vendor/compiler-rt/compiler-rt-trunk-r375505vendor/compiler-rt

1 files changed, 1124 insertions, 0 deletions

diff --git a/lib/sanitizer_common/sanitizer_win.cpp b/lib/sanitizer_common/sanitizer_win.cpp
new file mode 100644
index 000000000000..36dde49d8708
--- /dev/null
+++ b/lib/sanitizer_common/sanitizer_win.cpp
@@ -0,0 +1,1124 @@
+//===-- sanitizer_win.cpp -------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between AddressSanitizer and ThreadSanitizer
+// run-time libraries and implements windows-specific functions from
+// sanitizer_libc.h.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+#if SANITIZER_WINDOWS
+
+#define WIN32_LEAN_AND_MEAN
+#define NOGDI
+#include <windows.h>
+#include <io.h>
+#include <psapi.h>
+#include <stdlib.h>
+
+#include "sanitizer_common.h"
+#include "sanitizer_file.h"
+#include "sanitizer_libc.h"
+#include "sanitizer_mutex.h"
+#include "sanitizer_placement_new.h"
+#include "sanitizer_win_defs.h"
+
+#if defined(PSAPI_VERSION) && PSAPI_VERSION == 1
+#pragma comment(lib, "psapi")
+#endif
+#if SANITIZER_WIN_TRACE
+#include <traceloggingprovider.h>
+//  Windows trace logging provider init
+#pragma comment(lib, "advapi32.lib")
+TRACELOGGING_DECLARE_PROVIDER(g_asan_provider);
+// GUID must be the same in utils/AddressSanitizerLoggingProvider.wprp
+TRACELOGGING_DEFINE_PROVIDER(g_asan_provider, "AddressSanitizerLoggingProvider",
+                             (0x6c6c766d, 0x3846, 0x4e6a, 0xa4, 0xfb, 0x5b,
+                              0x53, 0x0b, 0xd0, 0xf3, 0xfa));
+#else
+#define TraceLoggingUnregister(x)
+#endif
+
+// A macro to tell the compiler that this part of the code cannot be reached,
+// if the compiler supports this feature. Since we're using this in
+// code that is called when terminating the process, the expansion of the
+// macro should not terminate the process to avoid infinite recursion.
+#if defined(__clang__)
+# define BUILTIN_UNREACHABLE() __builtin_unreachable()
+#elif defined(__GNUC__) && \
+    (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5))
+# define BUILTIN_UNREACHABLE() __builtin_unreachable()
+#elif defined(_MSC_VER)
+# define BUILTIN_UNREACHABLE() __assume(0)
+#else
+# define BUILTIN_UNREACHABLE()
+#endif
+
+namespace __sanitizer {
+
+#include "sanitizer_syscall_generic.inc"
+
+// --------------------- sanitizer_common.h
+uptr GetPageSize() {
+  SYSTEM_INFO si;
+  GetSystemInfo(&si);
+  return si.dwPageSize;
+}
+
+uptr GetMmapGranularity() {
+  SYSTEM_INFO si;
+  GetSystemInfo(&si);
+  return si.dwAllocationGranularity;
+}
+
+uptr GetMaxUserVirtualAddress() {
+  SYSTEM_INFO si;
+  GetSystemInfo(&si);
+  return (uptr)si.lpMaximumApplicationAddress;
+}
+
+uptr GetMaxVirtualAddress() {
+  return GetMaxUserVirtualAddress();
+}
+
+bool FileExists(const char *filename) {
+  return ::GetFileAttributesA(filename) != INVALID_FILE_ATTRIBUTES;
+}
+
+uptr internal_getpid() {
+  return GetProcessId(GetCurrentProcess());
+}
+
+// In contrast to POSIX, on Windows GetCurrentThreadId()
+// returns a system-unique identifier.
+tid_t GetTid() {
+  return GetCurrentThreadId();
+}
+
+uptr GetThreadSelf() {
+  return GetTid();
+}
+
+#if !SANITIZER_GO
+void GetThreadStackTopAndBottom(bool at_initialization, uptr *stack_top,
+                                uptr *stack_bottom) {
+  CHECK(stack_top);
+  CHECK(stack_bottom);
+  MEMORY_BASIC_INFORMATION mbi;
+  CHECK_NE(VirtualQuery(&mbi /* on stack */, &mbi, sizeof(mbi)), 0);
+  // FIXME: is it possible for the stack to not be a single allocation?
+  // Are these values what ASan expects to get (reserved, not committed;
+  // including stack guard page) ?
+  *stack_top = (uptr)mbi.BaseAddress + mbi.RegionSize;
+  *stack_bottom = (uptr)mbi.AllocationBase;
+}
+#endif  // #if !SANITIZER_GO
+
+void *MmapOrDie(uptr size, const char *mem_type, bool raw_report) {
+  void *rv = VirtualAlloc(0, size, MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);
+  if (rv == 0)
+    ReportMmapFailureAndDie(size, mem_type, "allocate",
+                            GetLastError(), raw_report);
+  return rv;
+}
+
+void UnmapOrDie(void *addr, uptr size) {
+  if (!size || !addr)
+    return;
+
+  MEMORY_BASIC_INFORMATION mbi;
+  CHECK(VirtualQuery(addr, &mbi, sizeof(mbi)));
+
+  // MEM_RELEASE can only be used to unmap whole regions previously mapped with
+  // VirtualAlloc. So we first try MEM_RELEASE since it is better, and if that
+  // fails try MEM_DECOMMIT.
