANITIZER_WEAK_ATTRIBUTE extern void *__libc_stack_end;
 330 }
 331
 332 #if !SANITIZER_GO
 333 static void ReadNullSepFileToArray(const char *path, char ***arr,
 334                                    int arr_size) {
 335   char *buff;
 336   uptr buff_size = 0;
 337   *arr = (char **)MmapOrDie(arr_size * sizeof(char *), "NullSepFileArray");
 338   ReadFileToBuffer(path, &buff, &buff_size, 1024 * 1024);
 339   (*arr)[0] = buff;
 340   int count, i;
 341   for (count = 1, i = 1; ; i++) {
 342     if (buff[i] == 0) {
 343       if (buff[i+1] == 0) break;
 344       (*arr)[count] = &buff[i+1];
 345       CHECK_LE(count, arr_size - 1);  // FIXME: make this more flexible.
 346       count++;
 347     }
 348   }
 349   (*arr)[count] = 0;
 350 }
 351 #endif
 352
 353 static void GetArgsAndEnv(char*** argv, char*** envp) {
 354 #if !SANITIZER_GO
 355   if (&__libc_stack_end) {
 356 #endif
 357     uptr* stack_end = (uptr*)__libc_stack_end;
 358     int argc = *stack_end;
 359     *argv = (char**)(stack_end + 1);
 360     *envp = (char**)(stack_end + argc + 2);
 361 #if !SANITIZER_GO
 362   } else {
 363     static const int kMaxArgv = 2000, kMaxEnvp = 2000;
 364     ReadNullSepFileToArray("/proc/self/cmdline", argv, kMaxArgv);
 365     ReadNullSepFileToArray("/proc/self/environ", envp, kMaxEnvp);
 366   }
 367 #endif
 368 }
 369
 370 void ReExec() {
 371   char **argv, **envp;
 372   GetArgsAndEnv(&argv, &envp);
 373   uptr rv = internal_execve("/proc/self/exe", argv, envp);
 374   int rverrno;
 375   CHECK_EQ(internal_iserror(rv, &rverrno), true);
 376   Printf("execve failed, errno %d\n", rverrno);
 377   Die();
 378 }
 379
 380 // Stub implementation of GetThreadStackAndTls for Go.
 381 #if SANITIZER_GO
 382 void GetThreadStackAndTls(bool main, uptr *stk_addr, uptr *stk_size,
 383                           uptr *tls_addr, uptr *tls_size) {
 384   *stk_addr = 0;
 385   *stk_size = 0;
 386   *tls_addr = 0;
 387   *tls_size = 0;
 388 }
 389 #endif  // SANITIZER_GO
 390
 391 void PrepareForSandboxing(__sanitizer_sandbox_arguments *args) {
 392   // Some kinds of sandboxes may forbid filesystem access, so we won't be able
 393   // to read the file mappings from /proc/self/maps. Luckily, neither the
 394   // process will be able to load additional libraries, so it's fine to use the
 395   // cached mappings.
 396   MemoryMappingLayout::CacheMemoryMappings();
 397   // Same for /proc/self/exe in the symbolizer.
