commands: Fix memory allocation in assign

Also use the safer snprintf since we just computed the size.

Signed-off-by: Quentin Glidic <sardemff7+git@sardemff7.net>

sway/commands.c

@@ -177,10 +177,10 @@ static struct cmd_results *cmd_assign(int argc, char **argv) {
 	}
 
 	char *movecmd = "move container to workspace ";
-	int arglen = strlen(*argv);
-	char *cmdlist = calloc(1, sizeof(movecmd) + arglen);
+	int arglen = strlen(movecmd) + strlen(*argv) + 1;
+	char *cmdlist = calloc(1, arglen);
 
-	sprintf(cmdlist, "%s%s", movecmd, *argv);
+	snprintf(cmdlist, arglen, "%s%s", movecmd, *argv);
 
 	struct criteria *crit = malloc(sizeof(struct criteria));
 	crit->crit_raw = strdup(criteria);