+  if (VirtualFree(addr, 0, MEM_RELEASE) == 0) {
+    if (VirtualFree(addr, size, MEM_DECOMMIT) == 0) {
+      Report("ERROR: %s failed to "
+             "deallocate 0x%zx (%zd) bytes at address %p (error code: %d)\n",
+             SanitizerToolName, size, size, addr, GetLastError());
+      CHECK("unable to unmap" && 0);
+    }
+  }
+}
+
+static void *ReturnNullptrOnOOMOrDie(uptr size, const char *mem_type,
+                                     const char *mmap_type) {
+  error_t last_error = GetLastError();
+  if (last_error == ERROR_NOT_ENOUGH_MEMORY)
+    return nullptr;
+  ReportMmapFailureAndDie(size, mem_type, mmap_type, last_error);
+}
+
+void *MmapOrDieOnFatalError(uptr size, const char *mem_type) {
+  void *rv = VirtualAlloc(0, size, MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);
+  if (rv == 0)
+    return ReturnNullptrOnOOMOrDie(size, mem_type, "allocate");
+  return rv;
+}
+
+// We want to map a chunk of address space aligned to 'alignment'.
+void *MmapAlignedOrDieOnFatalError(uptr size, uptr alignment,
+                                   const char *mem_type) {
+  CHECK(IsPowerOfTwo(size));
+  CHECK(IsPowerOfTwo(alignment));
+
+  // Windows will align our allocations to at least 64K.
+  alignment = Max(alignment, GetMmapGranularity());
+
+  uptr mapped_addr =
+      (uptr)VirtualAlloc(0, size, MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);
+  if (!mapped_addr)
+    return ReturnNullptrOnOOMOrDie(size, mem_type, "allocate aligned");
+
+  // If we got it right on the first try, return. Otherwise, unmap it and go to
+  // the slow path.
+  if (IsAligned(mapped_addr, alignment))
+    return (void*)mapped_addr;
+  if (VirtualFree((void *)mapped_addr, 0, MEM_RELEASE) == 0)
+    ReportMmapFailureAndDie(size, mem_type, "deallocate", GetLastError());
+
+  // If we didn't get an aligned address, overallocate, find an aligned address,
+  // unmap, and try to allocate at that aligned address.
+  int retries = 0;
+  const int kMaxRetries = 10;
+  for (; retries < kMaxRetries &&
+         (mapped_addr == 0 || !IsAligned(mapped_addr, alignment));
+       retries++) {
+    // Overallocate size + alignment bytes.
+    mapped_addr =
+        (uptr)VirtualAlloc(0, size + alignment, MEM_RESERVE, PAGE_NOACCESS);
+    if (!mapped_addr)
+      return ReturnNullptrOnOOMOrDie(size, mem_type, "allocate aligned");
+
+    // Find the aligned address.
+    uptr aligned_addr = RoundUpTo(mapped_addr, alignment);
+
+    // Free the overallocation.
+    if (VirtualFree((void *)mapped_addr, 0, MEM_RELEASE) == 0)
+      ReportMmapFailureAndDie(size, mem_type, "deallocate", GetLastError());
+
+    // Attempt to allocate exactly the number of bytes we need at the aligned
+    // address. This may fail for a number of reasons, in which case we continue
+    // the loop.
+    mapped_addr = (uptr)VirtualAlloc((void *)aligned_addr, size,
+                                     MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);
+  }
+
+  // Fail if we can't make this work quickly.
+  if (retries == kMaxRetries && mapped_addr == 0)
+    return ReturnNullptrOnOOMOrDie(size, mem_type, "allocate aligned");
+
+  return (void *)mapped_addr;
+}
+
+bool MmapFixedNoReserve(uptr fixed_addr, uptr size, const char *name) {
+  // FIXME: is this really "NoReserve"? On Win32 this does not matter much,
+  // but on Win64 it does.
+  (void)name;  // unsupported
+#if !SANITIZER_GO && SANITIZER_WINDOWS64
+  // On asan/Windows64, use MEM_COMMIT would result in error
+  // 1455:ERROR_COMMITMENT_LIMIT.
+  // Asan uses exception handler to commit page on demand.
+  void *p = VirtualAlloc((LPVOID)fixed_addr, size, MEM_RESERVE, PAGE_READWRITE);
+#else
+  void *p = VirtualAlloc((LPVOID)fixed_addr, size, MEM_RESERVE | MEM_COMMIT,
+                         PAGE_READWRITE);
+#endif
+  if (p == 0) {
+    Report("ERROR: %s failed to "
+           "allocate %p (%zd) bytes at %p (error code: %d)\n",
+           SanitizerToolName, size, size, fixed_addr, GetLastError());
+    return false;
+  }
+  return true;
+}
+
+bool MmapFixedSuperNoReserve(uptr fixed_addr, uptr size, const char *name) {
+  // FIXME: Windows support large pages too. Might be worth checking
+  return MmapFixedNoReserve(fixed_addr, size, name);
+}
+
+// Memory space mapped by 'MmapFixedOrDie' must have been reserved by
+// 'MmapFixedNoAccess'.
+void *MmapFixedOrDie(uptr fixed_addr, uptr size, const char *name) {
+  void *p = VirtualAlloc((LPVOID)fixed_addr, size,
+      MEM_COMMIT, PAGE_READWRITE);
+  if (p == 0) {
+    char mem_type[30];
+    internal_snprintf(mem_type, sizeof(mem_type), "memory at address 0x%zx",
+                      fixed_addr);
+    ReportMmapFailureAndDie(size, mem_type, "allocate", GetLastError());
+  }
+  return p;
+}
+
+// Uses fixed_addr for now.
