lib/msan/msan_interceptors.cc

//===-- msan_interceptors.cc ----------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a part of MemorySanitizer.
//
// Interceptors for standard library functions.
//===----------------------------------------------------------------------===//

#include "interception/interception.h"
#include "msan.h"
#include "msan_platform_limits_posix.h"
#include "sanitizer_common/sanitizer_common.h"
#include "sanitizer_common/sanitizer_libc.h"

#include <stdarg.h>
// ACHTUNG! No other system header includes in this file.
// Ideally, we should get rid of stdarg.h as well.

typedef uptr size_t;
typedef sptr ssize_t;
typedef u64  off_t;
typedef u64  off64_t;
using namespace __msan;

#define ENSURE_MSAN_INITED() do { \
    CHECK(!msan_init_is_running);       \
  if (!msan_inited) { \
    __msan_init(); \
  } \
} while (0)

#define CHECK_UNPOISONED(x, n) \
  do { \
    sptr offset = __msan_test_shadow(x, n);                 \
    if (offset >= 0 && flags()->report_umrs) {              \
      GET_CALLER_PC_BP_SP;                                  \
      (void)sp;                                             \
      Printf("UMR in %s at offset %d inside [%p, +%d) \n",  \
             __FUNCTION__, offset, x, n);                   \
      __msan::PrintWarningWithOrigin(                       \
        pc, bp, __msan_get_origin((char*)x + offset));      \
    }                                                       \
  } while (0)

static void *fast_memset(void *ptr, int c, size_t n);
static void *fast_memcpy(void *dst, const void *src, size_t n);

INTERCEPTOR(size_t, fread, void *ptr, size_t size, size_t nmemb, void *file) {
  ENSURE_MSAN_INITED();
  size_t res = REAL(fread)(ptr, size, nmemb, file);
  if (res > 0)
    __msan_unpoison(ptr, res *size);
  return res;
}

INTERCEPTOR(size_t, fread_unlocked, void *ptr, size_t size, size_t nmemb,
            void *file) {
  ENSURE_MSAN_INITED();
  size_t res = REAL(fread_unlocked)(ptr, size, nmemb, file);
  if (res > 0)
    __msan_unpoison(ptr, res *size);
  return res;
}

INTERCEPTOR(ssize_t, read, int fd, void *ptr, size_t count) {
  ENSURE_MSAN_INITED();
  ssize_t res = REAL(read)(fd, ptr, count);
  if (res > 0)
    __msan_unpoison(ptr, res);
  return res;
}

INTERCEPTOR(ssize_t, pread, int fd, void *ptr, size_t count, off_t offset) {
  ENSURE_MSAN_INITED();
  ssize_t res = REAL(pread)(fd, ptr, count, offset);
  if (res > 0)
    __msan_unpoison(ptr, res);
  return res;
}

INTERCEPTOR(ssize_t, pread64, int fd, void *ptr, size_t count, off64_t offset) {
  ENSURE_MSAN_INITED();
  ssize_t res = REAL(pread64)(fd, ptr, count, offset);
  if (res > 0)
    __msan_unpoison(ptr, res);
  return res;
}

INTERCEPTOR(ssize_t, readlink, const char *path, char *buf, size_t bufsiz) {
  ENSURE_MSAN_INITED();
  ssize_t res = REAL(readlink)(path, buf, bufsiz);
  if (res > 0)
    __msan_unpoison(buf, res);
  return res;
}

INTERCEPTOR(void *, readdir, void *a) {
  ENSURE_MSAN_INITED();
  void *res = REAL(readdir)(a);
  __msan_unpoison(res, __msan::struct_dirent_sz);
  return res;
}

INTERCEPTOR(void *, memcpy, void *dest, const void *src, size_t n) {
  return __msan_memcpy(dest, src, n);
}

INTERCEPTOR(void *, memmove, void *dest, const void *src, size_t n) {
  return __msan_memmove(dest, src, n);
}

INTERCEPTOR(void *, memset, void *s, int c, size_t n) {
  return __msan_memset(s, c, n);
}

INTERCEPTOR(int, posix_memalign, void **memptr, size_t alignment, size_t size) {
  GET_MALLOC_STACK_TRACE;
  CHECK_EQ(alignment & (alignment - 1), 0);
  *memptr = MsanReallocate(&stack, 0, size, alignment, false);
  CHECK_NE(memptr, 0);
  return 0;
}