 398 #if !SANITIZER_GO
 399   if (Symbolizer *sym = Symbolizer::GetOrNull())
 400     sym->PrepareForSandboxing();
 401   CovPrepareForSandboxing(args);
 402 #endif
 403 }
 404
 405 enum MutexState {
 406   MtxUnlocked = 0,
 407   MtxLocked = 1,
 408   MtxSleeping = 2
 409 };
 410
 411 BlockingMutex::BlockingMutex(LinkerInitialized) {
 412   CHECK_EQ(owner_, 0);
 413 }
 414
 415 BlockingMutex::BlockingMutex() {
 416   internal_memset(this, 0, sizeof(*this));
 417 }
 418
 419 void BlockingMutex::Lock() {
 420   atomic_uint32_t *m = reinterpret_cast<atomic_uint32_t *>(&opaque_storage_);
 421   if (atomic_exchange(m, MtxLocked, memory_order_acquire) == MtxUnlocked)
 422     return;
 423   while (atomic_exchange(m, MtxSleeping, memory_order_acquire) != MtxUnlocked) {
 424 #if SANITIZER_FREEBSD
 425     _umtx_op(m, UMTX_OP_WAIT_UINT, MtxSleeping, 0, 0);
 426 #else
 427     internal_syscall(SYSCALL(futex), (uptr)m, FUTEX_WAIT, MtxSleeping, 0, 0, 0);
 428 #endif
 429   }
 430 }
 431
 432 void BlockingMutex::Unlock() {
 433   atomic_uint32_t *m = reinterpret_cast<atomic_uint32_t *>(&opaque_storage_);
 434   u32 v = atomic_exchange(m, MtxUnlocked, memory_order_relaxed);
 435   CHECK_NE(v, MtxUnlocked);
 436   if (v == MtxSleeping) {
 437 #if SANITIZER_FREEBSD
 438     _umtx_op(m, UMTX_OP_WAKE, 1, 0, 0);
 439 #else
 440     internal_syscall(SYSCALL(futex), (uptr)m, FUTEX_WAKE, 1, 0, 0, 0);
 441 #endif
 442   }
 443 }
 444
 445 void BlockingMutex::CheckLocked() {
 446   atomic_uint32_t *m = reinterpret_cast<atomic_uint32_t *>(&opaque_storage_);
 447   CHECK_NE(MtxUnlocked, atomic_load(m, memory_order_relaxed));
 448 }
 449
 450 // ----------------- sanitizer_linux.h
 451 // The actual size of this structure is specified by d_reclen.
 452 // Note that getdents64 uses a different structure format. We only provide the
 453 // 32-bit syscall here.
 454 struct linux_dirent {
 455 #if SANITIZER_X32
 456   u64 d_ino;
 457   u64 d_off;
 458 #else
 459   unsigned long      d_ino;
 460   unsigned long      d_off;
 461 #endif
 462   unsigned short     d_reclen;
 463   char               d_name[256];
 464 };
 465
 466 // Syscall wrappers.
 467 uptr internal_ptrace(int request, int pid, void *addr, void *data) {
 468   return internal_syscall(SYSCALL(ptrace), request, pid, (uptr)addr,
 469                           (uptr)data);
 470 }
 471
 472 uptr internal_waitpid(int pid, int *status, int options) {
 473   return internal_syscall(SYSCALL(wait4), pid, (uptr)status, options,
 474                           0 /* rusage */);
 475 }
 476
 477 uptr internal_getpid() {
 478   return internal_syscall(SYSCALL(getpid));
 479 }
 480
 481 uptr internal_getppid() {
 482   return internal_syscall(SYSCALL(getppid));
 483 }
 484
 485 uptr internal_getdents(fd_t fd, struct linux_dirent *dirp, unsigned int count) {
 486 #if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
 487   return internal_syscall(SYSCALL(getdents64), fd, (uptr)dirp, count);
 488 #else
 489   return internal_syscall(SYSCALL(getdents), fd, (uptr)dirp, count);
 490 #endif
 491 }
 492
 493 uptr internal_lseek(fd_t fd, OFF_T offset, int whence) {
 494   return internal_syscall(SYSCALL(lseek), fd, offset, whence);
 495 }
 496
 497 #if SANITIZER_LINUX
 498 uptr internal_prctl(int option, uptr arg2, uptr arg3, uptr arg4, uptr arg5) {
 499   return internal_syscall(SYSCALL(prctl), option, arg2, arg3, arg4, arg5);
 500 }
 501 #endif
 502
 503 uptr internal_sigaltstack(const struct sigaltstack *ss,
 504                          struct sigaltstack *oss) {
 505   return internal_syscall(SYSCALL(sigaltstack), (uptr)ss, (uptr)oss);
 506 }
 507
 508 int internal_fork() {
 509   return internal_syscall(SYSCALL(fork));
 510 }
 511
 512 #if SANITIZER_LINUX
 513 // Doesn't set sa_restorer, use with caution (see below).
