From e40e01c1dd58c12a763d9614ff38dd7a984c9787 Mon Sep 17 00:00:00 2001
From: Greg Price <gnprice@gmail.com>
Date: Sat, 21 Mar 2020 22:20:02 -0700
Subject: [PATCH 01/16] doc: Files in the store have modes 444/555, not 644/755

This line has been this way since it was written, in 9e08f5efe
in 2006.

I think it was just a small mistake then; Eelco's thesis earlier
that year says the permission on each file is set to 0444 or 0555
in a derivation's output as part of the build process.  In any
case I'm pretty sure that's the behavior now.
---
 doc/manual/command-ref/nix-store.xml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/manual/command-ref/nix-store.xml b/doc/manual/command-ref/nix-store.xml
index e8bbd16e8..1ddb5408d 100644
--- a/doc/manual/command-ref/nix-store.xml
+++ b/doc/manual/command-ref/nix-store.xml
@@ -1139,7 +1139,7 @@ the information that Nix considers important.  For instance,
 timestamps are elided because all files in the Nix store have their
 timestamp set to 0 anyway.  Likewise, all permissions are left out
 except for the execute bit, because all files in the Nix store have
-644 or 755 permission.</para>
+444 or 555 permission.</para>
 
 <para>Also, a NAR archive is <emphasis>canonical</emphasis>, meaning
 that “equal” paths always produce the same NAR archive.  For instance,

From c34a20e1f60486140f0ddc5657c077d2fdc9c7f5 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 26 Nov 2018 19:55:48 +0100
Subject: [PATCH 02/16] EvalState::allocAttr(): Add convenience method

(cherry picked from commit c02da997570ac0d9b595d787bea8cb5a4e3cc1f5)
---
 src/libexpr/attr-set.cc | 6 ++++++
 src/libexpr/eval.hh     | 1 +
 2 files changed, 7 insertions(+)

diff --git a/src/libexpr/attr-set.cc b/src/libexpr/attr-set.cc
index 0785897d2..b1d61a285 100644
--- a/src/libexpr/attr-set.cc
+++ b/src/libexpr/attr-set.cc
@@ -43,6 +43,12 @@ Value * EvalState::allocAttr(Value & vAttrs, const Symbol & name)
 }
 
 
+Value * EvalState::allocAttr(Value & vAttrs, const std::string & name)
+{
+    return allocAttr(vAttrs, symbols.create(name));
+}
+
+
 void Bindings::sort()
 {
     std::sort(begin(), end());
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index eac53b894..5efad8707 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -272,6 +272,7 @@ public:
     Env & allocEnv(size_t size);
 
     Value * allocAttr(Value & vAttrs, const Symbol & name);
+    Value * allocAttr(Value & vAttrs, const std::string & name);
 
     Bindings * allocBindings(size_t capacity);
 

From 5a7e7fc35f934872a9e3e9e9043ff6894b36637a Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 17 Feb 2020 15:53:59 +0100
Subject: [PATCH 03/16] Use std::string_view

(cherry picked from commit 6529490cc10018d5191e50c482ac1180b96b1a3c)
---
 src/libstore/derivations.cc | 6 +++---
 src/libstore/derivations.hh | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index 205b90e55..973ddc86a 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -65,7 +65,7 @@ bool BasicDerivation::isBuiltin() const
 
 
 StorePath writeDerivation(ref<Store> store,
-    const Derivation & drv, const string & name, RepairFlag repair)
+    const Derivation & drv, std::string_view name, RepairFlag repair)
 {
     auto references = cloneStorePathSet(drv.inputSrcs);
     for (auto & i : drv.inputDrvs)
@@ -73,8 +73,8 @@ StorePath writeDerivation(ref<Store> store,
     /* Note that the outputs of a derivation are *not* references
        (that can be missing (of course) and should not necessarily be
        held during a garbage collection). */
-    string suffix = name + drvExtension;
-    string contents = drv.unparse(*store, false);
+    auto suffix = std::string(name) + drvExtension;
+    auto contents = drv.unparse(*store, false);
     return settings.readOnlyMode
         ? store->computeStorePathForText(suffix, contents, references)
         : store->addTextToStore(suffix, contents, references, repair);
diff --git a/src/libstore/derivations.hh b/src/libstore/derivations.hh
index c2df66229..7222d25e5 100644
--- a/src/libstore/derivations.hh
+++ b/src/libstore/derivations.hh
@@ -79,7 +79,7 @@ class Store;
 
 /* Write a derivation to the Nix store, and return its path. */
 StorePath writeDerivation(ref<Store> store,
-    const Derivation & drv, const string & name, RepairFlag repair = NoRepair);
+    const Derivation & drv, std::string_view name, RepairFlag repair = NoRepair);
 
 /* Read a derivation from a file. */
 Derivation readDerivation(const Store & store, const Path & drvPath);

From edc34cc1a2865777cee6b325f705fb218955b593 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 2 May 2019 21:09:52 +0200
Subject: [PATCH 04/16] Add function for quoting strings

(cherry picked from commit 7dcf5b011a0942ecf953f2b607c4c8d0e9e652c7)
---
 src/libstore/build.cc     |  2 +-
 src/libstore/store-api.cc |  7 +------
 src/libutil/util.cc       | 22 ----------------------
 src/libutil/util.hh       | 22 ++++++++++++++++++++--
 4 files changed, 22 insertions(+), 31 deletions(-)

diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 9c6aedfa5..7efa81a62 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -1904,7 +1904,7 @@ void DerivationGoal::startBuilder()
             concatStringsSep(", ", parsedDrv->getRequiredSystemFeatures()),
             worker.store.printStorePath(drvPath),
             settings.thisSystem,
-            concatStringsSep(", ", settings.systemFeatures));
+            concatStringsSep<StringSet>(", ", settings.systemFeatures));
 
     if (drv->isBuiltin())
         preloadNSS();
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index b043feb0a..aacbe5e0b 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -741,12 +741,7 @@ std::string Store::showPaths(const StorePathSet & paths)
 
 string showPaths(const PathSet & paths)
 {
-    string s;
-    for (auto & i : paths) {
-        if (s.size() != 0) s += ", ";
-        s += "'" + i + "'";
-    }
-    return s;
+    return concatStringsSep(", ", quoteStrings(paths));
 }
 
 
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 012f1d071..52a1394f2 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -1205,28 +1205,6 @@ template StringSet tokenizeString(std::string_view s, const string & separators)
 template vector<string> tokenizeString(std::string_view s, const string & separators);
 
 
-string concatStringsSep(const string & sep, const Strings & ss)
-{
-    string s;
-    for (auto & i : ss) {
-        if (s.size() != 0) s += sep;
-        s += i;
-    }
-    return s;
-}
-
-
-string concatStringsSep(const string & sep, const StringSet & ss)
-{
-    string s;
-    for (auto & i : ss) {
-        if (s.size() != 0) s += sep;
-        s += i;
-    }
-    return s;
-}
-
-
 string chomp(const string & s)
 {
     size_t i = s.find_last_not_of(" \n\r\t");
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 3bfebcd15..559ed4332 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -345,8 +345,26 @@ template<class C> C tokenizeString(std::string_view s, const string & separators
 
 /* Concatenate the given strings with a separator between the
    elements. */
-string concatStringsSep(const string & sep, const Strings & ss);
-string concatStringsSep(const string & sep, const StringSet & ss);
+template<class C>
+string concatStringsSep(const string & sep, const C & ss)
+{
+    string s;
+    for (auto & i : ss) {
+        if (s.size() != 0) s += sep;
+        s += i;
+    }
+    return s;
+}
+
+
+/* Add quotes around a collection of strings. */
+template<class C> Strings quoteStrings(const C & c)
+{
+    Strings res;
+    for (auto & s : c)
+        res.push_back("'" + s + "'");
+    return res;
+}
 
 
 /* Remove trailing whitespace from a string. */

From 1eb952d27ac0714a99a5f7b0e8c7034e7ac0bc0d Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 8 Apr 2019 14:20:58 +0200
Subject: [PATCH 05/16] findAlongAttrPath(): Throw AttrPathNotFound

(cherry picked from commit 6b0ca8e803710342af70e257935724c5ad84ca04)
---
 src/libexpr/attr-path.cc | 4 ++--
 src/libexpr/attr-path.hh | 2 ++
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/libexpr/attr-path.cc b/src/libexpr/attr-path.cc
index 06b472d8b..843585631 100644
--- a/src/libexpr/attr-path.cc
+++ b/src/libexpr/attr-path.cc
@@ -70,7 +70,7 @@ Value * findAlongAttrPath(EvalState & state, const string & attrPath,
 
             Bindings::iterator a = v->attrs->find(state.symbols.create(attr));
             if (a == v->attrs->end())
-                throw Error(format("attribute '%1%' in selection path '%2%' not found") % attr % attrPath);
+                throw AttrPathNotFound("attribute '%1%' in selection path '%2%' not found", attr, attrPath);
             v = &*a->value;
         }
 
