Hooks: hook the realloc paths that act as pure malloc/free.

include/jemalloc/internal/hook.h

@@ -16,9 +16,13 @@
  *
  * For realloc and rallocx, if the expansion happens in place, the expansion
  * hook is called.  If it is moved, then the alloc hook is called on the new
- * location, and then the free hook is called on the old location.
+ * location, and then the free hook is called on the old location (i.e. both
+ * hooks are invoked in between the alloc and the dalloc).
  *
- * If we return NULL from OOM, then usize might not be trustworthy.
+ * If we return NULL from OOM, then usize might not be trustworthy.  Calling
+ * realloc(NULL, size) only calls the alloc hook, and calling realloc(ptr, 0)
+ * only calls the free hook.  (Calling realloc(NULL, 0) is treated as malloc(0),
+ * and only calls the alloc hook).
  *
  * Reentrancy:
  *   Is not protected against.  If your hooks allocate, then the hooks will be

src/jemalloc.c

@@ -2311,11 +2311,12 @@ isfree(tsd_t *tsd, void *ptr, size_t usize, tcache_t *tcache, bool slow_path) {
 JEMALLOC_EXPORT JEMALLOC_ALLOCATOR JEMALLOC_RESTRICT_RETURN
 void JEMALLOC_NOTHROW *
 JEMALLOC_ALLOC_SIZE(2)
-je_realloc(void *ptr, size_t size) {
+je_realloc(void *ptr, size_t arg_size) {
 	void *ret;
 	tsdn_t *tsdn JEMALLOC_CC_SILENCE_INIT(NULL);
 	size_t usize JEMALLOC_CC_SILENCE_INIT(0);
 	size_t old_usize = 0;
+	size_t size = arg_size;
 
 	LOG("core.realloc.entry", "ptr: %p, size: %zu\n", ptr, size);
 
@@ -2331,6 +2332,9 @@ je_realloc(void *ptr, size_t size) {
 				tcache = NULL;
 			}
 
+			uintptr_t args[3] = {(uintptr_t)ptr, size};
+			hook_invoke_dalloc(hook_dalloc_realloc, ptr, args);
+
 			ifree(tsd, ptr, tcache, true);
 
 			LOG("core.realloc.exit", "result: %p", NULL);
@@ -2386,6 +2390,12 @@ je_realloc(void *ptr, size_t size) {
 		dopts.item_size = size;
 
 		imalloc(&sopts, &dopts);
+		if (sopts.slow) {
+			uintptr_t args[3] = {(uintptr_t)ptr, arg_size};
+			hook_invoke_alloc(hook_alloc_realloc, ret,
+			    (uintptr_t)ret, args);
+		}
+
 		return ret;
 	}
 

test/unit/hook.c

@@ -179,7 +179,6 @@ TEST_END
 
 TEST_BEGIN(test_hooks_alloc_simple) {
 	/* "Simple" in the sense that we're not in a realloc variant. */
-
 	hooks_t hooks = {&test_alloc_hook, NULL, NULL};
 	void *handle = hook_install(TSDN_NULL, &hooks, (void *)123);
 	assert_ptr_ne(handle, NULL, "Hook installation failed");
@@ -364,6 +363,54 @@ TEST_BEGIN(test_hooks_expand_simple) {
 }
 TEST_END
 
+TEST_BEGIN(test_hooks_realloc_as_malloc_or_free) {
+	hooks_t hooks = {&test_alloc_hook, &test_dalloc_hook,
+		&test_expand_hook};
+	void *handle = hook_install(TSDN_NULL, &hooks, (void *)123);
+	assert_ptr_ne(handle, NULL, "Hook installation failed");
+
+	void *volatile ptr;
+
+	/* realloc(NULL, size) as malloc */
+	reset();
+	ptr = realloc(NULL, 1);
+	assert_d_eq(call_count, 1, "Hook not called");
+	assert_ptr_eq(arg_extra, (void *)123, "Wrong extra");
+	assert_d_eq(arg_type, (int)hook_alloc_realloc, "Wrong hook type");
+	assert_ptr_eq(ptr, arg_result, "Wrong result");
+	assert_u64_eq((uintptr_t)ptr, (uintptr_t)arg_result_raw,
+	    "Wrong raw result");
+	assert_u64_eq((uintptr_t)NULL, arg_args_raw[0], "Wrong argument");
+	assert_u64_eq((uintptr_t)1, arg_args_raw[1], "Wrong argument");
+	free(ptr);
+
+	/* realloc(ptr, 0) as free */
+	ptr = malloc(1);
+	reset();
+	realloc(ptr, 0);
+	assert_d_eq(call_count, 1, "Hook not called");
+	assert_ptr_eq(arg_extra, (void *)123, "Wrong extra");
+	assert_d_eq(arg_type, (int)hook_dalloc_realloc, "Wrong hook type");
+	assert_ptr_eq(ptr, arg_address, "Wrong pointer freed");
+	assert_u64_eq((uintptr_t)ptr, arg_args_raw[0], "Wrong raw arg");
+	assert_u64_eq((uintptr_t)0, arg_args_raw[1], "Wrong raw arg");
+
+	/* realloc(NULL, 0) as malloc(0) */
+	reset();
+	ptr = realloc(NULL, 0);
+	assert_d_eq(call_count, 1, "Hook not called");
+	assert_ptr_eq(arg_extra, (void *)123, "Wrong extra");
+	assert_d_eq(arg_type, (int)hook_alloc_realloc, "Wrong hook type");
+	assert_ptr_eq(ptr, arg_result, "Wrong result");
+	assert_u64_eq((uintptr_t)ptr, (uintptr_t)arg_result_raw,
+	    "Wrong raw result");
+	assert_u64_eq((uintptr_t)NULL, arg_args_raw[0], "Wrong argument");
+	assert_u64_eq((uintptr_t)0, arg_args_raw[1], "Wrong argument");
+	free(ptr);
+
+	hook_remove(TSDN_NULL, handle);
+}
+TEST_END
 
 int
 main(void) {
@@ -374,5 +421,6 @@ main(void) {
 	    test_hooks_remove,
 	    test_hooks_alloc_simple,
 	    test_hooks_dalloc_simple,
-	    test_hooks_expand_simple);
+	    test_hooks_expand_simple,
+	    test_hooks_realloc_as_malloc_or_free);
 }