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/** * zsh.c : 简单的shell程序 * * created: zh * date: 2014.5.28~2014.6.8 * version1.0: first version * * *********************************************/

#include <stdlib.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <pwd.h>
#include <libgen.h>
#include <sys/types.h>

#include <readline/readline.h>
#include <readline/history.h>


int do_exit(int, char **);
int do_export(int, char **);
int do_echo(int, char **);
int do_cd(int, char **);
int do_history(int, char **);

void do_line(char *line);
void do_pipe_cmd(char *line);
int do_simple_cmd(int argc, char **argv, int prefd[], int postfd[]);
int isBgProgram(int len, char *line[10]);
char **arrayToPointer(int num, char *argv[10]);
int predo_for_redirect(int argc, char **argv, int *re);

char lastdir[100];
char **arg;

typedef int (*buildin_cmd_handle) (int, char **);
typedef struct {
    const char *cmd;
    buildin_cmd_handle handle;
} CMD_ENTRY;

const CMD_ENTRY buildin_cmd_table[] = {
    {"exit", do_exit},
    {"cd", do_cd},
    {"echo", do_echo},
    {"export", do_export},
    {"history", do_history},
    {0, 0}
};


void history_finish()
{
    append_history(history_length, "/tmp/msh_history");
    history_truncate_file("/tmp/msh_history", history_max_entries);
}

/** * 用于获取函数句柄 */
buildin_cmd_handle get_cmd_handle(const char *cmd)
{
    int i = 0;
    while (buildin_cmd_table[i].cmd) {
    if (strcmp(buildin_cmd_table[i].cmd, cmd) == 0)
        return buildin_cmd_table[i].handle;
    i++;
    }
    return 0;
}

/** * 用于显示历史输入信息 */
void display_history_list()
{
    HIST_ENTRY **h = history_list();
    if (h) {
    int i = 0;
    while (h[i]) {
        printf("%d: %s
", i, h[i]->line);
        i++;
    }
    }
}

/*** * 功能：执行exit命令，退出shell解释器 * 输入：argc：命令行字符串数目；argv：命令行字符串组 */
int do_exit(int argc, char **argv)
{
    int val = 0;
    if (argc > 1)
    val = atoi(argv[1]);
    //free_resource();
    history_finish();
    exit(val);
    return 0;
}
/*** * 功能：执行cd命令，切换shell当前路径 * 输入：argc：命令行字符串数目；argv：命令行字符串组 */
int do_cd(int argc, char **argv)
{
    char *dir;
    char cwd[100];

    if (argc == 1) {
    if (!(dir = getenv("HOME"))) {
        printf("cd: %s
", strerror(errno));
        return -1;
    }
    } else if (argc == 2) {
    if (strcmp(argv[1], "-") == 0) {
        dir = lastdir;
    } else if (strcmp(argv[1], "~") == 0) {
        if (!(dir = getenv("HOME"))) {
        printf("cd: %s
", strerror(errno));
        return -1;
        }
    } else
        dir = argv[1];
    } else {
    printf("Usage: cd [dir]
");
    return -1;
    }
    getcwd(cwd, 99);
    if (chdir(dir) == -1) {
    printf("cd: %s
", strerror(errno));
    return -1;
    }
    strcpy(lastdir, cwd);
    return 0;
}
/*** * 功能：执行export命令，导入或显示环境变量 * 输入：argc：命令行字符串数目；argv：命令行字符串组 */
int do_export(int argc, char **argv)
{
    int i = 1;
    char *p;
    while (argv[i]) {
    if ((p = strchr(argv[i], '='))) {
        *p = 0;
        if (strpbrk(argv[i], "~`!@#$%^&*()-_+=|\\{}[];:'\"<>,.?/")) {
        *p = '=';
        printf("export: %s: not a valid indentifier
", argv[i]);
        i++;
        continue;
        }

