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Fix segfault on infinite recursion in some cases

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This fixes a segfault on infinite function call recursion (rather than
infinite thunk recursion) by tracking the function call depth in
`EvalState`.

Additionally, to avoid printing extremely long stack traces, stack
frames are now deduplicated, with a `(19997 duplicate traces omitted)`
message. This should only really be triggered in infinite recursion
scenarios.

Before:

    $ nix-instantiate --eval --expr '(x: x x) (x: x x)'
    Segmentation fault: 11

After:

    $ nix-instantiate --eval --expr '(x: x x) (x: x x)'
    error: stack overflow

           at «string»:1:14:
                1| (x: x x) (x: x x)
                 |              ^

    $ nix-instantiate --eval --expr '(x: x x) (x: x x)' --show-trace
    error:
           … from call site
             at «string»:1:1:
                1| (x: x x) (x: x x)
                 | ^

           … while calling anonymous lambda
             at «string»:1:2:
                1| (x: x x) (x: x x)
                 |  ^

           … from call site
             at «string»:1:5:
                1| (x: x x) (x: x x)
                 |     ^

           … while calling anonymous lambda
             at «string»:1:11:
                1| (x: x x) (x: x x)
                 |           ^

           … from call site
             at «string»:1:14:
                1| (x: x x) (x: x x)
                 |              ^

           (19997 duplicate traces omitted)

           error: stack overflow
           at «string»:1:14:
                1| (x: x x) (x: x x)
                 |              ^
This commit is contained in:
Rebecca Turner 2023-12-15 11:52:21 -08:00
parent a21c762dab
commit 7434caca05
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12 changed files with 358 additions and 4 deletions
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3
src/libexpr/eval-settings.hh
View file

@ -124,6 +124,9 @@ struct EvalSettings : Config
Setting<bool> traceVerbose{this, false, "trace-verbose",
"Whether `builtins.traceVerbose` should trace its first argument when evaluated."};
Setting<unsigned int> maxCallDepth{this, 10000, "max-call-depth",
"The maximum function call depth to allow before erroring."};
};
extern EvalSettings evalSettings;