For the current set of examples this doesn't matter. This also adds another example where we use the Connection to store data, just to check that actually works. Thanks: James @ purpleidea, Dan Berrangé --- plugins/golang/nbdkit-golang-plugin.pod | 10 +- plugins/golang/Makefile.am | 9 + plugins/golang/examples/disk/disk.go | 168 ++++++++++++++++++ .../golang/examples/dump-plugin/dumpplugin.go | 8 +- plugins/golang/examples/minimal/minimal.go | 6 +- plugins/golang/examples/ramdisk/ramdisk.go | 18 +- .../src/libguestfs.org/nbdkit/nbdkit.go | 42 ++--- plugins/golang/test/test.go | 14 +- 8 files changed, 226 insertions(+), 49 deletions(-) diff --git a/plugins/golang/nbdkit-golang-plugin.pod b/plugins/golang/nbdkit-golang-plugin.pod index b15bb481..90732289 100644 --- a/plugins/golang/nbdkit-golang-plugin.pod +++ b/plugins/golang/nbdkit-golang-plugin.pod @@ -62,16 +62,16 @@ C<GetSize> and C<PRead>. What connects the two is the C<Open> callback which is called when the client has connected and where you should return a new instance of your connection struct. For example: - func (p MyPlugin) Load() { + func (p *MyPlugin) Load() { // global callback used for initializing the plugin } - func (p MyPlugin) Open(readonly bool) (nbdkit.ConnectionInterface, error) { + func (p *MyPlugin) Open(readonly bool) (nbdkit.ConnectionInterface, error) { // new client has connected return &MyConnection{}, nil } - func (c MyConnection) GetSize() (uint64, error) { + func (c *MyConnection) GetSize() (uint64, error) { // called per-client return virtual_size, nil } @@ -106,11 +106,11 @@ unless you also implement a C<CanWrite> callback that returns true. The same applies to C<Flush> (C<CanFlush>), C<Trim> (C<CanTrim>) and C<Zero> (C<CanZero>). - func (c MyConnection) CanWrite() (bool, error) { + func (c *MyConnection) CanWrite() (bool, error) { return true, nil } - func (c MyConnection) PWrite(buf []byte, offset uint64, + func (c *MyConnection) PWrite(buf []byte, offset uint64, flags uint32) error { // ... } diff --git a/plugins/golang/Makefile.am b/plugins/golang/Makefile.am index 74ad4a72..91711724 100644 --- a/plugins/golang/Makefile.am +++ b/plugins/golang/Makefile.am @@ -42,6 +42,7 @@ EXTRA_DIST = \ $(plugin_sources) \ config-test.go \ dump-plugin-examples.sh \ + examples/disk/disk.go \ examples/dump-plugin/dumpplugin.go \ examples/minimal/minimal.go \ examples/ramdisk/ramdisk.go \ @@ -58,11 +59,19 @@ if HAVE_GOLANG # Examples. noinst_DATA = \ + examples/disk/nbdkit-godisk-plugin.so \ examples/dump-plugin/nbdkit-godump-plugin.so \ examples/minimal/nbdkit-gominimal-plugin.so \ examples/ramdisk/nbdkit-goramdisk-plugin.so \ $(NULL) +examples/disk/nbdkit-godisk-plugin.so: \ + $(plugin_sources) examples/disk/disk.go + cd examples/disk && \ + PKG_CONFIG_PATH="$(abs_top_builddir)/server/local$${PKG_CONFIG_PATH:+:$$PKG_CONFIG_PATH}" \ + GOPATH="$(abs_builddir)" \ + $(GOLANG) build -o nbdkit-godisk-plugin.so -buildmode=c-shared + examples/dump-plugin/nbdkit-godump-plugin.so: \ $(plugin_sources) examples/dump-plugin/dumpplugin.go cd examples/dump-plugin && \ diff --git a/plugins/golang/examples/disk/disk.go b/plugins/golang/examples/disk/disk.go new file mode 100644 index 00000000..37f449e0 --- /dev/null +++ b/plugins/golang/examples/disk/disk.go @@ -0,0 +1,168 @@ +/* Example plugin. + * Copyright (C) 2013-2020 Red Hat Inc. + * + * 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" + "io/ioutil" + "libguestfs.org/nbdkit" + "os" + "strconv" + "unsafe" +) + +var pluginName = "disk" + +type DiskPlugin struct { + nbdkit.Plugin +} + +type DiskConnection struct { + nbdkit.Connection + fd *os.File +} + +var size uint64 +var size_set = false + +func (p *DiskPlugin) 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 *DiskPlugin) ConfigComplete() error { + if !size_set { + return nbdkit.PluginError{Errmsg: "size parameter is required"} + } + return nil +} + +func (p *DiskPlugin) Open(readonly bool) (nbdkit.ConnectionInterface, error) { + // Open a temporary file. + fd, err := ioutil.TempFile("/var/tmp", "nbdkitdisk") + if err != nil { + return nil, err + } + os.Remove(fd.Name()) + + // Truncate it to the right size. + err = fd.Truncate(int64(size)) + if err != nil { + return nil, err + } + + // Store the file descriptor of the temporary file in the + // Connection struct. + return &DiskConnection{fd: fd}, nil +} + +func (c *DiskConnection) Close() { + c.fd.Close() +} + +func (c *DiskConnection) GetSize() (uint64, error) { + // Return the size of the disk. We could just return the + // global "size" here, but make the example more interesting. + info, err := c.fd.Stat() + if err != nil { + return 0, err + } + return uint64(info.Size()), nil +} + +// Multi-conn is NOT safe because each client sees a different disk. +func (c *DiskConnection) CanMultiConn() (bool, error) { + return false, nil +} + +func (c *DiskConnection) PRead(buf []byte, offset uint64, + flags uint32) error { + n, err := c.fd.ReadAt(buf, int64(offset)) + if err != nil { + return err + } + // NBD requests must always read/write the whole requested + // amount, or else fail. Actually we should loop here (XXX). + if n != len(buf) { + return nbdkit.PluginError{Errmsg: "short read"} + } + return nil +} + +// Note that CanWrite is required in golang plugins, otherwise PWrite +// will never be called. +func (c *DiskConnection) CanWrite() (bool, error) { + return true, nil +} + +func (c *DiskConnection) PWrite(buf []byte, offset uint64, + flags uint32) error { + n, err := c.fd.WriteAt(buf, int64(offset)) + if err != nil { + return err + } + // NBD requests must always read/write the whole requested + // amount, or else fail. Actually we should loop here (XXX). + if n != len(buf) { + return nbdkit.PluginError{Errmsg: "short write"} + } + 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, &DiskPlugin{}) +} + +// This is never(?) called, but must exist. +func main() {} diff --git a/plugins/golang/examples/dump-plugin/dumpplugin.go b/plugins/golang/examples/dump-plugin/dumpplugin.go index 518be078..d30ec3f1 100644 --- a/plugins/golang/examples/dump-plugin/dumpplugin.go +++ b/plugins/golang/examples/dump-plugin/dumpplugin.go @@ -51,19 +51,19 @@ type DumpConnection struct { var size uint64 = 1024 * 1024 -func (p DumpPlugin) DumpPlugin() { +func (p *DumpPlugin) DumpPlugin() { fmt.Println("golang_dump_plugin=1") } -func (p DumpPlugin) Open(readonly bool) (nbdkit.ConnectionInterface, error) { +func (p *DumpPlugin) Open(readonly bool) (nbdkit.ConnectionInterface, error) { return &DumpConnection{}, nil } -func (c DumpConnection) GetSize() (uint64, error) { +func (c *DumpConnection) GetSize() (uint64, error) { return size, nil } -func (c DumpConnection) PRead(buf []byte, offset uint64, +func (c *DumpConnection) PRead(buf []byte, offset uint64, flags uint32) error { for i := 0; i < len(buf); i++ { buf[i] = 0 diff --git a/plugins/golang/examples/minimal/minimal.go b/plugins/golang/examples/minimal/minimal.go index e010bfcb..0f862889 100644 --- a/plugins/golang/examples/minimal/minimal.go +++ b/plugins/golang/examples/minimal/minimal.go @@ -50,15 +50,15 @@ type MinimalConnection struct { var size uint64 = 1024 * 1024 -func (p MinimalPlugin) Open(readonly bool) (nbdkit.ConnectionInterface, error) { +func (p *MinimalPlugin) Open(readonly bool) (nbdkit.ConnectionInterface, error) { return &MinimalConnection{}, nil } -func (c MinimalConnection) GetSize() (uint64, error) { +func (c *MinimalConnection) GetSize() (uint64, error) { return size, nil } -func (c MinimalConnection) PRead(buf []byte, offset uint64, +func (c *MinimalConnection) PRead(buf []byte, offset uint64, flags uint32) error { for i := 0; i < len(buf); i++ { buf[i] = 0 diff --git a/plugins/golang/examples/ramdisk/ramdisk.go b/plugins/golang/examples/ramdisk/ramdisk.go index c848f575..78cb1f4c 100644 --- a/plugins/golang/examples/ramdisk/ramdisk.go +++ b/plugins/golang/examples/ramdisk/ramdisk.go @@ -53,7 +53,7 @@ var size uint64 var size_set = false var disk []byte -func (p RAMDiskPlugin) Config(key string, value string) error { +func (p *RAMDiskPlugin) Config(key string, value string) error { if key == "size" { var err error size, err = strconv.ParseUint(value, 0, 64) @@ -67,33 +67,33 @@ func (p RAMDiskPlugin) Config(key string, value string) error { } } -func (p RAMDiskPlugin) ConfigComplete() error { +func (p *RAMDiskPlugin) ConfigComplete() error { if !size_set { return nbdkit.PluginError{Errmsg: "size parameter is required"} } return nil } -func (p RAMDiskPlugin) GetReady() error { +func (p *RAMDiskPlugin) GetReady() error { // Allocate the RAM disk. disk = make([]byte, size) return nil } -func (p RAMDiskPlugin) Open(readonly bool) (nbdkit.ConnectionInterface, error) { +func (p *RAMDiskPlugin) Open(readonly bool) (nbdkit.ConnectionInterface, error) { return &RAMDiskConnection{}, nil } -func (c RAMDiskConnection) GetSize() (uint64, error) { +func (c *RAMDiskConnection) GetSize() (uint64, error) { return size, nil } // Clients are allowed to make multiple connections safely. -func (c RAMDiskConnection) CanMultiConn() (bool, error) { +func (c *RAMDiskConnection) CanMultiConn() (bool, error) { return true, nil } -func (c RAMDiskConnection) PRead(buf []byte, offset uint64, +func (c *RAMDiskConnection) PRead(buf []byte, offset uint64, flags uint32) error { copy(buf, disk[offset:int(offset)+len(buf)]) return nil @@ -101,11 +101,11 @@ func (c RAMDiskConnection) PRead(buf []byte, offset uint64, // Note that CanWrite is required in golang plugins, otherwise PWrite // will never be called. -func (c RAMDiskConnection) CanWrite() (bool, error) { +func (c *RAMDiskConnection) CanWrite() (bool, error) { return true, nil } -func (c RAMDiskConnection) PWrite(buf []byte, offset uint64, +func (c *RAMDiskConnection) PWrite(buf []byte, offset uint64, flags uint32) error { copy(disk[offset:int(offset)+len(buf)], buf) return nil diff --git a/plugins/golang/src/libguestfs.org/nbdkit/nbdkit.go b/plugins/golang/src/libguestfs.org/nbdkit/nbdkit.go index 155034d9..8e9e9bbd 100644 --- a/plugins/golang/src/libguestfs.org/nbdkit/nbdkit.go +++ b/plugins/golang/src/libguestfs.org/nbdkit/nbdkit.go @@ -145,83 +145,83 @@ type ConnectionInterface interface { type Plugin struct{} type Connection struct{} -func (p Plugin) Load() { +func (p *Plugin) Load() { } -func (p Plugin) Unload() { +func (p *Plugin) Unload() { } -func (p Plugin) DumpPlugin() { +func (p *Plugin) DumpPlugin() { } -func (p Plugin) Config(key string, value string) error { +func (p *Plugin) Config(key string, value string) error { return nil } -func (p Plugin) ConfigComplete() error { +func (p *Plugin) ConfigComplete() error { return nil } -func (p Plugin) GetReady() error { +func (p *Plugin) GetReady() error { return nil } -func (p Plugin) PreConnect(readonly bool) error { +func (p *Plugin) PreConnect(readonly bool) error { return nil } -func (p Plugin) Open(readonly bool) (ConnectionInterface, error) { +func (p *Plugin) Open(readonly bool) (ConnectionInterface, error) { panic("plugin