more iolayer goodness:

[imager.git] / iolayer.h

#ifndef _IOLAYER_H_
#define _IOLAYER_H_


/* How the IO layer works:
 * 
 * Start by getting an io_glue object.  Then define its
 * datasource via io_obj_setp_buffer or io_obj_setp_cb.  Before
 * using the io_glue object be sure to call io_glue_commit_types().
 * After that data can be read via the io_glue->readcb() method.
 *
 */


#include <stdio.h>
#ifndef _MSC_VER
#include <unistd.h>
#endif
#include <sys/types.h>

/* #define BBSIZ 1096 */
#define BBSIZ 16384
#define IO_FAKE_SEEK 1<<0L
#define IO_TEMP_SEEK 1<<1L


typedef enum { FDSEEK, FDNOSEEK, BUFFER, CBSEEK, CBNOSEEK, BUFCHAIN } io_type;

#ifdef _MSC_VER
typedef int ssize_t;
#endif

typedef struct i_io_glue_t i_io_glue_t;

/* compatibility for now */
typedef i_io_glue_t io_glue;

/* Callbacks we give out */

typedef ssize_t(*readp) (io_glue *ig, void *buf, size_t count);
typedef ssize_t(*writep)(io_glue *ig, const void *buf, size_t count);
typedef off_t  (*seekp) (io_glue *ig, off_t offset, int whence);
typedef void   (*closep)(io_glue *ig);
typedef ssize_t(*sizep) (io_glue *ig);

typedef void   (*closebufp)(void *p);
typedef void (*i_io_destroy_t)(i_io_glue_t *ig);


/* Callbacks we get */

typedef ssize_t(*readl) (void *p, void *buf, size_t count);
typedef ssize_t(*writel)(void *p, const void *buf, size_t count);
typedef off_t  (*seekl) (void *p, off_t offset, int whence);
typedef void   (*closel)(void *p);
typedef void   (*destroyl)(void *p);
typedef ssize_t(*sizel) (void *p);

extern char *io_type_names[];



/* Structures to describe data sources */

typedef struct {
  io_type	type;
  int		fd;
} io_fdseek;

typedef struct {
  io_type	type;		/* Must be first parameter */
  char		*name;		/* Data source name */
  char		*data;
  size_t	len;
  closebufp     closecb;        /* free memory mapped segment or decrement refcount */
  void          *closedata;
} io_buffer;

typedef struct {
  io_type	type;		/* Must be first parameter */
  char		*name;		/* Data source name */
  void		*p;		/* Callback data */
  readl		readcb;
  writel	writecb;
  seekl		seekcb;
  closel        closecb;
  destroyl      destroycb;
} io_cb;

typedef union {
  io_type       type;
  io_fdseek     fdseek;
  io_buffer	buffer;
  io_cb		cb;
} io_obj;

struct i_io_glue_t {
  io_obj	source;
  int		flags;		/* Flags */
  void		*exdata;	/* Pair specific data */
  readp		readcb;
  writep	writecb;
  seekp		seekcb;
  closep	closecb;
  sizep		sizecb;
  i_io_destroy_t destroycb;
};

void io_glue_commit_types(io_glue *ig);
void io_glue_gettypes    (io_glue *ig, int reqmeth);


/* XS functions */
io_glue *io_new_fd(int fd);
io_glue *io_new_bufchain(void);
io_glue *io_new_buffer(char *data, size_t len, closebufp closecb, void *closedata);
io_glue *io_new_cb(void *p, readl readcb, writel writecb, seekl seekcb, closel closecb, destroyl destroycb);
size_t   io_slurp(io_glue *ig, unsigned char **c);
void     io_glue_destroy(io_glue *ig);

#define i_io_type(ig) ((ig)->source.ig_type)
#define i_io_read(ig, buf, size) ((ig)->readcb((ig), (buf), (size)))
#define i_io_write(ig, data, size) ((ig)->writecb((ig), (data), (size)))
#define i_io_seek(ig, offset, whence) ((ig)->seekcb((ig), (offset), (whence)))
#define i_io_close(ig) ((ig)->closecb(ig))

#endif /* _IOLAYER_H_ */