@@ -82,7 +82,7 @@ Value * findAlongAttrPath(EvalState & state, const string & attrPath,
                     % attrPath % showType(*v));
 
             if (attrIndex >= v->listSize())
-                throw Error(format("list index %1% in selection path '%2%' is out of range") % attrIndex % attrPath);
+                throw AttrPathNotFound("list index %1% in selection path '%2%' is out of range", attrIndex, attrPath);
 
             v = v->listElems()[attrIndex];
         }
diff --git a/src/libexpr/attr-path.hh b/src/libexpr/attr-path.hh
index 716e5ba27..fcccc39c8 100644
--- a/src/libexpr/attr-path.hh
+++ b/src/libexpr/attr-path.hh
@@ -7,6 +7,8 @@
 
 namespace nix {
 
+MakeError(AttrPathNotFound, Error);
+
 Value * findAlongAttrPath(EvalState & state, const string & attrPath,
     Bindings & autoArgs, Value & vIn);
 

From c1ca4f0accdb96295b27dadacd20b3db745e1d2d Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 7 Feb 2020 14:08:24 +0100
Subject: [PATCH 06/16] findAlongAttrPath(): Return position

(cherry picked from commit 0b013a54dc570395bed887369f8dd622b8ce337b)
---
 src/libexpr/attr-path.cc                 | 9 ++++++---
 src/libexpr/attr-path.hh                 | 2 +-
 src/nix-build/nix-build.cc               | 2 +-
 src/nix-env/nix-env.cc                   | 4 ++--
 src/nix-instantiate/nix-instantiate.cc   | 2 +-
 src/nix-prefetch-url/nix-prefetch-url.cc | 2 +-
 src/nix/installables.cc                  | 2 +-
 src/nix/upgrade-nix.cc                   | 2 +-
 8 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/src/libexpr/attr-path.cc b/src/libexpr/attr-path.cc
index 843585631..1e22f5708 100644
--- a/src/libexpr/attr-path.cc
+++ b/src/libexpr/attr-path.cc
@@ -32,7 +32,7 @@ static Strings parseAttrPath(const string & s)
 }
 
 
-Value * findAlongAttrPath(EvalState & state, const string & attrPath,
+std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const string & attrPath,
     Bindings & autoArgs, Value & vIn)
 {
     Strings tokens = parseAttrPath(attrPath);
@@ -41,6 +41,7 @@ Value * findAlongAttrPath(EvalState & state, const string & attrPath,
         Error(format("attribute selection path '%1%' does not match expression") % attrPath);
 
     Value * v = &vIn;
+    Pos pos = noPos;
 
     for (auto & attr : tokens) {
 
@@ -72,6 +73,7 @@ Value * findAlongAttrPath(EvalState & state, const string & attrPath,
             if (a == v->attrs->end())
                 throw AttrPathNotFound("attribute '%1%' in selection path '%2%' not found", attr, attrPath);
             v = &*a->value;
+            pos = *a->pos;
         }
 
         else if (apType == apIndex) {
@@ -85,11 +87,12 @@ Value * findAlongAttrPath(EvalState & state, const string & attrPath,
                 throw AttrPathNotFound("list index %1% in selection path '%2%' is out of range", attrIndex, attrPath);
 
             v = v->listElems()[attrIndex];
+            pos = noPos;
         }
 
     }
 
-    return v;
+    return {v, pos};
 }
 
 
@@ -98,7 +101,7 @@ Pos findDerivationFilename(EvalState & state, Value & v, std::string what)
     Value * v2;
     try {
         auto dummyArgs = state.allocBindings(0);
-        v2 = findAlongAttrPath(state, "meta.position", *dummyArgs, v);
+        v2 = findAlongAttrPath(state, "meta.position", *dummyArgs, v).first;
     } catch (Error &) {
         throw Error("package '%s' has no source location information", what);
     }
diff --git a/src/libexpr/attr-path.hh b/src/libexpr/attr-path.hh
index fcccc39c8..3e78e2899 100644
--- a/src/libexpr/attr-path.hh
+++ b/src/libexpr/attr-path.hh
@@ -9,7 +9,7 @@ namespace nix {
 
 MakeError(AttrPathNotFound, Error);
 
-Value * findAlongAttrPath(EvalState & state, const string & attrPath,
+std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const string & attrPath,
     Bindings & autoArgs, Value & vIn);
 
 /* Heuristic to find the filename and lineno or a nix value. */
diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index 27ec7d0fe..1bda159d0 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -314,7 +314,7 @@ static void _main(int argc, char * * argv)
         state->eval(e, vRoot);
 
         for (auto & i : attrPaths) {
-            Value & v(*findAlongAttrPath(*state, i, *autoArgs, vRoot));
+            Value & v(*findAlongAttrPath(*state, i, *autoArgs, vRoot).first);
             state->forceValue(v);
             getDerivations(*state, v, "", *autoArgs, drvs, false);
         }
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index 106dfe0b6..c7e553d0c 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -178,7 +178,7 @@ static void loadDerivations(EvalState & state, Path nixExprPath,
     Value vRoot;
     loadSourceExpr(state, nixExprPath, vRoot);
 
-    Value & v(*findAlongAttrPath(state, pathPrefix, autoArgs, vRoot));
+    Value & v(*findAlongAttrPath(state, pathPrefix, autoArgs, vRoot).first);
 
     getDerivations(state, v, pathPrefix, autoArgs, elems, true);
 
@@ -408,7 +408,7 @@ static void queryInstSources(EvalState & state,
             Value vRoot;
             loadSourceExpr(state, instSource.nixExprPath, vRoot);
             for (auto & i : args) {
-                Value & v(*findAlongAttrPath(state, i, *instSource.autoArgs, vRoot));
+                Value & v(*findAlongAttrPath(state, i, *instSource.autoArgs, vRoot).first);
                 getDerivations(state, v, "", *instSource.autoArgs, elems, true);
             }
             break;
diff --git a/src/nix-instantiate/nix-instantiate.cc b/src/nix-instantiate/nix-instantiate.cc
index 5a886d69d..617d927a4 100644
--- a/src/nix-instantiate/nix-instantiate.cc
+++ b/src/nix-instantiate/nix-instantiate.cc
@@ -39,7 +39,7 @@ void processExpr(EvalState & state, const Strings & attrPaths,
     state.eval(e, vRoot);
 
     for (auto & i : attrPaths) {
-        Value & v(*findAlongAttrPath(state, i, autoArgs, vRoot));
+        Value & v(*findAlongAttrPath(state, i, autoArgs, vRoot).first);
         state.forceValue(v);
 
         PathSet context;
diff --git a/src/nix-prefetch-url/nix-prefetch-url.cc b/src/nix-prefetch-url/nix-prefetch-url.cc
index cc0891811..18ced94b1 100644
--- a/src/nix-prefetch-url/nix-prefetch-url.cc
+++ b/src/nix-prefetch-url/nix-prefetch-url.cc
@@ -120,7 +120,7 @@ static int _main(int argc, char * * argv)
             Path path = resolveExprPath(lookupFileArg(*state, args.empty() ? "." : args[0]));
             Value vRoot;
             state->evalFile(path, vRoot);
-            Value & v(*findAlongAttrPath(*state, attrPath, autoArgs, vRoot));
+            Value & v(*findAlongAttrPath(*state, attrPath, autoArgs, vRoot).first);
             state->forceAttrs(v);
 
             /* Extract the URI. */
diff --git a/src/nix/installables.cc b/src/nix/installables.cc
index 8ce6bd06e..eb6fca62b 100644
--- a/src/nix/installables.cc
+++ b/src/nix/installables.cc
@@ -193,7 +193,7 @@ struct InstallableAttrPath : InstallableValue
 
         Bindings & autoArgs = *cmd.getAutoArgs(state);
 
-        Value * v = findAlongAttrPath(state, attrPath, autoArgs, *source);
+        auto v = findAlongAttrPath(state, attrPath, autoArgs, *source).first;
         state.forceValue(*v);
 
         return v;
diff --git a/src/nix/upgrade-nix.cc b/src/nix/upgrade-nix.cc
index 87f1f9d1b..c05c29517 100644
--- a/src/nix/upgrade-nix.cc
+++ b/src/nix/upgrade-nix.cc
@@ -145,7 +145,7 @@ struct CmdUpgradeNix : MixDryRun, StoreCommand
         auto v = state->allocValue();
         state->eval(state->parseExprFromString(*res.data, "/no-such-path"), *v);
         Bindings & bindings(*state->allocBindings(0));
-        auto v2 = findAlongAttrPath(*state, settings.thisSystem, bindings, *v);
+        auto v2 = findAlongAttrPath(*state, settings.thisSystem, bindings, *v).first;
 
         return store->parseStorePath(state->forceString(*v2));
     }

From 231a8aa2c2196a3ba6d6bd3dc9d6c50e23e20a8d Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 7 Feb 2020 14:22:01 +0100
Subject: [PATCH 07/16] nix edit: Support non-derivation attributes

E.g.

  $ nix edit .#nixosConfigurations.bla

now works.

