IO之Basic IO

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Basic I/O system的7个函数：creat(), remove(), open(), close(), read(), write(), ioctl()。creat()与remove()主要用于文件系统。函数声明如下

int creat (char *name, int flag);int remove(char *name);
/* flags */#define O_RDONLY   0x0000 /* open for reading only */#define O_WRONLY   0x0001 /* open for writing only */#define O_RDWR     0x0002 /* open for reading and writing */#define O_APPEND   0x0008 /* writes are guaranteed at file end */#define O_CREAT    0x0200 /* create a file if not existing */#define O_TRUNC    0x0400 /* open with truncation */#define O_EXCL     0x0800 /* error on open if file exists and O_CREAT is also set */#define O_SYNC     0x2000 /* do all writes synchronously on DosFs */#define O_NONBLOCK 0x4000 /* non blocking I/O */#define O_NOCTTY   0x8000 /* don't assign a controlling-terminal */#define O_DSYNC   0x10000 /* file data only integrity while writing */#define O_RSYNC   0x20000 /* sync read operations */int open    (    char *name,    int   flags,    int   mode  /* UNIX chmod-style file mode */    );int close (int fd);int read  (int fd, char *buffer, int maxBytes);int write (int fd, char *buffer, int nBytes);
/* ioctl function codes */#define FIONREAD        1   /* get num chars available to read */#define FIOFLUSH        2   /* flush any chars in buffers */#define FIOOPTIONS      3   /* set options (FIOSETOPTIONS) */#define FIOBAUDRATE     4   /* set serial baud rate */#define FIODISKFORMAT   5   /* format disk */#define FIODISKINIT     6   /* initialize disk directory */#define FIOSEEK         7   /* set current file char position */#define FIOWHERE        8   /* get current file char position */#define FIODIRENTRY     9   /* return a directory entry (obsolete)*/#define FIORENAME       10  /* rename a directory entry */#define FIOREADYCHANGE  11  /* is there media change on the device? */#define FIONWRITE       12  /* get num chars still to be written */#define FIODISKCHANGE   13  /* set a media change on the device */#define FIOCANCEL       14  /* cancel read or write on the device */#define FIOSQUEEZE      15  /* OBSOLETED since RT11 is obsoleted */#define FIONBIO         16  /* set non-blocking I/O; SOCKETS ONLY!*/#define FIONMSGS        17  /* return num msgs in pipe */#define FIOGETNAME      18  /* return file name in arg */#define FIOGETOPTIONS   19  /* get options */#define FIOSETOPTIONS   FIOOPTIONS  /* set options */#define FIOISATTY       20  /* is a tty */#define FIOSYNC         21  /* sync to disk */#define FIOPROTOHOOK    22  /* specify protocol hook routine */#define FIOPROTOARG     23  /* specify protocol argument */#define FIORBUFSET      24  /* alter the size of read buffer  */#define FIOWBUFSET      25  /* alter the size of write buffer */#define FIORFLUSH       26  /* flush any chars in read buffers */#define FIOWFLUSH       27  /* flush any chars in write buffers */#define FIOSELECT       28  /* wake up process in select on I/O */#define FIOUNSELECT     29  /* wake up process in select on I/O */#define FIONFREE        30  /* get free byte count on device */#define FIOMKDIR        31  /* create a directory */#define FIORMDIR        32  /* remove a directory */#define FIOLABELGET     33  /* get volume label */#define FIOLABELSET     34  /* set volume label */#define FIOATTRIBSET    35  /* set file attribute */#define FIOCONTIG       36  /* allocate contiguous space */#define FIOREADDIR      37  /* read a directory entry (POSIX) */#define FIOFSTATGET_OLD 38  /* get file status info - legacy */#define FIOUNMOUNT      39  /* unmount disk volume */#define FIOSCSICOMMAND  40  /* issue a SCSI command */#define FIONCONTIG      41  /* get size of max contig area on dev */#define FIOTRUNC        42  /* truncate file to specified length */#define FIOGETFL        43  /* get file mode, like fcntl(F_GETFL) */#define FIOTIMESET      44  /* change times on a file for utime() */#define FIOINODETONAME  45  /* given inode number, return filename*/#define FIOFSTATFSGET   46  /* get file system status info */#define FIOMOVE         47  /* move file, ala mv, (mv not rename) */
/* 64-bit ioctl codes, "long long *" expected as 3rd argument */#define FIOCHKDSK       48#define FIOCONTIG64     49#define FIONCONTIG64    50#define FIONFREE64      51#define FIONREAD64      52#define FIOSEEK64       53#define FIOWHERE64      54#define FIOTRUNC64      55
#define FIOCOMMITFS     56#define FIODATASYNC     57  /* sync to I/O data integrity */#define FIOLINK         58  /* create a link */#define FIOUNLINK       59  /* remove a link */#define FIOACCESS       60  /* support POSIX access() */#define FIOPATHCONF     61  /* support POSIX pathconf() */#define FIOFCNTL        62  /* support POSIX fcntl() */#define FIOCHMOD        63  /* support POSIX chmod() */#define FIOFSTATGET     64  /* get stat info - POSIX  */#define FIOUPDATE       65  /* update dosfs default create option */
/* These are for HRFS but can be used for other future file systems */#define FIOCOMMITPOLICYGETFS 66 /* get the file system commit policy */#define FIOCOMMITPOLICYSETFS 67 /* set the file system commit policy */#define FIOCOMMITPERIODGETFS 68 /* get periodic commit interval in ms */#define FIOCOMMITPERIODSETFS 69 /* set the file system's periodic  */#define FIOFSTATFSGET64      70 /* get file system status info */
/* the next two ioctls are for block-type storage media (e.g., disks) */#define FIODISCARDGET   70  /* does hardware want DISCARDs? - for xbdIoctl()*/#define FIODISCARD      71  /* mark sectors (sectorRange) as deleted */
#define FIOREADDIRPLUS  72  /* read a directory entry extention  */
int ioctl (int fd, int function,...);

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