Merge pull request 'bugfix/hanging-background-processes' (#54) from bugfix/hanging-background-processes into master

Reviewed-on: https://192.168.8.63/git/darthrubik/drharness/pulls/54

tests/test_tool_shell.sh

@@ -41,6 +41,15 @@ timeout 5s "${DRHARNESS}" -F chat3.json -n -m "This is a test" -t run_dangerous_
 
 echo "PASS: tool_shell"
 
+tool_call run_dangerous_shell '{"command":"printf \"test\"; sleep 10 &","timeout_seconds":1}' >> background_task_test.txt
+be_done 'done' >> background_task_test.txt
+
+# If we hit the timeout of the timeout utility then we fail
+timeout 5s "${DRHARNESS}" -F background_task_test.json -n -m "This is a test" -t run_dangerous_shell -d < "background_task_test.txt"
+
+echo "PASS: background_task_test"
+
+
 
 seq 1 1044 > long_file
 tool_call run_dangerous_shell '{"command":"cat long_file"}' >> mock_responses4.txt

tools/shell_tool.cpp

@@ -128,19 +128,20 @@ Tool make_shell_tool(bool safe) {
                     break; 
                 }
 
-                // 3. Read data if available - keep reading until no more data
+                // 3. Read data if available - read once, don't block waiting for more
+                // If POLLHUP is not set, a background process may keep the pipe open,
+                // so we can't read in a loop (would block waiting for more data).
                 if (pfd.revents & POLLIN) {
-                    while (true) {
-                        res = read(pfd.fd, buf.data(), buf.size());
-                        if (res < 0) {
-                            if (errno == EINTR) continue; // Restart if interrupted by signal
-                            break; // Error
-                        } else if (res == 0) { // EOF
-                            break;
-                        }
+                    res = read(pfd.fd, buf.data(), buf.size());
+                    if (res > 0) {
                         output += std::string(buf.data(), res);
                     }
-                    break;
+                    // If POLLHUP is also set, we're done
+                    if (pfd.revents & POLLHUP) {
+                        break;
+                    }
+                    // Otherwise, continue polling for more data or timeout
+                    // Don't break here - continue the loop
                 }
                 
             }