INTERCEPTOR(void, free, void *ptr) {
  ENSURE_MSAN_INITED();
  if (ptr == 0) return;
  MsanDeallocate(ptr);
}

INTERCEPTOR(size_t, strlen, const char *s) {
  ENSURE_MSAN_INITED();
  size_t res = REAL(strlen)(s);
  CHECK_UNPOISONED(s, res + 1);
  return res;
}

INTERCEPTOR(size_t, strnlen, const char *s, size_t n) {
  ENSURE_MSAN_INITED();
  size_t res = REAL(strnlen)(s, n);
  size_t scan_size = (res == n) ? res : res + 1;
  CHECK_UNPOISONED(s, scan_size);
  return res;
}

// FIXME: Add stricter shadow checks in str* interceptors (ex.: strcpy should
// check the shadow of the terminating \0 byte).

INTERCEPTOR(char *, strcpy, char *dest, const char *src) {  // NOLINT
  ENSURE_MSAN_INITED();
  size_t n = REAL(strlen)(src);
  char *res = REAL(strcpy)(dest, src);  // NOLINT
  __msan_copy_poison(dest, src, n + 1);
  return res;
}

INTERCEPTOR(char *, strncpy, char *dest, const char *src, size_t n) {  // NOLINT
  ENSURE_MSAN_INITED();
  size_t copy_size = REAL(strnlen)(src, n);
  if (copy_size < n)
    copy_size++;  // trailing \0
  char *res = REAL(strncpy)(dest, src, n);  // NOLINT
  __msan_copy_poison(dest, src, copy_size);
  return res;
}

INTERCEPTOR(char *, strdup, char *src) {
  ENSURE_MSAN_INITED();
  size_t n = REAL(strlen)(src);
  char *res = REAL(strdup)(src);
  __msan_copy_poison(res, src, n + 1);
  return res;
}

INTERCEPTOR(char *, gcvt, double number, size_t ndigit, char *buf) {
  ENSURE_MSAN_INITED();
  char *res = REAL(gcvt)(number, ndigit, buf);
  // DynamoRio tool will take care of unpoisoning gcvt result for us.
  if (!__msan_has_dynamic_component()) {
    size_t n = REAL(strlen)(buf);
    __msan_unpoison(buf, n + 1);
  }
  return res;
}

INTERCEPTOR(char *, strcat, char *dest, const char *src) {  // NOLINT
  ENSURE_MSAN_INITED();
  size_t src_size = REAL(strlen)(src);
  size_t dest_size = REAL(strlen)(dest);
  char *res = REAL(strcat)(dest, src);  // NOLINT
  __msan_copy_poison(dest + dest_size, src, src_size + 1);
  return res;
}

INTERCEPTOR(char *, strncat, char *dest, const char *src, size_t n) {  // NOLINT
  ENSURE_MSAN_INITED();
  size_t dest_size = REAL(strlen)(dest);
  size_t copy_size = REAL(strlen)(src);
  if (copy_size < n)
    copy_size++;  // trailing \0
  char *res = REAL(strncat)(dest, src, n);  // NOLINT
  __msan_copy_poison(dest + dest_size, src, copy_size);
  return res;
}

INTERCEPTOR(long, strtol, const char *nptr, char **endptr,  // NOLINT
            int base) {
  ENSURE_MSAN_INITED();
  long res = REAL(strtol)(nptr, endptr, base);  // NOLINT
  if (!__msan_has_dynamic_component()) {
    __msan_unpoison(endptr, sizeof(*endptr));
  }
  return res;
}

INTERCEPTOR(long long, strtoll, const char *nptr, char **endptr,  // NOLINT
            int base) {
  ENSURE_MSAN_INITED();
  long res = REAL(strtoll)(nptr, endptr, base);  //NOLINT
  if (!__msan_has_dynamic_component()) {
    __msan_unpoison(endptr, sizeof(*endptr));
  }
  return res;
}

INTERCEPTOR(unsigned long, strtoul, const char *nptr, char **endptr,  // NOLINT
            int base) {
  ENSURE_MSAN_INITED();
  unsigned long res = REAL(strtoul)(nptr, endptr, base);  // NOLINT
  if (!__msan_has_dynamic_component()) {
    __msan_unpoison(endptr, sizeof(*endptr));
  }
  return res;
}

INTERCEPTOR(unsigned long long, strtoull, const char *nptr,  // NOLINT
            char **endptr, int base) {
  ENSURE_MSAN_INITED();
  unsigned long res = REAL(strtoull)(nptr, endptr, base);  // NOLINT
  if (!__msan_has_dynamic_component()) {
    __msan_unpoison(endptr, sizeof(*endptr));
  }
  return res;
}