+// Will use offset instead once we've implemented this function for real.
+uptr ReservedAddressRange::Map(uptr fixed_addr, uptr size, const char *name) {
+  return reinterpret_cast<uptr>(MmapFixedOrDieOnFatalError(fixed_addr, size));
+}
+
+uptr ReservedAddressRange::MapOrDie(uptr fixed_addr, uptr size,
+                                    const char *name) {
+  return reinterpret_cast<uptr>(MmapFixedOrDie(fixed_addr, size));
+}
+
+void ReservedAddressRange::Unmap(uptr addr, uptr size) {
+  // Only unmap if it covers the entire range.
+  CHECK((addr == reinterpret_cast<uptr>(base_)) && (size == size_));
+  // We unmap the whole range, just null out the base.
+  base_ = nullptr;
+  size_ = 0;
+  UnmapOrDie(reinterpret_cast<void*>(addr), size);
+}
+
+void *MmapFixedOrDieOnFatalError(uptr fixed_addr, uptr size, const char *name) {
+  void *p = VirtualAlloc((LPVOID)fixed_addr, size,
+      MEM_COMMIT, PAGE_READWRITE);
+  if (p == 0) {
+    char mem_type[30];
+    internal_snprintf(mem_type, sizeof(mem_type), "memory at address 0x%zx",
+                      fixed_addr);
+    return ReturnNullptrOnOOMOrDie(size, mem_type, "allocate");
+  }
+  return p;
+}
+
+void *MmapNoReserveOrDie(uptr size, const char *mem_type) {
+  // FIXME: make this really NoReserve?
+  return MmapOrDie(size, mem_type);
+}
+
+uptr ReservedAddressRange::Init(uptr size, const char *name, uptr fixed_addr) {
+  base_ = fixed_addr ? MmapFixedNoAccess(fixed_addr, size) : MmapNoAccess(size);
+  size_ = size;
+  name_ = name;
+  (void)os_handle_;  // unsupported
+  return reinterpret_cast<uptr>(base_);
+}
+
+
+void *MmapFixedNoAccess(uptr fixed_addr, uptr size, const char *name) {
+  (void)name; // unsupported
+  void *res = VirtualAlloc((LPVOID)fixed_addr, size,
+                           MEM_RESERVE, PAGE_NOACCESS);
+  if (res == 0)
+    Report("WARNING: %s failed to "
+           "mprotect %p (%zd) bytes at %p (error code: %d)\n",
+           SanitizerToolName, size, size, fixed_addr, GetLastError());
+  return res;
+}
+
+void *MmapNoAccess(uptr size) {
+  void *res = VirtualAlloc(nullptr, size, MEM_RESERVE, PAGE_NOACCESS);
+  if (res == 0)
+    Report("WARNING: %s failed to "
+           "mprotect %p (%zd) bytes (error code: %d)\n",
+           SanitizerToolName, size, size, GetLastError());
+  return res;
+}
+
+bool MprotectNoAccess(uptr addr, uptr size) {
+  DWORD old_protection;
+  return VirtualProtect((LPVOID)addr, size, PAGE_NOACCESS, &old_protection);
+}
+
+void ReleaseMemoryPagesToOS(uptr beg, uptr end) {
+  // This is almost useless on 32-bits.
+  // FIXME: add madvise-analog when we move to 64-bits.
+}
+
+void SetShadowRegionHugePageMode(uptr addr, uptr size) {
+  // FIXME: probably similar to ReleaseMemoryToOS.
+}
+
+bool DontDumpShadowMemory(uptr addr, uptr length) {
+  // This is almost useless on 32-bits.
+  // FIXME: add madvise-analog when we move to 64-bits.
+  return true;
+}
+
+uptr FindAvailableMemoryRange(uptr size, uptr alignment, uptr left_padding,
+                              uptr *largest_gap_found,
+                              uptr *max_occupied_addr) {
+  uptr address = 0;
+  while (true) {
+    MEMORY_BASIC_INFORMATION info;
+    if (!::VirtualQuery((void*)address, &info, sizeof(info)))
+      return 0;
+
+    if (info.State == MEM_FREE) {
+      uptr shadow_address = RoundUpTo((uptr)info.BaseAddress + left_padding,
+                                      alignment);
+      if (shadow_address + size < (uptr)info.BaseAddress + info.RegionSize)
+        return shadow_address;
+    }
+
+    // Move to the next region.
+    address = (uptr)info.BaseAddress + info.RegionSize;
+  }
+  return 0;
+}
+
+bool MemoryRangeIsAvailable(uptr range_start, uptr range_end) {
+  MEMORY_BASIC_INFORMATION mbi;
+  CHECK(VirtualQuery((void *)range_start, &mbi, sizeof(mbi)));
+  return mbi.Protect == PAGE_NOACCESS &&
+         (uptr)mbi.BaseAddress + mbi.RegionSize >= range_end;
+}
+
+void *MapFileToMemory(const char *file_name, uptr *buff_size) {
+  UNIMPLEMENTED();
+}
+
+void *MapWritableFileToMemory(void *addr, uptr size, fd_t fd, OFF_T offset) {
+  UNIMPLEMENTED();
+}
+
+static const int kMaxEnvNameLength = 128;
+static const DWORD kMaxEnvValueLength = 32767;
+
+namespace {
+
+struct EnvVariable {
+  char name[kMaxEnvNameLength];
+  char value[kMaxEnvValueLength];
+};
+
+}  // namespace
+
+static const int kEnvVariables = 5;
+static EnvVariable env_vars[kEnvVariables];
+static int num_env_vars;
+
+const char *GetEnv(const char *name) {
+  // Note: this implementation caches the values of the environment variables
+  // and limits their quantity.
