uboot中命令行解析

Posted 2022-09-02 zhuangquan

1.命令行解析

命令行解析函数：run_command

int run_command (const char *cmd, int flag)

    cmd_tbl_t *cmdtp;
    char cmdbuf[CFG_CBSIZE];    /* working copy of cmd        */
    char *token;            /* start of token in cmdbuf    */
    char *sep;            /* end of token (separator) in cmdbuf */
    char finaltoken[CFG_CBSIZE];
    char *str = cmdbuf;
    char *argv[CFG_MAXARGS + 1];    /* NULL terminated    */
    int argc, inquotes;
    int repeatable = 1;
    int rc = 0;

#ifdef DEBUG_PARSER
    printf ("[RUN_COMMAND] cmd[%p]=\"", cmd);
    puts (cmd ? cmd : "NULL");    /* use puts - string may be loooong */
    puts ("\"\n");
#endif

    clear_ctrlc();        /* forget any previous Control C */

    if (!cmd || !*cmd) 
        return -1;    /* empty command */
    

    if (strlen(cmd) >= CFG_CBSIZE) 
        puts ("## Command too long!\n");
        return -1;
    

    strcpy (cmdbuf, cmd);

    /* Process separators and check for invalid
     * repeatable commands
     */

#ifdef DEBUG_PARSER
    printf ("[PROCESS_SEPARATORS] %s\n", cmd);
#endif
    while (*str) 

        /*
         * Find separator, or string end
         * Allow simple escape of ‘;‘ by writing "\;"
         */
　　　　　//将多命令拆解（比如：printenv ；saveenv）
        for (inquotes = 0, sep = str; *sep; sep++) 
            if ((*sep==‘\‘‘) &&
                (*(sep-1) != ‘\\‘))
                inquotes=!inquotes;

            if (!inquotes &&
                (*sep == ‘;‘) &&    /* separator        */
                ( sep != str) &&    /* past string start    */
                (*(sep-1) != ‘\\‘))    /* and NOT escaped    */
                break;
        

        /*
         * Limit the token to data between separators
         */
        token = str;
        if (*sep) 
            str = sep + 1;    /* start of command for next pass */
            *sep = ‘\0‘;
        
        else
            str = sep;    /* no more commands for next pass */
#ifdef DEBUG_PARSER
        printf ("token: \"%s\"\n", token);
#endif

        /* find macros in this token and replace them */
　　　　//处理字符串中的转义字符
        process_macros (token, finaltoken);

        /* Extract arguments */
　　　　//解析命令（比如md.w 0这个字符串就会解析成argv[0]="md.w"  argv=[1]="0"）
        if ((argc = parse_line (finaltoken, argv)) == 0) 
            rc = -1;    /* no command at all */
            continue;
        

        /* Look up command in command table */
　　　　//根据argv[0]，然后进行对比。找出相对应的命令，执行相对应得函数
        if ((cmdtp = find_cmd(argv[0])) == NULL) 
            printf ("Unknown command ‘%s‘ - try ‘help‘\n", argv[0]);
            rc = -1;    /* give up after bad command */
            continue;
        

        /* found - check max args */
        if (argc > cmdtp->maxargs) 
            printf ("Usage:\n%s\n", cmdtp->usage);
            rc = -1;
            continue;
        

#if (CONFIG_COMMANDS & CFG_CMD_BOOTD)
        /* avoid "bootd" recursion */
        if (cmdtp->cmd == do_bootd) 
#ifdef DEBUG_PARSER
            printf ("[%s]\n", finaltoken);
#endif
            if (flag & CMD_FLAG_BOOTD) 
                puts ("‘bootd‘ recursion detected\n");
                rc = -1;
                continue;
             else 
                flag |= CMD_FLAG_BOOTD;
            
        
#endif    /* CFG_CMD_BOOTD */

        /* OK - call function to do the command */
        if ((cmdtp->cmd) (cmdtp, flag, argc, argv) != 0) 
            rc = -1;
        

        repeatable &= cmdtp->repeatable;

        /* Did the user stop this? */
        if (had_ctrlc ())
            return 0;    /* if stopped then not repeatable */
    

    return rc ? rc : repeatable;