feat(builtin): add built-in command

.gitignore

@@ -0,0 +1,2 @@
+*.o
+dish

Makefile

@@ -1,4 +1,4 @@
-OBJ=main.o line.o loop.o exec.o
+OBJ=main.o line.o loop.o exec.o builtin.o
 CC=gcc
 CFLAGS= -O3 -Wall
 

builtin.c

@@ -0,0 +1,53 @@
+/*
+ * @Author: 1ridic 
+ * @Date: 2022-09-18 14:16:19 
+ * @Last Modified by: 1ridic
+ * @Last Modified time: 2022-09-18 14:28:01
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+int dish_cd(char **args);
+int dish_help(char **args);
+int dish_exit(char **args);
+
+char* builtin_cmd[] = {
+  "cd",
+  "help",
+  "exit"
+};
+
+int (*builtin_func[]) (char **) = {
+  &dish_cd,
+  &dish_help,
+  &dish_exit
+};
+
+int dish_cd(char **args)
+{
+  if (args[1] == NULL) {
+    fprintf(stderr, "dish: expected argument to \"cd\"\n");
+  } else {
+    if (chdir(args[1]) != 0) {
+      perror("dish");
+    }
+  }
+  return 0;
+}
+
+int dish_help(char **args)
+{
+   fprintf(stdout, "Yet another Shell with C.\n");
+   return 0;
+}
+
+int dish_exit(char **args)
+{
+  exit(EXIT_SUCCESS);
+}
+
+int getBuiltinNum() {
+  return sizeof(builtin_cmd) / sizeof(char *);
+}

builtin.h

@@ -0,0 +1,12 @@
+/*
+ * @Author: 1ridic 
+ * @Date: 2022-09-18 14:15:44 
+ * @Last Modified by: 1ridic
+ * @Last Modified time: 2022-09-18 14:41:38
+ */
+#ifndef _BUILTIN_H_
+#define _BUILTIN_H_
+
+int getBuiltinNum();
+
+#endif

exec.c

@@ -1,7 +1,18 @@
+/*
+ * @Author: 1ridic 
+ * @Date: 2022-09-18 14:14:23 
+ * @Last Modified by: 1ridic
+ * @Last Modified time: 2022-09-18 14:44:37
+ */
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/types.h>
+#include <string.h>
 #include <unistd.h>
+#include "builtin.h"
+
+extern int (*builtin_func[]) (char **);
+extern char* builtin_cmd[];
 
 int forkExec(char **args) {
   pid_t pid;
@@ -20,9 +31,29 @@ int forkExec(char **args) {
     /* fork error */
     perror("dish");
   } else {
+    extern char volatile isWaiting;
+    isWaiting = 1;
     /* parent process: wait child process*/
     pid=wait(&status);
+    isWaiting = 0;
     
   }
   return WEXITSTATUS(status);
 }
+
+int commandExec(char **args) {
+  int i;
+
+  if (args[0] == NULL) {
+    /* empty command */
+    return 1;
+  }
+
+  for (i = 0; i < getBuiltinNum(); i++) {
+    if (strcmp(args[0], builtin_cmd[i]) == 0) {
+      return (*builtin_func[i])(args);
+    }
+  }
+
+  return forkExec(args);
+}

exec.h

@@ -1,4 +1,11 @@
+/*
+ * @Author: 1ridic 
+ * @Date: 2022-09-18 14:13:40 
+ * @Last Modified by:   1ridic 
+ * @Last Modified time: 2022-09-18 14:13:40 
+ */
 #ifndef __EXEC_H__
 #define __EXEC_H__
 int forkExec(char **args);
+int commandExec(char **args);
 #endif

line.c

@@ -1,3 +1,9 @@
+/*
+ * @Author: 1ridic 
+ * @Date: 2022-09-18 14:14:05 
+ * @Last Modified by:   1ridic 
+ * @Last Modified time: 2022-09-18 14:14:05 
+ */
 #include "line.h"
 #include <stdio.h>
 #include <stdlib.h>

line.h

@@ -1,3 +1,9 @@
+/*
+ * @Author: 1ridic 
+ * @Date: 2022-09-18 14:14:28 
+ * @Last Modified by:   1ridic 
+ * @Last Modified time: 2022-09-18 14:14:28 
+ */
 #ifndef _LINE_H_
 #define _LINE_H_
 #define LINE_BUF_SIZE 1024

loop.c

@@ -1,3 +1,9 @@
+/*
+ * @Author: 1ridic 
+ * @Date: 2022-09-18 14:13:53 
+ * @Last Modified by:   1ridic 
+ * @Last Modified time: 2022-09-18 14:13:53 
+ */
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -9,11 +15,10 @@ int loop() {
   
   char *line;
   char **args;
-  int status = 1;
   printf("> ");
   line = readLine();
   args = splitLine(line);
-  status = forkExec(args);
+  commandExec(args);
   free(line);
   free(args);
   return 0;

loop.h

@@ -1,3 +1,9 @@
+/*
+ * @Author: 1ridic 
+ * @Date: 2022-09-18 14:14:19 
+ * @Last Modified by:   1ridic 
+ * @Last Modified time: 2022-09-18 14:14:19 
+ */
 #ifndef _LOOP_H_
 #define _LOOP_H_
 int loop();

main.c

@@ -1,12 +1,22 @@
+/*
+ * @Author: 1ridic 
+ * @Date: 2022-09-18 14:13:59 
+ * @Last Modified by: 1ridic
+ * @Last Modified time: 2022-09-18 14:21:48
+ */
 #include <signal.h>
 #include <stdio.h>
 #include <unistd.h>
 #include <stdlib.h>
 #include "loop.h"
 
+char volatile isWaiting = 0; 
 void intHandler(int dummy) {
+  if (isWaiting) {
+    return;
   printf("\nSIGINT exit.\n");
   exit(EXIT_FAILURE);
+  }
 }
 
 int main(int argc, char *argv[]) {