Draft of DupShell

DupShell.c

@@ -0,0 +1,60 @@
+#include "cse356header.h"
+#include "readline.c"
+#define MAX_ARGS 50
+#define MAX_PIPES 50
+const char * delim_no_pipe = " \t\n";
+
+void parse_argv(char *buffer, char *argv[])
+{
+	char *cp = buffer;
+	for(int argc = 0; argc < MAX_ARGS; argc++) {
+		if((argv[argc] = strtok(cp, delim_no_pipe)) == NULL)
+			break;
+		cp = NULL;
+	}
+}
+
+void parse_pipe(char *buffer, char *argv[])
+{
+	char *cp = buffer;
+	for(int argc = 0; argc < MAX_PIPES; argc++) {
+		if((argv[argc] = strtok(cp, "|")) == NULL)
+			break;
+		cp = NULL;
+	}
+}
+
+main()
+{
+	while (true) {
+		int argc;
+		char *argv[MAX_ARGS], *comm[MAX_PIPES];
+
+		write(1, "$ ", 2);
+		char buffer[256], buffer2[256];
+		readline(0, buffer, 255);
+		buffer[strlen(buffer) - 1] = '\0'; // get rid of cr
+		strcpy(buffer2, buffer);
+		parse_argv(buffer, argv);
+		if(strcmp("exit", argv[0]) == 0) exit(0);
+
+		int pipefd[2][2];
+		parse_pipe(buffer2, comm);
+		for(int i = 0; comm[i] != NULL; i++) {
+			pipe(pipefd[i % 2]);
+			write(1, "\"", 1);
+			write(1, comm[i], strlen(comm[i]));
+			write(1, "\"", 1);
+			if(fork() == 0) {
+				if(comm[i + 1] != NULL) {dup2(pipefd[i % 2][1], STDOUT_FILENO); close(pipefd[i % 2][0]);}
+				if(i != 0) {dup2(pipefd[(i + 1) % 2][0], STDIN_FILENO); close(pipefd[(i + 1) % 2][1]);}
+				parse_argv(comm[i], argv);
+				execvp(argv[0], argv);
+				perror("exec failed");
+				exit(1);
+			}
+			wait(NULL);
+		}
+	}
+	exit(0);
+}

makefile

@@ -1,4 +1,4 @@
-all: MyCopy ForkCopy PipeCopy timer MyShell MoreShell
+all: MyCopy ForkCopy PipeCopy timer MyShell MoreShell DupShell
 clear:
 	rm *.o
 MyCopy: MyCopy.o
@@ -25,3 +25,7 @@ MoreShell: MoreShell.o
 	g++ MoreShell.o -o MoreShell
 MoreShell.o:
 	g++ -c MoreShell.c
+DupShell: DupShell.o
+	g++ DupShell.o -o DupShell
+DupShell.o:
+	g++ -c DupShell.c