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-rw-r--r--src/libexpr/eval.hh3
-rw-r--r--src/libexpr/primops.cc56
-rw-r--r--src/libexpr/primops/context.cc187
-rw-r--r--src/libstore/build.cc2
-rw-r--r--src/libstore/local-store.cc2
-rw-r--r--src/libstore/ssh.cc3
-rw-r--r--src/libutil/util.cc24
-rw-r--r--src/libutil/util.hh10
-rwxr-xr-xsrc/nix-build/nix-build.cc4
-rw-r--r--src/nix/edit.cc5
-rw-r--r--src/nix/repl.cc2
-rw-r--r--src/nix/run.cc4
12 files changed, 196 insertions, 106 deletions
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index d0f298e168e9..9fe3878916d5 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -316,6 +316,9 @@ private:
 /* Return a string representing the type of the value `v'. */
 string showType(const Value & v);
 
+/* Decode a context string ‘!<name>!<path>’ into a pair <path,
+   name>. */
+std::pair<string, string> decodeContext(const string & s);
 
 /* If `path' refers to a directory, then append "/default.nix". */
 Path resolveExprPath(Path path);
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 60698f7402e0..0da9f702f4bb 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -687,21 +687,12 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
             }
         }
 
-        /* See prim_unsafeDiscardOutputDependency. */
-        else if (path.at(0) == '~')
-            drv.inputSrcs.insert(string(path, 1));
-
         /* Handle derivation outputs of the form ‘!<name>!<path>’. */
         else if (path.at(0) == '!') {
             std::pair<string, string> ctx = decodeContext(path);
             drv.inputDrvs[ctx.first].insert(ctx.second);
         }
 
-        /* Handle derivation contexts returned by
-           ‘builtins.storePath’. */
-        else if (isDerivation(path))
-            drv.inputDrvs[path] = state.store->queryDerivationOutputNames(path);
-
         /* Otherwise it's a source file. */
         else
             drv.inputSrcs.insert(path);
@@ -1004,13 +995,8 @@ static void prim_toFile(EvalState & state, const Pos & pos, Value * * args, Valu
     PathSet refs;
 
     for (auto path : context) {
-        if (path.at(0) == '=') path = string(path, 1);
-        if (isDerivation(path)) {
-            /* See prim_unsafeDiscardOutputDependency. */
-            if (path.at(0) != '~')
-                throw EvalError(format("in 'toFile': the file '%1%' cannot refer to derivation outputs, at %2%") % name % pos);
-            path = string(path, 1);
-        }
+        if (path.at(0) != '/')
+            throw EvalError(format("in 'toFile': the file '%1%' cannot refer to derivation outputs, at %2%") % name % pos);
         refs.insert(path);
     }
 
@@ -1794,41 +1780,6 @@ static void prim_stringLength(EvalState & state, const Pos & pos, Value * * args
 }
 
