🆕 cd命令

user/apps/shell/Makefile

@@ -1,7 +1,10 @@
-all: shell.o cmd.o
+all: shell.o cmd.o cmd_help.o
 
 shell.o: shell.c
 	gcc $(CFLAGS) -c shell.c  -o shell.o
 
 cmd.o: cmd.c
 	gcc $(CFLAGS) -c cmd.c  -o cmd.o
+
+cmd_help.o: cmd_help.c
+	gcc $(CFLAGS) -c cmd_help.c  -o cmd_help.o

user/apps/shell/cmd.c

@@ -3,6 +3,12 @@
 #include <libc/stdio.h>
 #include <libc/stddef.h>
 #include <libsystem/syscall.h>
+#include <libc/string.h>
+#include <libc/errno.h>
+#include <libc/unistd.h>
+#include <libc/stdlib.h>
+
+#include "cmd_help.h"
 
 // 当前工作目录（在main_loop中初始化）
 char *shell_current_path = NULL;
@@ -22,6 +28,7 @@ struct built_in_cmd_t shell_cmds[] =
         {"rmdir", shell_cmd_rmdir},
         {"reboot", shell_cmd_reboot},
         {"touch", shell_cmd_touch},
+        {"help", shell_help},
 
 };
 // 总共的内建命令数量
@@ -69,8 +76,112 @@ void shell_run_built_in_command(int index, int argc, char **argv)
  * @param argv
  * @return int
  */
-// todo:
-int shell_cmd_cd(int argc, char **argv) {}
+
+int shell_cmd_cd(int argc, char **argv)
+{
+
+    int current_dir_len = strlen(shell_current_path);
+    if (argc < 2)
+    {
+        shell_help_cd();
+        goto done;
+    }
+    // 进入当前文件夹
+    if (!strcmp(".", argv[1]))
+        goto done;
+
+    // 进入父目录
+    if (!strcmp("..", argv[1]))
+    {
+
+        // 当前已经是根目录
+        if (!strcmp("/", shell_current_path))
+            goto done;
+
+        // 返回到父目录
+        int index = current_dir_len - 1;
+        for (; index > 1; --index)
+        {
+            if (shell_current_path[index] == '/')
+                break;
+        }
+        shell_current_path[index] = '\0';
+
+        // printf("switch to \" %s \"\n", shell_current_path);
+        goto done;
+    }
+
+    int dest_len = strlen(argv[1]);
+    // 路径过长
+    if (dest_len >= SHELL_CWD_MAX_SIZE - 1)
+    {
+        printf("ERROR: Path too long!\n");
+        goto fail;
+    }
+
+    if (argv[1][0] == '/')
+    {
+        // ======进入绝对路径=====
+        int ec = chdir(argv[1]);
+        if (ec == -1)
+            ec = errno;
+        if (ec == 0)
+        {
+            // 获取新的路径字符串
+            char *new_path = (char *)malloc(dest_len + 2);
+            memset(new_path, 0, dest_len + 2);
+            strncpy(new_path, argv[1], dest_len);
+
+            // 释放原有的路径字符串的内存空间
+            free(shell_current_path);
+
+            shell_current_path = new_path;
+
+            shell_current_path[dest_len] = '\0';
+            return 0;
+        }
+        else
+            goto fail;; // 出错则直接忽略
+    }
+    else
+    {
+        int new_len = current_dir_len + dest_len;
+        // ======进入相对路径=====
+        if (new_len >= SHELL_CWD_MAX_SIZE - 1)
+        {
+            printf("ERROR: Path too long!\n");
+            goto fail;
+        }
+
+        // 拼接出新的字符串
+        char *new_path = (char *)malloc(new_len + 2);
+        memset(new_path, 0, sizeof(new_path));
+        strncpy(new_path, shell_current_path, current_dir_len);
+
+        if (current_dir_len > 1)
+            new_path[current_dir_len] = '/';
+        strcat(new_path, argv[1]);
+
+        if (chdir(new_path) == 0) // 成功切换目录
+        {
+            free(shell_current_path);
+            new_path[new_len] = '\0';
+            shell_current_path = new_path;
+            goto done;
+        }
+        else
+        {
+            printf("ERROR: Cannot switch to directory: %s\n", new_path);
+            goto fail;
+        }
+    }
+
+fail:;
+done:;
+    // 释放参数所占的内存
+    free(argv);
+    return 0;
+}
 
 /**
  * @brief 查看文件夹下的文件列表
@@ -80,7 +191,10 @@ int shell_cmd_cd(int argc, char **argv) {}
  * @return int
  */
 // todo:
-int shell_cmd_ls(int argc, char **argv) {}
+int shell_cmd_ls(int argc, char **argv)
+{
+    return 0;
+}
 
