[tibs] Consolidate uses of Process and fix warnings

Fix warnings by using the non-deprecated APIs, and while we're at it
consolidate all the uses into a single place that checks the result and
collects stdout. Inspired by SwiftPM's checkNonZeroExit.

Author: benlangmuir

Sources/ISDBTibs/Process.swift

@@ -0,0 +1,60 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import Foundation
+
+extension Process {
+
+  enum TibsProcessError: Error {
+    case nonZeroExit(TerminationReason, Int32)
+    case invalidUTF8Output(Data)
+  }
+
+  /// Runs a subprocess and returns its output as a String if it has a zero exit.
+  static func tibs_checkNonZeroExit(
+    arguments: [String],
+    environment: [String: String]? = nil
+  ) throws -> String {
+    let p = Process()
+    let out = Pipe()
+
+    if #available(macOS 10.13, *) {
+      p.executableURL = URL(fileURLWithPath: arguments[0], isDirectory: false)
+    } else {
+      p.launchPath = arguments[0]
+    }
+
+    p.arguments = Array(arguments[1...])
+    if let environment = environment {
+      p.environment = environment
+    }
+    p.standardOutput = out
+
+    if #available(macOS 10.13, *) {
+      try p.run()
+    } else {
+      p.launch()
+    }
+
+    p.waitUntilExit()
+
+    if p.terminationReason != .exit || p.terminationStatus != 0 {
+      throw TibsProcessError.nonZeroExit(p.terminationReason, p.terminationStatus)
+    }
+
+    let data = out.fileHandleForReading.readDataToEndOfFile()
+    guard let str = String(data: data, encoding: .utf8) else {
+      throw TibsProcessError.invalidUTF8Output(data)
+    }
+    return str
+  }
+}

Sources/ISDBTibs/TibsBuilder.swift

@@ -118,19 +118,7 @@ extension TibsBuilder {
 
   /// *For Testing* Build and collect a list of commands that were (re)built.
   public func _buildTest() throws -> Set<String> {
-    let pipe = Pipe()
-
-    do {
-      try buildImpl { process in
-        process.standardOutput = pipe
-      }
-    } catch TibsBuilder.Error.buildFailure(let tc, let ts) {
-      let out = String(data: pipe.fileHandleForReading.readDataToEndOfFile(), encoding: .utf8)!
-      print(out)
-      throw TibsBuilder.Error.buildFailure(tc, exitCode: ts)
-    }
-
-    let out = String(data: pipe.fileHandleForReading.readDataToEndOfFile(), encoding: .utf8)!
+    let out = try buildImpl()
     var rest = out.startIndex..<out.endIndex
 
     var result = Set<String>()
@@ -144,21 +132,16 @@ extension TibsBuilder {
     return result
   }
 
-  func buildImpl(processCustomization: (Process) -> () = { _ in }) throws {
+  @discardableResult
+  func buildImpl() throws -> String {
     guard let ninja = toolchain.ninja?.path else {
       throw Error.noNinjaBinaryConfigured
     }
 
-    let p = Process()
-    p.launchPath = ninja
-    p.arguments = ["-C", buildRoot.path]
-
-    processCustomization(p)
-
-    p.launch()
-    p.waitUntilExit()
-    if p.terminationReason != .exit || p.terminationStatus != 0 {
-      throw Error.buildFailure(p.terminationReason, exitCode: p.terminationStatus)
+    do {
+      return try Process.tibs_checkNonZeroExit(arguments: [ninja, "-C", buildRoot.path])
+    } catch Process.TibsProcessError.nonZeroExit(let reason, let code) {
+      throw Error.buildFailure(reason, exitCode: code)
     }
   }
 }
@@ -367,24 +350,7 @@ extension TibsBuilder {
 }
 