 
-static void prim_unsafeDiscardStringContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
-{
-    PathSet context;
-    string s = state.coerceToString(pos, *args[0], context);
-    mkString(v, s, PathSet());
-}
-
-
-static void prim_hasContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
-{
-    PathSet context;
-    state.forceString(*args[0], context, pos);
-    mkBool(v, !context.empty());
-}
-
-
-/* Sometimes we want to pass a derivation path (i.e. pkg.drvPath) to a
-   builder without causing the derivation to be built (for instance,
-   in the derivation that builds NARs in nix-push, when doing
-   source-only deployment).  This primop marks the string context so
-   that builtins.derivation adds the path to drv.inputSrcs rather than
-   drv.inputDrvs. */
-static void prim_unsafeDiscardOutputDependency(EvalState & state, const Pos & pos, Value * * args, Value & v)
-{
-    PathSet context;
-    string s = state.coerceToString(pos, *args[0], context);
-
-    PathSet context2;
-    for (auto & p : context)
-        context2.insert(p.at(0) == '=' ? "~" + string(p, 1) : p);
-
-    mkString(v, s, context2);
-}
-
-
 /* Return the cryptographic hash of a string in base-16. */
 static void prim_hashString(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -2299,9 +2250,6 @@ void EvalState::createBaseEnv()
     addPrimOp("toString", 1, prim_toString);
     addPrimOp("__substring", 3, prim_substring);
     addPrimOp("__stringLength", 1, prim_stringLength);
-    addPrimOp("__hasContext", 1, prim_hasContext);
-    addPrimOp("__unsafeDiscardStringContext", 1, prim_unsafeDiscardStringContext);
-    addPrimOp("__unsafeDiscardOutputDependency", 1, prim_unsafeDiscardOutputDependency);
     addPrimOp("__hashString", 2, prim_hashString);
     addPrimOp("__match", 2, prim_match);
     addPrimOp("__split", 2, prim_split);
diff --git a/src/libexpr/primops/context.cc b/src/libexpr/primops/context.cc
new file mode 100644
index 000000000000..2d79739ea047
--- /dev/null
+++ b/src/libexpr/primops/context.cc
@@ -0,0 +1,187 @@
+#include "primops.hh"
+#include "eval-inline.hh"
+#include "derivations.hh"
+
+namespace nix {
+
+static void prim_unsafeDiscardStringContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    PathSet context;
+    string s = state.coerceToString(pos, *args[0], context);
+    mkString(v, s, PathSet());
+}
+
+static RegisterPrimOp r1("__unsafeDiscardStringContext", 1, prim_unsafeDiscardStringContext);
+
+
+static void prim_hasContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    PathSet context;
+    state.forceString(*args[0], context, pos);
+    mkBool(v, !context.empty());
+}
+
+static RegisterPrimOp r2("__hasContext", 1, prim_hasContext);
+
+
+/* Sometimes we want to pass a derivation path (i.e. pkg.drvPath) to a
+   builder without causing the derivation to be built (for instance,
+   in the derivation that builds NARs in nix-push, when doing
+   source-only deployment).  This primop marks the string context so
+   that builtins.derivation adds the path to drv.inputSrcs rather than
+   drv.inputDrvs. */
+static void prim_unsafeDiscardOutputDependency(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    PathSet context;
+    string s = state.coerceToString(pos, *args[0], context);
+
+    PathSet context2;
+    for (auto & p : context)
+        context2.insert(p.at(0) == '=' ? string(p, 1) : p);
+
+    mkString(v, s, context2);
+}
+
+static RegisterPrimOp r3("__unsafeDiscardOutputDependency", 1, prim_unsafeDiscardOutputDependency);
+
+
+/* Extract the context of a string as a structured Nix value.
+
+   The context is represented as an attribute set whose keys are the
+   paths in the context set and whose values are attribute sets with
+   the following keys:
+     path: True if the relevant path is in the context as a plain store
+           path (i.e. the kind of context you get when interpolating
+           a Nix path (e.g. ./.) into a string). False if missing.
+     allOutputs: True if the relevant path is a derivation and it is
+                  in the context as a drv file with all of its outputs
+                  (i.e. the kind of context you get when referencing
+                  .drvPath of some derivation). False if missing.
+     outputs: If a non-empty list, the relevant path is a derivation
+              and the provided outputs are referenced in the context
+              (i.e. the kind of context you get when referencing
+              .outPath of some derivation). Empty list if missing.
+   Note that for a given path any combination of the above attributes
+   may be present.
+*/
+static void prim_getContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    struct ContextInfo {
+        bool path = false;
+        bool allOutputs = false;
+        Strings outputs;
+    };
+    PathSet context;
+    state.forceString(*args[0], context, pos);
+    auto contextInfos = std::map<Path, ContextInfo>();
+    for (const auto & p : context) {
+        Path drv;
+        string output;
+        const Path * path = &p;
+        if (p.at(0) == '=') {
+            drv = string(p, 1);
+            path = &drv;
+        } else if (p.at(0) == '!') {
+            std::pair<string, string> ctx = decodeContext(p);
+            drv = ctx.first;
+            output = ctx.second;
+            path = &drv;
+        }
+        auto isPath = drv.empty();
+        auto isAllOutputs = (!drv.empty()) && output.empty();
+
+        auto iter = contextInfos.find(*path);
+        if (iter == contextInfos.end()) {
+            contextInfos.emplace(*path, ContextInfo{isPath, isAllOutputs, output.empty() ? Strings{} : Strings{std::move(output)}});
+        } else {
+            if (isPath)
+                iter->second.path = true;
+            else if (isAllOutputs)
+                iter->second.allOutputs = true;
+            else
+                iter->second.outputs.emplace_back(std::move(output));
+        }
+    }
+
+    state.mkAttrs(v, contextInfos.size());
+
+    auto sPath = state.symbols.create("path");
+    auto sAllOutputs = state.symbols.create("allOutputs");
+    for (const auto & info : contextInfos) {
+        auto & infoVal = *state.allocAttr(v, state.symbols.create(info.first));
+        state.mkAttrs(infoVal, 3);
+        if (info.second.path)
+            mkBool(*state.allocAttr(infoVal, sPath), true);
+        if (info.second.allOutputs)
+            mkBool(*state.allocAttr(infoVal, sAllOutputs), true);
+        if (!info.second.outputs.empty()) {
+            auto & outputsVal = *state.allocAttr(infoVal, state.sOutputs);
+            state.mkList(outputsVal, info.second.outputs.size());
+            size_t i = 0;
+            for (const auto & output : info.second.outputs) {
+                mkString(*(outputsVal.listElems()[i++] = state.allocValue()), output);
+            }
+        }
+        infoVal.attrs->sort();
+    }
+    v.attrs->sort();
+}
+
+static RegisterPrimOp r4("__getContext", 1, prim_getContext);
+
+
+/* Append the given context to a given string.
+
+   See the commentary above unsafeGetContext for details of the
+   context representation.
+*/
+static void prim_appendContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    PathSet context;
+    auto orig = state.forceString(*args[0], context, pos);
+
+    state.forceAttrs(*args[1], pos);
+
+    auto sPath = state.symbols.create("path");
+    auto sAllOutputs = state.symbols.create("allOutputs");
+    for (auto & i : *args[1]->attrs) {
+        if (!state.store->isStorePath(i.name))
+            throw EvalError("Context key '%s' is not a store path, at %s", i.name, i.pos);
+        if (!settings.readOnlyMode)
+            state.store->ensurePath(i.name);
+        state.forceAttrs(*i.value, *i.pos);
+        auto iter = i.value->attrs->find(sPath);
+        if (iter != i.value->attrs->end()) {
+            if (state.forceBool(*iter->value, *iter->pos))
+                context.insert(i.name);
+        }
+
+        iter = i.value->attrs->find(sAllOutputs);
+        if (iter != i.value->attrs->end()) {
+            if (state.forceBool(*iter->value, *iter->pos)) {
+                if (!isDerivation(i.name)) {
+                    throw EvalError("Tried to add all-outputs context of %s, which is not a derivation, to a string, at %s", i.name, i.pos);
+                }
+                context.insert("=" + string(i.name));
+            }
+        }
+
+        iter = i.value->attrs->find(state.sOutputs);
+        if (iter != i.value->attrs->end()) {
+            state.forceList(*iter->value, *iter->pos);
+            if (iter->value->listSize() && !isDerivation(i.name)) {
+                throw EvalError("Tried to add derivation output context of %s, which is not a derivation, to a string, at %s", i.name, i.pos);
+            }
+            for (unsigned int n = 0; n < iter->value->listSize(); ++n) {
+                auto name = state.forceStringNoCtx(*iter->value->listElems()[n], *iter->pos);
+                context.insert("!" + name + "!" + string(i.name));
+            }
+        }
+    }
+
+    mkString(v, orig, context);
+}
+
+static RegisterPrimOp r5("__appendContext", 2, prim_appendContext);
+
+}
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 59abae9b90db..47ee8b48f4b4 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -2193,7 +2193,6 @@ void DerivationGoal::startBuilder()
         userNamespaceSync.create();
 
