From 6c5a96a47420059ce7ed1a6a6d6c13085accc90c Mon Sep 17 00:00:00 2001
From: Nick Cooke <36927374+ncooke3@users.noreply.github.com>
Date: Thu, 30 Nov 2023 11:58:55 -0500
Subject: [PATCH] [Release Tooling] Fix bug where process is frozen when
 running commands with chatty outputs (#12160)

---
 ReleaseTooling/Sources/Utils/ShellUtils.swift | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/ReleaseTooling/Sources/Utils/ShellUtils.swift b/ReleaseTooling/Sources/Utils/ShellUtils.swift
index 17db91708bd..e3fe860cded 100644
--- a/ReleaseTooling/Sources/Utils/ShellUtils.swift
+++ b/ReleaseTooling/Sources/Utils/ShellUtils.swift
@@ -147,6 +147,17 @@ public extension Shell {
       print("----------------- COMMAND OUTPUT -----------------")
     }
     task.launch()
+    // If we are not outputting to the console, there is a possibility that
+    // the output pipe gets filled (e.g. when running a command that generates
+    // lots of output). In this scenario, the process will hang and
+    // `task.waitUntilExit()` will never return. To work around this issue,
+    // calling `outHandle.readDataToEndOfFile()` before `task.waitUntilExit()`
+    // will read from the pipe until the process ends.
+    var outData: Data!
+    if !outputToConsole {
+      outData = outHandle.readDataToEndOfFile()
+    }
+
     task.waitUntilExit()
     if outputToConsole { print("----------------- END COMMAND OUTPUT -----------------") }
 
@@ -154,7 +165,6 @@ public extension Shell {
     if outputToConsole {
       fullOutput = output.joined(separator: "\n")
     } else {
-      let outData = outHandle.readDataToEndOfFile()
       // Force unwrapping since we know it's UTF8 coming from the console.
       fullOutput = String(data: outData, encoding: .utf8)!
     }