Fixed null argv segfault and cli.c can handle --help option

groundStation/src/cli/cli.c

@@ -2,6 +2,7 @@
 #include <string.h>
 #include <err.h>
 #include <libgen.h>
+#include <getopt.h>
 
 #include "cli.h"
 
@@ -9,9 +10,20 @@ int main(int argc, char **argv)
 {
 	int cmdID = -1;
 	char * command;
+	int c;
 	int i , useSymlink = 0;
 	struct backend_conn  *conn;
+	static int needHelp = 0;
+	static struct option long_options[] = {
+ 		/* These options don’t set a flag. We distinguish them by their indices. */
+ 		{"help",	no_argument,	&needHelp,	1},
+ 		{0, 0, 0, 0}
+ 	};
 
+ 	int option_index = 0;
+	c = getopt_long(argc, argv, "", long_options, &option_index);
+
+	// Determine if the cli was called using a symlink
 	command = basename(argv[0]);
 	for(i = 0; i < MAX_COMMANDS; ++i) {
 		if (strncmp(command, commandNames[i], strlen(commandNames[i])) == 0)
@@ -21,6 +33,28 @@ int main(int argc, char **argv)
 		}
 	}
 
+	// Verify the user has entered enough information to continue
+	if(argc < 2 && !useSymlink) {
+		printf("Incorrect usage :\n");
+		printf("\n\tUsage : ./Cli command [options] \n");
+		printf("\tFor a list of available commands run ./Cli --help\n\n");
+		printf("\tFor a list of available options for a command run ./Cli command --help\n");
+		return -1;
+	}
+
+	// If the user runs './Cli help' , provide the user with a list of commands available.
+	if(needHelp) {
+		printf("Usage : ./Cli command [options]\n");
+		printf("For a list of available options for a command run ./Cli command --help\n\n");
+		printf("Available commands include the following\n");
+		for(int i = 0; i < MAX_COMMANDS; ++i) {
+			printf("\t '%s'\n",commandNames[i]);
+		}
+		return 0;
+	}
+
+
+	// recognize which cli command the user has entered
 	if(cmdID == -1) {
 		command = argv[1];
 		for(i = 0; i < MAX_COMMANDS; ++i) {
@@ -32,22 +66,41 @@ int main(int argc, char **argv)
 	}
 
 	if(cmdID == -1){
-		printf("Could not match input with a command. Please try again...\n");
+		printf("Could not match '%s' with a command. Please try again...\n", command);
+		printf("For help running the program, run ./Cli --help\n");
 		return -1;
 	}
 
 	printf("Parsed Command : %s\n", commandNames[cmdID]);
-	conn = ucart_backendConnect();
-	if(conn == NULL) {
-		return -1;
+
+	/**
+	 * I the user has asked for help, and we have already found
+	 *  the command that they are trying to use. Then we need
+	 *  to be able to provide the help info wihtout the 
+	 *  requirement of the backend
+	 *
+	 * It is important to note that this will only work if the 
+	 * 	command the user has asked for handles this help case 
+	 * 
+	 */
+
+	// Only require the backend if we will need to use it.
+	if(!needHelp) {
+		// Create the connection to the backend
+		conn = ucart_backendConnect();
+		if(conn == NULL) {
+			return -1;
+		}
 	}
 
+	// Call the appropriate function
 	if(useSymlink) {
 		(*cli_functions[cmdID]) (conn, argc, &argv[0]);
 	}else {
 		(*cli_functions[cmdID]) (conn, argc-1, &argv[1]);
 	}
 
+	// Disconnect from the backend
 	ucart_backendDisconnect(conn);
     return 0;
-}
+}
\ No newline at end of file

groundStation/src/cli/cli.h

@@ -4,7 +4,8 @@
 #include "cli_monitor.h"
 #include "cli_setpid.h"
 #include "cli_getpid.h"
-// #include "cli_getimu.h"
+#include "cli_getimu.h"
+
 enum CommandNameIds{
 	CMD_MONITOR,
 	CMD_GETPID,
@@ -17,16 +18,14 @@ typedef int (*cli_function_ptr)(struct backend_conn *, int, char **);
 static cli_function_ptr cli_functions[] = {
 	&cli_monitor,
 	&cli_getpid,
-	&cli_setpid
-	//&cli_getimu
+	&cli_setpid,
+	&cli_getimu
 };
 
 static char* commandNames[MAX_COMMANDS] = {
 	"monitor",
 	"getpid",
 	"setpid",
-	"getImu"
+	"getimu"
 };
-
-
 #endif

groundStation/src/cli/cli_getimu.c

+#include <stdio.h>
+
+#include "cli_getimu.h"
+
+int cli_getimu(struct backend_conn * conn, int argc, char ** argv) {
+	printf("This functionality has not been added yet\n");
+	return 0;
+}

groundStation/src/cli/cli_getimu.h

 #ifndef CLI_GETIMU_H
 #define CLI_GETIMU_H
+
 #include "frontend_getimu.h"
 
-int cli_getimu(
-		struct backend_conn * conn,
-		struct frontend_pid_data * pid_data);
+int cli_getimu(struct backend_conn * conn, int argc, char ** argv);
 
 #endif
\ No newline at end of file

groundStation/src/cli/cli_monitor.c

@@ -17,7 +17,6 @@ int cli_monitor(struct backend_conn * conn,	int argc, char **argv) {
 	int count, rate = 10;
 	int forever = 0;
 
-
  	while ((c = getopt(argc, argv, "fc:r:")) != -1) {
 		switch(c) {
 			case 'c' :

groundStation/src/frontend/frontend_getimu.h

+#ifndef FRONTEND_GETIMU_H
+#define FRONTEND_GETIMU_H
+
+#include "frontend_common.h"
+
+#endif
\ No newline at end of file