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primops: add builtins.convertHash

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Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
This commit is contained in:
Yueh-Shun Li 2023-01-29 14:03:06 +08:00 • committed by Yueh-Shun Li
parent 6b47635180
commit 5088e6563a
4 changed files with 129 additions and 0 deletions
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95
src/libexpr/primops.cc
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@ -3774,6 +3774,101 @@ static RegisterPrimOp primop_hashString({
.fun = prim_hashString,
});
static void prim_convertHash(EvalState & state, const PosIdx pos, Value * * args, Value & v)
{
state.forceAttrs(*args[0], pos, "while evaluating the first argument passed to builtins.convertHash");
auto &inputAttrs = args[0]->attrs;
Bindings::iterator iteratorHash = getAttr(state, state.symbols.create("hash"), inputAttrs, "while locating the attribute 'hash'");
auto hash = state.forceStringNoCtx(*iteratorHash->value, pos, "while evaluating the attribute 'hash'");
Bindings::iterator iteratorHashAlgo = inputAttrs->find(state.symbols.create("hashAlgo"));
std::optional<HashType> ht = std::nullopt;
if (iteratorHashAlgo != inputAttrs->end()) {
ht = parseHashType(state.forceStringNoCtx(*iteratorHashAlgo->value, pos, "while evaluating the attribute 'hashAlgo'"));
}
Bindings::iterator iteratorToHashFormat = getAttr(state, state.symbols.create("toHashFormat"), args[0]->attrs, "while locating the attribute 'toHashFormat'");
HashFormat hf = parseHashFormat(state.forceStringNoCtx(*iteratorToHashFormat->value, pos, "while evaluating the attribute 'toHashFormat'"));
v.mkString(Hash::parseAny(hash, ht).to_string(hf, hf == HashFormat::SRI));
}
static RegisterPrimOp primop_convertHash({
.name = "__convertHash",
.args = {"args"},
.doc = R"(
Return the specified representation of a hash string, based on the attributes presented in *args*:
- `hash`
The hash to be converted.
The hash format is detected automatically.
- `hashAlgo`
The algorithm used to create the hash. Must be one of
- `"md5"`
- `"sha1"`
- `"sha256"`
- `"sha512"`
The attribute may be omitted when `hash` is an [SRI hash](https://www.w3.org/TR/SRI/#the-integrity-attribute) or when the hash is prefixed with the hash algorithm name followed by a colon.
That `<hashAlgo>:<hashBody>` syntax is supported for backwards compatibility with existing tooling.
- `toHashFormat`
The format of the resulting hash. Must be one of
- `"base16"`
- `"base32"`
- `"base64"`
- `"sri"`
The result hash is the *toHashFormat* representation of the hash *hash*.
> **Example**
>
> Convert a SHA256 hash in Base16 to SRI:
>
> ```nix
> builtins.convertHash {
> hash = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855";
> toHashFormat = "sri";
> hashAlgo = "sha256";
> }
> ```
>
> "sha256-47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU="
> **Example**
>
> Convert a SHA256 hash in SRI to Base16:
>
> ```nix
> builtins.convertHash {
> hash = "sha256-47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=";
> toHashFormat = "base16";
> }
> ```
>
> "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
> **Example**
>
> Convert a hash in the form `<hashAlgo>:<hashBody>` in Base16 to SRI:
>
> ```nix
> builtins.convertHash {
> hash = "sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855";
> toHashFormat = "sri";
> }
> ```
>
> "sha256-47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU="
)",
.fun = prim_convertHash,
});
struct RegexCache
{
// TODO use C++20 transparent comparison when available