        if (setenv(argv[i], p + 1, 1) == -1)
        printf("export: %s
", strerror(errno));
        *p = '=';
    }
    i++;
    }
    return 0;
}
/*** * 功能：执行echo命令，回显变量 * 输入：argc：命令行字符串数目；argv：命令行字符串组 */
int do_echo(int argc, char **argv)
{
    int i = 1;
    int j;
    int argn = 0;
    int arge = 0;
    if (argv[1]) {
    if (strcmp(argv[1], "-n") == 0) {
        argn = 1;
        i = 2;
    } else if (strcmp(argv[1], "-e") == 0) {
        arge = 1;
        i = 2;
    } else if ((strcmp(argv[1], "-ne") == 0)
           || (strcmp(argv[1], "-en") == 0)) {
        argn = arge = 1;
        i = 2;
    }
    }
    j = i;
    while (argv[i]) {
    if (i > j)
        printf(" %s", argv[i]);
    else
        printf("%s", argv[i]);
    i++;
    }
    if (argn == 0)
    printf("
");

    return 0;
}
/*** * 功能：执行history命令，显示历史信息 * 输入：argc：命令行字符串数目；argv：命令行字符串组 */
int do_history(int argc, char **argv)
{
    display_history_list();
    return 0;
}

/** * 设置shell命令提示符，可通过设置环境变量envprompt改变 */
void setShellPrompt(char *prompt)
{
    char host[100];
    char cwd[100];
    struct passwd *pwp;
    if (gethostname(host, 99) == -1) {
    strcpy(host, "unknown");
    } else {
    char *p = strchr(host, '.');
    if (p)
        *p = 0;
    }
    if (!getcwd(cwd, 99)) {
    strcpy(cwd, "unknown");
    } else {
    if (strcmp(cwd, "/") != 0)
        strcpy(cwd, basename(cwd));
    }
    pwp = getpwuid(getuid());
    sprintf(prompt, "[%s@%s %s]# ", (pwp ? pwp->pw_name : "unknown"), host,
        cwd);
}

/** * 释放程序中申请的内存 */
void free_source(int num, char **name)
{
    int n;
    for (n = 0; n < num; n++) {
        free(name[n]);
        name[n] = 0;
    }
}


int main(int argc, char **argv)
{

    char prompt[200];
    setShellPrompt(prompt);
    //signal(SIGINT,SIG_IGN);

    char *line;         //char line[300];//
    line = malloc(200);
    memset(line, 0, 200);

    char *env;
    env = malloc(strlen(prompt) + 11);
    strcpy(env, "envprompt=");
    strcat(env, prompt);
    putenv(env);

    char *tmpline;
    tmpline = malloc(strlen(prompt));
    while (1) {

    tmpline = getenv("envprompt");
    if (!(line = readline(tmpline))) {
        break;
    }
    if (*line) {
        add_history(line);
    }
    //printf("%s + %d
",line, strlen(line));
    do_line(line);
    putenv(line);

    }
    free(env);
    env = NULL;
    free(tmpline);
    tmpline = NULL;
    free(line);
    line = NULL;

    return 0;

}

/** * 功能：解析输入命令，并按";"解析命令，并传入到函数do_pipe_cmd() * 输入：原始命令行 */
void do_line(char *line)
{
    int len, i, j = 0, k = 0;
    char *argv[20];
    int m = 0;
    len = strlen(line);
    //printf("---%s---||---%d---
",line,len);
    for (i = 0; i <= len; i++) {
    if (line[i] == ';') {
        if ((argv[k] = (char *) malloc((i - j) * sizeof(char))) == 0) {
        fprintf(stderr, "error! can't malloc space for argv
");
        } else {
        memset(argv[k], 0, (i - j) * sizeof(char));
        for (m = 0; m < i - j; m++) {
            argv[k][m] = line[j + m];
        }
        argv[k][m] = '\0';
        //printf("---%s---
",argv[k]);
        do_pipe_cmd(argv[k]);
        j = i + 1;
        k++;

        }
    } else if (line[i] == '
' || (i == len && i != 0)) {
        if ((argv[k] = (char *) malloc((i - j) * sizeof(char))) == 0) {
        fprintf(stderr, "error! can't malloc space for argv
");
        } else {
        memset(argv[k], 0, (i - j) * sizeof(char));
        //printf("(i - j) * sizeof(char) is %d
",(i - j) * sizeof(char)); 
        //printf("---%s---%d---%d---
",argv[k],m,strlen(argv[k]));
        for (m = 0; m < i - j; m++) {
            argv[k][m] = line[j + m];
        }
        argv[k][m] = '\0';
        //printf("---%s---%d---%d---
",argv[k],m,strlen(argv[k]));
        do_pipe_cmd(argv[k]);
        j = i;
        k++;
        }
    }
    }
    free_source(k - 1, argv);

