Fix path concatenation.

2 files changed, 13 insertions, 9 deletions

diff --git a/filesystem/include/filesystem.h b/filesystem/include/filesystem.h
index 62bd7f0..3dce87f 100644
--- a/filesystem/include/filesystem.h
+++ b/filesystem/include/filesystem.h
@@ -15,5 +15,5 @@ void* read_file(const char* filepath);
 
 /// Make a path relative to the parent directory of a file.
 bool make_relative_path(
-    size_t max_path_length, const char* filepath, const char* path,
-    char* relative);
+    const char* filepath, const char* path, char* relative,
+    size_t relative_length);
diff --git a/filesystem/src/filesystem.c b/filesystem/src/filesystem.c
index 6c0dcfb..5a8eeec 100644
--- a/filesystem/src/filesystem.c
+++ b/filesystem/src/filesystem.c
@@ -56,20 +56,23 @@ cleanup:
 }
 
 bool make_relative_path(
-    size_t max_path_length, const char* filepath, const char* path,
-    char* relative) {
+    const char* filepath, const char* path, char* relative,
+    size_t relative_length) {
   assert(filepath);
   assert(path);
   assert(relative);
 
-  // Handle empty filepath.
   const size_t filepath_len = strlen(filepath);
+  const size_t path_len     = strlen(path);
+  assert(filepath_len < relative_length);
+  assert(path_len < relative_length);
+
+  // Handle empty filepath.
   if (filepath_len == 0) {
-    memcpy(relative, path, max_path_length);
+    memcpy(relative, path, path_len);
     return true;
   }
 
-  memcpy(relative, filepath, max_path_length);
   // Search for the last / in the tile map file path to get its parent
   // directory.
   assert(filepath_len > 0);
@@ -83,10 +86,11 @@ bool make_relative_path(
 
   // Copy the tile set file path where the parent dir ends.
   // Make sure there is enough space in the output.
-  const size_t path_len = strlen(path);
-  if ((tm_dir_len + path_len + 1) >= max_path_length) {
+  if ((tm_dir_len + path_len + 1) >= relative_length) {
     return false;
   }
+  memcpy(relative, filepath, tm_dir_len);
   memcpy(&relative[tm_dir_len], path, path_len);
+
   return true;
 }