Better delayed-initialization for malloc et al.

Author: nicolasnoble

acorn/src/malloc_wrapper.c

@@ -31,11 +31,11 @@ static void free_wrap(void * p) {
 
 void init_malloc_wrapper() {
     malloc_sem = xSemaphoreCreateRecursiveMutex();
-    old_malloc = malloc;
-    old_realloc = realloc;
-    old_free = free;
-    malloc = malloc_wrap;
-    realloc = realloc_wrap;
-    free = free_wrap;
+    old_malloc = malloc_ptr;
+    old_realloc = realloc_ptr;
+    old_free = free_ptr;
+    malloc_ptr = malloc_wrap;
+    realloc_ptr = realloc_wrap;
+    free_ptr = free_wrap;
 }
 

libc/include/malloc.h

@@ -7,10 +7,6 @@
 
 BEGIN_DECL
 
-// Due to chicken-and-egg issues, we may need to call this from other modules.
-// Only call it from global constructors however.
-void _uc_sdk_ensure_malloc_exists();
-
 typedef void * (*malloc_t)(size_t size);
 typedef void (*free_t)(void * ptr);
 typedef void * (*realloc_t)(void * ptr, size_t size);
@@ -19,9 +15,13 @@ void * base_malloc(size_t size);
 void base_free(void * ptr);
 void * base_realloc(void * ptr, size_t size);
 
-extern malloc_t malloc;
-extern free_t free;
-extern realloc_t realloc;
+void * malloc(size_t size);
+void free(void * ptr);
+void * realloc(void * ptr, size_t size);
+
+extern malloc_t malloc_ptr;
+extern free_t free_ptr;
+extern realloc_t realloc_ptr;
 
 static __inline__ void * calloc(size_t nmemb, size_t size) {
     uint8_t * r = (uint8_t *)malloc(nmemb * size);

libc/src/initfini.c

@@ -81,6 +81,6 @@ void exit(int return_code) {
 }
 
 void libc_init() {
-    __sinit(_impure_ptr);
     __libc_init_array();
+    __sinit(_impure_ptr);
 }

libc/src/malloc.c

@@ -199,14 +199,18 @@ void base_free(void * ptr) {
     cur->prev->next = cur->next;
 }
 
-malloc_t malloc = base_malloc;
-free_t free = base_free;
-realloc_t realloc = base_realloc;
+malloc_t malloc_ptr = NULL;
+free_t free_ptr = NULL;
+realloc_t realloc_ptr = NULL;
 
-// Due to chicken-and-egg issues, we may need to call this from other modules.
-// Only call it from global constructors however.
-void _uc_sdk_ensure_malloc_exists() {
-    malloc = base_malloc;
-    free = base_free;
-    realloc = base_realloc;
+void * malloc(size_t size) {
+    return malloc_ptr ? malloc_ptr(size) : base_malloc(size);
+}
+
+void free(void * ptr) {
+    free_ptr ? free_ptr(ptr) : base_free(ptr);
+}
+
+void * realloc(void * ptr, size_t size) {
+    return realloc_ptr ? realloc_ptr(size) : base_realloc(ptr, size);
 }

os/src/fio.c

@@ -41,7 +41,6 @@ __attribute__((constructor)) static void fio_init() {
     fio_fds[0].fdread = stdin_read;
     fio_fds[1].fdwrite = stdout_write;
     fio_fds[2].fdwrite = stdout_write;
-    _uc_sdk_ensure_malloc_exists();
     fio_sem = xSemaphoreCreateMutex();
 }
 

os/src/sbrk.c

@@ -21,7 +21,7 @@ void * sbrk(ptrdiff_t incr) {
     prev_heap_end = heap_end ? heap_end : (void *) &__heap_start;
 
     /* Align to always be on 8-byte boundaries */
-    next_heap_end = (void *)((((uintptr_t)heap_end + incr) + 7) & ~7);
+    next_heap_end = (void *)((((uintptr_t)prev_heap_end + incr) + 7) & ~7);
 
     /* Check if this allocation would exceed the end of the ram - would probably get into the stack first however */
     if (next_heap_end > stack_min) {