d038a67bd3
This removes a dynamic stack allocation, making the derivation unparsing logic robust against overflows when large strings are added to a derivation. Overflow behavior depends on the platform and stack configuration. For instance, x86_64-linux/glibc behaves as (somewhat) expected: $ (ulimit -s 20000; nix-instantiate tests/lang/eval-okay-big-derivation-attr.nix) error: stack overflow (possible infinite recursion) $ (ulimit -s 40000; nix-instantiate tests/lang/eval-okay-big-derivation-attr.nix) error: expression does not evaluate to a derivation (or a set or list of those) However, on aarch64-darwin: $ nix-instantiate big-attr.nix ~ zsh: segmentation fault nix-instantiate big-attr.nix This indicates a slight flaw in the single stack protection page approach that is not encountered with normal stack frames.
13 lines
392 B
Nix
13 lines
392 B
Nix
let
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sixteenBytes = "0123456789abcdef";
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times16 = s: builtins.concatStringsSep "" [s s s s s s s s s s s s s s s s];
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exp = n: x: if n == 1 then x else times16 (exp (n - 1) x);
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sixteenMegabyte = exp 6 sixteenBytes;
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in
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assert builtins.stringLength sixteenMegabyte == 16777216;
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derivation {
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name = "big-derivation-attr";
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builder = "/x";
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system = "y";
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bigAttr = sixteenMegabyte;
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}
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