在Unix中定義的文件在哪裏

Question

我知道FILE是一個typedef-ed結構，但我可以在哪裏查找使用手冊頁的struct FILE的實際定義？

Answer 1

如果你開始在/usr/include/stdio.h，你會發現這條線：

typedef struct _IO_FILE FILE; 

就在/usr/include grepping爲__IO_FILE表明，該結構在/usr/include/libio.h

我/usr/include/libio.h定義顯示__IO_FILE定義如下：

struct _IO_FILE { 
    int _flags;  /* High-order word is _IO_MAGIC; rest is flags. */ 
#define _IO_file_flags _flags 

    /* The following pointers correspond to the C++ streambuf protocol. */ 
    /* Note: Tk uses the _IO_read_ptr and _IO_read_end fields directly. */ 
    char* _IO_read_ptr; /* Current read pointer */ 
    char* _IO_read_end; /* End of get area. */ 
    char* _IO_read_base; /* Start of putback+get area. */ 
    char* _IO_write_base; /* Start of put area. */ 
    char* _IO_write_ptr; /* Current put pointer. */ 
    char* _IO_write_end; /* End of put area. */ 
    char* _IO_buf_base; /* Start of reserve area. */ 
    char* _IO_buf_end; /* End of reserve area. */ 
    /* The following fields are used to support backing up and undo. */ 
    char *_IO_save_base; /* Pointer to start of non-current get area. */ 
    char *_IO_backup_base; /* Pointer to first valid character of backup area */ 
    char *_IO_save_end; /* Pointer to end of non-current get area. */ 

    struct _IO_marker *_markers; 

    struct _IO_FILE *_chain; 

    int _fileno; 
#if 0 
    int _blksize; 
#else 
    int _flags2; 
#endif 
    _IO_off_t _old_offset; /* This used to be _offset but it's too small. */ 

#define __HAVE_COLUMN /* temporary */ 
    /* 1+column number of pbase(); 0 is unknown. */ 
    unsigned short _cur_column; 
    signed char _vtable_offset; 
    char _shortbuf[1]; 

    /* char* _save_gptr; char* _save_egptr; */ 

    _IO_lock_t *_lock; 
#ifdef _IO_USE_OLD_IO_FILE 
}; 

struct _IO_FILE_complete 
{ 
    struct _IO_FILE _file; 
#endif 
#if defined _G_IO_IO_FILE_VERSION && _G_IO_IO_FILE_VERSION == 0x20001 
    _IO_off64_t _offset; 
# if defined _LIBC || defined _GLIBCPP_USE_WCHAR_T 
    /* Wide character stream stuff. */ 
    struct _IO_codecvt *_codecvt; 
    struct _IO_wide_data *_wide_data; 
    struct _IO_FILE *_freeres_list; 
    void *_freeres_buf; 
    size_t _freeres_size; 
# else 
    void *__pad1; 
    void *__pad2; 
    void *__pad3; 
    void *__pad4; 
    size_t __pad5; 
# endif 
    int _mode; 
    /* Make sure we don't get into trouble again. */ 
    char _unused2[15 * sizeof (int) - 4 * sizeof (void *) - sizeof (size_t)]; 
#endif 
};