 /**
  * @brief 显示当前工作目录的命令
@@ -93,6 +207,8 @@ int shell_cmd_pwd(int argc, char **argv)
 {
     if (shell_current_path)
         printf("%s\n", shell_current_path);
+
+    free(argv);
 }
 
 /**

user/apps/shell/cmd.h

@@ -1,5 +1,8 @@
 #pragma once
 
+// cwd字符串的最大大小
+#define SHELL_CWD_MAX_SIZE  256
+
 /**
  * @brief shell内建命令结构体
  * 

user/apps/shell/cmd_help.c

@@ -0,0 +1,23 @@
+#include "cmd_help.h"
+#include <libc/stdio.h>
+struct help_table_item_t
+{
+    void (*func)();
+};
+struct help_table_item_t help_table[] = {
+    {shell_help_cd},
+};
+
+static const int help_table_num = sizeof(help_table) / sizeof(struct help_table_item_t);
+
+void shell_help()
+{
+    printf("Help:\n");
+    for (int i = 0; i < help_table_num; ++i)
+        help_table[i].func();
+}
+
+void shell_help_cd()
+{
+    printf("Example of cd: cd [destination]\n");
+}

user/apps/shell/cmd_help.h

@@ -0,0 +1,10 @@
+#pragma once
+
+#include "cmd.h"
+void shell_help();
+
+/**
+ * @brief cd命令的帮助信息
+ * 
+ */
+void shell_help_cd();

user/apps/shell/shell.c

@@ -42,9 +42,10 @@ static void main_loop(int kb_fd)
     unsigned char input_buffer[INPUT_BUFFER_SIZE] = {0};
 
     // 初始化当前工作目录的路径
-    shell_current_path = (char *)malloc(256);
-    memset(shell_current_path, 0, 256);
-    shell_current_path = "/";
+    shell_current_path = (char *)malloc(3);
+    memset(shell_current_path, 0, 3);
+    shell_current_path[0] = '/';
+    shell_current_path[1] = '\0';
 
     // shell命令行的主循环
     while (true)
@@ -52,17 +53,22 @@ static void main_loop(int kb_fd)
         int argc = 0;
         char **argv;
 
-        printf("[DragonOS] # ");
+        printf("[DragonOS] %s # ", shell_current_path);
         memset(input_buffer, 0, INPUT_BUFFER_SIZE);
 
         // 循环读取每一行到buffer
-        shell_readline(kb_fd, input_buffer);
+        int count = shell_readline(kb_fd, input_buffer);
 
-        int cmd_num = parse_command(input_buffer, &argc, &argv);
-        printf("\n");
-        if (cmd_num >= 0)
-            shell_run_built_in_command(cmd_num, argc, argv);
-        
+        if (count)
+        {
+            int cmd_num = parse_command(input_buffer, &argc, &argv);
+            printf("\n");
+            if (cmd_num >= 0)
+                shell_run_built_in_command(cmd_num, argc, argv);
+
+        }
+        else
+            printf("\n");
     }
 }
 
@@ -120,13 +126,14 @@ int shell_readline(int fd, char *buf)
  */
 int parse_command(char *buf, int *argc, char ***argv)
 {
+    // printf("parse command\n");
     int index = 0; // 当前访问的是buf的第几位
     // 去除命令前导的空格
     while (index < INPUT_BUFFER_SIZE && buf[index] == ' ')
         ++index;
 
     // 计算参数数量
-    for (int i = index; i < INPUT_BUFFER_SIZE - 1; ++i)
+    for (int i = index; i < (INPUT_BUFFER_SIZE - 1); ++i)
     {
         // 到达了字符串末尾
         if (!buf[i])
@@ -140,13 +147,12 @@ int parse_command(char *buf, int *argc, char ***argv)
     // 为指向每个指令的指针分配空间
     *argv = (char **)malloc(sizeof(char **) * (*argc));
     memset(*argv, 0, sizeof(char **) * (*argc));
-
     // 将每个命令都单独提取出来
     for (int i = 0; i < *argc && index < INPUT_BUFFER_SIZE; ++i)
     {
         // 提取出命令，以空格作为分割
         *((*argv) + i) = &buf[index];
-        while (index < INPUT_BUFFER_SIZE - 1 && buf[index] && buf[index] != ' ')
+        while (index < (INPUT_BUFFER_SIZE - 1) && buf[index] && buf[index] != ' ')
             ++index;
         buf[index++] = '\0';