daemon: Use 'Agent' to spawn 'guix substitute --query'.

* nix/libstore/local-store.hh (RunningSubstituter): Remove.
(LocalStore)[runningSubstituter]: Change to unique_ptr<Agent>.
[setSubstituterEnv, didSetSubstituterEnv]: Remove.
[getLineFromSubstituter, getIntLineFromSubstituter]: Take an 'Agent'.
* nix/libstore/local-store.cc (LocalStore::~LocalStore): Remove
reference to 'runningSubstituter'.
(LocalStore::setSubstituterEnv, LocalStore::startSubstituter): Remove.
(LocalStore::getLineFromSubstituter): Adjust to 'run' being an 'Agent'.
(LocalStore::querySubstitutablePaths): Spawn substituter agent if
needed.  Adjust to 'Agent' interface.
(LocalStore::querySubstitutablePathInfos): Likewise.
* nix/libstore/build.cc (SubstitutionGoal::tryToRun): Remove call to
'setSubstituterEnv' and add 'setenv' call for "_NIX_OPTIONS" instead.
(SubstitutionGoal::finished): Remove 'readLine' call for 'dummy'.
* guix/scripts/substitute.scm (%allow-unauthenticated-substitutes?):
Remove second argument to 'make-parameter'.
(process-query): Call 'warn-about-missing-authentication'
when (%allow-unauthenticated-substitutes?) is #t.
(guix-substitute): Wrap body in 'parameterize'.  Set 'guix-warning-port'
too.  No longer exit when 'substitute-urls' returns the empty list.  No
longer print newline initially.
* tests/substitute.scm (test-quit): Parameterize 'current-error-port' to
account for the port changes in 'guix-substitute'.

1 files changed, 3 insertions, 3 deletions

diff --git a/nix/libstore/build.cc b/nix/libstore/build.cc
index 8413819114..7e9ab3f39c 100644
--- a/nix/libstore/build.cc
+++ b/nix/libstore/build.cc
@@ -2986,8 +2986,6 @@ void SubstitutionGoal::tryToRun()
     if (pathExists(destPath))
         deletePath(destPath);
 
-    worker.store.setSubstituterEnv();
-
     /* Fill in the arguments. */
     Strings args;
     args.push_back("guix");
@@ -2999,6 +2997,9 @@ void SubstitutionGoal::tryToRun()
     /* Fork the substitute program. */
     pid = startProcess([&]() {
 
+	/* Communicate substitute-urls & co. to 'guix substitute'.  */
+        setenv("_NIX_OPTIONS", settings.pack().c_str(), 1);
+
         commonChildInit(logPipe);
 
         if (dup2(outPipe.writeSide, STDOUT_FILENO) == -1)
@@ -3041,7 +3042,6 @@ void SubstitutionGoal::finished()
     logPipe.readSide.close();
 
     /* Get the hash info from stdout. */
-    string dummy = readLine(outPipe.readSide);
     string expectedHashStr = statusOk(status) ? readLine(outPipe.readSide) : "";
     outPipe.readSide.close();