string.sha1 prints hex digits in a non-standard way

[Laupetin]

What seems to be the problem? The hex string produced by the string.sha1 function prints the result in a non-standard way. To be exact, for each byte it swaps the higher and lower 4 bits compared to what other implementations do.

So for example if one byte of the hash was 0xAF, the string would contain FA instead.

What did you expect to happen?

I expected the resulting string to match the output of other tools, e.g. sha1sum.

How can we reproduce this?

premake5.lua

require("premake", ">=5.0.0-beta7")
print(string.sha1(io.readfile("./test.txt")))

test.txt

foobar

What have you tried so far?

The problem seems to be here i guess: https://github.com/premake/premake-core/blob/ef053905fdc68c763ebea79025a7e0fa8172c368/src/host/string_sha1.c#L175-L176

The code first adds the lower 4 bits to the string, then the upper 4 bits. Standard way to print a hex string would however first print the upper 4 bits, then the lower 4 bits.

I would have made a PR, however this has been implemented this way for 10 years now, so I wasn't sure if this is even something that should be fixed or if it was left like this intentionally? If it is something to fix, I can make one though.

• [ ] Visual Studio 2022 (vs2022)
• [ ] Visual Studio 2019 (vs2019)
• [ ] Visual Studio 2017 (vs2017)
• [ ] Visual Studio 2015 (vs2015)
• [ ] Visual Studio 2012 (vs2012)
• [ ] Visual Studio 2010 (vs2010)
• [ ] Visual Studio 2008 (vs2008)
• [ ] Visual Studio 2005 (vs2005)
• [ ] GNU Makefile (gmake)
• [ ] GNU Makefile Legacy (gmakelegacy)
• [ ] XCode (xcode)
• [ ] Codelite
• [x] Other (Please list below)

not related to any specific action

What version of Premake are you using? premake5 (Premake Build Script Generator) 5.0.0-beta7

Anything else we should know?

[Jarod42]

Fixing it might break people using our method and comparing with previous computed one :-/