 514 int internal_sigaction_norestorer(int signum, const void *act, void *oldact) {
 515   __sanitizer_kernel_sigaction_t k_act, k_oldact;
 516   internal_memset(&k_act, 0, sizeof(__sanitizer_kernel_sigaction_t));
 517   internal_memset(&k_oldact, 0, sizeof(__sanitizer_kernel_sigaction_t));
 518   const __sanitizer_sigaction *u_act = (__sanitizer_sigaction *)act;
 519   __sanitizer_sigaction *u_oldact = (__sanitizer_sigaction *)oldact;
 520   if (u_act) {
 521     k_act.handler = u_act->handler;
 522     k_act.sigaction = u_act->sigaction;
 523     internal_memcpy(&k_act.sa_mask, &u_act->sa_mask,
 524                     sizeof(__sanitizer_kernel_sigset_t));
 525     k_act.sa_flags = u_act->sa_flags;
 526     // FIXME: most often sa_restorer is unset, however the kernel requires it
 527     // to point to a valid signal restorer that calls the rt_sigreturn syscall.
 528     // If sa_restorer passed to the kernel is NULL, the program may crash upon
 529     // signal delivery or fail to unwind the stack in the signal handler.
 530     // libc implementation of sigaction() passes its own restorer to
 531     // rt_sigaction, so we need to do the same (we'll need to reimplement the
 532     // restorers; for x86_64 the restorer address can be obtained from
 533     // oldact->sa_restorer upon a call to sigaction(xxx, NULL, oldact).
 534     k_act.sa_restorer = u_act->sa_restorer;
 535   }
 536
 537   uptr result = internal_syscall(SYSCALL(rt_sigaction), (uptr)signum,
 538       (uptr)(u_act ? &k_act : NULL),
 539       (uptr)(u_oldact ? &k_oldact : NULL),
 540       (uptr)sizeof(__sanitizer_kernel_sigset_t));
 541
 542   if ((result == 0) && u_oldact) {
 543     u_oldact->handler = k_oldact.handler;
 544     u_oldact->sigaction = k_oldact.sigaction;
 545     internal_memcpy(&u_oldact->sa_mask, &k_oldact.sa_mask,
 546                     sizeof(__sanitizer_kernel_sigset_t));
 547     u_oldact->sa_flags = k_oldact.sa_flags;
 548     u_oldact->sa_restorer = k_oldact.sa_restorer;
 549   }
 550   return result;
 551 }
 552 #endif  // SANITIZER_LINUX
 553
 554 uptr internal_sigprocmask(int how, __sanitizer_sigset_t *set,
 555     __sanitizer_sigset_t *oldset) {
 556 #if SANITIZER_FREEBSD
 557   return internal_syscall(SYSCALL(sigprocmask), how, set, oldset);
 558 #else
 559   __sanitizer_kernel_sigset_t *k_set = (__sanitizer_kernel_sigset_t *)set;
 560   __sanitizer_kernel_sigset_t *k_oldset = (__sanitizer_kernel_sigset_t *)oldset;
 561   return internal_syscall(SYSCALL(rt_sigprocmask), (uptr)how,
 562                           (uptr)&k_set->sig[0], (uptr)&k_oldset->sig[0],
 563                           sizeof(__sanitizer_kernel_sigset_t));
 564 #endif
 565 }
 566
 567 void internal_sigfillset(__sanitizer_sigset_t *set) {
 568   internal_memset(set, 0xff, sizeof(*set));
 569 }
 570
 571 #if SANITIZER_LINUX
 572 void internal_sigdelset(__sanitizer_sigset_t *set, int signum) {
 573   signum -= 1;
 574   CHECK_GE(signum, 0);
 575   CHECK_LT(signum, sizeof(*set) * 8);
 576   __sanitizer_kernel_sigset_t *k_set = (__sanitizer_kernel_sigset_t *)set;
 577   const uptr idx = signum / (sizeof(k_set->sig[0]) * 8);
 578   const uptr bit = signum % (sizeof(k_set->sig[0]) * 8);
 579   k_set->sig[idx] &= ~(1 << bit);
 580 }
 581 #endif  // SANITIZER_LINUX
 582
 583 // ThreadLister implementation.
