allocators: extract crtdbg allocator into its own file

The Windows-specific crtdbg allocator is currently mixed into the
crtdbg stacktracing compilation unit, making it harder to find
than necessary. Extract it and move it into the new "allocators/"
subdirectory to improve discoverability.

This change means that the crtdbg compilation unit is now
compiled unconditionally, whereas it has previously only been
compiled on Windows platforms. Thus we now have additional guards
around the code so that it will only be compiled if
GIT_MSVC_CRTDBG is defined. This also allows us to move over the
fallback-implementation of `git_win32_crtdbg_init_allocator` into
the same compilation unit.

src/alloc.c

@@ -7,11 +7,8 @@
 
 #include "alloc.h"
 
-#if defined(GIT_MSVC_CRTDBG)
-# include "win32/w32_crtdbg_stacktrace.h"
-#else
-# include "allocators/stdalloc.h"
-#endif
+#include "allocators/stdalloc.h"
+#include "allocators/win32_crtdbg.h"
 
 git_allocator git__allocator;
 
@@ -44,12 +41,3 @@ int git_allocator_setup(git_allocator *allocator)
 	memcpy(&git__allocator, allocator, sizeof(*allocator));
 	return 0;
 }
-
-#if !defined(GIT_MSVC_CRTDBG)
-int git_win32_crtdbg_init_allocator(git_allocator *allocator)
-{
-	GIT_UNUSED(allocator);
-	git_error_set(GIT_EINVALID, "crtdbg memory allocator not available");
-	return -1;
-}
-#endif

src/allocators/win32_crtdbg.c

+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include "win32_crtdbg.h"
+
+#if defined(GIT_MSVC_CRTDBG)
+
+#include "win32/w32_crtdbg_stacktrace.h"
+
+static void *crtdbg__malloc(size_t len, const char *file, int line)
+{
+	void *ptr = _malloc_dbg(len, _NORMAL_BLOCK, git_win32__crtdbg_stacktrace(1,file), line);
+	if (!ptr) git_error_set_oom();
+	return ptr;
+}
+
+static void *crtdbg__calloc(size_t nelem, size_t elsize, const char *file, int line)
+{
+	void *ptr = _calloc_dbg(nelem, elsize, _NORMAL_BLOCK, git_win32__crtdbg_stacktrace(1,file), line);
+	if (!ptr) git_error_set_oom();
+	return ptr;
+}
+
+static char *crtdbg__strdup(const char *str, const char *file, int line)
+{
+	char *ptr = _strdup_dbg(str, _NORMAL_BLOCK, git_win32__crtdbg_stacktrace(1,file), line);
+	if (!ptr) git_error_set_oom();
+	return ptr;
+}
+
+static char *crtdbg__strndup(const char *str, size_t n, const char *file, int line)
+{
+	size_t length = 0, alloclength;
+	char *ptr;
+
+	length = p_strnlen(str, n);
+
+	if (GIT_ADD_SIZET_OVERFLOW(&alloclength, length, 1) ||
+		!(ptr = crtdbg__malloc(alloclength, file, line)))
+		return NULL;
+
+	if (length)
+		memcpy(ptr, str, length);
+
+	ptr[length] = '\0';
+
+	return ptr;
+}
+
+static char *crtdbg__substrdup(const char *start, size_t n, const char *file, int line)
+{
+	char *ptr;
+	size_t alloclen;
+
+	if (GIT_ADD_SIZET_OVERFLOW(&alloclen, n, 1) ||
+		!(ptr = crtdbg__malloc(alloclen, file, line)))
+		return NULL;
+
+	memcpy(ptr, start, n);
+	ptr[n] = '\0';
+	return ptr;
+}
+
+static void *crtdbg__realloc(void *ptr, size_t size, const char *file, int line)
+{
+	void *new_ptr = _realloc_dbg(ptr, size, _NORMAL_BLOCK, git_win32__crtdbg_stacktrace(1,file), line);
+	if (!new_ptr) git_error_set_oom();
+	return new_ptr;
+}
+
+static void *crtdbg__reallocarray(void *ptr, size_t nelem, size_t elsize, const char *file, int line)
+{
+	size_t newsize;
+
+	return GIT_MULTIPLY_SIZET_OVERFLOW(&newsize, nelem, elsize) ?
+		NULL : _realloc_dbg(ptr, newsize, _NORMAL_BLOCK, git_win32__crtdbg_stacktrace(1,file), line);
+}
+
+static void *crtdbg__mallocarray(size_t nelem, size_t elsize, const char *file, int line)
+{
+	return crtdbg__reallocarray(NULL, nelem, elsize, file, line);
+}
+
+static void crtdbg__free(void *ptr)
+{
+	free(ptr);
+}
+
+int git_win32_crtdbg_init_allocator(git_allocator *allocator)
+{
+	allocator->gmalloc = crtdbg__malloc;
+	allocator->gcalloc = crtdbg__calloc;
+	allocator->gstrdup = crtdbg__strdup;
+	allocator->gstrndup = crtdbg__strndup;
+	allocator->gsubstrdup = crtdbg__substrdup;
+	allocator->grealloc = crtdbg__realloc;
+	allocator->greallocarray = crtdbg__reallocarray;
+	allocator->gmallocarray = crtdbg__mallocarray;
+	allocator->gfree = crtdbg__free;
+	return 0;
+}
+
+#else
+
+int git_win32_crtdbg_init_allocator(git_allocator *allocator)
+{
+	GIT_UNUSED(allocator);
+	git_error_set(GIT_EINVALID, "crtdbg memory allocator not available");
+	return -1;
+}
+
+#endif

