Added test harness

main.c

@@ -4,6 +4,7 @@
 #include <stddef.h>
 #include <unistd.h>
 #include <sys/mman.h>
+#include <string.h>
 
 #include "alloc_api.h"
 
@@ -23,9 +24,10 @@ struct AllocationRecord {
   uintptr_t size;
   void *allocation;
   void *reference;
+  int id;
   struct AllocationRecord *next;
   struct AllocationRecord *prev;
-}
+};
 
 void insert_record(struct AllocationRecord *dummy, void *allocation, uintptr_t size) {
   struct AllocationRecord *record = malloc(sizeof(struct AllocationRecord));
@@ -34,9 +36,11 @@ void insert_record(struct AllocationRecord *dummy, void *allocation, uintptr_t s
   record->reference = malloc(size);
   record->next = dummy;
   record->prev = dummy->prev;
+  record->id = dummy->id;
   dummy->prev->next = record;
   dummy->prev = record;
   dummy->size += 1;
+  dummy->id += 1;
   memcpy(record->reference, allocation, size);
 }
 
@@ -48,6 +52,14 @@ void delete_record(struct AllocationRecord *dummy, struct AllocationRecord *dele
   dummy->size -= 1;
 }
 
+struct AllocationRecord *get_record(struct AllocationRecord *dummy, int which) {
+  struct AllocationRecord *head = dummy->next;
+  while (--which) {
+    head = head->next;
+  }
+  return head;
+}
+
 int validate_record(struct AllocationRecord *record) {
   if (memcmp(record->allocation, record->reference, record->size) != 0) {
     return 0;
@@ -55,8 +67,48 @@ int validate_record(struct AllocationRecord *record) {
   return 1;
 }
 
+void new_region(struct AllocationRecord *dummy, struct Arena *arena) {
+  int size = 1 + (rand() % 8192);
+  int align = 1 << (rand() % 4);
+  void *region = alloc(arena, size, align);
+  if (region == NULL) {
+    printf("memory allocator broke, we have 1L though\n");
+    return;
+  }
+  for (int ii = 0; ii < size; ii++) {
+    ((char*) region)[ii] = (char) rand();
+  }
+  insert_record(dummy, region, size);
+}
+
+void delete_region(struct AllocationRecord *dummy, struct Arena *arena) {
+  if (dummy->size == 0) {
+    return;
+  }
+  uintptr_t which = rand() % dummy->size;
+  struct AllocationRecord *zap = get_record(dummy, which);
+  unalloc(arena, zap->allocation);
+  delete_record(dummy, zap);
+}
+
+int act(struct AllocationRecord *dummy, struct Arena *arena) {
+  if (rand() & 1) {
+    new_region(dummy, arena);
+  } else {
+    delete_region(dummy, arena);
+  }
+  int die = 0;
+  struct AllocationRecord *head = dummy->next;
+  while (head != dummy) {
+    if (!validate_record(head)) {
+      printf("validation failed at id %i\n", head->id);
+      die = 1;
+    }
+  }
+  return die;
+}
+
 int main() {
-	printf("Hello, World!\n");
   struct Arena arena = {
     NULL,
     NULL,
@@ -65,5 +117,16 @@ int main() {
   };
   void *reg = alloc(&arena, 20, 4);
   unalloc(&arena, reg);
+  struct AllocationRecord dummy = {
+    .size = 0,
+    .allocation = NULL,
+    .reference = NULL,
+    .id = 0,
+  };
+  dummy.next = &dummy;
+  dummy.prev = &dummy;
+  for (int ii = 0; ii < 100; ii++) {
+    act(&dummy, &arena);
+  }
 	return 0;
 }

util.c

@@ -15,7 +15,7 @@ void* align_after(void* address, int align) {
     rv = (void*) (addr + align - align % offset);
   }
 #ifdef DEBUG
-  printf("aligning %p at alignment %lx to %p\n", address, align, rv);
+  printf("aligning %p at alignment %x to %p\n", address, align, rv);
 #endif
   return rv;
 }