(cherry picked from commit d2032edb2f86e955a8a7724a27c0c3225f386500)
---
 src/libexpr/attr-path.cc |  2 +-
 src/libexpr/attr-path.hh |  1 +
 src/nix/command.hh       |  9 ++-------
 src/nix/edit.cc          | 10 ++++++++--
 src/nix/eval.cc          |  2 +-
 src/nix/installables.cc  | 10 +++++-----
 6 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/src/libexpr/attr-path.cc b/src/libexpr/attr-path.cc
index 1e22f5708..4545bfd72 100644
--- a/src/libexpr/attr-path.cc
+++ b/src/libexpr/attr-path.cc
@@ -103,7 +103,7 @@ Pos findDerivationFilename(EvalState & state, Value & v, std::string what)
         auto dummyArgs = state.allocBindings(0);
         v2 = findAlongAttrPath(state, "meta.position", *dummyArgs, v).first;
     } catch (Error &) {
-        throw Error("package '%s' has no source location information", what);
+        throw NoPositionInfo("package '%s' has no source location information", what);
     }
 
     // FIXME: is it possible to extract the Pos object instead of doing this
diff --git a/src/libexpr/attr-path.hh b/src/libexpr/attr-path.hh
index 3e78e2899..fce160da7 100644
--- a/src/libexpr/attr-path.hh
+++ b/src/libexpr/attr-path.hh
@@ -8,6 +8,7 @@
 namespace nix {
 
 MakeError(AttrPathNotFound, Error);
+MakeError(NoPositionInfo, Error);
 
 std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const string & attrPath,
     Bindings & autoArgs, Value & vIn);
diff --git a/src/nix/command.hh b/src/nix/command.hh
index 00eb46903..a954a7d04 100644
--- a/src/nix/command.hh
+++ b/src/nix/command.hh
@@ -3,17 +3,12 @@
 #include "args.hh"
 #include "common-eval-args.hh"
 #include "path.hh"
+#include "eval.hh"
 
 namespace nix {
 
 extern std::string programPath;
 
-struct Value;
-class Bindings;
-class EvalState;
-struct Pos;
-class Store;
-
 /* A command that requires a Nix store. */
 struct StoreCommand : virtual Command
 {
@@ -48,7 +43,7 @@ struct Installable
 
     Buildable toBuildable();
 
-    virtual Value * toValue(EvalState & state)
+    virtual std::pair<Value *, Pos> toValue(EvalState & state)
     {
         throw Error("argument '%s' cannot be evaluated", what());
     }
diff --git a/src/nix/edit.cc b/src/nix/edit.cc
index ca410cd1f..1683eada0 100644
--- a/src/nix/edit.cc
+++ b/src/nix/edit.cc
@@ -29,9 +29,15 @@ struct CmdEdit : InstallableCommand
     {
         auto state = getEvalState();
 
-        auto v = installable->toValue(*state);
+        auto [v, pos] = installable->toValue(*state);
 
-        Pos pos = findDerivationFilename(*state, *v, installable->what());
+        try {
+            pos = findDerivationFilename(*state, *v, installable->what());
+        } catch (NoPositionInfo &) {
+        }
+
+        if (pos == noPos)
+            throw Error("cannot find position information for '%s", installable->what());
 
         stopProgressBar();
 
diff --git a/src/nix/eval.cc b/src/nix/eval.cc
index 276fdf003..6398fc58e 100644
--- a/src/nix/eval.cc
+++ b/src/nix/eval.cc
@@ -52,7 +52,7 @@ struct CmdEval : MixJSON, InstallableCommand
 
         auto state = getEvalState();
 
-        auto v = installable->toValue(*state);
+        auto v = installable->toValue(*state).first;
         PathSet context;
 
         stopProgressBar();
diff --git a/src/nix/installables.cc b/src/nix/installables.cc
index eb6fca62b..013218cd9 100644
--- a/src/nix/installables.cc
+++ b/src/nix/installables.cc
@@ -121,7 +121,7 @@ struct InstallableValue : Installable
     {
         auto state = cmd.getEvalState();
 
-        auto v = toValue(*state);
+        auto v = toValue(*state).first;
 
         Bindings & autoArgs = *cmd.getAutoArgs(*state);
 
@@ -169,11 +169,11 @@ struct InstallableExpr : InstallableValue
 
     std::string what() override { return text; }
 
-    Value * toValue(EvalState & state) override
+    std::pair<Value *, Pos> toValue(EvalState & state) override
     {
         auto v = state.allocValue();
         state.eval(state.parseExprFromString(text, absPath(".")), *v);
-        return v;
+        return {v, noPos};
     }
 };
 
@@ -187,7 +187,7 @@ struct InstallableAttrPath : InstallableValue
 
     std::string what() override { return attrPath; }
 
-    Value * toValue(EvalState & state) override
+    std::pair<Value *, Pos> toValue(EvalState & state) override
     {
         auto source = cmd.getSourceExpr(state);
 
@@ -196,7 +196,7 @@ struct InstallableAttrPath : InstallableValue
         auto v = findAlongAttrPath(state, attrPath, autoArgs, *source).first;
         state.forceValue(*v);
 
-        return v;
+        return {v, noPos};
     }
 };
 

From 76e7d958ed8a1502cb060300093c120311d10cac Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 22 Jan 2020 21:58:07 +0100
Subject: [PATCH 08/16] Fix coverage build

https://hydra.nixos.org/build/110757285
(cherry picked from commit b430a81a1fbf6c792ba49e3aefe46256263430e5)
---
 src/libexpr/function-trace.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/libexpr/function-trace.cc b/src/libexpr/function-trace.cc
index af1486f78..c6057b384 100644
--- a/src/libexpr/function-trace.cc
+++ b/src/libexpr/function-trace.cc
@@ -1,4 +1,5 @@
 #include "function-trace.hh"
+#include "logging.hh"
 
 namespace nix {
 

From f9611c7ae48abd4506a93691c25f067a0e8e73b4 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 21 Oct 2019 17:17:15 +0200
Subject: [PATCH 09/16] buildenv: Eliminate global variables, other cleanup

(cherry picked from commit b82f75464d1e5ae9a00d8004e5dd7b1ca05059e4)
---
 src/libstore/build.cc             |   1 +
 src/libstore/builtins.hh          |   1 -
 src/libstore/builtins/buildenv.cc | 128 ++++++++++++++----------------
 src/libstore/builtins/buildenv.hh |  21 +++++
 4 files changed, 81 insertions(+), 70 deletions(-)
 create mode 100644 src/libstore/builtins/buildenv.hh

diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 7efa81a62..dc6a2c606 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -6,6 +6,7 @@
 #include "archive.hh"
 #include "affinity.hh"
 #include "builtins.hh"
+#include "builtins/buildenv.hh"
 #include "download.hh"
 #include "finally.hh"
 #include "compression.hh"
diff --git a/src/libstore/builtins.hh b/src/libstore/builtins.hh
index 87d6ce665..66597e456 100644
--- a/src/libstore/builtins.hh
+++ b/src/libstore/builtins.hh
@@ -6,7 +6,6 @@ namespace nix {
 
 // TODO: make pluggable.
 void builtinFetchurl(const BasicDerivation & drv, const std::string & netrcData);
-void builtinBuildenv(const BasicDerivation & drv);
 void builtinUnpackChannel(const BasicDerivation & drv);
 
 }
diff --git a/src/libstore/builtins/buildenv.cc b/src/libstore/builtins/buildenv.cc
index 096593886..c1c85d0bf 100644
--- a/src/libstore/builtins/buildenv.cc
+++ b/src/libstore/builtins/buildenv.cc
@@ -1,4 +1,4 @@
-#include "builtins.hh"
+#include "buildenv.hh"
 
 #include <sys/stat.h>
 #include <sys/types.h>
@@ -7,16 +7,14 @@
 
 namespace nix {
 
-typedef std::map<Path,int> Priorities;
-
-// FIXME: change into local variables.
-
-static Priorities priorities;
-
-static unsigned long symlinks;
+struct State
+{
+    std::map<Path, int> priorities;
+    unsigned long symlinks = 0;
+};
 
 /* For each activated package, create symlinks */
-static void createLinks(const Path & srcDir, const Path & dstDir, int priority)
+static void createLinks(State & state, const Path & srcDir, const Path & dstDir, int priority)
 {
     DirEntries srcFiles;
 
@@ -67,7 +65,7 @@ static void createLinks(const Path & srcDir, const Path & dstDir, int priority)
             auto res = lstat(dstFile.c_str(), &dstSt);
             if (res == 0) {
                 if (S_ISDIR(dstSt.st_mode)) {
-                    createLinks(srcFile, dstFile, priority);
+                    createLinks(state, srcFile, dstFile, priority);
                     continue;
                 } else if (S_ISLNK(dstSt.st_mode)) {
                     auto target = canonPath(dstFile, true);
@@ -77,8 +75,8 @@ static void createLinks(const Path & srcDir, const Path & dstDir, int priority)
                         throw SysError(format("unlinking '%1%'") % dstFile);
                     if (mkdir(dstFile.c_str(), 0755) == -1)
                         throw SysError(format("creating directory '%1%'"));
-                    createLinks(target, dstFile, priorities[dstFile]);
-                    createLinks(srcFile, dstFile, priority);
+                    createLinks(state, target, dstFile, state.priorities[dstFile]);
+                    createLinks(state, srcFile, dstFile, priority);
                     continue;
                 }
             } else if (errno != ENOENT)
@@ -90,7 +88,7 @@ static void createLinks(const Path & srcDir, const Path & dstDir, int priority)
             auto res = lstat(dstFile.c_str(), &dstSt);
             if (res == 0) {
                 if (S_ISLNK(dstSt.st_mode)) {
-                    auto prevPriority = priorities[dstFile];
+                    auto prevPriority = state.priorities[dstFile];
                     if (prevPriority == priority)
                         throw Error(
                                 "packages '%1%' and '%2%' have the same priority %3%; "
@@ -109,67 +107,30 @@ static void createLinks(const Path & srcDir, const Path & dstDir, int priority)
         }
 
         createSymlink(srcFile, dstFile);
-        priorities[dstFile] = priority;
-        symlinks++;
+        state.priorities[dstFile] = priority;
+        state.symlinks++;
     }
 }
 
