f3dc231250
* Formalise the notion of fixed-output derivations, i.e., derivations for which a cryptographic hash of the output is known in advance. Changes to such derivations should not propagate upwards through the dependency graph. Previously this was done by specifying the hash component of the output path through the `id' attribute, but this is insecure since you can lie about it (i.e., you can specify any hash and then produce a completely different output). Now the responsibility for checking the output is moved from the builder to Nix itself. A fixed-output derivation can be created by specifying the `outputHash' and `outputHashAlgo' attributes, the latter taking values `md5', `sha1', and `sha256', and the former specifying the actual hash in hexadecimal or in base-32 (auto-detected by looking at the length of the attribute value). MD5 is included for compatibility but should be considered deprecated. * Removed the `drvPath' pseudo-attribute in derivation results. It's no longer necessary. * Cleaned up the support for multiple output paths in derivation store expressions. Each output now has a unique identifier (e.g., `out', `devel', `docs'). Previously there was no way to tell output paths apart at the store expression level. * `nix-hash' now has a flag `--base32' to specify that the hash should be printed in base-32 notation. * `fetchurl' accepts parameters `sha256' and `sha1' in addition to `md5'. * `nix-prefetch-url' now prints out a SHA-1 hash in base-32. (TODO: a flag to specify the hash.)
23 lines
757 B
Nix
23 lines
757 B
Nix
# Argh, this thing is duplicated (more-or-less) in Nixpkgs. Need to
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# find a way to combine them.
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{system, url, outputHash ? "", outputHashAlgo ? "", md5 ? "", sha1 ? "", sha256 ? ""}:
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assert (outputHash != "" && outputHashAlgo != "")
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|| md5 != "" || sha1 != "" || sha256 != "";
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derivation {
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name = baseNameOf (toString url);
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builder = ./builder.sh;
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# Compatibility with Nix <= 0.7.
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id = md5;
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# New-style output content requirements.
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outputHashAlgo = if outputHashAlgo != "" then outputHashAlgo else
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if sha256 != "" then "sha256" else if sha1 != "" then "sha1" else "md5";
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outputHash = if outputHash != "" then outputHash else
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if sha256 != "" then sha256 else if sha1 != "" then sha1 else md5;
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inherit system url;
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}
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