t1utils/1.40 miscompiles without -D_GNU_SOURCE

[nthykier]

Hi,

I received a bug that my 1.40 upload of t1utils to Debian was broken because "memmem" was implicitly declared. This causes the compiler to assume it returns "int" instead of a pointer, which unsurprisingly leads to very broken results.

I see three things we can do to improve this:

1. The build system/code should ensure the function is declared before use. -D_GNU_SOURCE works for my case, but may not be portable to all target platforms you want to support (at least, I presume that is the case, since you wrote a compat version of memmem()).

2. I think it would be prudent make the implicit declaration a hard error, given how unlikely it is that we ever want that. I think the gcc syntax for that is -Werror=implicit-function-declaration. At least, I intend to enable that in the packaging (but I would probably check it too late to catch it in your releases).

3. Add a regression test suite to see that basic functionally works.

(Original report in Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=869756)

FYI, I got another bug coming - hopefully later today if time permits.

[nthykier]

Indeed, -Werror=implicit-function-declaration is the correct syntax for gcc.

[kohler]

3f1ddda has my preferred fix for this issue

[nthykier]

Sorry for the delay. :)

I have tried the patch and it does seem to fix the miscompile. I have tested that the build succeeds with -Werror=implicit-function-declaration (and fails without your changes). :)

For the Debian package, I will keep the -D_GNU_SOURCE for now as I assume the platform provided version of memmem is optimized better.

Thanks for fixing the issue. :)

[lucaswerkmeister]

Sorry to bother you, but could you perhaps publish a release version with this fix? Arch, Manjaro and Gentoo users are currently unable to build LilyPond because t1asm segfaults when a 64-bit pointer is truncated to 32-bit int due to the missing memmem declaration. (I’m not sure if it affects all Arch/Manjaro/Gentoo users on 64-bit platforms, but you can find several reports in this thread.)

[fedelibre]

For the records, I've filed a bug report to Fedora tracker to include the patch in Fedora.

[fedelibre]

I understand that only one commit, which was not included in 1.41 git tag and source tarball for a mistake, does not justify a new release. What about pointing the tag to that commit and upload a new tarball here?

In the meanwhile I'll propose a patch to include that commit in Fedora package.
But fixing the tarball would be more correct IMO and solve the problem for any distro.

[hanwen]

@kohler - gentle ping?

[dvzrv]

@kohler can you please tag a new version?
Unpatched t1utils breaks the build for lilypond on Arch Linux (https://bugs.archlinux.org/task/57999).

Thanks!

[kohler]

Done