1 files changed, 12 insertions, 5 deletions
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index a1654917dc30..73139d6d551a 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -156,7 +156,7 @@ public:
         abort();
     }
 
-    void trace(const format & f);
+    void trace(const FormatOrString & fs);
 
     string getName()
     {
@@ -417,9 +417,9 @@ void Goal::amDone(ExitCode result)
 }
 
 
-void Goal::trace(const format & f)
+void Goal::trace(const FormatOrString & fs)
 {
-    debug(format("%1%: %2%") % name % f);
+    debug("%1%: %2%", name, fs.s);
 }
 
 
@@ -652,6 +652,11 @@ HookInstance::HookInstance()
         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)
+            throw SysError("dupping builder's stdout/stderr");
+
         Strings args = {
             baseNameOf(settings.buildHook),
             std::to_string(verbosity),
@@ -1189,7 +1194,7 @@ void DerivationGoal::outputsSubstituted()
     for (auto & i : drv->inputSrcs) {
         if (worker.store.isValidPath(i)) continue;
         if (!settings.useSubstitutes)
-            throw Error(format("dependency of '%1%' of '%2%' does not exist, and substitution is disabled")
+            throw Error(format("dependency '%1%' of '%2%' does not exist, and substitution is disabled")
                 % i % drvPath);
         addWaitee(worker.makeSubstitutionGoal(i));
     }
@@ -1458,7 +1463,7 @@ void replaceValidPath(const Path & storePath, const Path tmpPath)
        tmpPath (the replacement), so we have to move it out of the
        way first.  We'd better not be interrupted here, because if
        we're repairing (say) Glibc, we end up with a broken system. */
-    Path oldPath = (format("%1%.old-%2%-%3%") % storePath % getpid() % rand()).str();
+    Path oldPath = (format("%1%.old-%2%-%3%") % storePath % getpid() % random()).str();
     if (pathExists(storePath))
         rename(storePath.c_str(), oldPath.c_str());
     if (rename(tmpPath.c_str(), storePath.c_str()) == -1)
@@ -2944,6 +2949,8 @@ void DerivationGoal::runChild()
 
                 if (drv->builder == "builtin:fetchurl")
                     builtinFetchurl(drv2, netrcData);
+                else if (drv->builder == "builtin:buildenv")
+                    builtinBuildenv(drv2);
                 else
                     throw Error(format("unsupported builtin function '%1%'") % string(drv->builder, 8));
                 _exit(0);