From 693e68e09c9a17ca72b074bd2e575bf435647b45 Mon Sep 17 00:00:00 2001 From: Matthew Bauer Date: Wed, 28 Aug 2019 12:26:08 -0400 Subject: [PATCH] Set maximum name length in Nix MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Previously we allowed any length of name for Nix derivations. This is bad because different file systems have different max lengths. To make things predictable, I have picked a max. This was done by trying to build this derivation: derivation { name = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"; builder = "/no-such-path"; system = "x86_64-linux"; } Take off one a and it will not lead to file name too long. That ends up being 212 a’s. An even smaller max could be picked if we want to support more file systems. Working backwards, this is why: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-${name}.drv.chroot > 255 - 32 - 1 - 4 - 7 = 211 --- src/libstore/store-api.cc | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc index f5608d38..3bb9db0b 100644 --- a/src/libstore/store-api.cc +++ b/src/libstore/store-api.cc @@ -97,6 +97,10 @@ void checkStoreName(const string & name) reasons (e.g., "." and ".."). */ if (string(name, 0, 1) == ".") 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') ||