         options.allowVfork = false;
-        options.restoreMountNamespace = false;
 
         Pid helper = startProcess([&]() {
 
@@ -2260,7 +2259,6 @@ void DerivationGoal::startBuilder()
 #endif
     {
         options.allowVfork = !buildUser && !drv->isBuiltin();
-        options.restoreMountNamespace = false;
         pid = startProcess([&]() {
             runChild();
         }, options);
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 5b4e7ca4ca99..485fdd691932 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -366,8 +366,6 @@ void LocalStore::makeStoreWritable()
         throw SysError("getting info about the Nix store mount point");
 
     if (stat.f_flag & ST_RDONLY) {
-        saveMountNamespace();
-
         if (unshare(CLONE_NEWNS) == -1)
             throw SysError("setting up a private mount namespace");
 
diff --git a/src/libstore/ssh.cc b/src/libstore/ssh.cc
index cf133b57cb20..5e0e44935cca 100644
--- a/src/libstore/ssh.cc
+++ b/src/libstore/ssh.cc
@@ -1,5 +1,4 @@
 #include "ssh.hh"
-#include "affinity.hh"
 
 namespace nix {
 
@@ -35,9 +34,7 @@ std::unique_ptr<SSHMaster::Connection> SSHMaster::startCommand(const std::string
 
     auto conn = std::make_unique<Connection>();
     conn->sshPid = startProcess([&]() {
-        restoreAffinity();
         restoreSignals();
-        restoreMountNamespace();
 
         close(in.writeSide.get());
         close(out.readSide.get());
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index ce50334e1e62..7eca35577b01 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -936,8 +936,6 @@ pid_t startProcess(std::function<void()> fun, const ProcessOptions & options)
                 throw SysError("setting death signal");
 #endif
             restoreAffinity();
-            if (options.restoreMountNamespace)
-                restoreMountNamespace();
             fun();
         } catch (std::exception & e) {
             try {
@@ -1506,26 +1504,4 @@ std::unique_ptr<InterruptCallback> createInterruptCallback(std::function<void()>
     return std::unique_ptr<InterruptCallback>(res.release());
 }
 
