Tidy up the allocator shim, which is now Windows only.

base/allocator/allocator_shim_win.cc

Index: base/allocator/allocator_shim_win.cc
diff --git a/base/allocator/allocator_shim_win.cc b/base/allocator/allocator_shim_win.cc
index 0ebaa6b54c7e20baa29d7a2fab7e0d35120e75e3..1e7fe19f9520e0fd091c521e7d02ce306cd21c4e 100644
--- a/base/allocator/allocator_shim_win.cc
+++ b/base/allocator/allocator_shim_win.cc
@@ -11,32 +11,41 @@
 // This shim make it possible to perform additional checks on allocations
 // before passing them to the Heap functions.
 
-// new_mode behaves similarly to MSVC's _set_new_mode.
-// If flag is 0 (default), calls to malloc will behave normally.
-// If flag is 1, calls to malloc will behave like calls to new,
-// and the std_new_handler will be invoked on failure.
-// Can be set by calling _set_new_mode().
-static int new_mode = 0;
+// Heap functions are stripped from libcmt.lib using the prep_libc.py
+// for each object file stripped, we re-implement them here to allow us to
+// perform additional checks:
+// 1. Enforcing the maximum size that can be allocated to 2Gb.
+// 2. Calling new_handler if malloc fails.
+
+extern "C" {
+// We set this to 1 because part of the CRT uses a check of _crtheap != 0
+// to test whether the CRT has been initialized.  Once we've ripped out
+// the allocators from libcmt, we need to provide this definition so that
+// the rest of the CRT is still usable.
+// heapinit.c
+void* _crtheap = reinterpret_cast<void*>(1);
+}
 
 namespace {
 
-// This is a simple allocator based on the windows heap.
 const size_t kWindowsPageSize = 4096;
 const size_t kMaxWindowsAllocation = INT_MAX - kWindowsPageSize;
-static HANDLE win_heap;
+int new_mode = 0;
 
 // VS2013 crt uses the process heap as its heap, so we do the same here.
 // See heapinit.c in VS CRT sources.
 bool win_heap_init() {
-  win_heap = GetProcessHeap();
-  if (win_heap == NULL)
+  // Set the _crtheap global here.  THis allows us to offload most of the
+  // memory management to the CRT, except the functions we need to shim.
+  _crtheap = GetProcessHeap();
+  if (_crtheap == NULL)
     return false;
 
   ULONG enable_lfh = 2;
   // NOTE: Setting LFH may fail.  Vista already has it enabled.
   //       And under the debugger, it won't use LFH.  So we
   //       ignore any errors.
-  HeapSetInformation(win_heap, HeapCompatibilityInformation, &enable_lfh,
+  HeapSetInformation(_crtheap, HeapCompatibilityInformation, &enable_lfh,
                      sizeof(enable_lfh));
 
   return true;
@@ -44,12 +53,12 @@ bool win_heap_init() {
 
 void* win_heap_malloc(size_t size) {
   if (size < kMaxWindowsAllocation)
-    return HeapAlloc(win_heap, 0, size);
+    return HeapAlloc(_crtheap, 0, size);
   return NULL;
 }
 
 void win_heap_free(void* size) {
-  HeapFree(win_heap, 0, size);
+  HeapFree(_crtheap, 0, size);
 }
 
 void* win_heap_realloc(void* ptr, size_t size) {
@@ -60,49 +69,14 @@ void* win_heap_realloc(void* ptr, size_t size) {
     return NULL;
   }
   if (size < kMaxWindowsAllocation)
-    return HeapReAlloc(win_heap, 0, ptr, size);
+    return HeapReAlloc(_crtheap, 0, ptr, size);
   return NULL;
 }
 
-size_t win_heap_msize(void* ptr) {
-  return HeapSize(win_heap, 0, ptr);
-}
-
-void* win_heap_memalign(size_t alignment, size_t size) {
-  // Reserve enough space to ensure we can align and set aligned_ptr[-1] to the
-  // original allocation for use with win_heap_memalign_free() later.
-  size_t allocation_size = size + (alignment - 1) + sizeof(void*);
-
-  // Check for overflow.  Alignment and size are checked in allocator_shim.
-  if (size >= allocation_size || alignment >= allocation_size) {
-    return NULL;
-  }
-
-  // Since we're directly calling the allocator function, before OOM handling,
-  // we need to NULL check to ensure the allocation succeeded.
-  void* ptr = win_heap_malloc(allocation_size);
-  if (!ptr)
-    return ptr;
-
-  char* aligned_ptr = static_cast<char*>(ptr) + sizeof(void*);
-  aligned_ptr +=
-      alignment - reinterpret_cast<uintptr_t>(aligned_ptr) & (alignment - 1);
-
-  reinterpret_cast<void**>(aligned_ptr)[-1] = ptr;
-  return aligned_ptr;
-}
-
-void win_heap_memalign_free(void* ptr) {
-  if (ptr)
-    win_heap_free(static_cast<void**>(ptr)[-1]);
-}
-
 void win_heap_term() {
-  win_heap = NULL;
+  _crtheap = NULL;
 }
 
-}  // namespace
-
 // Call the new handler, if one has been set.
 // Returns true on successfully calling the handler, false otherwise.
 inline bool call_new_handler(bool nothrow, size_t size) {
@@ -120,8 +94,71 @@ inline bool call_new_handler(bool nothrow, size_t size) {
   return false;
 }
 