-typedef std::set<Path> FileProp;
-
-static FileProp done;
-static FileProp postponed = FileProp{};
-
-static Path out;
-
-static void addPkg(const Path & pkgDir, int priority)
+void buildProfile(const Path & out, Packages && pkgs)
 {
-    if (!done.insert(pkgDir).second) return;
-    createLinks(pkgDir, out, priority);
+    State state;
 
-    try {
-        for (const auto & p : tokenizeString<std::vector<string>>(
-                readFile(pkgDir + "/nix-support/propagated-user-env-packages"), " \n"))
-            if (!done.count(p))
-                postponed.insert(p);
-    } catch (SysError & e) {
-        if (e.errNo != ENOENT && e.errNo != ENOTDIR) throw;
-    }
-}
+    std::set<Path> done, postponed;
 
-struct Package {
-    Path path;
-    bool active;
-    int priority;
-    Package(Path path, bool active, int priority) : path{path}, active{active}, priority{priority} {}
-};
+    auto addPkg = [&](const Path & pkgDir, int priority) {
+        if (!done.insert(pkgDir).second) return;
+        createLinks(state, pkgDir, out, priority);
 
-typedef std::vector<Package> Packages;
-
-void builtinBuildenv(const BasicDerivation & drv)
-{
-    auto getAttr = [&](const string & name) {
-        auto i = drv.env.find(name);
-        if (i == drv.env.end()) throw Error("attribute '%s' missing", name);
-        return i->second;
-    };
-
-    out = getAttr("out");
-    createDirs(out);
-
-    /* Convert the stuff we get from the environment back into a
-     * coherent data type. */
-    Packages pkgs;
-    auto derivations = tokenizeString<Strings>(getAttr("derivations"));
-    while (!derivations.empty()) {
-        /* !!! We're trusting the caller to structure derivations env var correctly */
-        auto active = derivations.front(); derivations.pop_front();
-        auto priority = stoi(derivations.front()); derivations.pop_front();
-        auto outputs = stoi(derivations.front()); derivations.pop_front();
-        for (auto n = 0; n < outputs; n++) {
-            auto path = derivations.front(); derivations.pop_front();
-            pkgs.emplace_back(path, active != "false", priority);
+        try {
+            for (const auto & p : tokenizeString<std::vector<string>>(
+                    readFile(pkgDir + "/nix-support/propagated-user-env-packages"), " \n"))
+                if (!done.count(p))
+                    postponed.insert(p);
+        } catch (SysError & e) {
+            if (e.errNo != ENOENT && e.errNo != ENOTDIR) throw;
         }
-    }
+    };
 
     /* Symlink to the packages that have been installed explicitly by the
      * user. Process in priority order to reduce unnecessary
@@ -189,13 +150,42 @@ void builtinBuildenv(const BasicDerivation & drv)
      */
     auto priorityCounter = 1000;
     while (!postponed.empty()) {
-        auto pkgDirs = postponed;
-        postponed = FileProp{};
+        std::set<Path> pkgDirs;
+        postponed.swap(pkgDirs);
         for (const auto & pkgDir : pkgDirs)
             addPkg(pkgDir, priorityCounter++);
     }
 
-    printError("created %d symlinks in user environment", symlinks);
+    printError("created %d symlinks in user environment", state.symlinks);
+}
+
+void builtinBuildenv(const BasicDerivation & drv)
+{
+    auto getAttr = [&](const string & name) {
+        auto i = drv.env.find(name);
+        if (i == drv.env.end()) throw Error("attribute '%s' missing", name);
+        return i->second;
+    };
+
+    Path out = getAttr("out");
+    createDirs(out);
+
+    /* Convert the stuff we get from the environment back into a
+     * coherent data type. */
+    Packages pkgs;
+    auto derivations = tokenizeString<Strings>(getAttr("derivations"));
+    while (!derivations.empty()) {
+        /* !!! We're trusting the caller to structure derivations env var correctly */
+        auto active = derivations.front(); derivations.pop_front();
+        auto priority = stoi(derivations.front()); derivations.pop_front();
+        auto outputs = stoi(derivations.front()); derivations.pop_front();
+        for (auto n = 0; n < outputs; n++) {
+            auto path = derivations.front(); derivations.pop_front();
+            pkgs.emplace_back(path, active != "false", priority);
+        }
+    }
+
+    buildProfile(out, std::move(pkgs));
 
     createSymlink(getAttr("manifest"), out + "/manifest.nix");
 }
diff --git a/src/libstore/builtins/buildenv.hh b/src/libstore/builtins/buildenv.hh
new file mode 100644
index 000000000..0a37459b0
--- /dev/null
+++ b/src/libstore/builtins/buildenv.hh
@@ -0,0 +1,21 @@
+#pragma once
+
+#include "derivations.hh"
+#include "store-api.hh"
+
+namespace nix {
+
+struct Package {
+    Path path;
+    bool active;
+    int priority;
+    Package(Path path, bool active, int priority) : path{path}, active{active}, priority{priority} {}
+};
+
+typedef std::vector<Package> Packages;
+
+void buildProfile(const Path & out, Packages && pkgs);
+
+void builtinBuildenv(const BasicDerivation & drv);
+
+}

From 4260a22a55d7afc931b22e8c41282fbd0ed18a77 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 8 Jan 2020 15:34:06 +0100
Subject: [PATCH 10/16] absPath(): Use std::optional

(cherry picked from commit 1bf9eb21b75f0d93d9c1633ea2e6fdf840047e79)
---
 src/libutil/util.cc | 6 +++---
 src/libutil/util.hh | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 52a1394f2..097ff210a 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -97,10 +97,10 @@ void replaceEnv(std::map<std::string, std::string> newEnv)
 }
 
 
-Path absPath(Path path, Path dir)
+Path absPath(Path path, std::optional<Path> dir)
 {
     if (path[0] != '/') {
-        if (dir == "") {
+        if (!dir) {
 #ifdef __GNU__
             /* GNU (aka. GNU/Hurd) doesn't have any limitation on path
                lengths and doesn't define `PATH_MAX'.  */
@@ -116,7 +116,7 @@ Path absPath(Path path, Path dir)
             free(buf);
 #endif
         }
-        path = dir + "/" + path;
+        path = *dir + "/" + path;
     }
     return canonPath(path);
 }
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 559ed4332..8c2cef9e1 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -46,7 +46,7 @@ void clearEnv();
 /* Return an absolutized path, resolving paths relative to the
    specified directory, or the current directory otherwise.  The path
    is also canonicalised. */
-Path absPath(Path path, Path dir = "");
+Path absPath(Path path, std::optional<Path> dir = {});
 
 /* Canonicalise a path by removing all `.' or `..' components and
    double or trailing slashes.  Optionally resolves all symlink

From 7a8de57d3e7e53a4f6d8060c7201f3fbbe6cd325 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 24 Mar 2020 14:17:10 +0100
Subject: [PATCH 11/16] Pretty-print 'nix why-depends' / 'nix-store -q --tree'
 output

Extracted from 678301072f05b650dc15c5edb4c25f08f0d6cace.
---
 src/libutil/util.hh        | 34 ++++++++++++++++++++++++++++++++++
 src/nix-store/nix-store.cc | 15 +++++----------
 src/nix/why-depends.cc     |  7 +------
 tests/dependencies.sh      |  8 ++++----
 4 files changed, 44 insertions(+), 20 deletions(-)

diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 8c2cef9e1..acef682cd 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -451,6 +451,13 @@ void ignoreException();
 #define ANSI_BLUE "\e[34;1m"
 
 
+/* Tree formatting. */
+constexpr char treeConn[] = "├───";
+constexpr char treeLast[] = "└───";
+constexpr char treeLine[] = "│   ";
+constexpr char treeNull[] = "    ";
+
+
 /* Truncate a string to 'width' printable characters. If 'filterAll'
    is true, all ANSI escape sequences are filtered out. Otherwise,
    some escape sequences (such as colour setting) are copied but not
@@ -576,4 +583,31 @@ extern PathFilter defaultPathFilter;
 AutoCloseFD createUnixDomainSocket(const Path & path, mode_t mode);
 
