nix-shell/nix-build: Support .drv files again

Fixes #1663.

Also handle '!<output-name>' (#1694).

3 files changed, 33 insertions, 2 deletions

diff --git a/src/libexpr/get-drvs.cc b/src/libexpr/get-drvs.cc
index d5bc42352a26..d38ed2df3b18 100644
--- a/src/libexpr/get-drvs.cc
+++ b/src/libexpr/get-drvs.cc
@@ -1,6 +1,7 @@
 #include "get-drvs.hh"
 #include "util.hh"
 #include "eval-inline.hh"
+#include "derivations.hh"
 
 #include <cstring>
 #include <regex>
@@ -15,6 +16,33 @@ DrvInfo::DrvInfo(EvalState & state, const string & attrPath, Bindings * attrs)
 }
 
 
+DrvInfo::DrvInfo(EvalState & state, ref<Store> store, const std::string & drvPathWithOutputs)
+    : state(&state), attrs(nullptr), attrPath("")
+{
+    auto spec = parseDrvPathWithOutputs(drvPathWithOutputs);
+
+    drvPath = spec.first;
+
+    auto drv = store->derivationFromPath(drvPath);
+
+    name = storePathToName(drvPath);
+
+    if (spec.second.size() > 1)
+        throw Error("building more than one derivation output is not supported, in '%s'", drvPathWithOutputs);
+
+    outputName =
+        spec.second.empty()
+        ? get(drv.env, "outputName", "out")
+        : *spec.second.begin();
+
+    auto i = drv.outputs.find(outputName);
+    if (i == drv.outputs.end())
+        throw Error("derivation '%s' does not have output '%s'", drvPath, outputName);
+
+    outPath = i->second.path;
+}
+
+
 string DrvInfo::queryName() const
 {
     if (name == "" && attrs) {
diff --git a/src/libexpr/get-drvs.hh b/src/libexpr/get-drvs.hh
index 32294e458751..4d9128e3f448 100644
--- a/src/libexpr/get-drvs.hh
+++ b/src/libexpr/get-drvs.hh
@@ -37,6 +37,7 @@ public:
 
     DrvInfo(EvalState & state) : state(&state) { };
     DrvInfo(EvalState & state, const string & attrPath, Bindings * attrs);
+    DrvInfo(EvalState & state, ref<Store> store, const std::string & drvPathWithOutputs);
 
     string queryName() const;
     string querySystem() const;
diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index 21b0a18dd887..58366daa6e86 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -263,6 +263,8 @@ void mainWrapped(int argc, char * * argv)
     if (runEnv)
         setenv("IN_NIX_SHELL", pure ? "pure" : "impure", 1);
 
+    DrvInfos drvs;
+
     /* Parse the expressions. */
     std::vector<Expr *> exprs;
 
@@ -272,6 +274,8 @@ void mainWrapped(int argc, char * * argv)
         for (auto i : left) {
             if (fromArgs)
                 exprs.push_back(state.parseExprFromString(i, absPath(".")));
+            else if (store->isStorePath(i) && std::regex_match(i, std::regex(".*\\.drv(!.*)?")))
+                drvs.push_back(DrvInfo(state, store, i));
             else
                 /* If we're in a #! script, interpret filenames
                    relative to the script. */
@@ -280,8 +284,6 @@ void mainWrapped(int argc, char * * argv)
         }
 
     /* Evaluate them into derivations. */
-    DrvInfos drvs;
-
     if (attrPaths.empty()) attrPaths = {""};
 
     for (auto e : exprs) {