INTERCEPTOR(int, vsnprintf, char *str, uptr size,
            const char *format, va_list ap) {
  ENSURE_MSAN_INITED();
  int res = REAL(vsnprintf)(str, size, format, ap);
  if (!__msan_has_dynamic_component()) {
    __msan_unpoison(str, res + 1);
  }
  return res;
}

INTERCEPTOR(int, vsprintf, char *str, const char *format, va_list ap) {
  ENSURE_MSAN_INITED();
  int res = REAL(vsprintf)(str, format, ap);
  if (!__msan_has_dynamic_component()) {
    __msan_unpoison(str, res + 1);
  }
  return res;
}

INTERCEPTOR(int, vswprintf, void *str, uptr size, void *format, va_list ap) {
  ENSURE_MSAN_INITED();
  int res = REAL(vswprintf)(str, size, format, ap);
  if (!__msan_has_dynamic_component()) {
    __msan_unpoison(str, 4 * (res + 1));
  }
  return res;
}

INTERCEPTOR(int, sprintf, char *str, const char *format, ...) {  // NOLINT
  ENSURE_MSAN_INITED();
  va_list ap;
  va_start(ap, format);
  int res = vsprintf(str, format, ap);  // NOLINT
  va_end(ap);
  return res;
}

INTERCEPTOR(int, snprintf, char *str, uptr size, const char *format, ...) {
  ENSURE_MSAN_INITED();
  va_list ap;
  va_start(ap, format);
  int res = vsnprintf(str, size, format, ap);
  va_end(ap);
  return res;
}

INTERCEPTOR(int, swprintf, void *str, uptr size, void *format, ...) {
  ENSURE_MSAN_INITED();
  va_list ap;
  va_start(ap, format);
  int res = vswprintf(str, size, format, ap);
  va_end(ap);
  return res;
}

// size_t strftime(char *s, size_t max, const char *format,const struct tm *tm);
INTERCEPTOR(size_t, strftime, char *s, size_t max, const char *format,
            void *tm) {
  ENSURE_MSAN_INITED();
  size_t res = REAL(strftime)(s, max, format, tm);
  if (res) __msan_unpoison(s, res + 1);
  return res;
}

INTERCEPTOR(size_t, wcstombs, void *dest, void *src, size_t size) {
  ENSURE_MSAN_INITED();
  size_t res = REAL(wcstombs)(dest, src, size);
  if (res != (size_t)-1) __msan_unpoison(dest, res + 1);
  return res;
}

// size_t mbstowcs(wchar_t *dest, const char *src, size_t n);
INTERCEPTOR(size_t, mbstowcs, wchar_t *dest, const char *src, size_t n) {
  ENSURE_MSAN_INITED();
  size_t res = REAL(mbstowcs)(dest, src, n);
  if (res != (size_t)-1) __msan_unpoison(dest, (res + 1) * sizeof(wchar_t));
  return res;
}

INTERCEPTOR(size_t, wcslen, const wchar_t *s) {
  ENSURE_MSAN_INITED();
  size_t res = REAL(wcslen)(s);
  CHECK_UNPOISONED(s, sizeof(wchar_t) * (res + 1));
  return res;
}

// wchar_t *wcschr(const wchar_t *wcs, wchar_t wc);
INTERCEPTOR(wchar_t *, wcschr, void *s, wchar_t wc, void *ps) {
  ENSURE_MSAN_INITED();
  wchar_t *res = REAL(wcschr)(s, wc, ps);
  return res;
}

// wchar_t *wcscpy(wchar_t *dest, const wchar_t *src);
INTERCEPTOR(wchar_t *, wcscpy, wchar_t *dest, const wchar_t *src) {
  ENSURE_MSAN_INITED();
  wchar_t *res = REAL(wcscpy)(dest, src);
  __msan_copy_poison(dest, src, sizeof(wchar_t) * (REAL(wcslen)(src) + 1));
  return res;
}

// wchar_t *wmemcpy(wchar_t *dest, const wchar_t *src, size_t n);
INTERCEPTOR(wchar_t *, wmemcpy, wchar_t *dest, const wchar_t *src, size_t n) {
  ENSURE_MSAN_INITED();
  wchar_t *res = REAL(wmemcpy)(dest, src, n);
  __msan_copy_poison(dest, src, n * sizeof(wchar_t));
  return res;
}

