fix: Resolve critical bugs - file handle leaks and IndexError issues

Fixed multiple critical bugs identified during comprehensive code audit:

**Critical Fixes:**
- Fix file handle leaks in SDK client upload methods (sync and async)
  - Use context managers to ensure file handles are properly closed
  - Affects: sdk/src/fuzzforge_sdk/client.py lines 397, 484

**High Priority Fixes:**
- Fix IndexError in OSS-Fuzz stats parsing when accessing array elements
  - Add bounds checking before accessing parts[i+1]
  - Affects: workers/ossfuzz/activities.py lines 372-376

- Fix IndexError in exception handling URL parsing
  - Add empty string validation before splitting URL segments
  - Prevents crash when parsing malformed URLs
  - Affects: sdk/src/fuzzforge_sdk/exceptions.py lines 419-426

**Medium Priority Fixes:**
- Fix IndexError in Android workflow SARIF report parsing
  - Check if runs list is empty before accessing first element
  - Affects: backend/toolbox/workflows/android_static_analysis/workflow.py line 270

All fixes follow defensive programming practices with proper bounds checking
and resource management using context managers.

sdk/src/fuzzforge_sdk/client.py

@@ -393,10 +393,6 @@ class FuzzForgeClient:
             # Prepare multipart form data
             url = urljoin(self.base_url, f"/workflows/{workflow_name}/upload-and-submit")
 
-            files = {
-                "file": (filename, open(upload_file, "rb"), "application/gzip")
-            }
-
             data = {}
 
             if parameters:
@@ -418,13 +414,15 @@ class FuzzForgeClient:
                 # This is a placeholder - real implementation would need custom approach
                 pass
 
-            response = self._client.post(url, files=files, data=data)
+            # Use context manager to ensure file handle is closed
+            with open(upload_file, "rb") as f:
+                files = {
+                    "file": (filename, f, "application/gzip")
+                }
+                response = self._client.post(url, files=files, data=data)
 
-            # Close file handle
-            files["file"][1].close()
-
-            data = self._handle_response(response)
-            return RunSubmissionResponse(**data)
+            response_data = self._handle_response(response)
+            return RunSubmissionResponse(**response_data)
 
         finally:
             # Cleanup temporary tarball
@@ -480,10 +478,6 @@ class FuzzForgeClient:
             # Prepare multipart form data
             url = urljoin(self.base_url, f"/workflows/{workflow_name}/upload-and-submit")
 
-            files = {
-                "file": (filename, open(upload_file, "rb"), "application/gzip")
-            }
-
             data = {}
 
             if parameters:
@@ -494,10 +488,12 @@ class FuzzForgeClient:
 
             logger.info(f"Uploading {filename} to {workflow_name}...")
 
-            response = await self._async_client.post(url, files=files, data=data)
-
-            # Close file handle
-            files["file"][1].close()
+            # Use context manager to ensure file handle is closed
+            with open(upload_file, "rb") as f:
+                files = {
+                    "file": (filename, f, "application/gzip")
+                }
+                response = await self._async_client.post(url, files=files, data=data)
 
             response_data = await self._ahandle_response(response)
             return RunSubmissionResponse(**response_data)

sdk/src/fuzzforge_sdk/exceptions.py

@@ -415,16 +415,20 @@ def from_http_error(status_code: int, response_text: str, url: str) -> FuzzForge
         if "/workflows/" in url and "/submit" not in url:
             # Extract workflow name from URL
             parts = url.split("/workflows/")
-            if len(parts) > 1:
-                workflow_name = parts[1].split("/")[0]
-                return WorkflowNotFoundError(workflow_name, context=context)
+            if len(parts) > 1 and parts[1]:
+                workflow_segments = parts[1].split("/")
+                if workflow_segments and workflow_segments[0]:
+                    workflow_name = workflow_segments[0]
+                    return WorkflowNotFoundError(workflow_name, context=context)
 
         elif "/runs/" in url:
             # Extract run ID from URL
             parts = url.split("/runs/")
-            if len(parts) > 1:
-                run_id = parts[1].split("/")[0]
-                return RunNotFoundError(run_id, context)
+            if len(parts) > 1 and parts[1]:
+                run_segments = parts[1].split("/")
+                if run_segments and run_segments[0]:
+                    run_id = run_segments[0]
+                    return RunNotFoundError(run_id, context)
 
     elif status_code == 400:
         # Check for specific error patterns in response