emmalloc: Add an option to not define the standard exports

system/lib/emmalloc.c

@@ -37,6 +37,13 @@
  *  - Debugging and logging directly uses console.log via uses EM_ASM, not
  *    printf etc., to minimize any risk of debugging or logging depending on
  *    malloc.
+ *
+ * Exporting:
+ *
+ *  - By default we declare not only emmalloc_malloc, emmalloc_free, etc. but
+ *    also the standard library methods like malloc, free, and some aliases.
+ *    You can override this by defining EMMALLOC_NO_STD_EXPORTS, in which case
+ *    we only declare the emalloc_* ones but not the standard ones.
  */
 
 #include <stdalign.h>
@@ -63,7 +70,13 @@ static_assert((((int32_t)0x80000000U) >> 31) == -1, "This malloc implementation
 #define MALLOC_ALIGNMENT alignof(max_align_t)
 static_assert(alignof(max_align_t) == 8, "max_align_t must be correct");
 
+#ifdef EMMALLOC_NO_STD_EXPORTS
+#define EMMALLOC_EXPORT
+#define EMMALLOC_ALIAS(ALIAS, ORIGINAL)
+#else
 #define EMMALLOC_EXPORT __attribute__((weak, __visibility__("default")))
+#define EMMALLOC_ALIAS(ALIAS, ORIGINAL) extern __typeof(ORIGINAL) ALIAS __attribute__((alias(#ORIGINAL)));
+#endif
 
 #define MIN(x, y) ((x) < (y) ? (x) : (y))
 #define MAX(x, y) ((x) > (y) ? (x) : (y))
@@ -812,31 +825,37 @@ void *emmalloc_memalign(size_t alignment, size_t size)
   MALLOC_RELEASE();
   return ptr;
 }
-extern __typeof(emmalloc_memalign) emscripten_builtin_memalign __attribute__((alias("emmalloc_memalign")));
+EMMALLOC_ALIAS(emscripten_builtin_memalign, emmalloc_memalign);
 
+#ifndef EMMALLOC_NO_STD_EXPORTS
 void * EMMALLOC_EXPORT memalign(size_t alignment, size_t size)
 {
   return emmalloc_memalign(alignment, size);
 }
+#endif
 
+#ifndef EMMALLOC_NO_STD_EXPORTS
 void * EMMALLOC_EXPORT aligned_alloc(size_t alignment, size_t size)
 {
   if ((alignment % sizeof(void *) != 0) || (size % alignment) != 0)
     return 0;
   return emmalloc_memalign(alignment, size);
 }
+#endif
 
 void *emmalloc_malloc(size_t size)
 {
   return emmalloc_memalign(MALLOC_ALIGNMENT, size);
 }
-extern __typeof(emmalloc_malloc) emscripten_builtin_malloc __attribute__((alias("emmalloc_malloc")));
-extern __typeof(emmalloc_malloc) __libc_malloc __attribute__((alias("emmalloc_malloc")));
+EMMALLOC_ALIAS(emscripten_builtin_malloc, emmalloc_malloc);
+EMMALLOC_ALIAS(__libc_malloc, emmalloc_malloc);
 
+#ifndef EMMALLOC_NO_STD_EXPORTS
 void * EMMALLOC_EXPORT malloc(size_t size)
 {
   return emmalloc_malloc(size);
 }
+#endif
 
 size_t emmalloc_usable_size(void *ptr)
 {
@@ -858,10 +877,12 @@ size_t emmalloc_usable_size(void *ptr)
   return size - REGION_HEADER_SIZE;
 }
 
+#ifndef EMMALLOC_NO_STD_EXPORTS
 size_t EMMALLOC_EXPORT malloc_usable_size(void *ptr)
 {
   return emmalloc_usable_size(ptr);
 }
+#endif
 
 void emmalloc_free(void *ptr)
 {
@@ -932,13 +953,15 @@ void emmalloc_free(void *ptr)
   emmalloc_validate_memory_regions();
 #endif
 }
-extern __typeof(emmalloc_free) emscripten_builtin_free __attribute__((alias("emmalloc_free")));
-extern __typeof(emmalloc_free) __libc_free __attribute__((alias("emmalloc_free")));
+EMMALLOC_ALIAS(emscripten_builtin_free, emmalloc_free);
+EMMALLOC_ALIAS(__libc_free, emmalloc_free);
 
+#ifndef EMMALLOC_NO_STD_EXPORTS
 void EMMALLOC_EXPORT free(void *ptr)
 {
   return emmalloc_free(ptr);
 }
+#endif
 
 // Can be called to attempt to increase or decrease the size of the given region
 // to a new size (in-place). Returns 1 if resize succeeds, and 0 on failure.
@@ -1067,10 +1090,12 @@ void *emmalloc_aligned_realloc(void *ptr, size_t alignment, size_t size)
   return newptr;
 }
 
+#ifndef EMMALLOC_NO_STD_EXPORTS
 void * EMMALLOC_EXPORT aligned_realloc(void *ptr, size_t alignment, size_t size)
 {
   return emmalloc_aligned_realloc(ptr, alignment, size);
 }
+#endif
 
 // realloc_try() is like realloc(), but only attempts to try to resize the existing memory
 // area. If resizing the existing memory area fails, then realloc_try() will return 0
@@ -1154,12 +1179,14 @@ void *emmalloc_realloc(void *ptr, size_t size)
 {
   return emmalloc_aligned_realloc(ptr, MALLOC_ALIGNMENT, size);
 }
-extern __typeof(emmalloc_realloc) __libc_realloc __attribute__((alias("emmalloc_realloc")));
+EMMALLOC_ALIAS(__libc_realloc, emmalloc_realloc);
 