INTERCEPTOR(wchar_t *, wmemset, wchar_t *s, wchar_t c, size_t n) {
  CHECK(MEM_IS_APP(s));
  ENSURE_MSAN_INITED();
  wchar_t *res = (wchar_t *)fast_memset(s, c, n * sizeof(wchar_t));
  __msan_unpoison(s, n * sizeof(wchar_t));
  return res;
}

INTERCEPTOR(wchar_t *, wmemmove, wchar_t *dest, const wchar_t *src, size_t n) {
  ENSURE_MSAN_INITED();
  wchar_t *res = REAL(wmemmove)(dest, src, n);
  __msan_move_poison(dest, src, n * sizeof(wchar_t));
  return res;
}

INTERCEPTOR(int, wcscmp, const wchar_t *s1, const wchar_t *s2) {
  ENSURE_MSAN_INITED();
  int res = REAL(wcscmp)(s1, s2);
  return res;
}

INTERCEPTOR(double, wcstod, const wchar_t *nptr, wchar_t **endptr) {
  ENSURE_MSAN_INITED();
  double res = REAL(wcstod)(nptr, endptr);
  __msan_unpoison(endptr, sizeof(*endptr));
  return res;
}

// #define UNSUPPORTED(name) \
//   INTERCEPTOR(void, name, void) {                     \
//     Printf("MSAN: Unsupported %s\n", __FUNCTION__);   \
//     Die();                                            \
//   }

// FIXME: intercept the following functions:
// Note, they only matter when running without a dynamic tool.
// UNSUPPORTED(wcscoll_l)
// UNSUPPORTED(wcsnrtombs)
// UNSUPPORTED(wcstol)
// UNSUPPORTED(wcstoll)
// UNSUPPORTED(wcstold)
// UNSUPPORTED(wcstoul)
// UNSUPPORTED(wcstoull)
// UNSUPPORTED(wcsxfrm_l)
// UNSUPPORTED(wcsdup)
// UNSUPPORTED(wcsftime)
// UNSUPPORTED(wcsstr)
// UNSUPPORTED(wcsrchr)
// UNSUPPORTED(wctob)

INTERCEPTOR(int, gettimeofday, void *tv, void *tz) {
  ENSURE_MSAN_INITED();
  int res = REAL(gettimeofday)(tv, tz);
  if (tv)
    __msan_unpoison(tv, 16);
  if (tz)
    __msan_unpoison(tz, 8);
  return res;
}

INTERCEPTOR(char *, fcvt, double x, int a, int *b, int *c) {
  ENSURE_MSAN_INITED();
  char *res = REAL(fcvt)(x, a, b, c);
  if (!__msan_has_dynamic_component()) {
    __msan_unpoison(b, sizeof(*b));
    __msan_unpoison(c, sizeof(*c));
  }
  return res;
}

INTERCEPTOR(char *, getenv, char *name) {
  ENSURE_MSAN_INITED();
  char *res = REAL(getenv)(name);
  if (!__msan_has_dynamic_component()) {
    if (res)
      __msan_unpoison(res, REAL(strlen)(res) + 1);
  }
  return res;
}

INTERCEPTOR(int, __fxstat, int magic, int fd, void *buf) {
  ENSURE_MSAN_INITED();
  int res = REAL(__fxstat)(magic, fd, buf);
  if (!res)
    __msan_unpoison(buf, __msan::struct_stat_sz);
  return res;
}

INTERCEPTOR(int, __fxstat64, int magic, int fd, void *buf) {
  ENSURE_MSAN_INITED();
  int res = REAL(__fxstat64)(magic, fd, buf);
  if (!res)
    __msan_unpoison(buf, __msan::struct_stat64_sz);
  return res;
}

INTERCEPTOR(int, __xstat, int magic, char *path, void *buf) {
  ENSURE_MSAN_INITED();
  int res = REAL(__xstat)(magic, path, buf);
  if (!res)
    __msan_unpoison(buf, __msan::struct_stat_sz);
  return res;
}

INTERCEPTOR(int, __xstat64, int magic, char *path, void *buf) {
  ENSURE_MSAN_INITED();
  int res = REAL(__xstat64)(magic, path, buf);
  if (!res)
    __msan_unpoison(buf, __msan::struct_stat64_sz);
  return res;
}

