io_open()

Initialize an IO stream

Synopsis:

#include <img.h>

io_stream_t *io_open( io_open_f *open_f,
                      io_mode_t  mode, ...)

Arguments:

open_f

A pointer to a function to establish a stream. There are two functions supplied by the library: IO_FD (for fd-based reading/writing) and IO_MEM (for memory buffer based reading/writing). See below.

mode

The open mode, either IO_READ or IO_WRITE.

...

Additional parameters depending on the open_f specified, described below.

Library:

img

Description:

This function initializes a stream. The stream can be a fd-based, or a memory buffer, depending on the open_f specified:

IO_FD

Buffered streaming for unix-type fd's. An additional parmameter is required: an int specifying the (previously opened) fd that is ready for reading or writing.

IO_MEM

Streaming support for a memory buffer. Additional parameters are required (in order):

1. an unsigned to specify size of the memory buffer. This must be non-zero.
2. a void pointer to specify the address of the buffer.

When your application is finished with a stream, it should call io_close() to release it.

Returns:

A pointer to the stream object, or NULL if an error occurred (errno is set).

Errors:

ENOMEM

Insufficient memory to allocate structures.

EINVAL

Invalid open_f or mode.

ENOTSUP

Mode not supported for stream.

Classification:

Image library

See also:

io_close()