-static AutoCloseFD fdSavedMountNamespace;
-
-void saveMountNamespace()
-{
-#if __linux__
-    std::once_flag done;
-    std::call_once(done, []() {
-        fdSavedMountNamespace = open("/proc/self/ns/mnt", O_RDONLY);
-        if (!fdSavedMountNamespace)
-            throw SysError("saving parent mount namespace");
-    });
-#endif
-}
-
-void restoreMountNamespace()
-{
-#if __linux__
-    if (fdSavedMountNamespace && setns(fdSavedMountNamespace.get(), CLONE_NEWNS) == -1)
-        throw SysError("restoring parent mount namespace");
-#endif
-}
-
 }
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index d67bddc138c8..bda87bee433e 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -250,7 +250,6 @@ struct ProcessOptions
     bool dieWithParent = true;
     bool runExitHandlers = false;
     bool allowVfork = true;
-    bool restoreMountNamespace = true;
 };
 
 pid_t startProcess(std::function<void()> fun, const ProcessOptions & options = ProcessOptions());
@@ -515,13 +514,4 @@ typedef std::function<bool(const Path & path)> PathFilter;
 extern PathFilter defaultPathFilter;
 
 
-/* Save the current mount namespace. Ignored if called more than
-   once. */
-void saveMountNamespace();
-
-/* Restore the mount namespace saved by saveMountNamespace(). Ignored
-   if saveMountNamespace() was never called. */
-void restoreMountNamespace();
-
-
 }
diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index 11ea3b1f7ae1..618895d387d4 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -401,6 +401,8 @@ static void _main(int argc, char * * argv)
             } else
                 env[var.first] = var.second;
 
+        restoreAffinity();
+
         /* Run a shell using the derivation's environment.  For
            convenience, source $stdenv/setup to setup additional
            environment variables and shell functions.  Also don't
@@ -444,9 +446,7 @@ static void _main(int argc, char * * argv)
 
         auto argPtrs = stringsToCharPtrs(args);
 
-        restoreAffinity();
         restoreSignals();
-        restoreMountNamespace();
 
         execvp(shell.c_str(), argPtrs.data());
 
diff --git a/src/nix/edit.cc b/src/nix/edit.cc
index d8d5895bd867..c9671f76d0fa 100644
--- a/src/nix/edit.cc
+++ b/src/nix/edit.cc
@@ -3,7 +3,6 @@
 #include "eval.hh"
 #include "attr-path.hh"
 #include "progress-bar.hh"
-#include "affinity.hh"
 
 #include <unistd.h>
 
@@ -73,10 +72,6 @@ struct CmdEdit : InstallableCommand
 
         stopProgressBar();
 
-        restoreAffinity();
-        restoreSignals();
-        restoreMountNamespace();
-
         execvp(args.front().c_str(), stringsToCharPtrs(args).data());
 
         throw SysError("cannot run editor '%s'", editor);
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index dd3d9ed97495..227affc60e20 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -337,8 +337,6 @@ static int runProgram(const string & program, const Strings & args)
     if (pid == -1) throw SysError("forking");
     if (pid == 0) {
         restoreAffinity();
-        restoreSignals();
-        restoreMountNamespace();
         execvp(program.c_str(), stringsToCharPtrs(args2).data());
         _exit(1);
     }
diff --git a/src/nix/run.cc b/src/nix/run.cc
index 1297072989b9..35b763345872 100644
--- a/src/nix/run.cc
+++ b/src/nix/run.cc
@@ -153,9 +153,9 @@ struct CmdRun : InstallablesCommand
 
         stopProgressBar();
 
-        restoreAffinity();
         restoreSignals();
-        restoreMountNamespace();
+
+        restoreAffinity();
 
         /* If this is a diverted store (i.e. its "logical" location
            (typically /nix/store) differs from its "physical" location
generated by cgit-pink 1.4.1 (git 2.44.2) at 2025-02-03T23·08+0000