 
+// A Rust/Python-like enumerate() iterator adapter.
+// Borrowed from http://reedbeta.com/blog/python-like-enumerate-in-cpp17.
+template <typename T,
+          typename TIter = decltype(std::begin(std::declval<T>())),
+          typename = decltype(std::end(std::declval<T>()))>
+constexpr auto enumerate(T && iterable)
+{
+    struct iterator
+    {
+        size_t i;
+        TIter iter;
+        bool operator != (const iterator & other) const { return iter != other.iter; }
+        void operator ++ () { ++i; ++iter; }
+        auto operator * () const { return std::tie(i, *iter); }
+    };
+
+    struct iterable_wrapper
+    {
+        T iterable;
+        auto begin() { return iterator{ 0, std::begin(iterable) }; }
+        auto end() { return iterator{ 0, std::end(iterable) }; }
+    };
+
+    return iterable_wrapper{ std::forward<T>(iterable) };
+}
+
+
 }
diff --git a/src/nix-store/nix-store.cc b/src/nix-store/nix-store.cc
index c14d900ae..806ab7563 100644
--- a/src/nix-store/nix-store.cc
+++ b/src/nix-store/nix-store.cc
@@ -229,12 +229,6 @@ static StorePathSet maybeUseOutputs(const StorePath & storePath, bool useOutput,
 /* Some code to print a tree representation of a derivation dependency
    graph.  Topological sorting is used to keep the tree relatively
    flat. */
-
-const string treeConn = "+---";
-const string treeLine = "|   ";
-const string treeNull = "    ";
-
-
 static void printTree(const StorePath & path,
     const string & firstPad, const string & tailPad, StorePathSet & done)
 {
@@ -254,10 +248,11 @@ static void printTree(const StorePath & path,
     auto sorted = store->topoSortPaths(info->references);
     reverse(sorted.begin(), sorted.end());
 
-    for (auto i = sorted.begin(); i != sorted.end(); ++i) {
-        auto j = i; ++j;
-        printTree(*i, tailPad + treeConn,
-            j == sorted.end() ? tailPad + treeNull : tailPad + treeLine,
+    for (const auto &[n, i] : enumerate(sorted)) {
+        bool last = n + 1 == sorted.size();
+        printTree(i,
+            tailPad + (last ? treeLast : treeConn),
+            tailPad + (last ? treeNull : treeLine),
             done);
     }
 }
diff --git a/src/nix/why-depends.cc b/src/nix/why-depends.cc
index c24ae7c8e..d3b7a674a 100644
--- a/src/nix/why-depends.cc
+++ b/src/nix/why-depends.cc
@@ -143,11 +143,6 @@ struct CmdWhyDepends : SourceExprCommand
            and `dependency`. */
         std::function<void(Node &, const string &, const string &)> printNode;
 
-        const string treeConn = "╠═══";
-        const string treeLast = "╚═══";
-        const string treeLine = "║   ";
-        const string treeNull = "    ";
-
         struct BailOut { };
 
         printNode = [&](Node & node, const string & firstPad, const string & tailPad) {
@@ -157,7 +152,7 @@ struct CmdWhyDepends : SourceExprCommand
             std::cout << fmt("%s%s%s%s" ANSI_NORMAL "\n",
                 firstPad,
                 node.visited ? "\e[38;5;244m" : "",
-                firstPad != "" ? "=> " : "",
+                firstPad != "" ? "→ " : "",
                 pathS);
 
             if (node.path == dependencyPath && !all
diff --git a/tests/dependencies.sh b/tests/dependencies.sh
index df204d185..8d0fdc10f 100644
--- a/tests/dependencies.sh
+++ b/tests/dependencies.sh
@@ -6,7 +6,7 @@ drvPath=$(nix-instantiate dependencies.nix)
 
 echo "derivation is $drvPath"
 
-nix-store -q --tree "$drvPath" | grep '   +---.*builder1.sh'
+nix-store -q --tree "$drvPath" | grep '───.*builder1.sh'
 
 # Test Graphviz graph generation.
 nix-store -q --graph "$drvPath" > $TEST_ROOT/graph
@@ -22,9 +22,9 @@ nix-store -q --graph "$outPath" > $TEST_ROOT/graph
 if test -n "$dot"; then
     # Does it parse?
     $dot < $TEST_ROOT/graph
-fi    
+fi
 
-nix-store -q --tree "$outPath" | grep '+---.*dependencies-input-2'
+nix-store -q --tree "$outPath" | grep '───.*dependencies-input-2'
 
 echo "output path is $outPath"
 
@@ -49,4 +49,4 @@ nix-store -q --referrers-closure "$input2OutPath" | grep "$outPath"
 
 # Check that the derivers are set properly.
 test $(nix-store -q --deriver "$outPath") = "$drvPath"
-nix-store -q --deriver "$input2OutPath" | grep -q -- "-input-2.drv" 
+nix-store -q --deriver "$input2OutPath" | grep -q -- "-input-2.drv"

From 777e21e596ec85f18eddf8b286d9ba4995010835 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 11 Feb 2020 23:50:16 +0100
Subject: [PATCH 12/16] nix path-info --json: Print hash in SRI format

(cherry picked from commit 442e665d6d3fcbdee7dece2f62a597142f8784b1)
---
 src/libstore/store-api.cc | 6 ++++--
 src/libstore/store-api.hh | 1 +
 src/nix/path-info.cc      | 2 +-
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index aacbe5e0b..b9e894a9a 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -441,7 +441,9 @@ string Store::makeValidityRegistration(const StorePathSet & paths,
 
 
 void Store::pathInfoToJSON(JSONPlaceholder & jsonOut, const StorePathSet & storePaths,
-    bool includeImpureInfo, bool showClosureSize, AllowInvalidFlag allowInvalid)
+    bool includeImpureInfo, bool showClosureSize,
+    Base hashBase,
+    AllowInvalidFlag allowInvalid)
 {
     auto jsonList = jsonOut.list();
 
@@ -453,7 +455,7 @@ void Store::pathInfoToJSON(JSONPlaceholder & jsonOut, const StorePathSet & store
             auto info = queryPathInfo(storePath);
 
             jsonPath
-                .attr("narHash", info->narHash.to_string())
+                .attr("narHash", info->narHash.to_string(hashBase))
                 .attr("narSize", info->narSize);
 
             {
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index e0484de13..c57a6935e 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -561,6 +561,7 @@ public:
        each path is included. */
     void pathInfoToJSON(JSONPlaceholder & jsonOut, const StorePathSet & storePaths,
         bool includeImpureInfo, bool showClosureSize,
+        Base hashBase = Base32,
         AllowInvalidFlag allowInvalid = DisallowInvalid);
 
     /* Return the size of the closure of the specified path, that is,
diff --git a/src/nix/path-info.cc b/src/nix/path-info.cc
index bffa7b356..45ec297d2 100644
--- a/src/nix/path-info.cc
+++ b/src/nix/path-info.cc
@@ -89,7 +89,7 @@ struct CmdPathInfo : StorePathsCommand, MixJSON
             store->pathInfoToJSON(jsonRoot,
                 // FIXME: preserve order?
                 storePathsToSet(storePaths),
-                true, showClosureSize, AllowInvalid);
+                true, showClosureSize, SRI, AllowInvalid);
         }
 
         else {

From 6b824c78f1f6c2de95b594a440118e259d28def0 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 2 Dec 2019 15:56:37 +0100
Subject: [PATCH 13/16] nix: Add --refresh as an alias for --tarball-ttl 0

(cherry picked from commit e721f99817bb7154d8098c902e25f84521a90b7f)
---
 src/nix/main.cc | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/nix/main.cc b/src/nix/main.cc
index 41d44f431..5cb1ad25e 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -92,6 +92,11 @@ struct NixArgs : virtual MultiCommand, virtual MixCommonArgs
             .longName("no-net")
             .description("disable substituters and consider all previously downloaded files up-to-date")
             .handler([&]() { useNet = false; });
+
+        mkFlag()
+            .longName("refresh")
+            .description("consider all previously downloaded files out-of-date")
+            .handler([&]() { settings.tarballTtl = 0; });
     }
 
     void printFlags(std::ostream & out) override

From c85097da7c1ef06e2f1912c922110ff358de3aa2 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 28 Jan 2020 17:34:48 +0100
Subject: [PATCH 14/16] Fix --refresh with --no-net

https://hydra.nixos.org/build/110879699
(cherry picked from commit 5bbe793abf18414878a069399d1759673d693fb6)
---
 src/nix/main.cc | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/nix/main.cc b/src/nix/main.cc
index 5cb1ad25e..3b5f5516f 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -55,6 +55,7 @@ struct NixArgs : virtual MultiCommand, virtual MixCommonArgs
 {
     bool printBuildLogs = false;
     bool useNet = true;
+    bool refresh = false;
 
     NixArgs() : MultiCommand(*RegisterCommand::commands), MixCommonArgs("nix")
     {
@@ -96,7 +97,7 @@ struct NixArgs : virtual MultiCommand, virtual MixCommonArgs
         mkFlag()
             .longName("refresh")
             .description("consider all previously downloaded files out-of-date")
-            .handler([&]() { settings.tarballTtl = 0; });
+            .handler([&]() { refresh = true; });
     }
 
     void printFlags(std::ostream & out) override
@@ -181,6 +182,9 @@ void mainWrapped(int argc, char * * argv)
             downloadSettings.connectTimeout = 1;
     }
 