src/allocators/win32_crtdbg.h

+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#ifndef INCLUDE_allocators_crtdbg_h
+#define INCLUDE_allocators_crtdbg_h
+
+#include "common.h"
+
+#include "alloc.h"
+
+int git_win32_crtdbg_init_allocator(git_allocator *allocator);
+
+#endif

src/win32/w32_crtdbg_stacktrace.c

@@ -71,99 +71,6 @@ static bool g_limit_reached = false; /* had allocs after we filled row table */
 static unsigned int g_checkpoint_id = 0; /* to better label leak checkpoints */
 static bool g_transient_leaks_since_mark = false; /* payload for hook */
 
-static void *crtdbg__malloc(size_t len, const char *file, int line)
-{
-	void *ptr = _malloc_dbg(len, _NORMAL_BLOCK, git_win32__crtdbg_stacktrace(1,file), line);
-	if (!ptr) git_error_set_oom();
-	return ptr;
-}
-
-static void *crtdbg__calloc(size_t nelem, size_t elsize, const char *file, int line)
-{
-	void *ptr = _calloc_dbg(nelem, elsize, _NORMAL_BLOCK, git_win32__crtdbg_stacktrace(1,file), line);
-	if (!ptr) git_error_set_oom();
-	return ptr;
-}
-
-static char *crtdbg__strdup(const char *str, const char *file, int line)
-{
-	char *ptr = _strdup_dbg(str, _NORMAL_BLOCK, git_win32__crtdbg_stacktrace(1,file), line);
-	if (!ptr) git_error_set_oom();
-	return ptr;
-}
-
-static char *crtdbg__strndup(const char *str, size_t n, const char *file, int line)
-{
-	size_t length = 0, alloclength;
-	char *ptr;
-
-	length = p_strnlen(str, n);
-
-	if (GIT_ADD_SIZET_OVERFLOW(&alloclength, length, 1) ||
-		!(ptr = crtdbg__malloc(alloclength, file, line)))
-		return NULL;
-
-	if (length)
-		memcpy(ptr, str, length);
-
-	ptr[length] = '\0';
-
-	return ptr;
-}
-
-static char *crtdbg__substrdup(const char *start, size_t n, const char *file, int line)
-{
-	char *ptr;
-	size_t alloclen;
-
-	if (GIT_ADD_SIZET_OVERFLOW(&alloclen, n, 1) ||
-		!(ptr = crtdbg__malloc(alloclen, file, line)))
-		return NULL;
-
-	memcpy(ptr, start, n);
-	ptr[n] = '\0';
-	return ptr;
-}
-
-static void *crtdbg__realloc(void *ptr, size_t size, const char *file, int line)
-{
-	void *new_ptr = _realloc_dbg(ptr, size, _NORMAL_BLOCK, git_win32__crtdbg_stacktrace(1,file), line);
-	if (!new_ptr) git_error_set_oom();
-	return new_ptr;
-}
-
-static void *crtdbg__reallocarray(void *ptr, size_t nelem, size_t elsize, const char *file, int line)
-{
-	size_t newsize;
-
-	return GIT_MULTIPLY_SIZET_OVERFLOW(&newsize, nelem, elsize) ?
-		NULL : _realloc_dbg(ptr, newsize, _NORMAL_BLOCK, git_win32__crtdbg_stacktrace(1,file), line);
-}
-
-static void *crtdbg__mallocarray(size_t nelem, size_t elsize, const char *file, int line)
-{
-	return crtdbg__reallocarray(NULL, nelem, elsize, file, line);
-}
-
-static void crtdbg__free(void *ptr)
-{
-	free(ptr);
-}
-
-int git_win32_crtdbg_init_allocator(git_allocator *allocator)
-{
-	allocator->gmalloc = crtdbg__malloc;
-	allocator->gcalloc = crtdbg__calloc;
-	allocator->gstrdup = crtdbg__strdup;
-	allocator->gstrndup = crtdbg__strndup;
-	allocator->gsubstrdup = crtdbg__substrdup;
-	allocator->grealloc = crtdbg__realloc;
-	allocator->greallocarray = crtdbg__reallocarray;
-	allocator->gmallocarray = crtdbg__mallocarray;
-	allocator->gfree = crtdbg__free;
-	return 0;
-}
-
 /**
  * Compare function for bsearch on g_cs_index table.
  */

src/win32/w32_crtdbg_stacktrace.h

@@ -43,8 +43,6 @@
  * startup.  See tests/main.c for an example.
  */
 
-int git_win32_crtdbg_init_allocator(git_allocator *allocator);
-
 /**
  * Initialize our memory leak tracking and de-dup data structures.
  * This should ONLY be called by git_libgit2_init().