shell実装 (#8)

* ✨ implement fork exec routine

* 👷 add makefile

* 🐛 update makefile

* ✨ implement read fork exec loop

* 💚 enable debug build

* 💚 add make clean

* 💚 add warning flag

* ♻️ 関数に分割したら最適化オプションをつけないと動かないコードができた

* ✨ 解決

* ♻️ ゴミファイル削除

* Delete .idea directory

* ✨ bg実行機能を実装

* ✨ [pwd] サンプルのpwdを実装

* 👷 add pwd makefile

* 🙈 add pwd .gitignore

* ✨ 組み込みコマンド検索を実装

* ✨ 組み込みコマンド実行機能を実装

* 💚 fix pwd Makefile

* 👷 update Makefile for building internal commands

* ♻️ fix duplicate tab

* ♻️ ファイル分割

* 🐛 ^DでのSEGVを解決

* ✨ 親プロセス側は^Cを無視するように設定

* ♻️ rename function get_internal_cmd to get_inner_cmd

Author: 3to5thpower

.gitignore

@@ -0,0 +1,2 @@
+rcsh
+

Makefile

@@ -0,0 +1,14 @@
+subdirs := $(shell find . -maxdepth 2 -path "./commands/*")
+
+.PHONY: all $(subdirs) clean
+all: $(subdirs) rcsh
+
+$(subdirs):
+	$(MAKE) -C $@ $(MAKECMDGOALS)
+
+rcsh: rcsh.c
+	gcc rcsh.c -Wall -Wextra -g -o rcsh
+
+clean: $(subdirs)
+	rm rcsh
+

commands/pwd/.gitignore

@@ -0,0 +1 @@
+pwd

commands/pwd/Makefile

@@ -0,0 +1,6 @@
+all: pwd.c
+	gcc pwd.c -o pwd
+
+clean:
+	rm pwd
+

commands/pwd/pwd.c

@@ -0,0 +1,9 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+int main(void) {
+    const int BUFSIZE = 1024;
+    char* dirname = getcwd(NULL, BUFSIZE);
+    puts(dirname);
+}

inner_cmds.c

@@ -0,0 +1,68 @@
+#include <dirent.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+char **get_inner_cmd(int *cmd_num) {
+    const int MAX_CMD_COUNT = 32;
+    const int MAX_CMD_LENGTH = 128;
+    char **commands = calloc(MAX_CMD_COUNT, sizeof(char *));
+    int cmd_cnt = 0;
+
+    DIR *dir = opendir("./commands");
+    if (dir == NULL) {
+        fprintf(stderr, "unable to opendir ./commands\n");
+        exit(1);
+    }
+
+    struct dirent *entry;
+    while ((entry = readdir(dir)) != NULL) {
+        if (entry->d_name[0] == '.') {
+            continue;
+        }
+        int len = strlen(entry->d_name);
+        if (len > MAX_CMD_LENGTH) {
+            len = MAX_CMD_LENGTH;
+        }
+        char *cmd = calloc(len, sizeof(char));
+
+        strncpy(cmd, entry->d_name, len);
+        commands[cmd_cnt++] = cmd;
+        printf("found: %s\n", entry->d_name);
+    }
+
+    closedir(dir);
+    *cmd_num = cmd_cnt;
+    return commands;
+}
+
+char *check_inner_cmd(int cmd_cnt, char **cmds, char **argv) {
+    if (cmds == NULL) {
+        return argv[0];
+    }
+
+    const int MAX_CMD_LENGTH = 128;
+    char *cmd = malloc(sizeof(char) * MAX_CMD_LENGTH);
+    memset(cmd, 0, sizeof(char) * MAX_CMD_LENGTH);
+
+    for (int i = 0; i < cmd_cnt; i++) {
+        if (strcmp(argv[0], cmds[i])) {
+            continue;
+        }
+        snprintf(cmd, MAX_CMD_LENGTH, "./commands/%s/%s", cmds[i], cmds[i]);
+        break;
+    }
+    if (cmd[0] == '\0') {
+        free(cmd);
+        cmd = argv[0];
+    }
+
+    return cmd;
+}
+
+void free_inner_cmds(int cnt, char **cmds) {
+    for (int i = 0; i < cnt; i++) {
+        free(cmds[i]);
+    }
+    free(cmds);
+}

