[libc-commits] [PATCH] D140178: [libc] add fuzz target for strtointeger functions

[Michael Jones via Phabricator via libc-commits]

michaelrj added inline comments.


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Comment at: libc/fuzzing/stdlib/strtointeger_differential_fuzz.cpp:48
+    container[i] = data[i];
+    cleaner[i] = valid_chars[data[i] % sizeof(valid_chars)];
+  }
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sivachandra wrote:
> Why should we make the input clean? It defeats the purpose of fuzzing in a way. Since this is a differential fuzz setup, I am not really worried about garbage. Also, valid ASCII characters make half of the `uint8_t` range anyway. So, we don't have to worry about most of the `data` inputs being just invalid numbers. Also, the above list of valid chars does not have the `+` and `-` signs.
The reason I want to clean the input is because otherwise almost all of the inputs won't actually exercise the function at all. If the first character is a question mark (for example), then the function won't actually parse anything and it will return 0. Testing that isn't bad, but given that more than half of the ascii range falls into that category there will be a lot of cycles spent on those obvious cases instead of actually testing the branches.


Repository:
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  https://reviews.llvm.org/D140178/new/

https://reviews.llvm.org/D140178