nixbld: add Nix unstable patch for networked derivations

Fixes Gitea issue #7

nixbld-etc-nixos/configuration.nix

@@ -406,7 +406,7 @@ in
       patches = oa.patches or [] ++ [ ./nix-networked-derivations.diff ];
     });
     nixFlakes = super.nixFlakes.overrideAttrs(oa: {
-      patches = oa.patches or [] ++ [ ./nix-networked-derivations.diff ];
+      patches = oa.patches or [] ++ [ ./nix-3-networked-derivations.patch ];
     });
     hydra-unstable = super.hydra-unstable.overrideAttrs(oa: {
       patches = oa.patches or [] ++ [

nixbld-etc-nixos/nix-3-networked-derivations.patch

@@ -0,0 +1,87 @@
+From d7fc00b5770a7d194c0ba9e70a4cdb2ece621d5b Mon Sep 17 00:00:00 2001
+From: Astro <astro@spaceboyz.net>
+Date: Mon, 5 Oct 2020 14:18:59 +0200
+Subject: [PATCH] networked derivations
+
+---
+ src/libstore/build.cc | 19 ++++++++++++++-----
+ 1 file changed, 14 insertions(+), 5 deletions(-)
+
+diff --git a/src/libstore/build.cc b/src/libstore/build.cc
+index 0499273a4..40fe4e859 100644
+--- a/src/libstore/build.cc
++++ b/src/libstore/build.cc
+@@ -845,9 +845,16 @@ private:
+     /* The sort of derivation we are building. */
+     DerivationType derivationType;
+ 
++    bool networked;
++
+     /* Whether to run the build in a private network namespace. */
+     bool privateNetwork = false;
+ 
++    bool allowNetwork()
++    {
++        return derivationIsFixed(drv->type()) || networked;
++    }
++
+     typedef void (DerivationGoal::*GoalState)();
+     GoalState state;
+ 
+@@ -1293,6 +1300,8 @@ void DerivationGoal::haveDerivation()
+     parsedDrv = std::make_unique<ParsedDerivation>(drvPath, *drv);
+ 
+ 
++    networked = parsedDrv->getBoolAttr("__networked");
++
+     /* We are first going to try to create the invalid output paths
+        through substitutes.  If that doesn't work, we'll build
+        them. */
+@@ -2210,7 +2219,7 @@ void DerivationGoal::startBuilder()
+         else if (settings.sandboxMode == smDisabled)
+             useChroot = false;
+         else if (settings.sandboxMode == smRelaxed)
+-            useChroot = !(derivationIsImpure(derivationType)) && !noChroot;
++            useChroot = !allowNetwork() && !(derivationIsImpure(derivationType)) && !noChroot;
+     }
+ 
+     if (worker.store.storeDir != worker.store.realStoreDir) {
+@@ -2434,7 +2443,7 @@ void DerivationGoal::startBuilder()
+                 "nogroup:x:65534:\n") % sandboxGid).str());
+ 
+         /* Create /etc/hosts with localhost entry. */
+-        if (!(derivationIsImpure(derivationType)))
++        if (!allowNetwork())
+             writeFile(chrootRootDir + "/etc/hosts", "127.0.0.1 localhost\n::1 localhost\n");
+ 
+         /* Make the closure of the inputs available in the chroot,
+@@ -2621,7 +2630,7 @@ void DerivationGoal::startBuilder()
+            us.
+         */
+ 
+-        if (!(derivationIsImpure(derivationType)))
++        if (!allowNetwork())
+             privateNetwork = true;
+ 
+         userNamespaceSync.create();
+@@ -2833,7 +2842,7 @@ void DerivationGoal::initEnv()
+        to the builder is generally impure, but the output of
+        fixed-output derivations is by definition pure (since we
+        already know the cryptographic hash of the output). */
+-    if (derivationIsImpure(derivationType)) {
++    if (allowNetwork()) {
+         for (auto & i : parsedDrv->getStringsAttr("impureEnvVars").value_or(Strings()))
+             env[i] = getEnv(i).value_or("");
+     }
+@@ -3447,7 +3456,7 @@ void DerivationGoal::runChild()
+             /* Fixed-output derivations typically need to access the
+                network, so give them access to /etc/resolv.conf and so
+                on. */
+-            if (derivationIsImpure(derivationType)) {
++            if (allowNetwork()) {
+                 ss.push_back("/etc/resolv.conf");
+ 
+                 // Only use nss functions to resolve hosts and
+-- 
+2.28.0
+