mirror of
https://github.com/rwinkhart/go-winio.git
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108 lines
3.9 KiB
Go
108 lines
3.9 KiB
Go
package etw
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import (
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"bytes"
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"encoding/binary"
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"unsafe"
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"golang.org/x/sys/windows"
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)
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type eventDataDescriptorType uint8
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const (
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eventDataDescriptorTypeUserData eventDataDescriptorType = iota
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eventDataDescriptorTypeEventMetadata
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eventDataDescriptorTypeProviderMetadata
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)
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// Provider represents an ETW event provider. It is identified by a provider
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// name and ID (GUID), which should always have a 1:1 mapping to each other
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// (e.g. don't use multiple provider names with the same ID, or vice versa).
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type Provider struct {
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handle providerHandle
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metadata *bytes.Buffer
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}
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type providerHandle windows.Handle
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// ProviderState informs the provider EnableCallback what action is being
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// performed.
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type ProviderState uint32
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const (
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// ProviderStateDisable indicates the provider is being disabled.
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ProviderStateDisable ProviderState = iota
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// ProviderStateEnable indicates the provider is being enabled.
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ProviderStateEnable
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// ProviderStateCaptureState indicates the provider is having its current
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// state snap-shotted.
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ProviderStateCaptureState
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)
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// EnableCallback is the form of the callback function that receives provider
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// enable/disable notifications from ETW.
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type EnableCallback func(*windows.GUID, ProviderState, Level, uint64, uint64, uintptr)
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type eventDataDescriptor struct {
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ptr uint64
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size uint32
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dataType eventDataDescriptorType
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reserved1 uint8
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reserved2 uint16
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}
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func (descriptor *eventDataDescriptor) set(dataType eventDataDescriptorType, buffer *bytes.Buffer) {
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// Passing a pointer to Go-managed memory as part of a block of memory is
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// risky since the GC doesn't know about it. If we find a better way to do
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// this we should use it instead.
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descriptor.ptr = uint64(uintptr(unsafe.Pointer(&buffer.Bytes()[0])))
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descriptor.size = uint32(buffer.Len())
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descriptor.dataType = dataType
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}
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// NewProvider creates and registers a new provider.
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func NewProvider(name string, id *windows.GUID, callback EnableCallback) (*Provider, error) {
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innerCallback := func(sourceID *windows.GUID, state ProviderState, level Level, matchAnyKeyword uint64, matchAllKeyword uint64, filterData uintptr, _ uintptr) uintptr {
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if callback != nil {
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callback(sourceID, state, level, matchAnyKeyword, matchAllKeyword, filterData)
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}
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return 0
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}
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var providerHandle providerHandle
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if err := eventRegister(id, windows.NewCallback(innerCallback), 0, &providerHandle); err != nil {
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return nil, err
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}
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var metadataBuffer bytes.Buffer
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binary.Write(&metadataBuffer, binary.LittleEndian, uint16(0)) // Write empty size for buffer (to update later)
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binary.Write(&metadataBuffer, binary.LittleEndian, []byte(name)) // Provider name
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binary.Write(&metadataBuffer, binary.LittleEndian, byte(0)) // Null terminator for name
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binary.LittleEndian.PutUint16(metadataBuffer.Bytes(), uint16(metadataBuffer.Len())) // Update the size at the beginning of the buffer
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return &Provider{
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handle: providerHandle,
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metadata: &metadataBuffer,
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}, nil
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}
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// Close unregisters the provider.
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func (provider *Provider) Close() error {
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return eventUnregister(provider.handle)
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}
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// WriteEvent writes a single event to ETW, from this provider.
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func (provider *Provider) WriteEvent(event *Event) error {
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// Finalize the event metadata buffer by filling in the buffer length at the
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// beginning.
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binary.LittleEndian.PutUint16(event.Metadata.buffer.Bytes(), uint16(event.Metadata.buffer.Len()))
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var dataDescriptors [3]eventDataDescriptor
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dataDescriptors[0].set(eventDataDescriptorTypeProviderMetadata, provider.metadata)
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dataDescriptors[1].set(eventDataDescriptorTypeEventMetadata, &event.Metadata.buffer)
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dataDescriptors[2].set(eventDataDescriptorTypeUserData, &event.Data.buffer)
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return eventWriteTransfer(provider.handle, event.Descriptor, nil, nil, 3, &dataDescriptors[0])
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}
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