fix(acronc): input <cmd><EOF> will cause illegal memory access

Cause:
1. stdin got cmd -> request
2. stdin got EOF -> ac_disconnect -> ac_conn becomes NULL
3. socket got response -> ac_receive(ac_conn) -> crash

Conclusion: ordering issue between ac_disconnect and socket read.

Solution:

Best way: pause the input until command returns
Cons:
1. Lost the advantage of background execution of commands (has to wait until done)
2. It is unreliable to determine if a command is done: although the current server implementation will not send anything else after an error or cmd_result, Minecraft server itself or future server implementations may. The spec does not say anything on termination.
Acronc currently assumes that after receiving an error or cmd_result with the same request ID, it is done. Then, it resumes the stdin, reads the EOF, and then disconnect.

Worse way: Directly call uv_read_stop before ac_disconnect
Cons: It is going to lose anything, including command results. This is particularly undesirable for ad-hoc calls (i.e. echo list | acronc).

Therefore, the current approach is to block and read as much as we can (until error or cmd_result), then stop reading the socket before disconnecting as a double safe.

Signed-off-by: Trumeet <yuuta@yuuta.moe>

1 files changed, 4 insertions, 0 deletions

diff --git a/client/acronc/handler.h b/client/acronc/handler.h
index 5764387..1beab1c 100644
--- a/client/acronc/handler.h
+++ b/client/acronc/handler.h
@@ -15,6 +15,10 @@ int h_signal(void (*on_quit)(void));
 int h_stdin(int (*on_input)(ac_request_t *req),
             void (*on_close)(void));
 
+int stdin_start(void);
+
+void stdin_stop(void);
+
 int h_socket(ac_connection_parameters_t *p,
              const struct addrinfo *ai,
              void (*on_connect_result)(bool),