rcsh.c

@@ -0,0 +1,86 @@
+#include <ctype.h>
+#include <signal.h>
+#include <stdio.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "inner_cmds.c"
+#include "read_cmd.c"
+
+pid_t execute(char *, char **);
+void sigchld_wait(int);
+void sigint_ignore(int sig) { return; }
+
+int main(void) {
+    // bg実行終了後のリソース回収処理
+    if (signal(SIGCHLD, sigchld_wait) == SIG_ERR) {
+        fprintf(stderr, "rcsh: signal(SIGCHLD) failed\n");
+        exit(1);
+    }
+
+    int argc = 0, status;
+    bool exec_bg = false;
+    char **argv;
+    pid_t pid;
+
+    // 組み込みコマンドの取得
+    int inner_cmds_cnt;
+    char **inner_cmds = get_inner_cmd(&inner_cmds_cnt);
+
+    while (1) {
+        // ^Cを無視
+        if (signal(SIGINT, SIG_IGN) == SIG_ERR) {
+            fprintf(stderr, "rcsh: signal(SIGINT) failed\n");
+            exit(1);
+        }
+
+        // read
+        if ((argv = read_cmd(&argc, &exec_bg)) == NULL) {
+            break;
+        }
+
+        // no input
+        if (argc < 1) {
+            free_argv(argv);
+            continue;
+        }
+
+        // exit
+        if (strcmp(argv[0], "exit") == 0) {
+            free_argv(argv);
+            break;
+        }
+
+        // update cmdpath if internal command
+        char *cmd = check_inner_cmd(inner_cmds_cnt, inner_cmds, argv);
+
+        // execute
+        pid = execute(cmd, argv);
+
+        // wait
+        if (!exec_bg) {
+            wait(&status);
+        }
+
+        free_argv(argv);
+    }
+
+    free_inner_cmds(inner_cmds_cnt, inner_cmds);
+    return 0;
+}
+
+pid_t execute(char *cmd, char *argv[]) {
+    pid_t pid = fork();
+    if (pid != 0) return pid;
+
+    signal(SIGINT, SIG_DFL);
+    execvp(cmd, argv);
+    perror(argv[0]);
+    exit(1);
+}
+
+void sigchld_wait(int sig) {
+    int status;
+    waitpid(-1, &status, WNOHANG);
+    printf("process exited with status %d\n", WEXITSTATUS(status));
+}

read_cmd.c

@@ -0,0 +1,69 @@
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+char **read_cmd(int *argc, bool *exec_bg) {
+    const int BUFSIZE = 1024;
+    const char TOK_DELIM[] = " \t\r\n\a";
+
+    int arg_cnt = 0, max_argc = 10;
+    // char input[BUFSIZE];
+    char *input = malloc(sizeof(char) * BUFSIZE);
+    char **argv = malloc(max_argc * sizeof(char *));
+
+    // input
+    printf("rcsh> ");
+    if (fgets(input, BUFSIZE, stdin) == NULL) {
+        return NULL;
+    }
+    input[strlen(input) - 1] = '\0';
+
+    // バックグラウンド実行のフラグを設定
+    // 同時に引数から&記号を削除
+    char *pos_and;
+    if ((pos_and = strchr(input, '&')) != NULL) {
+        *exec_bg = true;
+        *pos_and = '\0';
+    }
+
+    // strtokは2回目の呼び出しではTOK_DELIMを一切含まない最初の部分をinputから切り出す
+    //この際word直後のTOK_DELIM文字は\0に置き換えられる
+    char *word = strtok(input, TOK_DELIM);
+    argv[arg_cnt++] = word;
+
+    while ((word = strtok(NULL, TOK_DELIM))) {
+        argv[arg_cnt++] = word;
+
+        //引数の個数が配列の要素数より多かった時の対処
+        if (arg_cnt >= max_argc) {
+            max_argc *= 2;
+
+            // reallocは第1引数の内容をコピーした新しい領域を返す.
+            argv = realloc(argv, max_argc * sizeof(char *));
+            if (argv == NULL) {
+                fprintf(stderr, "rcsh: allocation error\n");
+                exit(1);
+            }
+        }
+    }
+
+    // execvは最後にNULLが入っていないと動作しないので末尾にNULLを追加
+    if (argv[arg_cnt] != NULL) {
+        argv = realloc(argv, (arg_cnt + 1) * sizeof(char *));
+        argv[arg_cnt] = NULL;
+    }
+
+    // 入力が\nなど空白だった場合の処理
+    if (argv[0] == NULL) {
+        arg_cnt--;
+    }
+
+    *argc = arg_cnt;
+    return argv;
+}
+
+void free_argv(char **argv) {
+    free(*argv);
+    free(argv);
+}