From a93dade82118c68b3656ffb40d6a48ab66f2aa1a Mon Sep 17 00:00:00 2001
From: Alois Wohlschlager <alois1@gmx-topmail.de>
Date: Fri, 2 Aug 2024 18:32:24 +0200
Subject: [PATCH] libstore/ssh: only resume the logger when we paused it

In the SSH code, the logger was conditionally paused, but unconditionally
resumed. This was fine as long as resuming the logger was idempotent. Starting
with 0dd1d8ca1cdccfc620644a7f690ed35bcd2d1e74, it isn't any more, and the
behaviour of the code in question was missed. Consequently, an assertion
failure is triggered for example when performing builds against an "SSH" store
on localhost. Fix the issue by only resuming the logger when it has actually
been paused.

Fixes: https://git.lix.systems/lix-project/lix/issues/458
Change-Id: Ib1e4d047744a129f15730b7216f9c9368c2f4211
---
 src/libstore/ssh.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/libstore/ssh.cc b/src/libstore/ssh.cc
index 0d7bfa01d..8386b0e0a 100644
--- a/src/libstore/ssh.cc
+++ b/src/libstore/ssh.cc
@@ -65,10 +65,11 @@ std::unique_ptr<SSHMaster::Connection> SSHMaster::startCommand(const std::string
     ProcessOptions options;
     options.dieWithParent = false;
 
+    std::optional<Finally<std::function<void()>>> resumeLoggerDefer;
     if (!fakeSSH && !useMaster) {
         logger->pause();
+        resumeLoggerDefer.emplace([&]() { logger->resume(); });
     }
-    Finally cleanup = [&]() { logger->resume(); };
 
     conn->sshPid = startProcess([&]() {
         restoreProcessContext();