swaymsg: add timeout and type checks

This adds a 3 second timeout to the initial reply in swaymsg. This
prevents swaymsg from hanging when `swaymsg -t get_{inputs,seats}` is
used in i3. The timeout is removed when waiting for a subscribed event
or monitoring for subscribed events.

This also adds type checks to commands where i3 does not reply with all
of the properties that sway does (such as `modes` in `get_outputs`).

This is mostly just a behavioral adjustment since swaymsg should run on
i3. When running under i3, some command reply's (such as the one for
`get_outputs) may have more useful information in the raw json than the
pretty printed version.

3 files changed, 26 insertions, 1 deletions

diff --git a/common/ipc-client.c b/common/ipc-client.c
index 13e2dfa3..b6c03d13 100644
--- a/common/ipc-client.c
+++ b/common/ipc-client.c
@@ -69,6 +69,16 @@ int ipc_open_socket(const char *socket_path) {
         return socketfd;
 }
 
+bool ipc_set_recv_timeout(int socketfd, struct timeval tv) {
+        if (setsockopt(socketfd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)) == -1) {
+                sway_log_errno(SWAY_ERROR, "Failed to set ipc recv timeout");
+                return false;
+        }
+        sway_log(SWAY_DEBUG, "ipc recv timeout set to %ld.%06ld",
+                        tv.tv_sec, tv.tv_usec);
+        return true;
+}
+
 struct ipc_response *ipc_recv_response(int socketfd) {
         char data[IPC_HEADER_SIZE];
         uint32_t *data32 = (uint32_t *)(data + sizeof(ipc_magic));
diff --git a/include/ipc-client.h b/include/ipc-client.h
index c9f5b344..d3895023 100644
--- a/include/ipc-client.h
+++ b/include/ipc-client.h
@@ -1,7 +1,9 @@
 #ifndef _SWAY_IPC_CLIENT_H
 #define _SWAY_IPC_CLIENT_H
 
+#include <stdbool.h>
 #include <stdint.h>
+#include <sys/time.h>
 
 #include "ipc.h"
 
@@ -36,5 +38,9 @@ struct ipc_response *ipc_recv_response(int socketfd);
  * Free ipc_response struct
  */
 void free_ipc_response(struct ipc_response *response);
+/**
+ * Sets the receive timeout for the IPC socket
+ */
+bool ipc_set_recv_timeout(int socketfd, struct timeval tv);
 
 #endif
diff --git a/swaymsg/main.c b/swaymsg/main.c
index ccc847f5..518993af 100644
--- a/swaymsg/main.c
+++ b/swaymsg/main.c
@@ -7,6 +7,7 @@
 #include <stdint.h>
 #include <sys/un.h>
 #include <sys/socket.h>
+#include <sys/time.h>
 #include <ctype.h>
 #include <unistd.h>
 #include <json.h>
@@ -238,7 +239,8 @@ static void pretty_print_output(json_object *o) {
                 );
         }
 
-        size_t modes_len = json_object_array_length(modes);
+        size_t modes_len = json_object_is_type(modes, json_type_array)
+                ? json_object_array_length(modes) : 0;
         if (modes_len > 0) {
                 printf("  Available modes:\n");
                 for (size_t i = 0; i < modes_len; ++i) {
@@ -448,6 +450,8 @@ int main(int argc, char **argv) {
 
         int ret = 0;
         int socketfd = ipc_open_socket(socket_path);
+        struct timeval timeout = {.tv_sec = 3, .tv_usec = 0};
+        ipc_set_recv_timeout(socketfd, timeout);
         uint32_t len = strlen(command);
         char *resp = ipc_single_command(socketfd, type, command, &len);
         if (!quiet) {
@@ -478,6 +482,11 @@ int main(int argc, char **argv) {
         free(resp);
 
         if (type == IPC_SUBSCRIBE && ret == 0) {
+                // Remove the timeout for subscribed events
+                timeout.tv_sec = 0;
+                timeout.tv_usec = 0;
+                ipc_set_recv_timeout(socketfd, timeout);
+
                 do {
                         struct ipc_response *reply = ipc_recv_response(socketfd);
                         if (!reply) {