+  for (int i = 0; i < num_env_vars; i++) {
+    if (0 == internal_strcmp(name, env_vars[i].name))
+      return env_vars[i].value;
+  }
+  CHECK_LT(num_env_vars, kEnvVariables);
+  DWORD rv = GetEnvironmentVariableA(name, env_vars[num_env_vars].value,
+                                     kMaxEnvValueLength);
+  if (rv > 0 && rv < kMaxEnvValueLength) {
+    CHECK_LT(internal_strlen(name), kMaxEnvNameLength);
+    internal_strncpy(env_vars[num_env_vars].name, name, kMaxEnvNameLength);
+    num_env_vars++;
+    return env_vars[num_env_vars - 1].value;
+  }
+  return 0;
+}
+
+const char *GetPwd() {
+  UNIMPLEMENTED();
+}
+
+u32 GetUid() {
+  UNIMPLEMENTED();
+}
+
+namespace {
+struct ModuleInfo {
+  const char *filepath;
+  uptr base_address;
+  uptr end_address;
+};
+
+#if !SANITIZER_GO
+int CompareModulesBase(const void *pl, const void *pr) {
+  const ModuleInfo *l = (const ModuleInfo *)pl, *r = (const ModuleInfo *)pr;
+  if (l->base_address < r->base_address)
+    return -1;
+  return l->base_address > r->base_address;
+}
+#endif
+}  // namespace
+
+#if !SANITIZER_GO
+void DumpProcessMap() {
+  Report("Dumping process modules:\n");
+  ListOfModules modules;
+  modules.init();
+  uptr num_modules = modules.size();
+
+  InternalMmapVector<ModuleInfo> module_infos(num_modules);
+  for (size_t i = 0; i < num_modules; ++i) {
+    module_infos[i].filepath = modules[i].full_name();
+    module_infos[i].base_address = modules[i].ranges().front()->beg;
+    module_infos[i].end_address = modules[i].ranges().back()->end;
+  }
+  qsort(module_infos.data(), num_modules, sizeof(ModuleInfo),
+        CompareModulesBase);
+
+  for (size_t i = 0; i < num_modules; ++i) {
+    const ModuleInfo &mi = module_infos[i];
+    if (mi.end_address != 0) {
+      Printf("\t%p-%p %s\n", mi.base_address, mi.end_address,
+             mi.filepath[0] ? mi.filepath : "[no name]");
+    } else if (mi.filepath[0]) {
+      Printf("\t??\?-??? %s\n", mi.filepath);
+    } else {
+      Printf("\t???\n");
+    }
+  }
+}
+#endif
+
+void PrintModuleMap() { }
+
+void DisableCoreDumperIfNecessary() {
+  // Do nothing.
+}
+
+void ReExec() {
+  UNIMPLEMENTED();
+}
+
+void PlatformPrepareForSandboxing(__sanitizer_sandbox_arguments *args) {}
+
+bool StackSizeIsUnlimited() {
+  UNIMPLEMENTED();
+}
+
+void SetStackSizeLimitInBytes(uptr limit) {
+  UNIMPLEMENTED();
+}
+
+bool AddressSpaceIsUnlimited() {
+  UNIMPLEMENTED();
+}
+
+void SetAddressSpaceUnlimited() {
+  UNIMPLEMENTED();
+}
+
+bool IsPathSeparator(const char c) {
+  return c == '\\' || c == '/';
+}
+
+static bool IsAlpha(char c) {
+  c = ToLower(c);
+  return c >= 'a' && c <= 'z';
+}
+
+bool IsAbsolutePath(const char *path) {
+  return path != nullptr && IsAlpha(path[0]) && path[1] == ':' &&
+         IsPathSeparator(path[2]);
+}
+
+void SleepForSeconds(int seconds) {
+  Sleep(seconds * 1000);
+}
+
+void SleepForMillis(int millis) {
+  Sleep(millis);
+}
+
+u64 NanoTime() {
+  static LARGE_INTEGER frequency = {};
+  LARGE_INTEGER counter;
+  if (UNLIKELY(frequency.QuadPart == 0)) {
+    QueryPerformanceFrequency(&frequency);
+    CHECK_NE(frequency.QuadPart, 0);
+  }
+  QueryPerformanceCounter(&counter);
+  counter.QuadPart *= 1000ULL * 1000000ULL;
+  counter.QuadPart /= frequency.QuadPart;
+  return counter.QuadPart;
+}
+
+u64 MonotonicNanoTime() { return NanoTime(); }
+
+void Abort() {
+  internal__exit(3);
+}
+
+#if !SANITIZER_GO
+// Read the file to extract the ImageBase field from the PE header. If ASLR is
+// disabled and this virtual address is available, the loader will typically
+// load the image at this address. Therefore, we call it the preferred base. Any
+// addresses in the DWARF typically assume that the object has been loaded at
+// this address.
+static uptr GetPreferredBase(const char *modname) {
+  fd_t fd = OpenFile(modname, RdOnly, nullptr);
+  if (fd == kInvalidFd)
+    return 0;
+  FileCloser closer(fd);
+
+  // Read just the DOS header.