}

/** * 功能：解析输入命令，并按"|"解析简单命令，并传入到函数do_simple_cmd() * 输入：函数do_line()解析后的简单命令 */
void do_pipe_cmd(char *line)
{
    //printf("the line in pipe_cmd is %s
",line);
    int len, i, j = 0, k = 0;
    char *argv[20];
    int m;
    len = strlen(line);

    int prepipe = 0;
    int prefd[2];
    int postfd[2];
    char *args[10];
    int num = 0;

    for (i = 0; i <= len; i++) {
    if (line[i] == '|') {
        if ((argv[k] = (char *) malloc((i - j) * sizeof(char))) == 0) {
        fprintf(stderr, "error! can't malloc space for argv
");
        } else {
        memset(argv[k], 0, (i - j) * sizeof(char));
        for (m = 0; m < i - j; m++) {
            argv[k][m] = line[j + m];
        }
        argv[k][m] = '\0';
        num = add_arg(argv[k], args);

        j = i + 1;
        k++;

        pipe(postfd);
        if (prepipe)
            do_simple_cmd(num, arrayToPointer(num, args), prefd,
                  postfd);
        else
            do_simple_cmd(num, arrayToPointer(num, args), 0,
                  postfd);
        prepipe = 1;
        prefd[0] = postfd[0];
        prefd[1] = postfd[1];
        }
    } else if (i == len && i != 0) {
        if ((argv[k] = (char *) malloc((i - j) * sizeof(char))) == 0) {
        fprintf(stderr, "error! can't malloc space for argv
");
        } else {
        memset(argv[k], 0, (i - j) * sizeof(char));
        for (m = 0; m < i - j; m++) {
            argv[k][m] = line[j + m];
        }
        argv[k][m] = '\0';
        num = add_arg(argv[k], args);
        j = i;
        k++;

        pipe(postfd);
        if (prepipe) {
            do_simple_cmd(num, arrayToPointer(num, args), prefd,
                  postfd);

        } else {
            do_simple_cmd(num, arrayToPointer(num, args), 0, 0);
        }
        }
    }
    }
    free_source(k - 1, argv);
    free_source(k - 1, args);
    free_source(num, arg);

}
/** * 功能：执行简单命令 * 输入：argc：命令行字符串数目；argv：命令行字符串组 * prefd,postfd:管道参数 */
int do_simple_cmd(int argc, char **argv, int prefd[], int postfd[])
{
    int pid;
    int status;
    buildin_cmd_handle hd;
    if (argc == 0)
    return 0;

    if (prefd == 0 && postfd == 0) {

    if ((hd = get_cmd_handle(argv[0]))) {
        if (predo_for_redirect(argc, argv, 0))
        return 1;
        (*hd) (argc, argv);
        return 0;
    }
    }

    if ((pid = fork()) == 0) {  //子进程
    // 重置signal INT handle为默认
    int redirect = 0;
    signal(SIGINT, SIG_DFL);

    if (predo_for_redirect(argc, argv, &redirect))
        exit(1);

    if (redirect != 1 && prefd) {   
        close(prefd[1]);
        if (prefd[0] != STDIN_FILENO) {
        dup2(prefd[0], STDIN_FILENO);
        close(prefd[0]);
        }
    }
    if (redirect != 2 && postfd) {  
        close(postfd[0]);
        if (postfd[1] != STDOUT_FILENO) {
        dup2(postfd[1], STDOUT_FILENO);
        close(postfd[1]);
        }
    }
    if ((hd = get_cmd_handle(argv[0]))) {
        (*hd) (argc, argv);
        exit(0);
    }

    char buffer[100];
    if (file_exist(argv[0], buffer)) {
        execv(buffer, argv);
    } else {
        fprintf(stderr, "-zsh: %s: command not found
", argv[0]);
        exit(0);
    }
    } else if (pid < 0) {

    } else {
        if (isBgProgram(argc, argv) == 0) {
            //printf("this is not bg
");
            waitpid(pid, &status, 0);
        }
    }


    if (postfd) {       
    close(postfd[1]);   // 关闭这个fd.
    }
    return 0;
}

/** * 将指针数组转换为二维指针，恕我学识浅薄，尚不明白为何一定要这样， * 只是这样才能通过编译....容我再学习 */
char **arrayToPointer(int num, char *argv[10])
{
    arg = (char **) malloc((num) * sizeof(char *));
    memset(arg,0, (num)*sizeof(char *));
    int p = 0;
    for (p = 0; p < num && num < 10; p++) {
    arg[p] = argv[p];
    }
    return arg;
}

