Changes in uspace/lib/c/generic/malloc.c [9d58539:c828803] in mainline

File:

• uspace/lib/c/generic/malloc.c (modified) (10 diffs)

uspace/lib/c/generic/malloc.c

@@ -109 +109 @@
         (((uintptr_t) (area)->end) - sizeof(heap_block_foot_t))
 
+#define AREA_LAST_BLOCK_HEAD(area) \
+        ((uintptr_t) BLOCK_HEAD(((heap_block_foot_t *) AREA_LAST_BLOCK_FOOT(area))))
+
 /** Get header in heap block.
  *
@@ -285 +288 @@
         /* Align the heap area size on page boundary */
         size_t asize = ALIGN_UP(size, PAGE_SIZE);
-        void *astart = as_area_create((void *) -1, asize,
+        void *astart = as_area_create(AS_AREA_ANY, asize,
             AS_AREA_WRITE | AS_AREA_READ);
-        if (astart == (void *) -1)
+        if (astart == AS_MAP_FAILED)
                 return false;
         
@@ -346 +349 @@
                 return false;
         
-        /* Add new free block */
-        size_t net_size = (size_t) (end - area->end);
-        if (net_size > 0)
-                block_init(area->end, net_size, true, area);
+        heap_block_head_t *last_head =
+            (heap_block_head_t *) AREA_LAST_BLOCK_HEAD(area);
+        
+        if (last_head->free) {
+                /* Add the new space to the last block. */
+                size_t net_size = (size_t) (end - area->end) + last_head->size;
+                malloc_assert(net_size > 0);
+                block_init(last_head, net_size, true, area);
+        } else {
+                /* Add new free block */
+                size_t net_size = (size_t) (end - area->end);
+                if (net_size > 0)
+                        block_init(area->end, net_size, true, area);
+        }
         
         /* Update heap area parameters */
@@ -355 +368 @@
         
         return true;
-}
-
-/** Try to enlarge any of the heap areas
- *
- * Should be called only inside the critical section.
- *
- * @param size Gross size of item to allocate (bytes).
- *
- */
-static bool heap_grow(size_t size)
-{
-        if (size == 0)
-                return true;
-        
-        /* First try to enlarge some existing area */
-        for (heap_area_t *area = first_heap_area; area != NULL;
-            area = area->next) {
-                if (area_grow(area, size))
-                        return true;
-        }
-        
-        /* Eventually try to create a new area */
-        return area_create(AREA_OVERHEAD(size));
 }
 
@@ -661 +651 @@
 }
 
+/** Try to enlarge any of the heap areas.
+ *
+ * If successful, allocate block of the given size in the area.
+ * Should be called only inside the critical section.
+ *
+ * @param size  Gross size of item to allocate (bytes).
+ * @param align Memory address alignment.
+ *
+ * @return Allocated block.
+ * @return NULL on failure.
+ *
+ */
+static void *heap_grow_and_alloc(size_t size, size_t align)
+{
+        if (size == 0)
+                return NULL;
+        
+        /* First try to enlarge some existing area */
+        for (heap_area_t *area = first_heap_area; area != NULL;
+            area = area->next) {
+                
+                if (area_grow(area, size + align)) {
+                        heap_block_head_t *first =
+                            (heap_block_head_t *) AREA_LAST_BLOCK_HEAD(area);
+                        
+                        void *addr =
+                            malloc_area(area, first, NULL, size, align);
+                        malloc_assert(addr != NULL);
+                        return addr;
+                }
+        }
+        
+        /* Eventually try to create a new area */
+        if (area_create(AREA_OVERHEAD(size + align))) {
+                heap_block_head_t *first =
+                    (heap_block_head_t *) AREA_FIRST_BLOCK_HEAD(last_heap_area);
+                
+                void *addr =
+                    malloc_area(last_heap_area, first, NULL, size, align);
+                malloc_assert(addr != NULL);
+                return addr;
+        }
+        
+        return NULL;
+}
+
 /** Allocate a memory block
  *
@@ -679 +715 @@
         
         size_t falign = lcm(align, BASE_ALIGN);
-        size_t real_size = GROSS_SIZE(ALIGN_UP(size, falign));
-        
-        bool retry = false;
-        heap_block_head_t *split;
-        
-loop:
+        
+        /* Check for integer overflow. */
+        if (falign < align)
+                return NULL;
+        
+        /*
+         * The size of the allocated block needs to be naturally
+         * aligned, because the footer structure also needs to reside
+         * on a naturally aligned address in order to avoid unaligned
+         * memory accesses.
+         */
+        size_t gross_size = GROSS_SIZE(ALIGN_UP(size, BASE_ALIGN));
         
         /* Try the next fit approach */
-        split = next_fit;
+        heap_block_head_t *split = next_fit;
         
         if (split != NULL) {
-                void *addr = malloc_area(split->area, split, NULL, real_size,
+                void *addr = malloc_area(split->area, split, NULL, gross_size,
                     falign);
                 
@@ -703 +745 @@
                     AREA_FIRST_BLOCK_HEAD(area);
                 
-                void *addr = malloc_area(area, first, split, real_size,
+                void *addr = malloc_area(area, first, split, gross_size,
                     falign);
                 
@@ -710 +752 @@
         }
         
-        if (!retry) {
-                /* Try to grow the heap space */
-                if (heap_grow(real_size)) {
-                        retry = true;
-                        goto loop;
-                }
-        }
-        
-        return NULL;
+        /* Finally, try to grow heap space and allocate in the new area. */
+        return heap_grow_and_alloc(gross_size, falign);
 }
 
@@ -731 +766 @@
 void *calloc(const size_t nmemb, const size_t size)
 {
+        // FIXME: Check for overflow
+        
         void *block = malloc(nmemb * size);
         if (block == NULL)
@@ -870 +907 @@
         if (addr == NULL)
                 return;
-
+        
         futex_down(&malloc_futex);