+  IMAGE_DOS_HEADER dos_header;
+  uptr bytes_read;
+  if (!ReadFromFile(fd, &dos_header, sizeof(dos_header), &bytes_read) ||
+      bytes_read != sizeof(dos_header))
+    return 0;
+
+  // The file should start with the right signature.
+  if (dos_header.e_magic != IMAGE_DOS_SIGNATURE)
+    return 0;
+
+  // The layout at e_lfanew is:
+  // "PE\0\0"
+  // IMAGE_FILE_HEADER
+  // IMAGE_OPTIONAL_HEADER
+  // Seek to e_lfanew and read all that data.
+  char buf[4 + sizeof(IMAGE_FILE_HEADER) + sizeof(IMAGE_OPTIONAL_HEADER)];
+  if (::SetFilePointer(fd, dos_header.e_lfanew, nullptr, FILE_BEGIN) ==
+      INVALID_SET_FILE_POINTER)
+    return 0;
+  if (!ReadFromFile(fd, &buf[0], sizeof(buf), &bytes_read) ||
+      bytes_read != sizeof(buf))
+    return 0;
+
+  // Check for "PE\0\0" before the PE header.
+  char *pe_sig = &buf[0];
+  if (internal_memcmp(pe_sig, "PE\0\0", 4) != 0)
+    return 0;
+
+  // Skip over IMAGE_FILE_HEADER. We could do more validation here if we wanted.
+  IMAGE_OPTIONAL_HEADER *pe_header =
+      (IMAGE_OPTIONAL_HEADER *)(pe_sig + 4 + sizeof(IMAGE_FILE_HEADER));
+
+  // Check for more magic in the PE header.
+  if (pe_header->Magic != IMAGE_NT_OPTIONAL_HDR_MAGIC)
+    return 0;
+
+  // Finally, return the ImageBase.
+  return (uptr)pe_header->ImageBase;
+}
+
+void ListOfModules::init() {
+  clearOrInit();
+  HANDLE cur_process = GetCurrentProcess();
+
+  // Query the list of modules.  Start by assuming there are no more than 256
+  // modules and retry if that's not sufficient.
+  HMODULE *hmodules = 0;
+  uptr modules_buffer_size = sizeof(HMODULE) * 256;
+  DWORD bytes_required;
+  while (!hmodules) {
+    hmodules = (HMODULE *)MmapOrDie(modules_buffer_size, __FUNCTION__);
+    CHECK(EnumProcessModules(cur_process, hmodules, modules_buffer_size,
+                             &bytes_required));
+    if (bytes_required > modules_buffer_size) {
+      // Either there turned out to be more than 256 hmodules, or new hmodules
+      // could have loaded since the last try.  Retry.
+      UnmapOrDie(hmodules, modules_buffer_size);
+      hmodules = 0;
+      modules_buffer_size = bytes_required;
+    }
+  }
+
+  // |num_modules| is the number of modules actually present,
+  size_t num_modules = bytes_required / sizeof(HMODULE);
+  for (size_t i = 0; i < num_modules; ++i) {
+    HMODULE handle = hmodules[i];
+    MODULEINFO mi;
+    if (!GetModuleInformation(cur_process, handle, &mi, sizeof(mi)))
+      continue;
+
+    // Get the UTF-16 path and convert to UTF-8.
+    wchar_t modname_utf16[kMaxPathLength];
+    int modname_utf16_len =
+        GetModuleFileNameW(handle, modname_utf16, kMaxPathLength);
+    if (modname_utf16_len == 0)
+      modname_utf16[0] = '\0';
+    char module_name[kMaxPathLength];
+    int module_name_len =
+        ::WideCharToMultiByte(CP_UTF8, 0, modname_utf16, modname_utf16_len + 1,
+                              &module_name[0], kMaxPathLength, NULL, NULL);
+    module_name[module_name_len] = '\0';
+
+    uptr base_address = (uptr)mi.lpBaseOfDll;
+    uptr end_address = (uptr)mi.lpBaseOfDll + mi.SizeOfImage;
+
+    // Adjust the base address of the module so that we get a VA instead of an
+    // RVA when computing the module offset. This helps llvm-symbolizer find the
+    // right DWARF CU. In the common case that the image is loaded at it's
+    // preferred address, we will now print normal virtual addresses.
+    uptr preferred_base = GetPreferredBase(&module_name[0]);
+    uptr adjusted_base = base_address - preferred_base;
+
+    LoadedModule cur_module;
+    cur_module.set(module_name, adjusted_base);
+    // We add the whole module as one single address range.
+    cur_module.addAddressRange(base_address, end_address, /*executable*/ true,
+                               /*writable*/ true);
+    modules_.push_back(cur_module);
+  }
+  UnmapOrDie(hmodules, modules_buffer_size);
+}
+
+void ListOfModules::fallbackInit() { clear(); }
+
+// We can't use atexit() directly at __asan_init time as the CRT is not fully
+// initialized at this point.  Place the functions into a vector and use
+// atexit() as soon as it is ready for use (i.e. after .CRT$XIC initializers).
+InternalMmapVectorNoCtor<void (*)(void)> atexit_functions;
+
+int Atexit(void (*function)(void)) {
+  atexit_functions.push_back(function);
+  return 0;
+}
+
+static int RunAtexit() {
+  TraceLoggingUnregister(g_asan_provider);
+  int ret = 0;
+  for (uptr i = 0; i < atexit_functions.size(); ++i) {
+    ret |= atexit(atexit_functions[i]);
+  }
+  return ret;
+}
+
+#pragma section(".CRT$XID", long, read)
+__declspec(allocate(".CRT$XID")) int (*__run_atexit)() = RunAtexit;
+#endif
+
+// ------------------ sanitizer_libc.h
+fd_t OpenFile(const char *filename, FileAccessMode mode, error_t *last_error) {
+  // FIXME: Use the wide variants to handle Unicode filenames.
