Linux MUSL

[swoboderz]

So i have been experimenting with a MUSL libc and heres some problems i have run into.

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dots@gentpad ~ $ factorio
Error relocating /home/dots/Games/factorio/bin/x64/factorio: setcontext: symbol not found
Error relocating /home/dots/Games/factorio/bin/x64/factorio: makecontext: symbol not found
Error relocating /home/dots/Games/factorio/bin/x64/factorio: __res_nquery: symbol not found
Error relocating /home/dots/Games/factorio/bin/x64/factorio: __dn_expand: symbol not found

After installing libucontext from official repository:

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dots@gentpad ~ $ factorio
Error relocating /home/dots/Games/factorio/bin/x64/factorio: __res_nquery: symbol not found
Error relocating /home/dots/Games/factorio/bin/x64/factorio: __dn_expand: symbol not found

I do know the functions just above come from a libresolv but it seems the MUSL libc does not contain it. i tried doing a quick hack of designing the function signatures by creating a gcompat patch (glibc compat layer) myself with various combos of returning -1, 0, or x > 0 but it segfaults.

I can confirm it wasnt the libucontext but instead the patch, which changes the ld-linux (ld-musl) binary from the following:

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(lldb) run
Process 5712 launched: '/home/dots/Games/factorio/bin/x64/factorio' (x86_64)
Process 5712 stopped
* thread #1, name = 'ld-musl-x86_64.', stop reason = exec
    frame #0: 0x00007ffff7fc3027 libc.so`_dlstart
libc.so`_dlstart:
->  0x7ffff7fc3027 <+0>:  xorq   %rbp, %rbp
    0x7ffff7fc302a <+3>:  movq   %rsp, %rdi
    0x7ffff7fc302d <+6>:  leaq   0x37df4(%rip), %rsi
    0x7ffff7fc3034 <+13>: andq   $-0x10, %rsp
(lldb) continue
Process 5712 resuming
Process 5712 stopped
* thread #1, name = 'ld-musl-x86_64.', stop reason = signal SIGSEGV: invalid address (fault address: 0x0)
    frame #0: 0x000000000172b8e5
->  0x172b8e5: andw   (%rax,%r12,2), %dx
    0x172b8ea: jne    0x172b848
    0x172b8f0: andl   $0x1, %r15d
    0x172b8f4: je     0x172b910
(lldb)

I am wondering what it would actually take to get MUSL support. or any ideas on how to get around the unfound symbols (i had previously assumed the Mod menu would be broken before i found it segfaulting with my cheap imitation)
Thanks!

[Rseding91]

But why?

[swoboderz]

But why?

What do you mean?

[Rseding91]

Why try to get a 3rd party library working with the game when you could just *play* the game as is?

[swoboderz]

Why try to get a 3rd party library working with the game when you could just *play* the game as is?

there are differences between the MUSL libc ABI and the GLIBC ABI. MUSL is trying to become a full replacement, however there remains a package "gcompat" for more non-posix standards that glibc happenned to create to add support outside the MUSL libc. if you are unaware, a LibC maps C standard functions to a program. On my current operating system, factorio simply will not run because its not using the GNU Libc. Everything if installed up until the point of factorio was source compiled. so there was no issue.

[mrvn]

You should check your code. You obviously implemented the missing functions wrong.

res_nquery() is used to find the factorio server to check for updates, to download mods and for multiplayer. While you can probably play offline (which would allow a return -1 for the function) that would limit the game. Returning 0 seems kind of odd and returning x > 0 will definetly not work if you don't actually fill in the answer buffer.

You should write a dummy libresolv linked against musl.

[ptx0]

Why try to get a 3rd party library working with the game when you could just *play* the game as is?

well, Alpine Linux is based on musl instead of libc.

[swoboderz]

You should check your code. You obviously implemented the missing functions wrong.

res_nquery() is used to find the factorio server to check for updates, to download mods and for multiplayer. While you can probably play offline (which would allow a return -1 for the function) that would limit the game. Returning 0 seems kind of odd and returning x > 0 will definetly not work if you don't actually fill in the answer buffer.

You should write a dummy libresolv linked against musl.

I actually tried returning -1 and it proceeded to segfault anyway

[mrvn]

You should check your code. You obviously implemented the missing functions wrong.

res_nquery() is used to find the factorio server to check for updates, to download mods and for multiplayer. While you can probably play offline (which would allow a return -1 for the function) that would limit the game. Returning 0 seems kind of odd and returning x > 0 will definetly not work if you don't actually fill in the answer buffer.

You should write a dummy libresolv linked against musl.

I actually tried returning -1 and it proceeded to segfault anyway

Did you set h_errno? Returning an error of SUCCESS (or whatever value is in h_errno currently) might be confusing the code.

[vinzenz]

I actually tried returning -1 and it proceeded to segfault anyway

you can try stubbing res_ninit to return -1, so Factorio doesn't even try to engage with libresolv