recursion

pscat/pscat.c

@@ -7,44 +7,36 @@
 
 static char *program_name = "pscat";
 
-/* Originally designed to use parentheses but changed to brackets to escape the
- * hassle of escaping them from the Bourne shell. */
 #define L_PAREN '['
 #define R_PAREN ']'
 
-int main(int argc, char *argv[]){
-	char **psstart;
+int
+forking(char **argv){
 	int child;
-	int i;
-	unsigned int retval;
-	int terms;
+	char **corr;
 
-	retval = 0;
+	corr = corresponding_arg(argv, L_PAREN, R_PAREN);
+	*corr = NULL;
+	if(fork() == 0){
+		execvp(argv[1], argv+1);
+	}else{
+		wait(&child);
+		argv = corr;
+		if(*++argv == NULL)
+			return WIFEXITED(child) * WEXITSTATUS(child);
+		else
+			return forking(argv);
+	}
+}
 
-	if((terms = check_arg(++argv, L_PAREN, R_PAREN)) == 0){
+int main(int argc, char *argv[]){
+
+	if((check_arg(++argv, L_PAREN, R_PAREN)) == 0){
 		fprintf(stderr,
 			"Usage: %s \"[\" [utility [argument...]] \"]\" ...\n",
 			argv[-1] == NULL ? program_name : argv[-1]
 		);
 		return EX_USAGE;
-	}
-
-	/* loop starts with *argv -> the next L_PAREN */
-	for(i = 0; i < terms; ++i){
-		psstart = argv + 1;
-		argv = corresponding_arg(argv, L_PAREN, R_PAREN);
-		/* *argv -> the corresponding R_PAREN. turn it into NULL to
-		 * terminate the argument list to send to execvp(3) */
-		*argv = NULL;
-		if(fork() == 0){
-			execvp(psstart[0], psstart);
 	}else
-			wait(&child);
-		/* interpret status information from wait(2) */
-		if(WIFEXITED(child))
-			retval += WEXITSTATUS(child);
-		++argv;
-	}
-
-	return retval;
+		return forking(argv);
 }