From 3f192ac80ca421888c668896b63485486e1397ae Mon Sep 17 00:00:00 2001 From: Daniel Schaefer Date: Fri, 3 May 2019 14:30:29 +0200 Subject: Add builtins.hashFile For text files it is possible to do it like so: `builtins.hashString "sha256" (builtins.readFile /tmp/a)` but that doesn't work for binary files. With builtins.hashFile any kind of file can be conveniently hashed. --- src/libexpr/primops.cc | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'src/libexpr/primops.cc') diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc index 39073725e9c4..06f577f36fce 100644 --- a/src/libexpr/primops.cc +++ b/src/libexpr/primops.cc @@ -923,6 +923,20 @@ static void prim_findFile(EvalState & state, const Pos & pos, Value * * args, Va mkPath(v, state.checkSourcePath(state.findFile(searchPath, path, pos)).c_str()); } +/* Return the cryptographic hash of a file in base-16. */ +static void prim_hashFile(EvalState & state, const Pos & pos, Value * * args, Value & v) +{ + string type = state.forceStringNoCtx(*args[0], pos); + HashType ht = parseHashType(type); + if (ht == htUnknown) + throw Error(format("unknown hash type '%1%', at %2%") % type % pos); + + PathSet context; // discarded + Path p = state.coerceToPath(pos, *args[1], context); + + mkString(v, hashFile(ht, state.checkSourcePath(p)).to_string(Base16, false), context); +} + /* Read a directory (without . or ..) */ static void prim_readDir(EvalState & state, const Pos & pos, Value * * args, Value & v) { @@ -2202,6 +2216,7 @@ void EvalState::createBaseEnv() addPrimOp("__readFile", 1, prim_readFile); addPrimOp("__readDir", 1, prim_readDir); addPrimOp("__findFile", 2, prim_findFile); + addPrimOp("__hashFile", 2, prim_hashFile); // Creating files addPrimOp("__toXML", 1, prim_toXML); -- cgit 1.4.1