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Add builtins.hashFile

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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.
This commit is contained in:
Daniel Schaefer 2019-05-03 14:30:29 +02:00
parent f9a2ea4486
commit 3f192ac80c
9 changed files with 39 additions and 1 deletions
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15
src/libexpr/primops.cc
View file

@ -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);