+    if (args.refresh)
+        settings.tarballTtl = 0;
+
     args.command->prepare();
     args.command->run();
 }

From 0a10854f857e519d1455ff0f0be1f8401c40a11c Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 24 Mar 2020 14:26:13 +0100
Subject: [PATCH 15/16] Misc changes from the flakes branch

---
 .gitignore                              |  2 +-
 Makefile.config.in                      |  1 +
 src/libexpr/eval.hh                     |  2 +-
 src/libstore/build.cc                   | 16 ++++++++--------
 src/libstore/builtins/buildenv.cc       |  2 +-
 src/libstore/http-binary-cache-store.cc |  5 +++--
 src/libstore/local-store.cc             | 13 +++----------
 src/libstore/nar-info-disk-cache.cc     |  7 +------
 src/libstore/nar-info-disk-cache.hh     |  2 +-
 src/libstore/parsed-derivations.cc      |  6 +++++-
 src/libstore/parsed-derivations.hh      | 10 ++++++----
 src/libstore/profiles.cc                | 18 ++++++++++++++++++
 src/libstore/profiles.hh                |  4 ++++
 src/libstore/sqlite.cc                  | 25 +++++++++++++++++++++++--
 src/libstore/sqlite.hh                  | 10 +++++++---
 src/libstore/store-api.hh               |  5 +++++
 src/libutil/hash.hh                     | 12 ++++++++++++
 src/libutil/util.hh                     |  5 +++--
 src/nix-env/nix-env.cc                  | 17 ++---------------
 tests/binary-cache.sh                   |  4 ++--
 tests/config.nix.in                     |  2 +-
 tests/fetchGit.sh                       |  2 ++
 22 files changed, 110 insertions(+), 60 deletions(-)

diff --git a/.gitignore b/.gitignore
index e10c75418..e3186fa76 100644
--- a/.gitignore
+++ b/.gitignore
@@ -47,7 +47,7 @@ perl/Makefile.config
 /src/libexpr/nix.tbl
 
 # /src/libstore/
-/src/libstore/*.gen.hh
+*.gen.*
 
 /src/nix/nix
 
diff --git a/Makefile.config.in b/Makefile.config.in
index fe609ce06..e7a12089a 100644
--- a/Makefile.config.in
+++ b/Makefile.config.in
@@ -37,6 +37,7 @@ prefix = @prefix@
 sandbox_shell = @sandbox_shell@
 storedir = @storedir@
 sysconfdir = @sysconfdir@
+system = @system@
 doc_generate = @doc_generate@
 xmllint = @xmllint@
 xsltproc = @xsltproc@
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 5efad8707..1485dc7fe 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -368,7 +368,7 @@ struct EvalSettings : Config
         "Prefixes of URIs that builtin functions such as fetchurl and fetchGit are allowed to fetch."};
 
     Setting<bool> traceFunctionCalls{this, false, "trace-function-calls",
-        "Emit log messages for each function entry and exit at the 'vomit' log level (-vvvv)"};
+        "Emit log messages for each function entry and exit at the 'vomit' log level (-vvvv)."};
 };
 
 extern EvalSettings evalSettings;
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index dc6a2c606..0e3a23a4d 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -1398,7 +1398,7 @@ void DerivationGoal::tryToBuild()
        few seconds and then retry this goal. */
     PathSet lockFiles;
     for (auto & outPath : drv->outputPaths())
-        lockFiles.insert(worker.store.toRealPath(worker.store.printStorePath(outPath)));
+        lockFiles.insert(worker.store.Store::toRealPath(outPath));
 
     if (!outputLocks.lockPaths(lockFiles, "", false)) {
         worker.waitForAWhile(shared_from_this());
@@ -1429,7 +1429,7 @@ void DerivationGoal::tryToBuild()
     for (auto & i : drv->outputs) {
         if (worker.store.isValidPath(i.second.path)) continue;
         debug("removing invalid path '%s'", worker.store.printStorePath(i.second.path));
-        deletePath(worker.store.toRealPath(worker.store.printStorePath(i.second.path)));
+        deletePath(worker.store.Store::toRealPath(i.second.path));
     }
 
     /* Don't do a remote build if the derivation has the attribute
@@ -1686,7 +1686,7 @@ void DerivationGoal::buildDone()
 
         /* Delete unused redirected outputs (when doing hash rewriting). */
         for (auto & i : redirectedOutputs)
-            deletePath(worker.store.toRealPath(worker.store.printStorePath(i.second)));
+            deletePath(worker.store.Store::toRealPath(i.second));
 
         /* Delete the chroot (if we were using one). */
         autoDelChroot.reset(); /* this runs the destructor */
@@ -2072,7 +2072,7 @@ void DerivationGoal::startBuilder()
            environment using bind-mounts.  We put it in the Nix store
            to ensure that we can create hard-links to non-directory
            inputs in the fake Nix store in the chroot (see below). */
-        chrootRootDir = worker.store.toRealPath(worker.store.printStorePath(drvPath)) + ".chroot";
+        chrootRootDir = worker.store.Store::toRealPath(drvPath) + ".chroot";
         deletePath(chrootRootDir);
 
         /* Clean up the chroot directory automatically. */
@@ -2551,7 +2551,7 @@ static std::regex shVarName("[A-Za-z_][A-Za-z0-9_]*");
 
 void DerivationGoal::writeStructuredAttrs()
 {
-    auto & structuredAttrs = parsedDrv->getStructuredAttrs();
+    auto structuredAttrs = parsedDrv->getStructuredAttrs();
     if (!structuredAttrs) return;
 
     auto json = *structuredAttrs;
@@ -2917,7 +2917,7 @@ void DerivationGoal::addDependency(const StorePath & path)
 
         #if __linux__
 
-            Path source = worker.store.toRealPath(worker.store.printStorePath(path));
+            Path source = worker.store.Store::toRealPath(path);
             Path target = chrootRootDir + worker.store.printStorePath(path);
             debug("bind-mounting %s -> %s", target, source);
 
@@ -3579,7 +3579,7 @@ void DerivationGoal::registerOutputs()
         if (needsHashRewrite()) {
             auto r = redirectedOutputs.find(i.second.path);
             if (r != redirectedOutputs.end()) {
-                auto redirected = worker.store.toRealPath(worker.store.printStorePath(r->second));
+                auto redirected = worker.store.Store::toRealPath(r->second);
                 if (buildMode == bmRepair
                     && redirectedBadOutputs.count(i.second.path)
                     && pathExists(redirected))
@@ -3672,7 +3672,7 @@ void DerivationGoal::registerOutputs()
                     BuildError("hash mismatch in fixed-output derivation '%s':\n  wanted: %s\n  got:    %s",
                         worker.store.printStorePath(dest), h.to_string(SRI), h2.to_string(SRI)));
 
-                Path actualDest = worker.store.toRealPath(worker.store.printStorePath(dest));
+                Path actualDest = worker.store.Store::toRealPath(dest);
 
                 if (worker.store.isValidPath(dest))
                     std::rethrow_exception(delayedException);
diff --git a/src/libstore/builtins/buildenv.cc b/src/libstore/builtins/buildenv.cc
index c1c85d0bf..1b802d908 100644
--- a/src/libstore/builtins/buildenv.cc
+++ b/src/libstore/builtins/buildenv.cc
@@ -156,7 +156,7 @@ void buildProfile(const Path & out, Packages && pkgs)
             addPkg(pkgDir, priorityCounter++);
     }
 
-    printError("created %d symlinks in user environment", state.symlinks);
+    debug("created %d symlinks in user environment", state.symlinks);
 }
 
 void builtinBuildenv(const BasicDerivation & drv)
diff --git a/src/libstore/http-binary-cache-store.cc b/src/libstore/http-binary-cache-store.cc
index d4ae36662..011794c62 100644
--- a/src/libstore/http-binary-cache-store.cc
+++ b/src/libstore/http-binary-cache-store.cc
@@ -163,10 +163,11 @@ static RegisterStoreImplementation regStore([](
     const std::string & uri, const Store::Params & params)
     -> std::shared_ptr<Store>
 {
+    static bool forceHttp = getEnv("_NIX_FORCE_HTTP") == "1";
     if (std::string(uri, 0, 7) != "http://" &&
         std::string(uri, 0, 8) != "https://" &&
-        (getEnv("_NIX_FORCE_HTTP_BINARY_CACHE_STORE") != "1" || std::string(uri, 0, 7) != "file://")
-        ) return 0;
+        (!forceHttp || std::string(uri, 0, 7) != "file://"))
+        return 0;
     auto store = std::make_shared<HttpBinaryCacheStore>(params, uri);
     store->init();
     return store;
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index cd2e86f29..ae7513ad8 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -298,9 +298,7 @@ void LocalStore::openDB(State & state, bool create)
     /* Open the Nix database. */
     string dbPath = dbDir + "/db.sqlite";
     auto & db(state.db);
-    if (sqlite3_open_v2(dbPath.c_str(), &db.db,
-            SQLITE_OPEN_READWRITE | (create ? SQLITE_OPEN_CREATE : 0), 0) != SQLITE_OK)
-        throw Error(format("cannot open Nix database '%1%'") % dbPath);
+    state.db = SQLite(dbPath, create);
 
