Update wapp_str8_alloc_buf to make a single big allocation

src/core/strings/str8/str8.c

@@ -1,9 +1,12 @@
 #include "str8.h"
 #include "aliases.h"
 #include "mem_allocator.h"
+#include <stddef.h>
 #include <string.h>
 #include <stdbool.h>
 
+#define STR8_BUF_ALLOC_SIZE(CAPACITY) (sizeof(Str8) + sizeof(c8) * CAPACITY)
+
 internal Str8List node_to_list(Str8Node *node);
 
 Str8 *wapp_str8_alloc_buf(const Allocator *allocator, u64 capacity) {
@@ -13,18 +16,12 @@ Str8 *wapp_str8_alloc_buf(const Allocator *allocator, u64 capacity) {
     goto RETURN_STR8;
   }
 
-  str = wapp_mem_allocator_alloc(allocator, sizeof(Str8));
+  str = wapp_mem_allocator_alloc(allocator, STR8_BUF_ALLOC_SIZE(capacity));
   if (!str) {
     goto RETURN_STR8;
   }
 
-  c8 *buf = wapp_mem_allocator_alloc(allocator, sizeof(c8) * capacity);
+  str->buf      = (u8 *)str + sizeof(Str8);
-  if (!buf) {
-    wapp_mem_allocator_free(allocator, (void **)&str, sizeof(Str8));
-    goto RETURN_STR8;
-  }
-
-  str->buf      = buf;
   str->size     = 0;
   str->capacity = capacity;
 
@@ -97,6 +94,14 @@ RETURN_ALLOC_SUBSTR:
   return output;
 }
 
+void wapp_str8_dealloc_buf(const Allocator *allocator, Str8 **str) {
+  if (!allocator || !str || !(*str)) {
+    return;
+  }
+
+  wapp_mem_allocator_free(allocator, (void **)str, STR8_BUF_ALLOC_SIZE((*str)->capacity));
+}
+
 c8 wapp_str8_get(const Str8 *str, u64 index) {
   if (index >= str->size) {
     return '\0';

src/core/strings/str8/str8.h

@@ -61,6 +61,9 @@ Str8 *wapp_str8_alloc_buf(const Allocator *allocator, u64 capacity);
 Str8 *wapp_str8_alloc_cstr(const Allocator *allocator, const char *str);
 Str8 *wapp_str8_alloc_str8(const Allocator *allocator, Str8RO *str);
 Str8 *wapp_str8_alloc_substr(const Allocator *allocator, Str8RO *str, u64 start, u64 end);
+// Only needed for allocators like malloc where each allocation has to be freed on its own.
+// No need to use it for allocators like Arena.
+void wapp_str8_dealloc_buf(const Allocator *allocator, Str8 **str);
 
 /**
  * Str8 utilities