+  fd_t res;
+  if (mode == RdOnly) {
+    res = CreateFileA(filename, GENERIC_READ,
+                      FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
+                      nullptr, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr);
+  } else if (mode == WrOnly) {
+    res = CreateFileA(filename, GENERIC_WRITE, 0, nullptr, CREATE_ALWAYS,
+                      FILE_ATTRIBUTE_NORMAL, nullptr);
+  } else {
+    UNIMPLEMENTED();
+  }
+  CHECK(res != kStdoutFd || kStdoutFd == kInvalidFd);
+  CHECK(res != kStderrFd || kStderrFd == kInvalidFd);
+  if (res == kInvalidFd && last_error)
+    *last_error = GetLastError();
+  return res;
+}
+
+void CloseFile(fd_t fd) {
+  CloseHandle(fd);
+}
+
+bool ReadFromFile(fd_t fd, void *buff, uptr buff_size, uptr *bytes_read,
+                  error_t *error_p) {
+  CHECK(fd != kInvalidFd);
+
+  // bytes_read can't be passed directly to ReadFile:
+  // uptr is unsigned long long on 64-bit Windows.
+  unsigned long num_read_long;
+
+  bool success = ::ReadFile(fd, buff, buff_size, &num_read_long, nullptr);
+  if (!success && error_p)
+    *error_p = GetLastError();
+  if (bytes_read)
+    *bytes_read = num_read_long;
+  return success;
+}
+
+bool SupportsColoredOutput(fd_t fd) {
+  // FIXME: support colored output.
+  return false;
+}
+
+bool WriteToFile(fd_t fd, const void *buff, uptr buff_size, uptr *bytes_written,
+                 error_t *error_p) {
+  CHECK(fd != kInvalidFd);
+
+  // Handle null optional parameters.
+  error_t dummy_error;
+  error_p = error_p ? error_p : &dummy_error;
+  uptr dummy_bytes_written;
+  bytes_written = bytes_written ? bytes_written : &dummy_bytes_written;
+
+  // Initialize output parameters in case we fail.
+  *error_p = 0;
+  *bytes_written = 0;
+
+  // Map the conventional Unix fds 1 and 2 to Windows handles. They might be
+  // closed, in which case this will fail.
+  if (fd == kStdoutFd || fd == kStderrFd) {
+    fd = GetStdHandle(fd == kStdoutFd ? STD_OUTPUT_HANDLE : STD_ERROR_HANDLE);
+    if (fd == 0) {
+      *error_p = ERROR_INVALID_HANDLE;
+      return false;
+    }
+  }
+
+  DWORD bytes_written_32;
+  if (!WriteFile(fd, buff, buff_size, &bytes_written_32, 0)) {
+    *error_p = GetLastError();
+    return false;
+  } else {
+    *bytes_written = bytes_written_32;
+    return true;
+  }
+}
+
+uptr internal_sched_yield() {
+  Sleep(0);
+  return 0;
+}
+
+void internal__exit(int exitcode) {
+  TraceLoggingUnregister(g_asan_provider);
+  // ExitProcess runs some finalizers, so use TerminateProcess to avoid that.
+  // The debugger doesn't stop on TerminateProcess like it does on ExitProcess,
+  // so add our own breakpoint here.
+  if (::IsDebuggerPresent())
+    __debugbreak();
+  TerminateProcess(GetCurrentProcess(), exitcode);
+  BUILTIN_UNREACHABLE();
+}
+
+uptr internal_ftruncate(fd_t fd, uptr size) {
+  UNIMPLEMENTED();
+}
+
+uptr GetRSS() {
+  PROCESS_MEMORY_COUNTERS counters;
+  if (!GetProcessMemoryInfo(GetCurrentProcess(), &counters, sizeof(counters)))
+    return 0;
+  return counters.WorkingSetSize;
+}
+
+void *internal_start_thread(void (*func)(void *arg), void *arg) { return 0; }
+void internal_join_thread(void *th) { }
+
+// ---------------------- BlockingMutex ---------------- {{{1
+
+BlockingMutex::BlockingMutex() {
+  CHECK(sizeof(SRWLOCK) <= sizeof(opaque_storage_));
+  internal_memset(this, 0, sizeof(*this));
+}
+
+void BlockingMutex::Lock() {
+  AcquireSRWLockExclusive((PSRWLOCK)opaque_storage_);
+  CHECK_EQ(owner_, 0);
+  owner_ = GetThreadSelf();
+}
+
+void BlockingMutex::Unlock() {
+  CheckLocked();
+  owner_ = 0;
+  ReleaseSRWLockExclusive((PSRWLOCK)opaque_storage_);
+}
+
+void BlockingMutex::CheckLocked() {
+  CHECK_EQ(owner_, GetThreadSelf());
+}
+
+uptr GetTlsSize() {
+  return 0;
+}
+
+void InitTlsSize() {
+}
+
+void GetThreadStackAndTls(bool main, uptr *stk_addr, uptr *stk_size,
+                          uptr *tls_addr, uptr *tls_size) {
+#if SANITIZER_GO
+  *stk_addr = 0;
+  *stk_size = 0;
+  *tls_addr = 0;
+  *tls_size = 0;
+#else
+  uptr stack_top, stack_bottom;
+  GetThreadStackTopAndBottom(main, &stack_top, &stack_bottom);
+  *stk_addr = stack_bottom;
+  *stk_size = stack_top - stack_bottom;
+  *tls_addr = 0;
+  *tls_size = 0;
+#endif
+}
+
+void ReportFile::Write(const char *buffer, uptr length) {
+  SpinMutexLock l(mu);
+  ReopenIfNecessary();
+  if (!WriteToFile(fd, buffer, length)) {
+    // stderr may be closed, but we may be able to print to the debugger
+    // instead.  This is the case when launching a program from Visual Studio,
+    // and the following routine should write to its console.