 #ifdef __CYGWIN__
     /* The cygwin version of sqlite3 has a patch which calls
@@ -312,11 +310,6 @@ void LocalStore::openDB(State & state, bool create)
     SetDllDirectoryW(L"");
 #endif
 
-    if (sqlite3_busy_timeout(db, 60 * 60 * 1000) != SQLITE_OK)
-        throwSQLiteError(db, "setting timeout");
-
-    db.exec("pragma foreign_keys = 1");
-
     /* !!! check whether sqlite has been built with foreign key
        support */
 
@@ -350,7 +343,7 @@ void LocalStore::openDB(State & state, bool create)
 
     /* Initialise the database schema, if necessary. */
     if (create) {
-        const char * schema =
+        static const char schema[] =
 #include "schema.sql.gen.hh"
             ;
         db.exec(schema);
@@ -1275,7 +1268,7 @@ bool LocalStore::verifyStore(bool checkContents, RepairFlag repair)
                 else
                     hashSink = std::make_unique<HashModuloSink>(info->narHash.type, storePathToHash(printStorePath(info->path)));
 
-                dumpPath(toRealPath(printStorePath(i)), *hashSink);
+                dumpPath(Store::toRealPath(i), *hashSink);
                 auto current = hashSink->finish();
 
                 if (info->narHash != nullHash && info->narHash != current.first) {
diff --git a/src/libstore/nar-info-disk-cache.cc b/src/libstore/nar-info-disk-cache.cc
index 907645d86..442541330 100644
--- a/src/libstore/nar-info-disk-cache.cc
+++ b/src/libstore/nar-info-disk-cache.cc
@@ -78,12 +78,7 @@ public:
 
         state->db = SQLite(dbPath);
 
-        if (sqlite3_busy_timeout(state->db, 60 * 60 * 1000) != SQLITE_OK)
-            throwSQLiteError(state->db, "setting timeout");
-
-        // We can always reproduce the cache.
-        state->db.exec("pragma synchronous = off");
-        state->db.exec("pragma main.journal_mode = truncate");
+        state->db.isCache();
 
         state->db.exec(schema);
 
diff --git a/src/libstore/nar-info-disk-cache.hh b/src/libstore/nar-info-disk-cache.hh
index 878acbb87..04de2c5eb 100644
--- a/src/libstore/nar-info-disk-cache.hh
+++ b/src/libstore/nar-info-disk-cache.hh
@@ -10,7 +10,7 @@ class NarInfoDiskCache
 public:
     typedef enum { oValid, oInvalid, oUnknown } Outcome;
 
-    virtual ~NarInfoDiskCache() { };
+    virtual ~NarInfoDiskCache() { }
 
     virtual void createCache(const std::string & uri, const Path & storeDir,
         bool wantMassQuery, int priority) = 0;
diff --git a/src/libstore/parsed-derivations.cc b/src/libstore/parsed-derivations.cc
index d0f289a0f..45c033c66 100644
--- a/src/libstore/parsed-derivations.cc
+++ b/src/libstore/parsed-derivations.cc
@@ -1,5 +1,7 @@
 #include "parsed-derivations.hh"
 
+#include <nlohmann/json.hpp>
+
 namespace nix {
 
 ParsedDerivation::ParsedDerivation(StorePath && drvPath, BasicDerivation & drv)
@@ -9,13 +11,15 @@ ParsedDerivation::ParsedDerivation(StorePath && drvPath, BasicDerivation & drv)
     auto jsonAttr = drv.env.find("__json");
     if (jsonAttr != drv.env.end()) {
         try {
-            structuredAttrs = nlohmann::json::parse(jsonAttr->second);
+            structuredAttrs = std::make_unique<nlohmann::json>(nlohmann::json::parse(jsonAttr->second));
         } catch (std::exception & e) {
             throw Error("cannot process __json attribute of '%s': %s", drvPath.to_string(), e.what());
         }
     }
 }
 
+ParsedDerivation::~ParsedDerivation() { }
+
 std::optional<std::string> ParsedDerivation::getStringAttr(const std::string & name) const
 {
     if (structuredAttrs) {
diff --git a/src/libstore/parsed-derivations.hh b/src/libstore/parsed-derivations.hh
index cec868754..f4df5dd54 100644
--- a/src/libstore/parsed-derivations.hh
+++ b/src/libstore/parsed-derivations.hh
@@ -1,6 +1,6 @@
 #include "derivations.hh"
 
-#include <nlohmann/json.hpp>
+#include <nlohmann/json_fwd.hpp>
 
 namespace nix {
 
@@ -8,15 +8,17 @@ class ParsedDerivation
 {
     StorePath drvPath;
     BasicDerivation & drv;
-    std::optional<nlohmann::json> structuredAttrs;
+    std::unique_ptr<nlohmann::json> structuredAttrs;
 
 public:
 
     ParsedDerivation(StorePath && drvPath, BasicDerivation & drv);
 
-    const std::optional<nlohmann::json> & getStructuredAttrs() const
+    ~ParsedDerivation();
+
+    const nlohmann::json * getStructuredAttrs() const
     {
-        return structuredAttrs;
+        return structuredAttrs.get();
     }
 
     std::optional<std::string> getStringAttr(const std::string & name) const;
diff --git a/src/libstore/profiles.cc b/src/libstore/profiles.cc
index dae3f2d32..2bef51878 100644
--- a/src/libstore/profiles.cc
+++ b/src/libstore/profiles.cc
@@ -256,4 +256,22 @@ string optimisticLockProfile(const Path & profile)
 }
 
 
+Path getDefaultProfile()
+{
+    Path profileLink = getHome() + "/.nix-profile";
+    try {
+        if (!pathExists(profileLink)) {
+            replaceSymlink(
+                getuid() == 0
+                ? settings.nixStateDir + "/profiles/default"
+                : fmt("%s/profiles/per-user/%s/profile", settings.nixStateDir, getUserName()),
+                profileLink);
+        }
+        return absPath(readLink(profileLink), dirOf(profileLink));
+    } catch (Error &) {
+        return profileLink;
+    }
+}
+
+
 }
diff --git a/src/libstore/profiles.hh b/src/libstore/profiles.hh
index 5fa1533de..78645d8b6 100644
--- a/src/libstore/profiles.hh
+++ b/src/libstore/profiles.hh
@@ -64,4 +64,8 @@ void lockProfile(PathLocks & lock, const Path & profile);
    rebuilt. */
 string optimisticLockProfile(const Path & profile);
 
+/* Resolve ~/.nix-profile. If ~/.nix-profile doesn't exist yet, create
+   it. */
+Path getDefaultProfile();
+
 }
diff --git a/src/libstore/sqlite.cc b/src/libstore/sqlite.cc
index a061d64f3..eb1daafc5 100644
--- a/src/libstore/sqlite.cc
+++ b/src/libstore/sqlite.cc
@@ -25,11 +25,16 @@ namespace nix {
         throw SQLiteError("%s: %s (in '%s')", fs.s, sqlite3_errstr(exterr), path);
 }
 
-SQLite::SQLite(const Path & path)
+SQLite::SQLite(const Path & path, bool create)
 {
     if (sqlite3_open_v2(path.c_str(), &db,
-            SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, 0) != SQLITE_OK)
+            SQLITE_OPEN_READWRITE | (create ? SQLITE_OPEN_CREATE : 0), 0) != SQLITE_OK)
         throw Error(format("cannot open SQLite database '%s'") % path);
+
+    if (sqlite3_busy_timeout(db, 60 * 60 * 1000) != SQLITE_OK)
+        throwSQLiteError(db, "setting timeout");
+
+    exec("pragma foreign_keys = 1");
 }
 
 SQLite::~SQLite()
@@ -42,6 +47,12 @@ SQLite::~SQLite()
     }
 }
 
+void SQLite::isCache()
+{
+    exec("pragma synchronous = off");
+    exec("pragma main.journal_mode = truncate");
+}
+
 void SQLite::exec(const std::string & stmt)
 {
     retrySQLite<void>([&]() {
@@ -94,6 +105,16 @@ SQLiteStmt::Use & SQLiteStmt::Use::operator () (const std::string & value, bool
     return *this;
 }
 
+SQLiteStmt::Use & SQLiteStmt::Use::operator () (const unsigned char * data, size_t len, bool notNull)
+{
+    if (notNull) {
+        if (sqlite3_bind_blob(stmt, curArg++, data, len, SQLITE_TRANSIENT) != SQLITE_OK)
+            throwSQLiteError(stmt.db, "binding argument");
+    } else
+        bind();
+    return *this;
+}
+
 SQLiteStmt::Use & SQLiteStmt::Use::operator () (int64_t value, bool notNull)
 {
     if (notNull) {
diff --git a/src/libstore/sqlite.hh b/src/libstore/sqlite.hh
index bd012d9b9..fd04c9b07 100644
--- a/src/libstore/sqlite.hh
+++ b/src/libstore/sqlite.hh
@@ -5,8 +5,8 @@
 
 #include "types.hh"
 
