libexpr-c: fix nix_get_external #15954
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Can we have a unit test for this? |
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@xokdvium I replicated the test from python-nix and cloned some existing getter value tests |
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cc @roberth |
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…_value_out nix_get_external reads from an already-initialized nix_value (set via nix_init_external). Every other getter in the file (nix_get_bool, nix_get_int, nix_get_float, nix_get_string, nix_get_path_string) uses check_value_in, which asserts the value IS initialized. nix_get_external was the sole getter using check_value_out, which asserts the value is UNinitialized and throws "nix_value already initialized" for any valid external value — making the function always fail.
Regression test for the check_value_out → check_value_in fix: nix_get_external reads from an already-initialized value and must use check_value_in, not check_value_out (which asserts the value is NOT initialized). Added: - nix_get_external_roundtrip: create external → init → force → get back - nix_get_external_invalid: null and uninitialized value error paths - nix_get_external_value_content_null: null ExternalValue* gracefully
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Change explanation
nix_get_external reads from an already-initialized nix_value (set via nix_init_external). Every other getter in the file (nix_get_bool, nix_get_int, nix_get_float, nix_get_string, nix_get_path_string) uses check_value_in, which asserts the value IS initialized. nix_get_external was the sole getter using check_value_out, which asserts the value is UNinitialized and throws "nix_value already initialized" for any valid external value — making the function always fail.
Also made the value parameter const to match all other getters.
Motivation
I'm working on updating the cffi Python bindings from tweag so we can have the Nix we deserve in Python 😄
https://github.com/NixOS/nix/milestone/52
Context
I found this when creating unit tests at https://github.com/lillecarl/python-nix to cover the entire API surface and the external value tests just wouldn't pass.
@yorickvP