Simplify commonChildInit()

src/libstore/build/hook-instance.cc

@@ -35,7 +35,7 @@ HookInstance::HookInstance()
     /* Fork the hook. */
     pid = startProcess([&]() {
 
-        commonChildInit(fromHook);
+        commonChildInit(fromHook.writeSide.get());
 
         if (chdir("/") == -1) throw SysError("changing into /");
 

src/libstore/build/local-derivation-goal.cc

@@ -1649,7 +1649,7 @@ void LocalDerivationGoal::runChild()
 
     try { /* child */
 
-        commonChildInit(builderOut);
+        commonChildInit(builderOut.writeSide.get());
 
         try {
             setupSeccomp();

src/libutil/util.cc

@@ -1968,7 +1968,7 @@ std::string showBytes(uint64_t bytes)
 
 
 // FIXME: move to libstore/build
-void commonChildInit(Pipe & logPipe)
+void commonChildInit(int stderrFd)
 {
     logger = makeSimpleLogger();
 
@@ -1983,7 +1983,7 @@ void commonChildInit(Pipe & logPipe)
         throw SysError("creating a new session");
 
     /* Dup the write side of the logger pipe into stderr. */
-    if (dup2(logPipe.writeSide.get(), STDERR_FILENO) == -1)
+    if (dup2(stderrFd, STDERR_FILENO) == -1)
         throw SysError("cannot pipe standard error into log file");
 
     /* Dup stderr to stdout. */

src/libutil/util.hh

@@ -704,7 +704,7 @@ typedef std::function<bool(const Path & path)> PathFilter;
 extern PathFilter defaultPathFilter;
 
 /* Common initialisation performed in child processes. */
-void commonChildInit(Pipe & logPipe);
+void commonChildInit(int stderrFd);
 
 /* Create a Unix domain socket. */
 AutoCloseFD createUnixDomainSocket();