fix a bug with dirname seg faulting when passed a string literal

it doesnt like things in readonly memory i guess.

now we create an arena for the obj load and create a dynamically allocated copy of the string

6 files changed, 23 insertions, 8 deletions

diff --git a/examples/obj_loading/ex_obj_loading.c b/examples/obj_loading/ex_obj_loading.c
index ecb2e54..6e63938 100644
--- a/examples/obj_loading/ex_obj_loading.c
+++ b/examples/obj_loading/ex_obj_loading.c
@@ -60,8 +60,8 @@ int main() {
     render_frame_begin(&core->renderer);
 
     // Draw the backpack
-    transform model_tf =
-        transform_create(vec3(0.0, -0.4, 0.0), quat_ident(), 1.8);  // make the backpack a bit bigger
+    transform model_tf = transform_create(vec3(0.0, -0.4, 0.0), quat_ident(),
+                                          1.8);  // make the backpack a bit bigger
     draw_model(&core->renderer, &cam, backpack, model_tf, &our_scene);
 
     render_frame_end(&core->renderer);
diff --git a/src/platform/path.c b/src/platform/path.c
index e67102b..9572941 100644
--- a/src/platform/path.c
+++ b/src/platform/path.c
@@ -1,12 +1,17 @@
 #include "path.h"
 
 #include <libgen.h>
+#include <stdlib.h>
 #include <string.h>
+#include "mem.h"
 #include "str.h"
 
 #if defined(CEL_PLATFORM_LINUX) || defined(CEL_PLATFORM_MAC)
-path_opt path_parent(const char* path) {
-  char* path_dirname = dirname(path);
+path_opt path_parent(arena* a, const char* path) {
+  // Duplicate the string because dirname doesnt like const literals
+  char* path_copy = arena_alloc(a, strlen(path) + 1);
+  strcpy(path_copy, path);
+  char* path_dirname = dirname(path_copy);
   return (path_opt){ .path = str8_cstr_view(path_dirname), .has_value = true };
 }
 #endif
diff --git a/src/platform/path.h b/src/platform/path.h
index 0ec6993..73063ea 100644
--- a/src/platform/path.h
+++ b/src/platform/path.h
@@ -13,4 +13,4 @@ typedef struct path_opt {
   bool has_value;
 } path_opt;
 
-path_opt path_parent(const char* path);  // TODO: convert to using str8
\ No newline at end of file
+path_opt path_parent(arena* a, const char* path);  // TODO: convert to using str8
\ No newline at end of file
diff --git a/src/resources/obj.c b/src/resources/obj.c
index 56f885f..c6e9fa6 100644
--- a/src/resources/obj.c
+++ b/src/resources/obj.c
@@ -15,6 +15,7 @@
 #include "file.h"
 #include "log.h"
 #include "maths.h"
+#include "mem.h"
 #include "path.h"
 #include "render.h"
 #include "render_types.h"
@@ -40,8 +41,11 @@ bool model_load_obj_str(const char *file_string, str8 relative_path, model *out_
                         bool invert_textures_y);
 
 model_handle model_load_obj(core *core, const char *path, bool invert_textures_y) {
+  size_t arena_size = 1024;
+  arena scratch = arena_create(malloc(arena_size), arena_size);
+
   TRACE("Loading model at Path %s\n", path);
-  path_opt relative_path = path_parent(path);
+  path_opt relative_path = path_parent(&scratch, path);
   if (!relative_path.has_value) {
     WARN("Couldnt get a relative path for the path to use for loading materials & textures later");
   }
@@ -61,6 +65,9 @@ model_handle model_load_obj(core *core, const char *path, bool invert_textures_y
 
   u32 index = model_darray_len(core->models);
   model_darray_push(core->models, model);
+
+  arena_free_all(&scratch);
+  arena_free_storage(&scratch);
   return (model_handle){ .raw = index };
 }
 
diff --git a/src/std/mem.c b/src/std/mem.c
index f5b92d4..d7c0f4c 100644
--- a/src/std/mem.c
+++ b/src/std/mem.c
@@ -16,7 +16,7 @@ void* arena_alloc_align(arena* a, size_t size, size_t align) {
     ERROR_EXIT("Arena ran out of memory\n");
   }
   void* p = a->begin + padding;
-  a->begin += padding + size;
+  a->curr += padding + size;
   return memset(p, 0, size);
 }
 void* arena_alloc(arena* a, size_t size) { return arena_alloc_align(a, size, DEFAULT_ALIGNMENT); }
@@ -29,4 +29,6 @@ arena arena_create(void* backing_buffer, size_t capacity) {
 
 void arena_free_all(arena* a) {
   a->curr = a->begin;  // pop everything at once and reset to the start.
-}
\ No newline at end of file
+}
+
+void arena_free_storage(arena* a) { free(a->begin); }
\ No newline at end of file
diff --git a/src/std/mem.h b/src/std/mem.h
index c3ec61d..2f92894 100644
--- a/src/std/mem.h
+++ b/src/std/mem.h
@@ -22,4 +22,5 @@ arena arena_create(void* backing_buffer, size_t capacity);
 void* arena_alloc(arena* a, size_t size);
 void* arena_alloc_align(arena* a, size_t size, size_t align);
 void arena_free_all(arena* a);
+void arena_free_storage(arena* a);
 // TODO: arena_resize
\ No newline at end of file