source: bootcd/isolinux/syslinux-6.03/gpxe/src/core/hw.c

#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <gpxe/refcnt.h>
#include <gpxe/process.h>
#include <gpxe/xfer.h>
#include <gpxe/open.h>

/** @file
 *
 * "Hello World" data source
 *
 */

struct hw {
        struct refcnt refcnt;
        struct xfer_interface xfer;
        struct process process;
};

static const char hw_msg[] = "Hello world!\n";

static void hw_finished ( struct hw *hw, int rc ) {
        xfer_nullify ( &hw->xfer );
        xfer_close ( &hw->xfer, rc );
        process_del ( &hw->process );
}

static void hw_xfer_close ( struct xfer_interface *xfer, int rc ) {
        struct hw *hw = container_of ( xfer, struct hw, xfer );

        hw_finished ( hw, rc );
}

static struct xfer_interface_operations hw_xfer_operations = {
        .close          = hw_xfer_close,
        .vredirect      = ignore_xfer_vredirect,
        .window         = unlimited_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = xfer_deliver_as_raw,
        .deliver_raw    = ignore_xfer_deliver_raw,
};

static void hw_step ( struct process *process ) {
        struct hw *hw = container_of ( process, struct hw, process );
        int rc;

        if ( xfer_window ( &hw->xfer ) ) {
                rc = xfer_deliver_raw ( &hw->xfer, hw_msg, sizeof ( hw_msg ) );
                hw_finished ( hw, rc );
        }
}

static int hw_open ( struct xfer_interface *xfer, struct uri *uri __unused ) {
        struct hw *hw;

        /* Allocate and initialise structure */
        hw = zalloc ( sizeof ( *hw ) );
        if ( ! hw )
                return -ENOMEM;
        xfer_init ( &hw->xfer, &hw_xfer_operations, &hw->refcnt );
        process_init ( &hw->process, hw_step, &hw->refcnt );

        /* Attach parent interface, mortalise self, and return */
        xfer_plug_plug ( &hw->xfer, xfer );
        ref_put ( &hw->refcnt );
        return 0;
}

struct uri_opener hw_uri_opener __uri_opener = {
        .scheme = "hw",
        .open = hw_open,
};