NixOS/nix

fetchTree: use last-modified HTTP header where possible

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#9,067 opened on 2023年9月29日

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featurefetchinggood first issue

説明

Is your feature request related to a problem? Please describe.

Currently fetchTree with type=tarball+http(s) gets lastModified from the mtime of the tarball contents. Some formats such as zip do not include this metadata, so lastModified ends up being incorrectly set to the current time.

type=file+http(s) does not set lastModified at all.

Describe the solution you'd like

Most webservers, when serving static files, will send a last-modified header set to the mtime of the served file. We could set lastModified to this value, or use it as fallback when mtime of contents is absent.

Describe alternatives you've considered

Do not set lastModified when mtime metadata is not present in archives. This should probably be done anyway when neither mtime nor last-modified is present.

Additional context

Priorities

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コントリビューターガイド

技術スタック
cpp
領域
backendcli
Issue 種別
feature
難度新しい貢献者にとっての実装難度です。1 は非常に小さな変更、5 は専門的な作業です。
3
推定時間経験ある貢献者が調査、実装、テスト、pull request 準備にかけるおおよその時間範囲です。
1-3 hours
活動状況Issue が今どれだけ取り組みやすいかを示します。新しい、活発、古い、ブロック中、またはメンテナー入力待ちなどです。
fresh
明確さ期待される変更、受け入れ条件、次の手順がどれだけ明確かを示します。
clear
前提条件
C++HTTP basicsNix source structure
初心者向け度初回貢献者にどれだけ取り組みやすいかを 1-100 で推定したスコアです。
50
調査方針
Investigate the fetchTree implementation in src/libfetchers/ (likely tarball.cc and file.cc). Look for how lastModified is currently set and where HTTP headers are available. Check if the HTTP response already passes headers; if not, modify the fetcher to parse the last modified header and use it as fallback when other mtime is absent. Consider edge cases where the header is missing or invalid.