 584 ThreadLister::ThreadLister(int pid)
 585   : pid_(pid),
 586     descriptor_(-1),
 587     buffer_(4096),
 588     error_(true),
 589     entry_((struct linux_dirent *)buffer_.data()),
 590     bytes_read_(0) {
 591   char task_directory_path[80];
 592   internal_snprintf(task_directory_path, sizeof(task_directory_path),
 593                     "/proc/%d/task/", pid);
 594   uptr openrv = internal_open(task_directory_path, O_RDONLY | O_DIRECTORY);
 595   if (internal_iserror(openrv)) {
 596     error_ = true;
 597     Report("Can't open /proc/%d/task for reading.\n", pid);
 598   } else {
 599     error_ = false;
 600     descriptor_ = openrv;
 601   }
 602 }
 603
 604 int ThreadLister::GetNextTID() {
 605   int tid = -1;
 606   do {
 607     if (error_)
 608       return -1;
 609     if ((char *)entry_ >= &buffer_[bytes_read_] && !GetDirectoryEntries())
 610       return -1;
 611     if (entry_->d_ino != 0 && entry_->d_name[0] >= '0' &&
 612         entry_->d_name[0] <= '9') {
 613       // Found a valid tid.
 614       tid = (int)internal_atoll(entry_->d_name);
 615     }
 616     entry_ = (struct linux_dirent *)(((char *)entry_) + entry_->d_reclen);
 617   } while (tid < 0);
 618   return tid;
 619 }
 620
 621 void ThreadLister::Reset() {
 622   if (error_ || descriptor_ < 0)
 623     return;
 624   internal_lseek(descriptor_, 0, SEEK_SET);
 625 }
 626
 627 ThreadLister::~ThreadLister() {
 628   if (descriptor_ >= 0)
 629     internal_close(descriptor_);
 630 }
 631
 632 bool ThreadLister::error() { return error_; }
 633
 634 bool ThreadLister::GetDirectoryEntries() {
 635   CHECK_GE(descriptor_, 0);
 636   CHECK_NE(error_, true);
 637   bytes_read_ = internal_getdents(descriptor_,
 638                                   (struct linux_dirent *)buffer_.data(),
 639                                   buffer_.size());
 640   if (internal_iserror(bytes_read_)) {
 641     Report("Can't read directory entries from /proc/%d/task.\n", pid_);
 642     error_ = true;
 643     return false;
 644   } else if (bytes_read_ == 0) {
 645     return false;
 646   }
 647   entry_ = (struct linux_dirent *)buffer_.data();
 648   return true;
 649 }
 650
 651 uptr GetPageSize() {
 652 #if SANITIZER_LINUX && (defined(__x86_64__) || defined(__i386__))
 653   return EXEC_PAGESIZE;
 654 #else
 655   return sysconf(_SC_PAGESIZE);  // EXEC_PAGESIZE may not be trustworthy.
 656 #endif
 657 }
 658
 659 static char proc_self_exe_cache_str[kMaxPathLength];
 660 static uptr proc_self_exe_cache_len = 0;
 661
 662 uptr ReadBinaryName(/*out*/char *buf, uptr buf_len) {
 663   uptr module_name_len = internal_readlink(
 664       "/proc/self/exe", buf, buf_len);
 665   int readlink_error;
 666   if (internal_iserror(module_name_len, &readlink_error)) {
 667     if (proc_self_exe_cache_len) {
 668       // If available, use the cached module name.
 669       CHECK_LE(proc_self_exe_cache_len, buf_len);
 670       internal_strncpy(buf, proc_self_exe_cache_str, buf_len);
 671       module_name_len = internal_strlen(proc_self_exe_cache_str);
 672     } else {
 673       // We can't read /proc/self/exe for some reason, assume the name of the
 674       // binary is unknown.
