Added basic error handling for SIGINT.

sample/bot_runner.c

@@ -1,3 +1,5 @@
+#include <errno.h>
+#include <signal.h>
 #include <stdio.h>
 #include <time.h>
 #include "sample_defender.h"
@@ -6,27 +8,33 @@
 #include "protocol.h"
 #include "bot.h"
 #include "api.h"
+#include "exceptions.h"
 
 #define SERVER_NAME "localhost"
 #define DEFAULT_SERVER_PORT 25565
 #define NUM_BOTS 2
 
+extern int errno;
+
 int main(int argc, char *argv[], char **envp)
 {
     char *server_name = SERVER_NAME;
-    int server_port = DEFAULT_SERVER_PORT;
+    int server_port = DEFAULT_SERVER_PORT;\
+
+    signal(SIGINT, internal_error);
+
     if (argc == 3) {
         server_name = argv[1];
         server_port = strtol(argv[2], NULL, 10);
         if (!server_port) {
-            printf("Expected arguments: ./mcc [<SERVER> [<PORT>]]\n");
-            return 0;
+            errno = 1001;
+            raise(SIGINT);
         }
     } else if (argc == 2) {
         server_name = argv[1];
     } else if (argc > 3) {
-        printf("Expected arguments: ./mcc [<SERVER> [<PORT>]]\n");
-        return 0;
+        errno = 1000;
+        raise(SIGINT);
     }
 
     bot_t *bots[NUM_BOTS];

sample/exceptions.h

@@ -0,0 +1,44 @@
+#include <stdio.h>
+#include <errno.h>
+#include <signal.h>
+#include <stdlib.h>
+
+/*
+ * Acts as an exception handler. Probably hacky, but works well. By declaring
+ * the extern int errno and registering internal_error as the SIGINT signal
+ * handler, this function prints nice error messages and writes to a log
+ * before quitting.
+ */
+
+static void internal_error(int signal) {
+    printf("\nCaught error. Code: %d\n", errno);
+    switch errno {
+        case 0:
+            printf("Program terminated by user.\n");
+            exit(EXIT_SUCCESS);
+        case 1000:
+            printf("Invalid arguments.\n"
+                   "Expected arguments: ./mcc [<SERVER> [<PORT>]]\n");
+            exit(EXIT_FAILURE);
+            break;
+        case 1001:
+            printf("Invalid port.\n"
+                   "Expected arguments: ./mcc [<SERVER> [<PORT>]]\n");
+            exit(EXIT_FAILURE);
+            break;
+        case 3000:
+            printf("Got a non-positive packet\n");
+            exit(EXIT_FAILURE);
+        case 3001:
+            printf("Got packet of size 0.\n");
+            exit(EXIT_FAILURE);
+        case 3002:
+            printf("Packet len isn't right.\n");
+            exit(EXIT_FAILURE);
+        default:
+            printf("Undocumented error code :(\n");
+            exit(EXIT_FAILURE);
+            break;
+    }
+
+}

src/api.c

@@ -53,7 +53,10 @@ bool next_int_token(int* value, char *string, char **saveptr)
 
 void execute_command(bot_t *bot, char *command, char *strargs)
 {
-    if (strcmp(command, "slot") == 0) {
+    if (strcmp(command, "help") == 0) {
+        send_play_serverbound_chat(bot, "Available commands:");
+        send_play_serverbound_chat(bot, "slot, ");
+    } else if (strcmp(command, "slot") == 0) {
         char **saveptr = calloc(1, sizeof(char *));
         bool valid_input = true;
         char *token = NULL;

src/bot.c

@@ -1,5 +1,7 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <signal.h>
+#include <errno.h>
 #include <sys/socket.h>
 #include <sys/types.h>
 #include <sys/time.h>
@@ -8,7 +10,6 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
-#include <assert.h>
 #include "bot.h"
 #include "protocol.h"
 #include "marshal.h"
@@ -195,17 +196,24 @@ int receive_packet(bot_t *bot)
     memset(bot->_data->buf, 0, bot->_data->packet_threshold);
     for (i = 0; i < 5; i++) {
         ret = receive_raw(bot, bot->_data->buf + i, 1);
-        if (ret <= 0)
-            return -1;
+        if (ret <= 0) {
+            errno = 3000;
+            raise(SIGINT);
+        }
         if (!expect_more(bot->_data->buf[i]))
             break;
     }
 
     len = varint32(bot->_data->buf, &packet_size);
-    if (packet_size == 0)
-        return -2;
+    if (packet_size == 0) {
+        errno = 3001;
+        raise(SIGINT);
+    }
 
-    assert(i != len);
+    if (i == len) {
+        errno = 3002;
+        raise(SIGINT);
+    }
 
     packet_size += len;
     received = i + 1;

src/protocol.c

@@ -1,4 +1,6 @@
 #include <stdio.h>
+#include <signal.h>
+#include <errno.h>
 #include "protocol.h"
 #include "marshal.h"
 #include "bot.h"
@@ -19,6 +21,8 @@
     length = format_packet(BOT, &PACKET, (void *) &packet);   \
     send_raw(bot, packet, length);                            \
 
+extern int errno;
+
 /*
  * Handshaking serverbound functions
  */
@@ -573,7 +577,10 @@ void *protocol_decode(bot_t *bot)
 {
     int32_t pid = receive_packet(bot);
     if (pid < 0) {
-        if (pid == -1) exit(123);
+        if (pid == -1) {
+            errno = 2000;
+            raise(SIGINT);            
+        }
         return NULL;
     }
     void *recv_struct = NULL;