stuff

02-TeenyTinyShell/ttsh.c

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+/*************************************
+ * 
+ * Class: CS3840 - YOUR SECTION HERE
+ * 
+ * Name(s): YOUR NAME(S) HERE
+ * 
+ * Lab: Teeny Tiny Shell
+ *
+ *************************************/
+
+#include <stdio.h>
+#include <string.h>
+
+#define INPUT_MAX 256
+#define CMD_MAX 5
+
+/* read_cmd_string()
+ *     Reads a line of text from the user
+ *         Parameters:  dest - target location for the input
+ *         Returns: int - 0 on success or 
+ *                        -1 on error
+ */
+int read_cmd_string(char dest[INPUT_MAX])
+{
+	// Read user input
+	if(fgets(dest, INPUT_MAX, stdin) == NULL) {
+		fprintf(stderr, "Unable to read user input\n");
+		return -1;
+	}
+
+	// Remove trailing return character
+	int len = strlen(dest);
+	if(dest[len-1] == '\n') {
+		dest[len - 1] = '\0';
+	}
+
+	return 0;
+}
+
+/* parse_commands()
+ *     Reads a line of text from the user
+ *         Parameters:  input - string containing user input
+ *                      cmd_strs - the target array for command strings
+ *         Returns: int - The number of commands found or
+ *                        -1 on error
+ */
+int parse_commands(char input[INPUT_MAX], char cmd_strs[CMD_MAX][INPUT_MAX])
+{
+	// Chop the input into command strings
+	int cmd_count = 0;
+	char* cmd_ptr = strtok(input, ";");
+	while(cmd_ptr) {
+		if(cmd_count >= CMD_MAX) {
+			fprintf(stderr, "Too many commands\n");
+			return -1;
+		}
+		strncpy(cmd_strs[cmd_count], cmd_ptr, INPUT_MAX);
+		cmd_count++;
+		cmd_ptr = strtok(NULL, ";");
+	}
+
+	return cmd_count;
+}
+
+int main()
+{
+	char user_input[INPUT_MAX];
+	char cmd_strs[CMD_MAX][INPUT_MAX];
+
+	// TODO need to be able to get input from
+	//    the user in a loop
+
+	// Print the input prompt
+	printf("$> ");
+
+	// Read user input
+	if(read_cmd_string(user_input) == -1) {
+		return 1;
+	}
+
+	// TODO: Figure out how to handle the 'quit' command
+
+	// Chop the input into command strings
+	int cmd_count = parse_commands(user_input, cmd_strs);
+	if(cmd_count == -1) {
+		return 1;
+	}
+
+	// Chop the commands into arguments and execute one at a time
+	for(int i = 0; i < cmd_count; i++) {
+		
+		// TODO: 
+		//    1) Chop the command into command line arguments
+		//        need to handle up to 10 arguments
+		//        NOTE: the command name is always the first argument
+		//    2) fork a process
+		//    3) execute the command with execvp
+
+	}
+	
+	return 0;
+}