 675       Report("WARNING: readlink(\"/proc/self/exe\") failed with errno %d, "
 676              "some stack frames may not be symbolized\n", readlink_error);
 677       module_name_len = internal_snprintf(buf, buf_len, "/proc/self/exe");
 678     }
 679     CHECK_LT(module_name_len, buf_len);
 680     buf[module_name_len] = '\0';
 681   }
 682   return module_name_len;
 683 }
 684
 685 void CacheBinaryName() {
 686   if (!proc_self_exe_cache_len) {
 687     proc_self_exe_cache_len =
 688         ReadBinaryName(proc_self_exe_cache_str, kMaxPathLength);
 689   }
 690 }
 691
 692 // Match full names of the form /path/to/base_name{-,.}*
 693 bool LibraryNameIs(const char *full_name, const char *base_name) {
 694   const char *name = full_name;
 695   // Strip path.
 696   while (*name != '\0') name++;
 697   while (name > full_name && *name != '/') name--;
 698   if (*name == '/') name++;
 699   uptr base_name_length = internal_strlen(base_name);
 700   if (internal_strncmp(name, base_name, base_name_length)) return false;
 701   return (name[base_name_length] == '-' || name[base_name_length] == '.');
 702 }
 703
 704 #if !SANITIZER_ANDROID
 705 // Call cb for each region mapped by map.
 706 void ForEachMappedRegion(link_map *map, void (*cb)(const void *, uptr)) {
 707 #if !SANITIZER_FREEBSD
 708   typedef ElfW(Phdr) Elf_Phdr;
 709   typedef ElfW(Ehdr) Elf_Ehdr;
 710 #endif  // !SANITIZER_FREEBSD
 711   char *base = (char *)map->l_addr;
 712   Elf_Ehdr *ehdr = (Elf_Ehdr *)base;
 713   char *phdrs = base + ehdr->e_phoff;
 714   char *phdrs_end = phdrs + ehdr->e_phnum * ehdr->e_phentsize;
 715
 716   // Find the segment with the minimum base so we can "relocate" the p_vaddr
 717   // fields.  Typically ET_DYN objects (DSOs) have base of zero and ET_EXEC
 718   // objects have a non-zero base.
 719   uptr preferred_base = (uptr)-1;
 720   for (char *iter = phdrs; iter != phdrs_end; iter += ehdr->e_phentsize) {
 721     Elf_Phdr *phdr = (Elf_Phdr *)iter;
 722     if (phdr->p_type == PT_LOAD && preferred_base > (uptr)phdr->p_vaddr)
 723       preferred_base = (uptr)phdr->p_vaddr;
 724   }
 725
 726   // Compute the delta from the real base to get a relocation delta.
 727   sptr delta = (uptr)base - preferred_base;
 728   // Now we can figure out what the loader really mapped.
 729   for (char *iter = phdrs; iter != phdrs_end; iter += ehdr->e_phentsize) {
 730     Elf_Phdr *phdr = (Elf_Phdr *)iter;
 731     if (phdr->p_type == PT_LOAD) {
 732       uptr seg_start = phdr->p_vaddr + delta;
 733       uptr seg_end = seg_start + phdr->p_memsz;
 734       // None of these values are aligned.  We consider the ragged edges of the
 735       // load command as defined, since they are mapped from the file.
 736       seg_start = RoundDownTo(seg_start, GetPageSizeCached());
 737       seg_end = RoundUpTo(seg_end, GetPageSizeCached());
 738       cb((void *)seg_start, seg_end - seg_start);
 739     }
 740   }
 741 }
 742 #endif
 743
 744 #if defined(__x86_64__) && SANITIZER_LINUX
 745 // We cannot use glibc's clone wrapper, because it messes with the child
 746 // task's TLS. It writes the PID and TID of the child task to its thread
 747 // descriptor, but in our case the child task shares the thread descriptor with
 748 // the parent (because we don't know how to allocate a new thread
 749 // descriptor to keep glibc happy). So the stock version of clone(), when
 750 // used with CLONE_VM, would end up corrupting the parent's thread descriptor.
