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OutputGrepper.swift
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OutputGrepper.swift
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//===----------------------------------------------------------------------===//
//
// This source file is part of the SwiftNIO open source project
//
// Copyright (c) 2020 Apple Inc. and the SwiftNIO project authors
// Licensed under Apache License v2.0
//
// See LICENSE.txt for license information
// See CONTRIBUTORS.txt for the list of SwiftNIO project authors
//
// SPDX-License-Identifier: Apache-2.0
//
//===----------------------------------------------------------------------===//
import NIO
import NIOFoundationCompat
import class Foundation.Pipe
internal struct OutputGrepper {
internal var result: EventLoopFuture<ProgramOutput>
internal var processOutputPipe: NIOFileHandle
internal static func make(group: EventLoopGroup) -> OutputGrepper {
let processToChannel = Pipe()
let deadPipe = Pipe() // just so we have an output...
let eventLoop = group.next()
let outputPromise = eventLoop.makePromise(of: ProgramOutput.self)
// We gotta `dup` everything because Pipe is bad and closes file descriptors on `deinit` :(
let channelFuture = NIOPipeBootstrap(group: group)
.channelOption(ChannelOptions.allowRemoteHalfClosure, value: true)
.channelInitializer { channel in
channel.pipeline.addHandlers([ByteToMessageHandler(NewlineFramer()),
GrepHandler(promise: outputPromise)])
}
.withPipes(inputDescriptor: dup(processToChannel.fileHandleForReading.fileDescriptor),
outputDescriptor: dup(deadPipe.fileHandleForWriting.fileDescriptor))
let processOutputPipe = NIOFileHandle(descriptor: dup(processToChannel.fileHandleForWriting.fileDescriptor))
processToChannel.fileHandleForReading.closeFile()
processToChannel.fileHandleForWriting.closeFile()
deadPipe.fileHandleForReading.closeFile()
deadPipe.fileHandleForWriting.closeFile()
channelFuture.cascadeFailure(to: outputPromise)
return OutputGrepper(result: outputPromise.futureResult,
processOutputPipe: processOutputPipe)
}
}
typealias ProgramOutput = String
private final class GrepHandler: ChannelInboundHandler {
typealias InboundIn = String
private let promise: EventLoopPromise<ProgramOutput>
init(promise: EventLoopPromise<ProgramOutput>) {
self.promise = promise
}
func errorCaught(context: ChannelHandlerContext, error: Error) {
self.promise.fail(error)
context.close(promise: nil)
}
func channelRead(context: ChannelHandlerContext, data: NIOAny) {
let line = self.unwrapInboundIn(data)
if line.lowercased().contains("fatal error") ||
line.lowercased().contains("precondition failed") ||
line.lowercased().contains("assertion failed") {
self.promise.succeed(line)
context.close(promise: nil)
}
}
func userInboundEventTriggered(context: ChannelHandlerContext, event: Any) {
if case .some(.inputClosed) = event as? ChannelEvent {
self.promise.succeed("")
context.close(promise: nil)
}
}
func handlerRemoved(context: ChannelHandlerContext) {
self.promise.fail(ChannelError.alreadyClosed)
}
}
private struct NewlineFramer: ByteToMessageDecoder {
typealias InboundOut = String
func decode(context: ChannelHandlerContext, buffer: inout ByteBuffer) throws -> DecodingState {
if let firstNewline = buffer.readableBytesView.firstIndex(of: UInt8(ascii: "\n")) {
let length = firstNewline - buffer.readerIndex + 1
context.fireChannelRead(self.wrapInboundOut(String(buffer.readString(length: length)!.dropLast())))
return .continue
} else {
return .needMoreData
}
}
}