+    OutputDebugStringA(buffer);
+  }
+}
+
+void SetAlternateSignalStack() {
+  // FIXME: Decide what to do on Windows.
+}
+
+void UnsetAlternateSignalStack() {
+  // FIXME: Decide what to do on Windows.
+}
+
+void InstallDeadlySignalHandlers(SignalHandlerType handler) {
+  (void)handler;
+  // FIXME: Decide what to do on Windows.
+}
+
+HandleSignalMode GetHandleSignalMode(int signum) {
+  // FIXME: Decide what to do on Windows.
+  return kHandleSignalNo;
+}
+
+// Check based on flags if we should handle this exception.
+bool IsHandledDeadlyException(DWORD exceptionCode) {
+  switch (exceptionCode) {
+    case EXCEPTION_ACCESS_VIOLATION:
+    case EXCEPTION_ARRAY_BOUNDS_EXCEEDED:
+    case EXCEPTION_STACK_OVERFLOW:
+    case EXCEPTION_DATATYPE_MISALIGNMENT:
+    case EXCEPTION_IN_PAGE_ERROR:
+      return common_flags()->handle_segv;
+    case EXCEPTION_ILLEGAL_INSTRUCTION:
+    case EXCEPTION_PRIV_INSTRUCTION:
+    case EXCEPTION_BREAKPOINT:
+      return common_flags()->handle_sigill;
+    case EXCEPTION_FLT_DENORMAL_OPERAND:
+    case EXCEPTION_FLT_DIVIDE_BY_ZERO:
+    case EXCEPTION_FLT_INEXACT_RESULT:
+    case EXCEPTION_FLT_INVALID_OPERATION:
+    case EXCEPTION_FLT_OVERFLOW:
+    case EXCEPTION_FLT_STACK_CHECK:
+    case EXCEPTION_FLT_UNDERFLOW:
+    case EXCEPTION_INT_DIVIDE_BY_ZERO:
+    case EXCEPTION_INT_OVERFLOW:
+      return common_flags()->handle_sigfpe;
+  }
+  return false;
+}
+
+bool IsAccessibleMemoryRange(uptr beg, uptr size) {
+  SYSTEM_INFO si;
+  GetNativeSystemInfo(&si);
+  uptr page_size = si.dwPageSize;
+  uptr page_mask = ~(page_size - 1);
+
+  for (uptr page = beg & page_mask, end = (beg + size - 1) & page_mask;
+       page <= end;) {
+    MEMORY_BASIC_INFORMATION info;
+    if (VirtualQuery((LPCVOID)page, &info, sizeof(info)) != sizeof(info))
+      return false;
+
+    if (info.Protect == 0 || info.Protect == PAGE_NOACCESS ||
+        info.Protect == PAGE_EXECUTE)
+      return false;
+
+    if (info.RegionSize == 0)
+      return false;
+
+    page += info.RegionSize;
+  }
+
+  return true;
+}
+
+bool SignalContext::IsStackOverflow() const {
+  return (DWORD)GetType() == EXCEPTION_STACK_OVERFLOW;
+}
+
+void SignalContext::InitPcSpBp() {
+  EXCEPTION_RECORD *exception_record = (EXCEPTION_RECORD *)siginfo;
+  CONTEXT *context_record = (CONTEXT *)context;
+
+  pc = (uptr)exception_record->ExceptionAddress;
+#ifdef _WIN64
+  bp = (uptr)context_record->Rbp;
+  sp = (uptr)context_record->Rsp;
+#else
+  bp = (uptr)context_record->Ebp;
+  sp = (uptr)context_record->Esp;
+#endif
+}
+
+uptr SignalContext::GetAddress() const {
+  EXCEPTION_RECORD *exception_record = (EXCEPTION_RECORD *)siginfo;
+  return exception_record->ExceptionInformation[1];
+}
+
+bool SignalContext::IsMemoryAccess() const {
+  return GetWriteFlag() != SignalContext::UNKNOWN;
+}
+
+bool SignalContext::IsTrueFaultingAddress() const {
+  // FIXME: Provide real implementation for this. See Linux and Mac variants.
+  return IsMemoryAccess();
+}
+
+SignalContext::WriteFlag SignalContext::GetWriteFlag() const {
+  EXCEPTION_RECORD *exception_record = (EXCEPTION_RECORD *)siginfo;
+  // The contents of this array are documented at
+  // https://msdn.microsoft.com/en-us/library/windows/desktop/aa363082(v=vs.85).aspx
+  // The first element indicates read as 0, write as 1, or execute as 8.  The
+  // second element is the faulting address.
+  switch (exception_record->ExceptionInformation[0]) {
+    case 0:
+      return SignalContext::READ;
+    case 1:
+      return SignalContext::WRITE;
+    case 8:
+      return SignalContext::UNKNOWN;
+  }
+  return SignalContext::UNKNOWN;
+}
+
+void SignalContext::DumpAllRegisters(void *context) {
+  // FIXME: Implement this.
