de727bccf9
Implement the fetchurl builtin, and lay the groundwork for implementing
the fetchTarball builtin (which works very similarly, and is implemented
using almost the same code in C++ nix).
An overview of how this works:
1. First, we check if the store path that *would* result from the
download already exists in the store - if it does, we just return
that
2. If we need to download the URL, TvixStoreIO has an `http_client:
reqwest::Client` field now which we use to make the request
3. As we're downloading the blob, we hash the data incrementally into a
SHA256 hasher
4. We compare the hash against the expected hash (if any) and bail out
if it doesn't match
5. Finally, we put the blob in the store and return the store path
Since the logic is very similar, this commit also implements a *chunk*
of `fetchTarball` (though the actual implementation will likely include
a refactor to some of the code reuse here).
The main thing that's missing here is caching of downloaded blobs when
fetchurl is called without a hash - I've opened b/381 to track the TODO
there.
Adding the `SSL_CERT_FILE` here is necessary to teach reqwest how to
load it during tests - see
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benches | ||
src | ||
Cargo.toml | ||
default.nix |