INTERCEPTOR(int, __lxstat, int magic, char *path, void *buf) {
  ENSURE_MSAN_INITED();
  int res = REAL(__lxstat)(magic, path, buf);
  if (!res)
    __msan_unpoison(buf, __msan::struct_stat_sz);
  return res;
}

INTERCEPTOR(int, __lxstat64, int magic, char *path, void *buf) {
  ENSURE_MSAN_INITED();
  int res = REAL(__lxstat64)(magic, path, buf);
  if (!res)
    __msan_unpoison(buf, __msan::struct_stat64_sz);
  return res;
}

INTERCEPTOR(int, pipe, int pipefd[2]) {
  if (msan_init_is_running)
    return REAL(pipe)(pipefd);
  ENSURE_MSAN_INITED();
  int res = REAL(pipe)(pipefd);
  if (!res)
    __msan_unpoison(pipefd, sizeof(int[2]));
  return res;
}

INTERCEPTOR(int, wait, int *status) {
  ENSURE_MSAN_INITED();
  int res = REAL(wait)(status);
  if (status)
    __msan_unpoison(status, sizeof(*status));
  return res;
}

INTERCEPTOR(int, waitpid, int pid, int *status, int options) {
  ENSURE_MSAN_INITED();
  int res = REAL(waitpid)(pid, status, options);
  if (status)
    __msan_unpoison(status, sizeof(*status));
  return res;
}

INTERCEPTOR(char *, fgets, char *s, int size, void *stream) {
  ENSURE_MSAN_INITED();
  char *res = REAL(fgets)(s, size, stream);
  if (res)
    __msan_unpoison(s, REAL(strlen)(s) + 1);
  return res;
}

INTERCEPTOR(char *, fgets_unlocked, char *s, int size, void *stream) {
  ENSURE_MSAN_INITED();
  char *res = REAL(fgets_unlocked)(s, size, stream);
  if (res)
    __msan_unpoison(s, REAL(strlen)(s) + 1);
  return res;
}

INTERCEPTOR(char *, getcwd, char *buf, size_t size) {
  ENSURE_MSAN_INITED();
  char *res = REAL(getcwd)(buf, size);
  if (res)
    __msan_unpoison(buf, REAL(strlen)(buf) + 1);
  return res;
}

INTERCEPTOR(char *, realpath, char *path, char *abspath) {
  ENSURE_MSAN_INITED();
  char *res = REAL(realpath)(path, abspath);
  if (res)
    __msan_unpoison(abspath, REAL(strlen)(abspath) + 1);
  return res;
}

INTERCEPTOR(int, getrlimit, int resource, void *rlim) {
  if (msan_init_is_running)
    return REAL(getrlimit)(resource, rlim);
  ENSURE_MSAN_INITED();
  int res = REAL(getrlimit)(resource, rlim);
  if (!res)
    __msan_unpoison(rlim, __msan::struct_rlimit_sz);
  return res;
}

INTERCEPTOR(int, getrlimit64, int resource, void *rlim) {
  if (msan_init_is_running)
    return REAL(getrlimit64)(resource, rlim);
  ENSURE_MSAN_INITED();
  int res = REAL(getrlimit64)(resource, rlim);
  if (!res)
    __msan_unpoison(rlim, __msan::struct_rlimit64_sz);
  return res;
}

INTERCEPTOR(int, statfs, const char *s, void *buf) {
  ENSURE_MSAN_INITED();
  int res = REAL(statfs)(s, buf);
  if (!res)
    __msan_unpoison(buf, __msan::struct_statfs_sz);
  return res;
}

INTERCEPTOR(int, fstatfs, int fd, void *buf) {
  ENSURE_MSAN_INITED();
  int res = REAL(fstatfs)(fd, buf);
  if (!res)
    __msan_unpoison(buf, __msan::struct_statfs_sz);
  return res;
}

INTERCEPTOR(int, statfs64, const char *s, void *buf) {
  ENSURE_MSAN_INITED();
  int res = REAL(statfs64)(s, buf);
  if (!res)
    __msan_unpoison(buf, __msan::struct_statfs64_sz);
  return res;
}

INTERCEPTOR(int, fstatfs64, int fd, void *buf) {
  ENSURE_MSAN_INITED();
  int res = REAL(fstatfs64)(fd, buf);
  if (!res)
    __msan_unpoison(buf, __msan::struct_statfs64_sz);
  return res;
}

INTERCEPTOR(int, uname, void *utsname) {
  ENSURE_MSAN_INITED();
  int res = REAL(uname)(utsname);
  if (!res) {
    __msan_unpoison(utsname, __msan::struct_utsname_sz);
  }
  return res;
}

