* nix-env -e: support uninstalling by path, so that one can say

    $ nix-env -e $(which firefox)

  or

    $ nix-env -e /nix/store/nywzlygrkfcgz7dfmhm5xixlx1l0m60v-pan-0.132

* nix-env -i: if an argument contains a slash anywhere, treat it as a
  path and follow it through symlinks into the Nix store.  This allows
  things like

    $ nix-build -A firefox
    $ nix-env -i ./result

* nix-env -q/-i/-e: don't complain when the `*' selector doesn't match
  anything.  In particular, `nix-env -q \*' doesn't fail anymore on an
  empty profile.

1 files changed, 20 insertions, 0 deletions

diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 9eb313da01ff..22a66ccabdb2 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -48,6 +48,26 @@ Path toStorePath(const Path & path)
 }
 
 
+Path followLinksToStore(const Path & _path)
+{
+    Path path = absPath(_path);
+    while (!isInStore(path)) {
+        if (!isLink(path)) break;
+        string target = readLink(path);
+        path = absPath(target, dirOf(path));
+    }
+    if (!isInStore(path))
+        throw Error(format("path `%1%' is not in the Nix store") % path);
+    return path;
+}
+
+
+Path followLinksToStorePath(const Path & path)
+{
+    return toStorePath(followLinksToStore(path));
+}
+
+
 void checkStoreName(const string & name)
 {
     string validChars = "+-._?=";