mmsio.h

libmms开发库源代码

#ifndef __MMS_IO_H__
#define __MMS_IO_H__

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

typedef off_t (*mms_io_write_func)(void *data, int socket, char *buf, off_t num);
typedef off_t (*mms_io_read_func)(void *data, int socket, char *buf, off_t num);

/* select states */
#define MMS_IO_READ_READY    1
#define MMS_IO_WRITE_READY   2

enum
  {
    MMS_IO_STATUS_READY, 		/* IO can be safely performed */
    MMS_IO_STATUS_ERROR,		/* There was IO error */
    MMS_IO_STATUS_ABORTED,		/* IO command was (somehow)
	   aborted. This is not error, but invalidates IO for further operations*/
    MMS_IO_STATUS_TIMEOUT		/* Timeout was exceeded */
  };

/*
 * Waits for a file descriptor/socket to change status.
 *
 * users can use this handler to provide their own implementations,
 * for example abortable ones
 *
 * params :
 *   data          whatever parameter may be needed by implementation
 *   fd            file/socket descriptor
 *   state         MMS_IO_READ_READY, MMS_IO_WRITE_READY
 *   timeout_sec   timeout in seconds
 *
 *
 * return value :
 *   MMS_IO_READY     the file descriptor is ready for cmd
 *   MMS_IO_ERROR     an i/o error occured
 *   MMS_IO_ABORTED   command aborted
 *   MMS_IO_TIMEOUT   the file descriptor is not ready after timeout_msec milliseconds
 * every other return value is interpreted same as MMS_IO_ABORTED
 */
typedef int (*mms_io_select_func)(void *data, int fd, int state, int timeout_msec);

/*
 * open a tcp connection
 *
 * params :
 *   stream        needed for reporting errors but may be NULL
 *   host          address of target
 *   port          port on target
 *
 * returns a socket descriptor or -1 if an error occured
 */
typedef int (*mms_io_tcp_connect_func)(void *data, const char *host, int port);

typedef struct
{
  mms_io_select_func select;
  void *select_data;
  mms_io_read_func read;
  void *read_data;
  mms_io_write_func write;
  void *write_data;
  mms_io_tcp_connect_func connect;
  void *connect_data;
} mms_io_t;

/* set default IO implementation, it will be used in absence of specific IO
   parameter. Structure is referenced, not copied, must remain valid for entire
   usage period. Passing NULL reverts to default, POSIX based implementation */
void mms_set_default_io_impl(const mms_io_t *io);
const mms_io_t* mms_get_default_io_impl();

#ifdef __cplusplus
}
#endif /* __cplusplus */

#endif /* __MMS_IO_H__ */