+}
+
+int SignalContext::GetType() const {
+  return static_cast<const EXCEPTION_RECORD *>(siginfo)->ExceptionCode;
+}
+
+const char *SignalContext::Describe() const {
+  unsigned code = GetType();
+  // Get the string description of the exception if this is a known deadly
+  // exception.
+  switch (code) {
+    case EXCEPTION_ACCESS_VIOLATION:
+      return "access-violation";
+    case EXCEPTION_ARRAY_BOUNDS_EXCEEDED:
+      return "array-bounds-exceeded";
+    case EXCEPTION_STACK_OVERFLOW:
+      return "stack-overflow";
+    case EXCEPTION_DATATYPE_MISALIGNMENT:
+      return "datatype-misalignment";
+    case EXCEPTION_IN_PAGE_ERROR:
+      return "in-page-error";
+    case EXCEPTION_ILLEGAL_INSTRUCTION:
+      return "illegal-instruction";
+    case EXCEPTION_PRIV_INSTRUCTION:
+      return "priv-instruction";
+    case EXCEPTION_BREAKPOINT:
+      return "breakpoint";
+    case EXCEPTION_FLT_DENORMAL_OPERAND:
+      return "flt-denormal-operand";
+    case EXCEPTION_FLT_DIVIDE_BY_ZERO:
+      return "flt-divide-by-zero";
+    case EXCEPTION_FLT_INEXACT_RESULT:
+      return "flt-inexact-result";
+    case EXCEPTION_FLT_INVALID_OPERATION:
+      return "flt-invalid-operation";
+    case EXCEPTION_FLT_OVERFLOW:
+      return "flt-overflow";
+    case EXCEPTION_FLT_STACK_CHECK:
+      return "flt-stack-check";
+    case EXCEPTION_FLT_UNDERFLOW:
+      return "flt-underflow";
+    case EXCEPTION_INT_DIVIDE_BY_ZERO:
+      return "int-divide-by-zero";
+    case EXCEPTION_INT_OVERFLOW:
+      return "int-overflow";
+  }
+  return "unknown exception";
+}
+
+uptr ReadBinaryName(/*out*/char *buf, uptr buf_len) {
+  // FIXME: Actually implement this function.
+  CHECK_GT(buf_len, 0);
+  buf[0] = 0;
+  return 0;
+}
+
+uptr ReadLongProcessName(/*out*/char *buf, uptr buf_len) {
+  return ReadBinaryName(buf, buf_len);
+}
+
+void CheckVMASize() {
+  // Do nothing.
+}
+
+void InitializePlatformEarly() {
+  // Do nothing.
+}
+
+void MaybeReexec() {
+  // No need to re-exec on Windows.
+}
+
+void CheckASLR() {
+  // Do nothing
+}
+
+void CheckMPROTECT() {
+  // Do nothing
+}
+
+char **GetArgv() {
+  // FIXME: Actually implement this function.
+  return 0;
+}
+
+char **GetEnviron() {
+  // FIXME: Actually implement this function.
+  return 0;
+}
+
+pid_t StartSubprocess(const char *program, const char *const argv[],
+                      fd_t stdin_fd, fd_t stdout_fd, fd_t stderr_fd) {
+  // FIXME: implement on this platform
+  // Should be implemented based on
+  // SymbolizerProcess::StarAtSymbolizerSubprocess
+  // from lib/sanitizer_common/sanitizer_symbolizer_win.cpp.
+  return -1;
+}
+
+bool IsProcessRunning(pid_t pid) {
+  // FIXME: implement on this platform.
+  return false;
+}
+
+int WaitForProcess(pid_t pid) { return -1; }
+
+// FIXME implement on this platform.
+void GetMemoryProfile(fill_profile_f cb, uptr *stats, uptr stats_size) { }
+
+void CheckNoDeepBind(const char *filename, int flag) {
+  // Do nothing.
+}
+
+// FIXME: implement on this platform.
+bool GetRandom(void *buffer, uptr length, bool blocking) {
+  UNIMPLEMENTED();
+}
+
+u32 GetNumberOfCPUs() {
+  SYSTEM_INFO sysinfo = {};
+  GetNativeSystemInfo(&sysinfo);
+  return sysinfo.dwNumberOfProcessors;
+}
+
+#if SANITIZER_WIN_TRACE
+// TODO(mcgov): Rename this project-wide to PlatformLogInit
+void AndroidLogInit(void) {
+  HRESULT hr = TraceLoggingRegister(g_asan_provider);
+  if (!SUCCEEDED(hr))
+    return;
+}
+
+void SetAbortMessage(const char *) {}
+
+void LogFullErrorReport(const char *buffer) {
+  if (common_flags()->log_to_syslog) {
+    InternalMmapVector<wchar_t> filename;
+    DWORD filename_length = 0;
+    do {
+      filename.resize(filename.size() + 0x100);
+      filename_length =
+          GetModuleFileNameW(NULL, filename.begin(), filename.size());
+    } while (filename_length >= filename.size());
+    TraceLoggingWrite(g_asan_provider, "AsanReportEvent",
+                      TraceLoggingValue(filename.begin(), "ExecutableName"),
+                      TraceLoggingValue(buffer, "AsanReportContents"));
+  }
+}
+#endif // SANITIZER_WIN_TRACE
+
+}  // namespace __sanitizer
+
+#endif  // _WIN32