Merge pull request #1631 from volatilityfoundation/issues/issue1408

Issues/issue1408 - Delete partial cache downloads

volatility3/framework/constants/__init__.py

@@ -120,6 +120,9 @@ OFFLINE = False
 REMOTE_ISF_URL = None  # 'http://localhost:8000/banners.json'
 """Remote URL to query for a list of ISF addresses"""
 
+DOWNLOAD_TIMEOUT = 30
+"""Length of time (in seconds) to wait for another process to download a resource before using it"""
+
 ###
 # DEPRECATED VALUES
 ###

volatility3/framework/layers/resources.py

@@ -177,33 +177,47 @@ class ResourceAccessor:
                     + ".cache",
                 )
 
+                try:
+                    content_length = int(fp.info().get("Content-Length", -1))
+                except (AttributeError, ValueError):
+                    # If our fp doesn't have an info member, carry on gracefully
+                    content_length = -1
+
                 if not os.path.exists(temp_filename):
                     vollog.debug(f"Caching file at: {temp_filename}")
+                    cache_file_size = -1
 
                     try:
-                        content_length = fp.info().get("Content-Length", -1)
-                    except AttributeError:
-                        # If our fp doesn't have an info member, carry on gracefully
-                        content_length = -1
-                    with open(temp_filename, "wb") as cache_file:
-                        count = 0
-                        block = fp.read(block_size)
-                        while block:
-                            count += len(block)
-                            if self._progress_callback:
-                                self._progress_callback(
-                                    count * 100 / max(count, int(content_length)),
-                                    f"Reading file {url}",
-                                )
-                            cache_file.write(block)
+                        with open(temp_filename, "wb") as cache_file:
+                            count = 0
                             block = fp.read(block_size)
+                            while block:
+                                count += len(block)
+                                if self._progress_callback:
+                                    self._progress_callback(
+                                        count * 100 / max(count, int(content_length)),
+                                        f"Reading file {url}",
+                                    )
+                                cache_file.write(block)
+                                block = fp.read(block_size)
+                            cache_file.seek(0, os.SEEK_END)
+                            cache_file_size = cache_file.tell()
+                    finally:
+                        if cache_file_size < content_length:
+                            os.remove(temp_filename)
+                            raise ValueError("Cached file did not download completely")
                 else:
-                    vollog.debug(f"Using already cached file at: {temp_filename}")
+                    vollog.debug(
+                        f"Trying to use already cached file at: {temp_filename}"
+                    )
+
                 # Re-open the cache with a different mode
                 # Since we don't want people thinking they're able to save to the cache file,
                 # open it in read mode only and allow breakages to happen if they wanted to write
                 curfile = open(temp_filename, mode="rb")
 
+        # Validate the hash or delete the temp_filename and report an error
+
         # Determine whether the file is a particular type of file, and if so, open it as such
         IMPORTED_MAGIC = False
         if HAS_MAGIC: