Auto-deleting mode-exclusive content files, new functions files.write_accessible() and files.delete_this()

_src/build.py

@@ -12,7 +12,7 @@ from functools import partial
 import apis # from itself
 import traceback
 from item import Item # from itself
-from files import save_this, link_this, scan_dir # from itself
+from files import save_this, link_this, scan_dir, delete_this # from itself
 from config import config # from itself
 
 def template_for(path: str) -> str:
@@ -198,6 +198,10 @@ if __name__ == '__main__':
     for path in content_files:
         print('F', path)
         
+        if path.endswith('.gmi'):
+            html_path = os.path.splitext(path)[0]+'.html'
+        else:
+            html_path = path
         item = Item(path)
         
         # parsing in gemini mode
@@ -244,7 +248,8 @@ if __name__ == '__main__':
             save_this('../'+path, content)
         else:
             print(' ! skipped for gemini')
-            # TODO: delete from gemini output
+            # delete from gemini output
+            delete_this('../'+path)
         
         # parsing in www mode
         if not 'mode' in item or item.mode == 'www':
@@ -273,10 +278,8 @@ if __name__ == '__main__':
                     content = evaluate_this(tpl_item.content, namespace)
             
             # convert to html
-            html_path = path
             if path.endswith('.gmi'):
                 content = gemtext2html(content)
-                html_path = os.path.splitext(path)[0]+'.html'
             
             if html_path.endswith('.html'):            
                 # TODO: html template
@@ -288,4 +291,5 @@ if __name__ == '__main__':
             save_this('../html/'+html_path, content)
         else:
             print(' ! skipped for www')
-            # TODO: delete from www output
+            # delete from www output
+            delete_this('../html/'+html_path)

_src/files.py

@@ -1,4 +1,5 @@
 import os
+import sys
 
 cache = {} # globally shared object to store file content
 
@@ -21,6 +22,10 @@ def save_this(path: str, content: str):
     """
     global cache
     
+    # access control
+    if not write_accessible(path, follow_symlinks=False):
+        raise PermissionError(f"Attempted to write to {os.path.abspath(path)}")
+    
     mkdir_this(os.path.dirname(path))
     with open(path, 'w') as fp:
         fp.write(content)
@@ -81,3 +86,39 @@ def scan_dir(path: str, orig_path=None) -> list:
             results += scan_dir(entry.path, orig_path)
     
     return results
+
+def write_accessible(path: str, follow_symlinks: bool = True) -> bool:
+    """Tells whether the file is in safe area (outside _src, .git, parent dirs)
+    Technically, nothing stops build.py from writing there, but to avoid data
+    loss as a result of a bug, you should always check what file you're trying
+    to delete or write to.
+    """
+    
+    PROTECTED_DIRS = (sys.path[0], '../_src', '../.git')
+    
+    path = os.path.realpath(path) if follow_symlinks else os.path.abspath(path)
+    project_root = os.path.dirname(sys.path[0])
+    
+    # protect upper dirs
+    if os.path.commonpath((path, project_root)) != project_root: return False
+    
+    # protect lower dirs
+    for protected in PROTECTED_DIRS:
+        protected = os.path.realpath(protected)
+        if os.path.commonpath((path, protected)) == protected:
+            return False
+    
+    return True
+
+def delete_this(path: str):
+    """Deletes a file if it exists"""
+    
+    if not write_accessible(path, follow_symlinks=False):
+        raise PermissionError(f"Attempted to delete {os.path.abspath(path)}")
+    
+    if not os.path.isfile(path): return
+    
+    os.unlink(path)
+    print('file deleted!')
+    
+    # TODO: cleanup empty directories