INTERCEPTOR(int, epoll_wait, int epfd, void *events, int maxevents,
    int timeout) {
  ENSURE_MSAN_INITED();
  int res = REAL(epoll_wait)(epfd, events, maxevents, timeout);
  if (res > 0) {
    __msan_unpoison(events, __msan::struct_epoll_event_sz * res);
  }
  return res;
}

INTERCEPTOR(int, epoll_pwait, int epfd, void *events, int maxevents,
    int timeout, void *sigmask) {
  ENSURE_MSAN_INITED();
  int res = REAL(epoll_pwait)(epfd, events, maxevents, timeout, sigmask);
  if (res > 0) {
    __msan_unpoison(events, __msan::struct_epoll_event_sz * res);
  }
  return res;
}

INTERCEPTOR(ssize_t, recv, int fd, void *buf, size_t len, int flags) {
  ENSURE_MSAN_INITED();
  ssize_t res = REAL(recv)(fd, buf, len, flags);
  if (res > 0)
    __msan_unpoison(buf, res);
  return res;
}

INTERCEPTOR(ssize_t, recvfrom, int fd, void *buf, size_t len, int flags,
    void *srcaddr, void *addrlen) {
  ENSURE_MSAN_INITED();
  ssize_t res = REAL(recvfrom)(fd, buf, len, flags, srcaddr, addrlen);
  if (res > 0)
    __msan_unpoison(buf, res);
  return res;
}

INTERCEPTOR(ssize_t, recvmsg, int fd, struct msghdr *msg, int flags) {
  ENSURE_MSAN_INITED();
  ssize_t res = REAL(recvmsg)(fd, msg, flags);
  if (res > 0) {
    for (size_t i = 0; i < __msan_get_msghdr_iovlen(msg); ++i)
      __msan_unpoison(__msan_get_msghdr_iov_iov_base(msg, i),
          __msan_get_msghdr_iov_iov_len(msg, i));
  }
  return res;
}

INTERCEPTOR(void *, calloc, size_t nmemb, size_t size) {
  GET_MALLOC_STACK_TRACE;
  if (!msan_inited) {
    // Hack: dlsym calls calloc before REAL(calloc) is retrieved from dlsym.
    const size_t kCallocPoolSize = 1024;
    static uptr calloc_memory_for_dlsym[kCallocPoolSize];
    static size_t allocated;
    size_t size_in_words = ((nmemb * size) + kWordSize - 1) / kWordSize;
    void *mem = (void*)&calloc_memory_for_dlsym[allocated];
    allocated += size_in_words;
    CHECK(allocated < kCallocPoolSize);
    return mem;
  }
  return MsanReallocate(&stack, 0, nmemb * size, sizeof(u64), true);
}

INTERCEPTOR(void *, realloc, void *ptr, size_t size) {
  GET_MALLOC_STACK_TRACE;
  return MsanReallocate(&stack, ptr, size, sizeof(u64), false);
}

INTERCEPTOR(void *, malloc, size_t size) {
  GET_MALLOC_STACK_TRACE;
  return MsanReallocate(&stack, 0, size, sizeof(u64), false);
}

INTERCEPTOR(void *, mmap, void *addr, size_t length, int prot, int flags,
            int fd, off_t offset) {
  ENSURE_MSAN_INITED();
  void *res = REAL(mmap)(addr, length, prot, flags, fd, offset);
  if (res != (void*)-1)
    __msan_unpoison(res, RoundUpTo(length, GetPageSize()));
  return res;
}

INTERCEPTOR(void *, mmap64, void *addr, size_t length, int prot, int flags,
            int fd, off64_t offset) {
  ENSURE_MSAN_INITED();
  void *res = REAL(mmap64)(addr, length, prot, flags, fd, offset);
  if (res != (void*)-1)
    __msan_unpoison(res, RoundUpTo(length, GetPageSize()));
  return res;
}

// static
void *fast_memset(void *ptr, int c, size_t n) {
  // hack until we have a really fast internal_memset
  if (sizeof(uptr) == 8 &&
      (n % 8) == 0 &&
      ((uptr)ptr % 8) == 0 &&
      (c == 0 || c == -1)) {
    // Printf("memset %p %zd %x\n", ptr, n, c);
    uptr to_store = c ? -1L : 0L;
    uptr *p = (uptr*)ptr;
    for (size_t i = 0; i < n / 8; i++)
      p[i] = to_store;
    return ptr;
  }
  return internal_memset(ptr, c, n);
}

