FATFS里的FIL结构体详解

FATFS里的FIL结构体：

FIL（file object 文件对象）掌控一个已打开的文件。由f_open()创建，由f_close()抛弃。应用程序除了可以修改结构里的cltbl，结构里的其他成员必须不能修改。注意，在此结构中一扇区的缓冲已被定义(_FS_TINY == 0下)，所以在这种设置下FIL结构不能被定义为auto variable。

/* File object structure (FIL) */

typedef struct {
	FFOBJID	obj;			/* Object identifier (must be the 1st member to detect invalid object pointer) */
	BYTE	flag;			/* File status flags */
	BYTE	err;			/* Abort flag (error code) */
	FSIZE_t	fptr;			/* File read/write pointer (Zeroed on file open) */
	DWORD	clust;			/* Current cluster of fpter (invalid when fptr is 0) */
	DWORD	sect;			/* Sector number appearing in buf[] (0:invalid) */
#if !FF_FS_READONLY
	DWORD	dir_sect;		/* Sector number containing the directory entry (not used at exFAT) */
	BYTE*	dir_ptr;		/* Pointer to the directory entry in the win[] (not used at exFAT) */
#endif
#if FF_USE_FASTSEEK
	DWORD*	cltbl;			/* Pointer to the cluster link map table (nulled on open, set by application) */
#endif
#if !FF_FS_TINY
	BYTE	buf[FF_MAX_SS];	/* File private data read/write window */
#endif
} FIL;