关于opendir函数的返回类型DIR

kare

函数原型为：
DIR *opendir(const char *pathname);
返回值数据类型为DIR，可是在包含文件中找到：
typedef struct __dirstream DIR;
但找不到struct __dirstream的具体定义。
请问struct __dirstream在那里定义？是如何定义的？
谢谢！


别人说在dirent.h里有如下定义：
struct dirent
{
        long                d_ino;                /* Always zero. */
        unsigned short        d_reclen;        /* Always zero. */
        unsigned short        d_namlen;        /* Length of name in d_name. */
        char*                d_name;                /* File name. */
        /* NOTE: The name in the dirent structure points to the name in the
         *       finddata_t structure in the DIR. */
};

typedef struct
{
        /* disk transfer area for this dir */
        struct _finddata_t        dd_dta;

        /* dirent struct to return from dir (NOTE: this makes this thread
         * safe as long as only one thread uses a particular DIR struct at
         * a time) */
        struct dirent                dd_dir;

        /* _findnext handle */
        long                        dd_handle;

        /*
         * Status of search:
         *   0 = not started yet (next entry to read is first entry)
         *  -1 = off the end
         *   positive = 0 based index of next entry
         */
        int                        dd_stat;

        /* given path for dir with search pattern (struct is extended) */
        char                        dd_name[1];
} DIR;
我的怎么没有，难道不是在/usr/include/dirent.h或/usr/include/bits/dirent.h中吗？