+#ifndef EMMALLOC_NO_STD_EXPORTS
 void * EMMALLOC_EXPORT realloc(void *ptr, size_t size)
 {
   return emmalloc_realloc(ptr, size);
 }
+#endif
 
 // realloc_uninitialized() is like realloc(), but old memory contents
 // will be undefined after reallocation. (old memory is not preserved in any case)
@@ -1177,10 +1204,12 @@ int emmalloc_posix_memalign(void **memptr, size_t alignment, size_t size)
   return *memptr ?  0 : 12/*ENOMEM*/;
 }
 
+#ifndef EMMALLOC_NO_STD_EXPORTS
 int EMMALLOC_EXPORT posix_memalign(void **memptr, size_t alignment, size_t size)
 {
   return emmalloc_posix_memalign(memptr, alignment, size);
 }
+#endif
 
 void *emmalloc_calloc(size_t num, size_t size)
 {
@@ -1190,12 +1219,14 @@ void *emmalloc_calloc(size_t num, size_t size)
     memset(ptr, 0, bytes);
   return ptr;
 }
-extern __typeof(emmalloc_calloc) __libc_calloc __attribute__((alias("emmalloc_calloc")));
+EMMALLOC_ALIAS(__libc_calloc, emmalloc_calloc);
 
+#ifndef EMMALLOC_NO_STD_EXPORTS
 void * EMMALLOC_EXPORT calloc(size_t num, size_t size)
 {
   return emmalloc_calloc(num, size);
 }
+#endif
 
 static int count_linked_list_size(Region *list)
 {
@@ -1286,12 +1317,14 @@ struct mallinfo emmalloc_mallinfo()
   return info;
 }
 
+#ifndef EMMALLOC_NO_STD_EXPORTS
 struct mallinfo EMMALLOC_EXPORT mallinfo()
 {
   return emmalloc_mallinfo();
 }
+#endif
 
-// Note! This function is not fully multithreadin safe: while this function is running, other threads should not be
+// Note! This function is not fully multithreading safe: while this function is running, other threads should not be
 // allowed to call sbrk()!
 static int trim_dynamic_heap_reservation(size_t pad)
 {
@@ -1352,10 +1385,12 @@ int emmalloc_trim(size_t pad)
   return success;
 }
 
+#ifndef EMMALLOC_NO_STD_EXPORTS
 int EMMALLOC_EXPORT malloc_trim(size_t pad)
 {
   return emmalloc_trim(pad);
 }
+#endif
 
 size_t emmalloc_dynamic_heap_size()
 {

test/other/test_emmalloc_in_addition.c

@@ -0,0 +1,36 @@
+#include <assert.h>
+#include <emscripten/console.h>
+#include <emscripten/emmalloc.h>
+
+int main() {
+  // Verify we can call both malloc and emmalloc_malloc, and that those are
+  // different functions, unless TEST_EMMALLOC_IS_MALLOC is set (in that case,
+  // emmalloc is malloc because we let emmalloc define the standard exports like
+  // malloc).
+
+  // We have allocated nothing so far, but there may be some initial allocation
+  // from startup.
+  size_t initial = emmalloc_dynamic_heap_size();
+  emscripten_console_logf("initial: %zu\n", initial);
+
+  const size_t ONE_MB = 1024 * 1024;
+  void* one = malloc(ONE_MB);
+  assert(one);
+#ifndef TEST_EMMALLOC_IS_MALLOC
+  // We have allocated using malloc, but not emmalloc, so emmalloc reports no
+  // change in usage.
+  assert(emmalloc_dynamic_heap_size() == initial);
+#else
+  // malloc == emmalloc_malloc, so emmalloc will report additional usage (of the
+  // size of the allocation, or perhaps more if it overallocated as an
+  // optimization).
+  assert(emmalloc_dynamic_heap_size() >= initial + ONE_MB);
+#endif
+
+  void* two = emmalloc_malloc(ONE_MB);
+  assert(two);
+  // We have allocated using emmalloc, so now emmalloc definitely reports usage.
+  assert(emmalloc_dynamic_heap_size() >= initial + ONE_MB);
+
+  emscripten_console_log("success");
+}

test/test_other.py

@@ -14018,3 +14018,18 @@ def test_hello_world_argv(self):
 
   def test_arguments_global(self):
     self.emcc(test_file('hello_world_argv.c'), ['-sENVIRONMENT=web', '-sSTRICT', '--closure=1', '-O2'])
+
+  @parameterized({
+    'no_std_exp':   (['-DEMMALLOC_NO_STD_EXPORTS'],),
+    # When we let emmalloc build with the standard exports like malloc,
+    # emmalloc == malloc.
+    'with_std_exp': (['-DTEST_EMMALLOC_IS_MALLOC'],),
+  })
+  def test_emmalloc_in_addition(self, args):
+    # Test that we can use emmalloc in addition to another malloc impl. When we
+    # build emmalloc using -DEMMALLOC_NO_STD_EXPORTS it will not export malloc
+    # etc., and only provide the emmalloc_malloc etc. family of functions that
+    # we can use.
+    emmalloc = path_from_root('system', 'lib', 'emmalloc.c')
+    self.run_process([EMCC, test_file('other/test_emmalloc_in_addition.c'), emmalloc] + args)
+    self.assertContained('success', self.run_js('a.out.js'))