3 files changed, 29 insertions, 25 deletions

diff --git a/src/libstore/build/derivation-goal.cc b/src/libstore/build/derivation-goal.cc
index 2781929e7..b7f8005ae 100644
--- a/src/libstore/build/derivation-goal.cc
+++ b/src/libstore/build/derivation-goal.cc
@@ -822,8 +822,8 @@ int DerivationGoal::getChildStatus()
 
 void DerivationGoal::closeReadPipes()
 {
-    hook->builderOut.readSide.reset();
-    hook->fromHook.readSide.reset();
+    hook->builderOut.reset();
+    hook->fromHook.reset();
     builderOutFD = nullptr;
 }
 
@@ -1135,7 +1135,7 @@ HookReply DerivationGoal::tryBuildHook(bool inBuildSlot)
         while (true) {
             auto s = [&]() {
                 try {
-                    return readLine(worker.hook.instance->fromHook.readSide.get());
+                    return readLine(worker.hook.instance->fromHook.get());
                 } catch (Error & e) {
                     e.addTrace({}, "while reading the response from the build hook");
                     throw;
@@ -1171,7 +1171,7 @@ HookReply DerivationGoal::tryBuildHook(bool inBuildSlot)
         if (e.errNo == EPIPE) {
             printError(
                 "build hook died unexpectedly: %s",
-                chomp(drainFD(worker.hook.instance->fromHook.readSide.get())));
+                chomp(drainFD(worker.hook.instance->fromHook.get())));
             worker.hook.instance.reset();
             return rpDecline;
         } else
@@ -1181,7 +1181,7 @@ HookReply DerivationGoal::tryBuildHook(bool inBuildSlot)
     hook = std::move(worker.hook.instance);
 
     try {
-        machineName = readLine(hook->fromHook.readSide.get());
+        machineName = readLine(hook->fromHook.get());
     } catch (Error & e) {
         e.addTrace({}, "while reading the machine name from the build hook");
         throw;
@@ -1204,15 +1204,15 @@ HookReply DerivationGoal::tryBuildHook(bool inBuildSlot)
     }
 
     hook->sink = FdSink();
-    hook->toHook.writeSide.reset();
+    hook->toHook.reset();
 
     /* Create the log file and pipe. */
     Path logFile = openLogFile();
 
     std::set<int> fds;
-    fds.insert(hook->fromHook.readSide.get());
-    fds.insert(hook->builderOut.readSide.get());
-    builderOutFD = &hook->builderOut.readSide;
+    fds.insert(hook->fromHook.get());
+    fds.insert(hook->builderOut.get());
+    builderOutFD = &hook->builderOut;
     worker.childStarted(shared_from_this(), fds, false);
 
     return rpAccept;
@@ -1309,7 +1309,7 @@ Goal::WorkResult DerivationGoal::handleChildOutput(int fd, std::string_view data
         return StillAlive{};
     }
 
-    if (hook && fd == hook->fromHook.readSide.get()) {
+    if (hook && fd == hook->fromHook.get()) {
         for (auto c : data)
             if (c == '\n') {
                 auto json = parseJSONMessage(currentHookLine);
diff --git a/src/libstore/build/hook-instance.cc b/src/libstore/build/hook-instance.cc
index 9a93646f4..d5da80c74 100644
--- a/src/libstore/build/hook-instance.cc
+++ b/src/libstore/build/hook-instance.cc
@@ -26,18 +26,21 @@ HookInstance::HookInstance()
     args.push_back(std::to_string(verbosity));
 
     /* Create a pipe to get the output of the child. */
-    fromHook.create();
+    Pipe fromHook_;
+    fromHook_.create();
 
     /* Create the communication pipes. */
-    toHook.create();
+    Pipe toHook_;
+    toHook_.create();
 
     /* Create a pipe to get the output of the builder. */
-    builderOut.create();
+    Pipe builderOut_;
+    builderOut_.create();
 
     /* Fork the hook. */
     pid = startProcess([&]() {
 
-        if (dup2(fromHook.writeSide.get(), STDERR_FILENO) == -1)
+        if (dup2(fromHook_.writeSide.get(), STDERR_FILENO) == -1)
             throw SysError("cannot pipe standard error into log file");
 
         commonChildInit();
@@ -45,16 +48,16 @@ HookInstance::HookInstance()
         if (chdir("/") == -1) throw SysError("changing into /");
 
         /* Dup the communication pipes. */
-        if (dup2(toHook.readSide.get(), STDIN_FILENO) == -1)
+        if (dup2(toHook_.readSide.get(), STDIN_FILENO) == -1)
             throw SysError("dupping to-hook read side");
 
         /* Use fd 4 for the builder's stdout/stderr. */
-        if (dup2(builderOut.writeSide.get(), 4) == -1)
+        if (dup2(builderOut_.writeSide.get(), 4) == -1)
             throw SysError("dupping builder's stdout/stderr");
 
         /* Hack: pass the read side of that fd to allow build-remote
            to read SSH error messages. */
-        if (dup2(builderOut.readSide.get(), 5) == -1)
+        if (dup2(builderOut_.readSide.get(), 5) == -1)
             throw SysError("dupping builder's stdout/stderr");
 
         execv(buildHook.c_str(), stringsToCharPtrs(args).data());
@@ -63,10 +66,11 @@ HookInstance::HookInstance()
     });
 
     pid.setSeparatePG(true);
-    fromHook.writeSide.reset();
-    toHook.readSide.reset();
+    fromHook = std::move(fromHook_.readSide);
+    toHook = std::move(toHook_.writeSide);
+    builderOut = std::move(builderOut_.readSide);
 
-    sink = FdSink(toHook.writeSide.get());
+    sink = FdSink(toHook.get());
     std::map<std::string, Config::SettingInfo> settings;
     globalConfig.getSettings(settings);
     for (auto & setting : settings)
@@ -78,7 +82,7 @@ HookInstance::HookInstance()
 HookInstance::~HookInstance()
 {
     try {
-        toHook.writeSide.reset();
+        toHook.reset();
         if (pid) pid.kill();
     } catch (...) {
         ignoreException();
diff --git a/src/libstore/build/hook-instance.hh b/src/libstore/build/hook-instance.hh
index 481158296..b8632d299 100644
--- a/src/libstore/build/hook-instance.hh
+++ b/src/libstore/build/hook-instance.hh
@@ -10,19 +10,19 @@ namespace nix {
 struct HookInstance
 {
     /**
-     * Pipes for talking to the build hook.
+     * Pipe for talking to the build hook.
      */
-    Pipe toHook;
+    AutoCloseFD toHook;
 
     /**
      * Pipe for the hook's standard output/error.
      */
-    Pipe fromHook;
+    AutoCloseFD fromHook;
 
     /**
      * Pipe for the builder's standard output/error.
      */
-    Pipe builderOut;
+    AutoCloseFD builderOut;
 
     /**
      * The process ID of the hook.