From c13193017fdcb910627698e343c2df4183d91f8f Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 26 Nov 2019 20:12:15 +0100
Subject: [PATCH] Disallow empty store path names

Fixes #3239.
---
 src/libstore/local-store.cc | 2 ++
 src/libstore/store-api.cc   | 9 +++++++--
 tests/referrers.sh          | 4 ++--
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index e9dd3f96e..7d127840a 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -585,6 +585,8 @@ void LocalStore::checkDerivationOutputs(const Path & drvPath, const Derivation &
 uint64_t LocalStore::addValidPath(State & state,
     const ValidPathInfo & info, bool checkOutputs)
 {
+    checkStoreName(storePathToName(info.path));
+
     if (info.ca != "" && !info.isContentAddressed(*this))
         throw Error("cannot add path '%s' to the Nix store because it claims to be content-addressed but isn't", info.path);
 
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 54430d3ba..0758907e7 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -90,17 +90,22 @@ void checkStoreName(const string & name)
         "Path names are alphanumeric and can include the symbols %1% "
         "and must not begin with a period. "
         "Note: If '%2%' is a source file and you cannot rename it on "
-        "disk, builtins.path { name = ... } can be used to give it an "
+        "disk, 'builtins.path { name = ... }' can be used to give it an "
         "alternative name.") % validChars % name;
 
+    if (name.empty())
+        throw Error(baseError % "it is an empty string");
+
     /* Disallow names starting with a dot for possible security
        reasons (e.g., "." and ".."). */
-    if (string(name, 0, 1) == ".")
+    if (name[0] == '.')
         throw Error(baseError % "it is illegal to start the name with a period");
+
     /* Disallow names longer than 211 characters. ext4’s max is 256,
        but we need extra space for the hash and .chroot extensions. */
     if (name.length() > 211)
         throw Error(baseError % "name must be less than 212 characters");
+
     for (auto & i : name)
         if (!((i >= 'A' && i <= 'Z') ||
               (i >= 'a' && i <= 'z') ||
diff --git a/tests/referrers.sh b/tests/referrers.sh
index 8ab8e5ddf..614dd8f5b 100644
--- a/tests/referrers.sh
+++ b/tests/referrers.sh
@@ -4,9 +4,9 @@ clearStore
 
 max=500
 
-reference=$NIX_STORE_DIR/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+reference=$NIX_STORE_DIR/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-bla
 touch $reference
-(echo $reference && echo && echo 0) | nix-store --register-validity 
+(echo $reference && echo && echo 0) | nix-store --register-validity
 
 echo "making registration..."