Assertion in boost::json::detail::pow10(int)

[pauldreik]

This was already reported in https://github.com/vinniefalco/json/issues/13#issuecomment-560517119, but here is a minimized version and I think it is good to have it in a separate issue.

I is the string 0.00....... with a lot of zeros following. Here it is, base 64 encoded:

MC4wMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAw
MDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAw
MDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAw
MDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAw
MDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAw
MDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDA=

Running it through the fuzzer gives the following output:

paul@tonfisk:~/code/delaktig/boost.json/fuzzing$ ./fuzzer old_crashes/crash_01.json 
INFO: Seed: 2483239189
INFO: Loaded 1 modules   (1092 inline 8-bit counters): 1092 [0x7d21a0, 0x7d25e4), 
INFO: Loaded 1 PC tables (1092 PCs): 1092 [0x5a1598,0x5a59d8), 
./fuzzer: Running 1 inputs 1 time(s) each.
Running: old_crashes/crash_01.json
fuzzer: ../include/boost/json/detail/impl/number.ipp:96: double boost::json::detail::pow10(int): Assertion `exp >= 0 && exp < 618' failed.

[vinniefalco]

\sigh the treatment of floating point numbers is my shame...

[pauldreik]

Well it is incredibly difficult to get right :-)

[vinniefalco]

It really is difficult, and unexpectedly so because..aren't computers supposed to be GOOD at math???

[vinniefalco]

Promising advances in the field of string to double conversion:
https://github.com/ulfjack/ryu/commits/parsing/ryu/s2d.c

[pauldreik]

This bug has been obsoleted by refactoring during the last six months, closing.