// static
void *fast_memcpy(void *dst, const void *src, size_t n) {
  // Same hack as in fast_memset above.
  if (sizeof(uptr) == 8 &&
      (n % 8) == 0 &&
      ((uptr)dst % 8) == 0 &&
      ((uptr)src % 8) == 0) {
    uptr *d = (uptr*)dst;
    uptr *s = (uptr*)src;
    for (size_t i = 0; i < n / 8; i++)
      d[i] = s[i];
    return dst;
  }
  return internal_memcpy(dst, src, n);
}

// These interface functions reside here so that they can use
// fast_memset, etc.
void __msan_unpoison(void *a, uptr size) {
  if (!MEM_IS_APP(a)) return;
  fast_memset((void*)MEM_TO_SHADOW((uptr)a), 0, size);
}

void __msan_poison(void *a, uptr size) {
  if (!MEM_IS_APP(a)) return;
  fast_memset((void*)MEM_TO_SHADOW((uptr)a),
              __msan::flags()->poison_heap_with_zeroes ? 0 : -1, size);
}

void __msan_poison_stack(void *a, uptr size) {
  if (!MEM_IS_APP(a)) return;
  fast_memset((void*)MEM_TO_SHADOW((uptr)a),
              __msan::flags()->poison_stack_with_zeroes ? 0 : -1, size);
}

void __msan_clear_and_unpoison(void *a, uptr size) {
  fast_memset(a, 0, size);
  fast_memset((void*)MEM_TO_SHADOW((uptr)a), 0, size);
}

void __msan_copy_origin(void *dst, const void *src, uptr size) {
  if (!__msan_get_track_origins()) return;
  if (!MEM_IS_APP(dst) || !MEM_IS_APP(src)) return;
  uptr d = MEM_TO_ORIGIN(dst);
  uptr s = MEM_TO_ORIGIN(src);
  uptr beg = d & ~3UL;  // align down.
  uptr end = (d + size + 3) & ~3UL;  // align up.
  s = s & ~3UL;  // align down.
  fast_memcpy((void*)beg, (void*)s, end - beg);
}

void __msan_copy_poison(void *dst, const void *src, uptr size) {
  if (!MEM_IS_APP(dst)) return;
  if (!MEM_IS_APP(src)) return;
  fast_memcpy((void*)MEM_TO_SHADOW((uptr)dst),
              (void*)MEM_TO_SHADOW((uptr)src), size);
  __msan_copy_origin(dst, src, size);
}

void __msan_move_poison(void *dst, const void *src, uptr size) {
  if (!MEM_IS_APP(dst)) return;
  if (!MEM_IS_APP(src)) return;
  internal_memmove((void*)MEM_TO_SHADOW((uptr)dst),
         (void*)MEM_TO_SHADOW((uptr)src), size);
  __msan_copy_origin(dst, src, size);
}

void *__msan_memcpy(void *dest, const void *src, size_t n) {
  ENSURE_MSAN_INITED();
  void *res = fast_memcpy(dest, src, n);
  __msan_copy_poison(dest, src, n);
  return res;
}

void *__msan_memset(void *s, int c, size_t n) {
  ENSURE_MSAN_INITED();
  void *res = fast_memset(s, c, n);
  __msan_unpoison(s, n);
  return res;
}

void *__msan_memmove(void *dest, const void *src, size_t n) {
  ENSURE_MSAN_INITED();
  void *res = REAL(memmove)(dest, src, n);
  __msan_move_poison(dest, src, n);
  return res;
}

