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Date: Mon, 4 Mar 2013 17:06:10 -0500
From: Rich Felker <dalias@...ifal.cx>
To: musl@...ts.openwall.com
Subject: Re: Fix for fields in utmp
On Sun, Mar 03, 2013 at 12:29:57AM +0100, Szabolcs Nagy wrote:
> > > > -int_fast16_t 8
> > > > -int_fast32_t 8
> > > > +int_fast16_t 4
> > > > +int_fast32_t 4
> > >
> > > these diffs may cause problems
> >
> > These are actually omitted from the ABI documents if I remember
>
> ok then keep it as is
This still should be checked. It _could_ be changed if it matters..
> > > > -regex_t 64
> > > > +regex_t 56
> >
> > I think this should be fixed to match.
>
> glibc's definition is something like:
>
> typedef struct {
> char *__x1;
> long __x2;
> long __x3;
> long __x4;
> char *__x5;
> char *__x6;
> size_t re_nsub;
> char __x7;
> } regex_t;
>
> musl's definition (only re_nsub and __opaque are used):
>
> typedef struct {
> size_t re_nsub;
> void *__opaque, *__padding[4];
> size_t __nsub2;
> } regex_t;
Fixed, even though it doesn't matter with the other ABI
incompatibility issues.
> > > > -regmatch_t 8
> > > > -regoff_t 4
> > > > +regmatch_t 16
> > > > +regoff_t 8
> >
> > These are a bug in glibc; their types do not conform to the
> > requirements imposed on regex.h and regexec().
>
> so regex abi wont be compatible
Yes, this will need some special dynamic linker glue if we want to be
able to run glibc libs/bins using regex. But it's likely they might
not work anyway without glibc extensions...
> > > > -siginfo_t 128
> > > > +siginfo_t 136
> >
> > This is probably a mistake, maybe in the padding..?
>
> yes, the si_fields union is 8byte aligned
Fixed.
> > > > -struct arpd_request 40
> > > > +struct arpd_request 28
> >
> > No idea.
>
> i think this is not used anymore
Fixed anyway.
> > > > -struct lastlog 292
> > > > +struct lastlog 296
> >
> > Probably needs to be checked.
>
> glibc's definition:
> (using the same hack for time_t as in utmpx)
This can probably be ignored. The files will be incompatible, but it's
intended that they not be used anyway..
> > > > -struct ntptimeval 72
> > > > +struct ntptimeval 32
> >
> > Should we change this? Probably.
>
> musl does not have ntp_gettime so it probably
> should not define this struct
You're probably right, but I'm holding off a bit on removing it in
case others have input..
> > > > -struct rusage 144
> > > > -struct sched_param 4
> > > > +struct rusage 272
> > > > +struct sched_param 48
> >
> > Not sure about rusage. For sched_param, we support the extra fields
> > for the sporadic server option even though we don't support it (and
> > Linux probably never will).
>
> musl's rusage (the difference is the __reserved part):
Should we change it or keep the extra reserved space?
> > > > -struct sockaddr_storage 128
> > > > +struct sockaddr_storage 136
> >
> > Probably wrong.
>
> wrong padding
Fixed.
> > > > -wctrans_t 8
> > > > -wctype_t 8
> > > > +wctrans_t 4
> > > > +wctype_t 4
> > >
> > > it seems wctype_t is unconditionally long in glibc
> >
> > As it should be. This is a bug in musl. Being an opaque type that
> > could (and often should) be implemented as a pointer, wctype_t should
> > always be pointer-sized.
>
> then this should be fixed
I will fix this, but as a separate commit since it actually has
nontrivial effects.
Rich
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