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/* Example plugin.
* Copyright Red Hat
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* * Neither the name of Red Hat nor the names of its contributors may be
* used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
package main
import (
"C"
"libguestfs.org/nbdkit"
"strconv"
"unsafe"
)
var pluginName = "ramdisk"
type RAMDiskPlugin struct {
nbdkit.Plugin
}
type RAMDiskConnection struct {
nbdkit.Connection
}
var size uint64
var size_set = false
var disk []byte
func (p *RAMDiskPlugin) Config(key string, value string) error {
if key == "size" {
var err error
size, err = strconv.ParseUint(value, 0, 64)
if err != nil {
return err
}
size_set = true
return nil
} else {
return nbdkit.PluginError{Errmsg: "unknown parameter"}
}
}
func (p *RAMDiskPlugin) ConfigComplete() error {
if !size_set {
return nbdkit.PluginError{Errmsg: "size parameter is required"}
}
return nil
}
func (p *RAMDiskPlugin) GetReady() error {
// Allocate the RAM disk.
disk = make([]byte, size)
return nil
}
func (p *RAMDiskPlugin) Open(readonly bool) (nbdkit.ConnectionInterface, error) {
return &RAMDiskConnection{}, nil
}
func (c *RAMDiskConnection) GetSize() (uint64, error) {
return size, nil
}
// Clients are allowed to make multiple connections safely.
func (c *RAMDiskConnection) CanMultiConn() (bool, error) {
return true, nil
}
func (c *RAMDiskConnection) PRead(buf []byte, offset uint64,
flags uint32) error {
copy(buf, disk[offset:int(offset)+len(buf)])
return nil
}
// Note that CanWrite is required in golang plugins, otherwise PWrite
// will never be called.
func (c *RAMDiskConnection) CanWrite() (bool, error) {
return true, nil
}
func (c *RAMDiskConnection) PWrite(buf []byte, offset uint64,
flags uint32) error {
copy(disk[offset:int(offset)+len(buf)], buf)
return nil
}
//----------------------------------------------------------------------
//
// The boilerplate below this line is required by all golang plugins,
// as well as importing "C" and "unsafe" modules at the top of the
// file.
//export plugin_init
func plugin_init() unsafe.Pointer {
// If your plugin needs to do any initialization, you can
// either put it here or implement a Load() method.
// ...
// Then you must call the following function.
return nbdkit.PluginInitialize(pluginName, &RAMDiskPlugin{})
}
// This is never(?) called, but must exist.
func main() {}
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