-class sqlite3;
-class sqlite3_stmt;
+struct sqlite3;
+struct sqlite3_stmt;
 
 namespace nix {
 
@@ -15,13 +15,16 @@ struct SQLite
 {
     sqlite3 * db = 0;
     SQLite() { }
-    SQLite(const Path & path);
+    SQLite(const Path & path, bool create = true);
     SQLite(const SQLite & from) = delete;
     SQLite& operator = (const SQLite & from) = delete;
     SQLite& operator = (SQLite && from) { db = from.db; from.db = 0; return *this; }
     ~SQLite();
     operator sqlite3 * () { return db; }
 
+    /* Disable synchronous mode, set truncate journal mode. */
+    void isCache();
+
     void exec(const std::string & stmt);
 };
 
@@ -52,6 +55,7 @@ struct SQLiteStmt
 
         /* Bind the next parameter. */
         Use & operator () (const std::string & value, bool notNull = true);
+        Use & operator () (const unsigned char * data, size_t len, bool notNull = true);
         Use & operator () (int64_t value, bool notNull = true);
         Use & bind(); // null
 
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index c57a6935e..0fa59be6a 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -677,6 +677,11 @@ public:
         return storePath;
     }
 
+    Path toRealPath(const StorePath & storePath)
+    {
+        return toRealPath(printStorePath(storePath));
+    }
+
     virtual void createUser(const std::string & userName, uid_t userId)
     { }
 
diff --git a/src/libutil/hash.hh b/src/libutil/hash.hh
index ffa43ecf5..ea9fca3e7 100644
--- a/src/libutil/hash.hh
+++ b/src/libutil/hash.hh
@@ -80,6 +80,18 @@ struct Hash
        or base-64. By default, this is prefixed by the hash type
        (e.g. "sha256:"). */
     std::string to_string(Base base = Base32, bool includeType = true) const;
+
+    std::string gitRev() const
+    {
+        assert(type == htSHA1);
+        return to_string(Base16, false);
+    }
+
+    std::string gitShortRev() const
+    {
+        assert(type == htSHA1);
+        return std::string(to_string(Base16, false), 0, 7);
+    }
 };
 
 
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index acef682cd..7c3a30242 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -476,10 +476,11 @@ string base64Decode(const string & s);
 /* Get a value for the specified key from an associate container, or a
    default value if the key doesn't exist. */
 template <class T>
-std::optional<std::string> get(const T & map, const std::string & key)
+std::optional<typename T::mapped_type> get(const T & map, const typename T::key_type & key)
 {
     auto i = map.find(key);
-    return i == map.end() ? std::optional<std::string>() : i->second;
+    if (i == map.end()) return {};
+    return std::optional<typename T::mapped_type>(i->second);
 }
 
 
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index c7e553d0c..e47b00acf 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -1428,21 +1428,8 @@ static int _main(int argc, char * * argv)
         if (globals.profile == "")
             globals.profile = getEnv("NIX_PROFILE").value_or("");
 
-        if (globals.profile == "") {
-            Path profileLink = getHome() + "/.nix-profile";
-            try {
-                if (!pathExists(profileLink)) {
-                    replaceSymlink(
-                        getuid() == 0
-                        ? settings.nixStateDir + "/profiles/default"
-                        : fmt("%s/profiles/per-user/%s/profile", settings.nixStateDir, getUserName()),
-                        profileLink);
-                }
-                globals.profile = absPath(readLink(profileLink), dirOf(profileLink));
-            } catch (Error &) {
-                globals.profile = profileLink;
-            }
-        }
+        if (globals.profile == "")
+            globals.profile = getDefaultProfile();
 
         op(globals, opFlags, opArgs);
 
diff --git a/tests/binary-cache.sh b/tests/binary-cache.sh
index eb58ae7c1..a3c3c7847 100644
--- a/tests/binary-cache.sh
+++ b/tests/binary-cache.sh
@@ -48,7 +48,7 @@ basicTests
 
 
 # Test HttpBinaryCacheStore.
-export _NIX_FORCE_HTTP_BINARY_CACHE_STORE=1
+export _NIX_FORCE_HTTP=1
 basicTests
 
 
@@ -126,7 +126,7 @@ badKey="$(cat $TEST_ROOT/pk2)"
 res=($(nix-store --generate-binary-cache-key foo.nixos.org-1 $TEST_ROOT/sk3 $TEST_ROOT/pk3))
 otherKey="$(cat $TEST_ROOT/pk3)"
 
-_NIX_FORCE_HTTP_BINARY_CACHE_STORE= nix copy --to file://$cacheDir?secret-key=$TEST_ROOT/sk1 $outPath
+_NIX_FORCE_HTTP= nix copy --to file://$cacheDir?secret-key=$TEST_ROOT/sk1 $outPath
 
 
 # Downloading should fail if we don't provide a key.
diff --git a/tests/config.nix.in b/tests/config.nix.in
index 51aed539c..0ec2eba6b 100644
--- a/tests/config.nix.in
+++ b/tests/config.nix.in
@@ -3,7 +3,7 @@ rec {
 
   path = "@coreutils@";
 
-  system = builtins.currentSystem;
+  system = "@system@";
 
   shared = builtins.getEnv "_NIX_TEST_SHARED";
 
diff --git a/tests/fetchGit.sh b/tests/fetchGit.sh
index 4c46bdf04..ed8fa14d6 100644
--- a/tests/fetchGit.sh
+++ b/tests/fetchGit.sh
@@ -9,6 +9,8 @@ clearStore
 
 repo=$TEST_ROOT/git
 
+export _NIX_FORCE_HTTP=1
+
 rm -rf $repo ${repo}-tmp $TEST_HOME/.cache/nix/gitv2
 
 git init $repo

From 7313aa267b5be1e5264e4577e7bc3daec2fef282 Mon Sep 17 00:00:00 2001
From: Greg Price <gnprice@gmail.com>
Date: Tue, 24 Mar 2020 21:15:01 -0700
Subject: [PATCH 16/16] installer: Fix terminal colors.

The install-multi-user script uses blue, green, and red colors, as
well as bold and underline, to add helpful formatting that helps
structure its rather voluminous output.

Unfortunately, the terminal escape sequences it uses are not quite
well-formed.  The relevant information is all there, just obscured
by some extra noise, a leading parameter `38`.  Empirically, the
result is:

 * On macOS, in both Terminal.app and iTerm2, the spurious `38` is
   ignored, the rest of the escape sequence is applied, and the colors
   show up as intended.

 * On Linux, in at least gnome-terminal and xterm, the spurious `38`
   and the next parameter after it are ignored, and what's left is
   applied.  So in the sequence `38;4;32`, the 4 (underline) is
   ignored but the 32 (green) takes effect; in a more typical sequence
   like `38;34`, the 34 (blue) is ignored and nothing happens.

These codes are all unchanged since this script's origins as a
Darwin-only script -- so the fact that they work fine in common macOS
terminals goes some way to explain how the bug arose.

Happily, we can make the colors work as intended by just deleting the
extra `38;`.  Tested in all four terminals mentioned above; the new
codes work correctly on all of them, and on the two macOS terminals
they work exactly the same as before.

---

In a bit more technical detail -- perhaps more than anyone, me
included, ever wanted to know, but now that I've gone and learned it
I'll write it down anyway :) -- here's what's happening in these codes:

An ECMA-48 "control sequence" begins with `\033[` aka "CSI", contains
any number of parameters as semicolon-separated decimal numbers (plus
sometimes other wrinkles), and ends with a byte from 0x40..0x7e.  In
our case, with `m` aka "SGR", "Select Graphic Rendition".

An SGR control sequence `\033[...m` sets colors, fonts, text styles,
etc.  In particular a parameter `31` means red, `32` green, `34` blue,
`4` underline, and `0` means reset to normal.  Those are all we use.

There is also a `38`.  This is used for setting colors too... but it
needs arguments.  `38;5;nn` is color nn from a 256-color palette, and
`38;2;rr;gg;bb` has the given RGB values.

There is no meaning defined for `38;1` or `38;34` etc.  On seeing a
parameter `38` followed by an unrecognized argument for it, apparently
some implementations (as seen on macOS) discard only the `38` and
others (as seen on Linux) discard the argument too before resuming.
---
 scripts/install-multi-user.sh | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/scripts/install-multi-user.sh b/scripts/install-multi-user.sh
index 35341543e..a0f1deb98 100644
--- a/scripts/install-multi-user.sh
+++ b/scripts/install-multi-user.sh
@@ -13,12 +13,12 @@ set -o pipefail
 # however tracking which bits came from which would be impossible.
 
 readonly ESC='\033[0m'
-readonly BOLD='\033[38;1m'
-readonly BLUE='\033[38;34m'
-readonly BLUE_UL='\033[38;4;34m'
-readonly GREEN='\033[38;32m'
-readonly GREEN_UL='\033[38;4;32m'
-readonly RED='\033[38;31m'
+readonly BOLD='\033[1m'
+readonly BLUE='\033[34m'
+readonly BLUE_UL='\033[4;34m'
+readonly GREEN='\033[32m'
+readonly GREEN_UL='\033[4;32m'
+readonly RED='\033[31m'
 
 readonly NIX_USER_COUNT="32"
 readonly NIX_BUILD_GROUP_ID="30000"