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haskell-nix / hnix-store

Haskell implementation of the Nix store
Apache License 2.0
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Nar parser fails with "not enough input" when parsing from a file handle #225

Closed sandydoo closed 10 months ago

sandydoo commented 10 months ago

I've tracked it down to this hGetSome, which consistently returns fewer bytes than requested at the same exact position in the my sample NAR.

To my eye, this doesn't look quite right. Instead of throwing an error, we should be looping to fetch the remaining bytes. Or we replace the hGetSome with hGet and block.

https://github.com/haskell-nix/hnix-store/blob/f0dfc6d67015c271a9423ef9687aa57d4f097283/hnix-store-core/src/System/Nix/Internal/Nar/Parser.hs#L415-L429

Sample error with debugging info

parseSymlink: "/nix/store/m6dn1fp69fqgp0dc8pjapi5n8gf59b02-coreutils-full-9.3/bin/chmod"
Consuming 1 bytes
Expecting raw string
expectStr: ")"
Consuming 1 bytes
Expecting raw string
expectStr: ")"
Consuming 5 bytes
Expecting raw string
Consuming 1 bytes
Expecting raw string
expectStr: "("
Consuming 4 bytes
Expecting raw string
expectStr: "name"
Consuming 5 bytes
Expecting raw string
parseEntry: "choom"
Consuming 4 bytes
Expecting raw string
expectStr: "node"
Consuming 1 bytes
Expecting raw string
expectStr: "("
Consuming 4 bytes
Expecting raw string
expectStr: "type"
Consuming 7 bytes
Expecting raw string
Consuming 6 bytes
Expecting raw string
expectStr: "target"
Consuming 75 bytes
"/nix/store/yq3k4g6sw1q35ydv11csn"
Left "Exception while unpacking NAR file: user error (consume: Not enough bytes in handle. Wanted 75 got 32)"