 751 uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg,
 752                     int *parent_tidptr, void *newtls, int *child_tidptr) {
 753   long long res;
 754   if (!fn || !child_stack)
 755     return -EINVAL;
 756   CHECK_EQ(0, (uptr)child_stack % 16);
 757   child_stack = (char *)child_stack - 2 * sizeof(unsigned long long);
 758   ((unsigned long long *)child_stack)[0] = (uptr)fn;
 759   ((unsigned long long *)child_stack)[1] = (uptr)arg;
 760   register void *r8 __asm__("r8") = newtls;
 761   register int *r10 __asm__("r10") = child_tidptr;
 762   __asm__ __volatile__(
 763                        /* %rax = syscall(%rax = SYSCALL(clone),
 764                         *                %rdi = flags,
 765                         *                %rsi = child_stack,
 766                         *                %rdx = parent_tidptr,
 767                         *                %r8  = new_tls,
 768                         *                %r10 = child_tidptr)
 769                         */
 770                        "syscall\n"
 771
 772                        /* if (%rax != 0)
 773                         *   return;
 774                         */
 775                        "testq  %%rax,%%rax\n"
 776                        "jnz    1f\n"
 777
 778                        /* In the child. Terminate unwind chain. */
 779                        // XXX: We should also terminate the CFI unwind chain
 780                        // here. Unfortunately clang 3.2 doesn't support the
 781                        // necessary CFI directives, so we skip that part.
 782                        "xorq   %%rbp,%%rbp\n"
 783
 784                        /* Call "fn(arg)". */
 785                        "popq   %%rax\n"
 786                        "popq   %%rdi\n"
 787                        "call   *%%rax\n"
 788
 789                        /* Call _exit(%rax). */
 790                        "movq   %%rax,%%rdi\n"
 791                        "movq   %2,%%rax\n"
 792                        "syscall\n"
 793
 794                        /* Return to parent. */
 795                      "1:\n"
 796                        : "=a" (res)
 797                        : "a"(SYSCALL(clone)), "i"(SYSCALL(exit)),
 798                          "S"(child_stack),
 799                          "D"(flags),
 800                          "d"(parent_tidptr),
 801                          "r"(r8),
 802                          "r"(r10)
 803                        : "rsp", "memory", "r11", "rcx");
 804   return res;
 805 }
 806 #endif  // defined(__x86_64__) && SANITIZER_LINUX
 807
 808 #if SANITIZER_ANDROID
 809 // This thing is not, strictly speaking, async signal safe, but it does not seem
 810 // to cause any issues. Alternative is writing to log devices directly, but
 811 // their location and message format might change in the future, so we'd really
 812 // like to avoid that.
 813 void AndroidLogWrite(const char *buffer) {
 814   char *copy = internal_strdup(buffer);
 815   char *p = copy;
 816   char *q;
 817   // __android_log_write has an implicit message length limit.
 818   // Print one line at a time.
 819   do {
 820     q = internal_strchr(p, '\n');
 821     if (q) *q = '\0';
 822     __android_log_write(ANDROID_LOG_INFO, NULL, p);
 823     if (q) p = q + 1;
 824   } while (q);
 825   InternalFree(copy);
 826 }
 827
 828 void GetExtraActivationFlags(char *buf, uptr size) {
 829   CHECK(size > PROP_VALUE_MAX);
 830   __system_property_get("asan.options", buf);
 831 }
 832 #endif
 833
 834 bool IsDeadlySignal(int signum) {
 835   return (signum == SIGSEGV) && common_flags()->handle_segv;
 836 }
 837
 838 }  // namespace __sanitizer
 839
 840 #endif  // SANITIZER_FREEBSD || SANITIZER_LINUX