Add tests for add-gc-root

src/nix/store-add-gc-root.cc

@@ -19,6 +19,12 @@ struct CmdAddGCRoot : StoreCommand
             .handler = {&links},
             .completer = completePath,
         });
+
+        addFlag({
+            .longName = "no-check",
+            .description = "Do not test the validity of created roots.",
+            .handler = {&checkResults, false},
+        });
     }
 
     std::string description() override
@@ -51,7 +57,9 @@ struct CmdAddGCRoot : StoreCommand
             if (checkResults) {
                 auto path = indirectRootStore.followLinksToStorePath(indirectPath);
                 indirectRootStore.addTempRoot(path);
-                // TODO: ensure `path` is safe from concurrent GC or fail.
+                if (!indirectRootStore.isValidPath(path)) {
+                    throw Error("Indirect root '%1%' is no a symbolic link to a valid store path", link);
+                }
             }
 
             indirectRootStore.addIndirectRoot(indirectPath);

tests/functional/local.mk

@@ -103,6 +103,7 @@ nix_tests = \
   nix-profile.sh \
   suggestions.sh \
   store-info.sh \
+  store-add-gc-root.sh \
   fetchClosure.sh \
   completions.sh \
   impure-derivations.sh \

tests/functional/meson.build

@@ -184,6 +184,7 @@ suites = [
       'debugger.sh',
       'extra-sandbox-profile.sh',
       'help.sh',
+      'store-add-gc-root.sh',
     ],
     'workdir': meson.current_build_dir(),
   },

tests/functional/store-add-gc-root.sh

@@ -0,0 +1,53 @@
+#!/usr/bin/env bash
+
+source common.sh
+
+clearStoreIfPossible
+
+function delete() { nix-store --delete "$storePath"; }
+function build() { nix build --no-link --print-out-paths -f simple.nix; }
+
+# Check that path can be deleted
+storePath=$(build)
+delete
+
+# Check that add-gc-root prevents deletion,
+# and removing the root make it deletable again.
+storePath=$(build)
+ln -sn "$storePath" myroot
+nix store add-gc-root myroot
+if delete; then false; fi
+rm myroot
+delete
+
+# Create several roots at once
+storePath=$(build)
+ln -sn "$storePath" myroot1
+ln -sn "$storePath" myroot2
+ln -sn "$storePath" myroot3
+nix store add-gc-root myroot1 myroot2 myroot3
+if delete; then false; fi
+rm myroot3 myroot2
+if delete; then false; fi
+rm myroot1
+delete
+
+# Test detection of invalid roots
+# 1. path deleted before root creation
+storePath=$(build)
+delete
+ln -sn "$storePath" myroot
+if nix store add-gc-root myroot; then false; fi
+nix store add-gc-root --no-check myroot
+rm myroot
+
+# 2. invalid path
+ln -sn /invalid-target myroot
+if nix store add-gc-root myroot; then false; fi
+nix store add-gc-root --no-check myroot
+rm myroot
+
+# Fail when trying to setup a direct root
+storePath=$(build)
+if nix store add-gc-root "$storePath"; then false; fi
+