-extern "C" {
+// Implement a C++ style allocation, which always calls the new_handler
+// on failure.
+inline void* generic_cpp_alloc(size_t size, bool nothrow) {
+  void* ptr;
+  for (;;) {
+    ptr = malloc(size);
+    if (ptr)
+      return ptr;
+    if (!call_new_handler(nothrow, size))
+      break;
+  }
+  return ptr;
+}
+
+}  // namespace
+
+// new.cpp
+void* operator new(size_t size) {
+  return generic_cpp_alloc(size, false);
+}
+
+// delete.cpp
+void operator delete(void* p) throw() {
+  free(p);
+}
+
+// new2.cpp
+void* operator new[](size_t size) {
+  return generic_cpp_alloc(size, false);
+}
 
+// delete2.cpp
+void operator delete[](void* p) throw() {
+  free(p);
+}
+
+// newopnt.cpp
+void* operator new(size_t size, const std::nothrow_t& nt) {
+  return generic_cpp_alloc(size, true);
+}
+
+// newaopnt.cpp
+void* operator new[](size_t size, const std::nothrow_t& nt) {
+  return generic_cpp_alloc(size, true);
+}
+
+// This function behaves similarly to MSVC's _set_new_mode.
+// If flag is 0 (default), calls to malloc will behave normally.
+// If flag is 1, calls to malloc will behave like calls to new,
+// and the std_new_handler will be invoked on failure.
+// Returns the previous mode.
+// new_mode.cpp
+int _set_new_mode(int flag) throw() {
+  int old_mode = new_mode;
+  new_mode = flag;
+  return old_mode;
+}
+
+// new_mode.cpp
+int _query_new_mode() {
+  return new_mode;
+}
+
+extern "C" {
+// malloc.c
 void* malloc(size_t size) {
   void* ptr;
   for (;;) {
@@ -135,11 +172,13 @@ void* malloc(size_t size) {
   return ptr;
 }
 
+// free.c
 void free(void* p) {
   win_heap_free(p);
   return;
 }
 
+// realloc.c
 void* realloc(void* ptr, size_t size) {
   // Webkit is brittle for allocators that return NULL for malloc(0).  The
   // realloc(0, 0) code path does not guarantee a non-NULL return, so be sure
@@ -162,60 +201,56 @@ void* realloc(void* ptr, size_t size) {
   return new_ptr;
 }
 
-
-size_t _msize(void* p) {
-  return win_heap_msize(p);
-}
-
+// heapinit.c
 intptr_t _get_heap_handle() {
-  return reinterpret_cast<intptr_t>(win_heap);
+  return reinterpret_cast<intptr_t>(_crtheap);
 }
 
-// The CRT heap initialization stub.
+// heapinit.c
 int _heap_init() {
   return win_heap_init() ? 1 : 0;
 }
 
-// The CRT heap cleanup stub.
+// heapinit.c
 void _heap_term() {
   win_heap_term();
 }
 
-// We set this to 1 because part of the CRT uses a check of _crtheap != 0
-// to test whether the CRT has been initialized.  Once we've ripped out
-// the allocators from libcmt, we need to provide this definition so that
-// the rest of the CRT is still usable.
-void* _crtheap = reinterpret_cast<void*>(1);
-
-// Provide support for aligned memory through Windows only _aligned_malloc().
-void* _aligned_malloc(size_t size, size_t alignment) {
-  // _aligned_malloc guarantees parameter validation, so do so here.  These
-  // checks are somewhat stricter than _aligned_malloc() since we're effectively
-  // using memalign() under the hood.
-  if (size == 0U || (alignment & (alignment - 1)) != 0U ||
-      (alignment % sizeof(void*)) != 0U)
+// calloc.c
+void* calloc(size_t n, size_t elem_size) {
+  // Overflow check.
+  const size_t size = n * elem_size;
+  if (elem_size != 0 && size / elem_size != n)
     return NULL;
 
-  void* ptr;
-  for (;;) {
-    ptr = win_heap_memalign(alignment, size);
-
-    if (ptr) {
-      return ptr;
-    }
-
-    if (!new_mode || !call_new_handler(true, size))
-      break;
+  void* result = malloc(size);
+  if (result != NULL) {
+    memset(result, 0, size);
   }
-  return ptr;
+  return result;
 }
 
-void _aligned_free(void* p) {
-  // Pointers allocated with win_heap_memalign() MUST be freed via
-  // win_heap_memalign_free() since the aligned pointer is not the real one.
-  win_heap_memalign_free(p);
+// recalloc.c
+void* _recalloc(void* p, size_t n, size_t elem_size) {
+  if (!p)
+    return calloc(n, elem_size);
+
+  // This API is a bit odd.
+  // Note: recalloc only guarantees zeroed memory when p is NULL.
+  //   Generally, calls to malloc() have padding.  So a request
+  //   to malloc N bytes actually malloc's N+x bytes.  Later, if
+  //   that buffer is passed to recalloc, we don't know what N
+  //   was anymore.  We only know what N+x is.  As such, there is
+  //   no way to know what to zero out.
+  const size_t size = n * elem_size;
+  if (elem_size != 0 && size / elem_size != n)
+    return NULL;
+  return realloc(p, size);
 }
 
-#include "generic_allocators.cc"
+// calloc_impl.c
+void* _calloc_impl(size_t n, size_t size) {
+  return calloc(n, size);
+}
 
 }  // extern C