/** * 功能：判断简单命令是否需要后台运行，通过“&”判别 */
int isBgProgram(int len, char **line)
{
    if (strcmp(line[len - 1], "&") == 0) {
    line[len - 1] = "\0";
    return 1;
    }
    return 0;
}

/** * 功能：将简单命令(字符串)转换为字符串数组，数组每个元素即为一个标记 */
int add_arg(char *line, char *args[10])
{

    int len, i, j = 0, k = 0;
    //char *args[10];
    len = strlen(line);
    int m = 0;

    char *newline;

    if ((newline = (char *) malloc(len * sizeof(char))) == 0) {
    fprintf(stderr, "error! can't malloc space for argv
");
    }
    for (i = 0; i <= len;) {
    if (line[i] == ' ' && line[i + 1] == ' ' || line[i] == '\t')
        i++;
    else {
        newline[j] = line[i];
        j++;
        i++;
    }
    }
    i = 0;
    while (newline[i] == ' ' || newline[i] == '\t')
    i++;

    j = i;          //重新置为零
    for (; i <= len; i++) {
    if (newline[i] == ' ') {
        if ((args[k] = (char *) malloc((i - j) * sizeof(char))) == 0) {
        fprintf(stderr, "error! can't malloc space for argv
");
        } else {
        memset(args[k], 0, (i - j) * sizeof(char));
        for (m = 0; m < i - j; m++) {
            args[k][m] = newline[j + m];
        }
        args[k][m] = '\0';
        j = i + 1;
        k++;
        }
    } else if (i == len) {
        if ((args[k] = (char *) malloc((i - j) * sizeof(char))) == 0) {
        fprintf(stderr, "error! can't malloc space for argv
");
        } else {

        for (m = 0; m < i - j; m++) {
            args[k][m] = newline[j + m];
        }
        args[k][m] = '\0';
        j = i;
        k++;
        }
    }
    }
    return k;
}

/** * 功能：判断文件是否存在 */
int file_exist(const char *file, char *buffer)
{
    int i = 0;
    const char *p;
    const char *path = getenv("PATH");

    p = path;
    while (*p != 0) {
    if (*p != ':')
        buffer[i++] = *p;
    else {
        buffer[i++] = '/';
        buffer[i] = 0;
        strcat(buffer, file);
        if (access(buffer, F_OK) == 0)
        return 1;
        i = 0;
    }
    p++;
    }
    const char *p2 = getenv("PWD");

    p = p2;
    i = 0;
    while (*p != 0) {
    buffer[i++] = *p;
    p++;
    }
    buffer[i++] = '/';
    buffer[i] = 0;
    strcat(buffer, file);
    if (access(buffer, F_OK) == 0)
    return 1;
    return 0;
}
/** * 功能：完成重定向功能 */
int predo_for_redirect(int argc, char **argv, int *re)
{
    int i;
    int redirect = 0;
    for (i = 1; i < argc; i++) {
    if (strcmp(argv[i], "<") == 0) {
        redirect = 1;
        argv[i] = 0;
        break;
    } else if (strcmp(argv[i], ">") == 0) {
        redirect = 2;
        argv[i] = 0;
        break;
    }
    }
    if (redirect) {     
    if (argv[i + 1]) {
        int fd;
        if (redirect == 2) {
            if ((fd =
                 open(argv[i + 1], O_WRONLY | O_CREAT | O_TRUNC,
                  S_IRUSR | S_IWUSR)) == -1) {
                fprintf(stderr, "Open out %s failed
", argv[i + 1]);
                return 1;
            }
            dup2(fd, STDOUT_FILENO);
        } else {        //redirect == 1
            if ((fd =
                 open(argv[i + 1], O_RDONLY,
                  S_IRUSR | S_IWUSR)) == -1) {
                fprintf(stderr, "Open in %s failed
", argv[i + 1]);
                return 1;
            }
            dup2(fd, STDIN_FILENO);
        }
    } else {
        fprintf(stderr, "Bad redirect, need more arg
");
        return 1;
    }
    }
    if (re)
    *re = redirect;
    return 0;
}