pwd.getpwuid fails with 0.0 as input about luaposix HOT 3 CLOSED

Thanks for the feedback.

Lua 5.1 stored all numbers (integers or floats) as 53 bit IEEE 754 doubles. More recent Lua releases including 5.4, but I forget when exactly, added real low level integer types. luaposix tries to work correctly with Lua 5.1 and newer, including luajit, within the constraints of the various apis exposed by each, but misses some corner cases in doing that.

Your suggestion uses a call that is not supported by Lua 5.1 and would prevent luaposix compiling there.

I thing passing a floating point number to getpwuid is not really sensible (even though older Lua interpreters will store it as a float internally) because UNIX uids are always integers -- there is no uid 1001.25! Better to change your code to pwd.getpwuid(0) IMHO.

Nonetheless, if you find a way to reliably force integer equivalent floats to real integers that works on luajit and Lua 5.1+ that is not too torturous, please do submit a PR.

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Thank you for your thorough answer.

Your suggestion uses a call that is not supported by Lua 5.1 and would prevent luaposix compiling there.

Are your referring to lua_tointegerx? I compiled luaposix with the suggestion for 5.1 and it works with Lua 5.1 and LuaJIT. What I did see is that LuaJIT, 5.1 and 5.2 would accept 1000.25, the others didn't. But that seems to be the same behaviour as now, if I tested this correctly.

The code in

I thing passing a floating point number to getpwuid is not really sensible (even though older Lua interpreters will store it as a float internally) because UNIX uids are always integers -- there is no uid 1001.25! Better to change your code to pwd.getpwuid(0) IMHO.

I do agree. It shouldn't be problem to use math.tointeger(). It was just really unfortunate that the behaviour changed and only for that one case.

Nonetheless, if you find a way to reliably force integer equivalent floats to real integers that works on luajit and Lua 5.1+ that is not too torturous,

Could you perhaps test my suggestion and see if it works for you as well? Hopefully, I didn't make a mistake compiling for 5.1

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I totally spaced on the compat code, and you are quite right! Let me see if I can merge this later today. Thanks for persevering with me 😁

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