 func xcrunSDKPath() -> String {
-  let p = Process()
-  p.launchPath = "/usr/bin/xcrun"
-  p.arguments = ["--show-sdk-path"]
-
-  let out = Pipe()
-  p.standardOutput = out
-
-  p.launch()
-  p.waitUntilExit()
-
-  if p.terminationReason != .exit || p.terminationStatus != 0 {
-    fatalError("unexpected non-zero exit \(p.terminationStatus) from xcrun --show-sdkpath")
-  }
-
-  let data = out.fileHandleForReading.readDataToEndOfFile()
-  guard var path = String(data: data, encoding: .utf8) else {
-    fatalError("invalid output \(data) from xcrun --show-sdkpath")
-  }
+  var path = try! Process.tibs_checkNonZeroExit(arguments: ["/usr/bin/xcrun", "--show-sdk-path"])
   if path.last == "\n" {
     path = String(path.dropLast())
   }

Sources/ISDBTibs/TibsToolchain.swift

@@ -40,17 +40,7 @@ public final class TibsToolchain {
 #endif
 
   public private(set) lazy var clangVersionOutput: String = {
-    let p = Process()
-    p.launchPath = clang.path
-    p.arguments = ["--version"]
-    let pipe = Pipe()
-    p.standardOutput = pipe
-    p.launch()
-    p.waitUntilExit()
-    guard p.terminationReason == .exit && p.terminationStatus == 0 else {
-      fatalError("could not get clang --version")
-    }
-    return String(data: pipe.fileHandleForReading.readDataToEndOfFile(), encoding: .utf8)!
+    return try! Process.tibs_checkNonZeroExit(arguments: [clang.path, "--version"])
   }()
 
   public private(set) lazy var clangHasIndexSupport: Bool = {
@@ -59,18 +49,7 @@ public final class TibsToolchain {
 
   public private(set) lazy var ninjaVersion: (Int, Int, Int) = {
     precondition(ninja != nil, "expected non-nil ninja in ninjaVersion")
-    let p = Process()
-    p.launchPath = ninja!.path
-    p.arguments = ["--version"]
-    let pipe = Pipe()
-    p.standardOutput = pipe
-    p.launch()
-    p.waitUntilExit()
-    guard p.terminationReason == .exit && p.terminationStatus == 0 else {
-      fatalError("could not get ninja --version")
-    }
-
-    var out = String(data: pipe.fileHandleForReading.readDataToEndOfFile(), encoding: .utf8)!
+    var out = try! Process.tibs_checkNonZeroExit(arguments: [ninja!.path, "--version"])
     out = out.trimmingCharacters(in: .whitespacesAndNewlines)
     let components = out.split(separator: ".", maxSplits: 3)
     guard let maj = Int(String(components[0])),
@@ -179,30 +158,17 @@ extension TibsToolchain {
 
 /// Returns the path to the given tool, as found by `xcrun --find` on macOS, or `which` on Linux.
 public func findTool(name: String) -> URL? {
-  let p = Process()
 #if os(macOS)
-  p.launchPath = "/usr/bin/xcrun"
-  p.arguments = ["--find", name]
+  let cmd = ["/usr/bin/xcrun", "--find", name]
 #else
-  p.launchPath = "/usr/bin/which"
-  p.arguments = [name]
+  let cmd = ["/usr/bin/which", name]
 #endif
-  let out = Pipe()
-  p.standardOutput = out
-
-  p.launch()
-  p.waitUntilExit()
-
-  if p.terminationReason != .exit || p.terminationStatus != 0 {
-    return nil
-  }
 
-  let data = out.fileHandleForReading.readDataToEndOfFile()
-  guard var path = String(data: data, encoding: .utf8) else {
+  guard var path = try? Process.tibs_checkNonZeroExit(arguments: cmd) else {
     return nil
   }
   if path.last == "\n" {
     path = String(path.dropLast())
   }
-  return URL(fileURLWithPath: path)
+  return URL(fileURLWithPath: path, isDirectory: false)
 }