iofunc_lseek_default()

Default handler for _IO_LSEEK messages

Synopsis:

#include <sys/iofunc.h>

int iofunc_lseek_default( resmgr_context_t* ctp,
                          io_lseek_t* msg,
                          iofunc_ocb_t* ocb );

Arguments:

ctp

A pointer to a resmgr_context_t structure that the resource-manager library uses to pass context information between functions.

msg

A pointer to the io_lseek_t structure that contains the message that the resource manager received. For more information, see the documentation for iofunc_lseek().

ocb

A pointer to the iofunc_ocb_t structure for the Open Control Block that was created when the client opened the resource.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The iofunc_lseek_default() function implements POSIX semantics for the client's lseek() call, which is received as an _IO_LSEEK message by the resource manager.

You can place this function directly into the io_funcs table passed to resmgr_attach(), at the lseek position, or you can call iofunc_func_init() to initialize all of the functions to their default values.

The iofunc_lseek_default() function calls iofunc_lseek() to do the actual work.

Returns:

-1

Success; the resource manager library should return a one-part IOV to the client.

EOK

The message is a combine message, and no error occurred.

EINVAL

The whence member in the _IO_LSEEK message wasn't one of SEEK_SET, SEEK_CUR, or SEEK_END, or the resulting position after the offset was applied resulted in a negative number (overflow).

EOVERFLOW

The resulting file offset is a value that can't be represented correctly in an object of type off_t.

Classification:

QNX Neutrino

See also:

iofunc_func_init(), iofunc_lseek(), iofunc_ocb_t, lseek(), resmgr_attach(), resmgr_context_t, resmgr_io_funcs_t

Writing a Resource Manager

Resource Managers chapter of Getting Started with QNX Neutrino