namespace __msan {
void InitializeInterceptors() {
  static int inited = 0;
  CHECK_EQ(inited, 0);
  CHECK(INTERCEPT_FUNCTION(mmap));
  CHECK(INTERCEPT_FUNCTION(mmap64));
  CHECK(INTERCEPT_FUNCTION(posix_memalign));
  CHECK(INTERCEPT_FUNCTION(malloc));
  CHECK(INTERCEPT_FUNCTION(calloc));
  CHECK(INTERCEPT_FUNCTION(realloc));
  CHECK(INTERCEPT_FUNCTION(free));
  CHECK(INTERCEPT_FUNCTION(fread));
  CHECK(INTERCEPT_FUNCTION(fread_unlocked));
  CHECK(INTERCEPT_FUNCTION(read));
  CHECK(INTERCEPT_FUNCTION(pread));
  CHECK(INTERCEPT_FUNCTION(pread64));
  CHECK(INTERCEPT_FUNCTION(readlink));
  CHECK(INTERCEPT_FUNCTION(readdir));
  CHECK(INTERCEPT_FUNCTION(memcpy));
  CHECK(INTERCEPT_FUNCTION(memset));
  CHECK(INTERCEPT_FUNCTION(memmove));
  CHECK(INTERCEPT_FUNCTION(wmemset));
  CHECK(INTERCEPT_FUNCTION(wmemcpy));
  CHECK(INTERCEPT_FUNCTION(wmemmove));
  CHECK(INTERCEPT_FUNCTION(strcpy));  // NOLINT
  CHECK(INTERCEPT_FUNCTION(strdup));
  CHECK(INTERCEPT_FUNCTION(strncpy));  // NOLINT
  CHECK(INTERCEPT_FUNCTION(strlen));
  CHECK(INTERCEPT_FUNCTION(strnlen));
  CHECK(INTERCEPT_FUNCTION(gcvt));
  CHECK(INTERCEPT_FUNCTION(strcat));  // NOLINT
  CHECK(INTERCEPT_FUNCTION(strncat));  // NOLINT
  CHECK(INTERCEPT_FUNCTION(strtol));
  CHECK(INTERCEPT_FUNCTION(strtoll));
  CHECK(INTERCEPT_FUNCTION(strtoul));
  CHECK(INTERCEPT_FUNCTION(strtoull));
  CHECK(INTERCEPT_FUNCTION(vsprintf));
  CHECK(INTERCEPT_FUNCTION(vsnprintf));
  CHECK(INTERCEPT_FUNCTION(vswprintf));
  CHECK(INTERCEPT_FUNCTION(sprintf));  // NOLINT
  CHECK(INTERCEPT_FUNCTION(snprintf));
  CHECK(INTERCEPT_FUNCTION(swprintf));
  CHECK(INTERCEPT_FUNCTION(strftime));
  CHECK(INTERCEPT_FUNCTION(wcstombs));
  CHECK(INTERCEPT_FUNCTION(mbstowcs));
  CHECK(INTERCEPT_FUNCTION(wcslen));
  CHECK(INTERCEPT_FUNCTION(wcschr));
  CHECK(INTERCEPT_FUNCTION(wcscpy));
  CHECK(INTERCEPT_FUNCTION(wcscmp));
  CHECK(INTERCEPT_FUNCTION(wcstod));
  CHECK(INTERCEPT_FUNCTION(getenv));
  CHECK(INTERCEPT_FUNCTION(gettimeofday));
  CHECK(INTERCEPT_FUNCTION(fcvt));
  CHECK(INTERCEPT_FUNCTION(__fxstat));
  CHECK(INTERCEPT_FUNCTION(__xstat));
  CHECK(INTERCEPT_FUNCTION(__lxstat));
  CHECK(INTERCEPT_FUNCTION(__fxstat64));
  CHECK(INTERCEPT_FUNCTION(__xstat64));
  CHECK(INTERCEPT_FUNCTION(__lxstat64));
  CHECK(INTERCEPT_FUNCTION(pipe));
  CHECK(INTERCEPT_FUNCTION(wait));
  CHECK(INTERCEPT_FUNCTION(waitpid));
  CHECK(INTERCEPT_FUNCTION(fgets));
  CHECK(INTERCEPT_FUNCTION(fgets_unlocked));
  CHECK(INTERCEPT_FUNCTION(getcwd));
  CHECK(INTERCEPT_FUNCTION(realpath));
  CHECK(INTERCEPT_FUNCTION(getrlimit));
  CHECK(INTERCEPT_FUNCTION(getrlimit64));
  CHECK(INTERCEPT_FUNCTION(statfs));
  CHECK(INTERCEPT_FUNCTION(fstatfs));
  CHECK(INTERCEPT_FUNCTION(statfs64));
  CHECK(INTERCEPT_FUNCTION(fstatfs64));
  CHECK(INTERCEPT_FUNCTION(uname));
  CHECK(INTERCEPT_FUNCTION(epoll_wait));
  CHECK(INTERCEPT_FUNCTION(epoll_pwait));
  CHECK(INTERCEPT_FUNCTION(recv));
  CHECK(INTERCEPT_FUNCTION(recvfrom));
  CHECK(INTERCEPT_FUNCTION(recvmsg));
  inited = 1;
}
}  // namespace __msan