must implement Open()") } -func (c Connection) Close() { +func (c *Connection) Close() { } -func (c Connection) GetSize() (uint64, error) { +func (c *Connection) GetSize() (uint64, error) { panic("plugin must implement GetSize()") } -func (c Connection) CanWrite() (bool, error) { +func (c *Connection) CanWrite() (bool, error) { return false, nil } -func (c Connection) CanFlush() (bool, error) { +func (c *Connection) CanFlush() (bool, error) { return false, nil } -func (c Connection) IsRotational() (bool, error) { +func (c *Connection) IsRotational() (bool, error) { return false, nil } -func (c Connection) CanTrim() (bool, error) { +func (c *Connection) CanTrim() (bool, error) { return false, nil } -func (c Connection) CanZero() (bool, error) { +func (c *Connection) CanZero() (bool, error) { return false, nil } -func (c Connection) CanMultiConn() (bool, error) { +func (c *Connection) CanMultiConn() (bool, error) { return false, nil } -func (c Connection) PRead(buf []byte, offset uint64, flags uint32) error { +func (c *Connection) PRead(buf []byte, offset uint64, flags uint32) error { panic("plugin must implement PRead()") } -func (c Connection) PWrite(buf []byte, offset uint64, flags uint32) error { +func (c *Connection) PWrite(buf []byte, offset uint64, flags uint32) error { panic("plugin CanWrite returns true, but no PWrite() function") } -func (c Connection) Flush(flags uint32) error { +func (c *Connection) Flush(flags uint32) error { panic("plugin CanFlush returns true, but no Flush() function") } -func (c Connection) Trim(count uint32, offset uint64, flags uint32) error { +func (c *Connection) Trim(count uint32, offset uint64, flags uint32) error { panic("plugin CanTrim returns true, but no Trim() function") } -func (c Connection) Zero(count uint32, offset uint64, flags uint32) error { +func (c *Connection) Zero(count uint32, offset uint64, flags uint32) error { panic("plugin CanZero returns true, but no Zero() function") } diff --git a/plugins/golang/test/test.go b/plugins/golang/test/test.go index 7186ffa8..e585a971 100644 --- a/plugins/golang/test/test.go +++ b/plugins/golang/test/test.go @@ -52,15 +52,15 @@ type TestConnection struct { var size uint64 var size_set = false -func (p TestPlugin) Load() { +func (p *TestPlugin) Load() { nbdkit.Debug("golang code running in the .load callback") } -func (p TestPlugin) Unload() { +func (p *TestPlugin) Unload() { nbdkit.Debug("golang code running in the .unload callback") } -func (p TestPlugin) Config(key string, value string) error { +func (p *TestPlugin) Config(key string, value string) error { if key == "size" { var err error size, err = strconv.ParseUint(value, 0, 64) @@ -74,24 +74,24 @@ func (p TestPlugin) Config(key string, value string) error { } } -func (p TestPlugin) ConfigComplete() error { +func (p *TestPlugin) ConfigComplete() error { if !size_set { return nbdkit.PluginError{Errmsg: "size parameter is required"} } return nil } -func (p TestPlugin) Open(readonly bool) (nbdkit.ConnectionInterface, error) { +func (p *TestPlugin) Open(readonly bool) (nbdkit.ConnectionInterface, error) { nbdkit.Debug("golang code running in the .open callback") return &TestConnection{}, nil } -func (c TestConnection) GetSize() (uint64, error) { +func (c *TestConnection) GetSize() (uint64, error) { nbdkit.Debug("golang code running in the .get_size callback") return size, nil } -func (c TestConnection) PRead(buf []byte, offset uint64, flags uint32) error { +func (c *TestConnection) PRead(buf []byte, offset uint64, flags uint32) error { nbdkit.Debug("golang code running in the .pread callback") for i := 0; i < len(buf); i++ { buf[i] = 0 -- 2.25.0