the issue at hand is that many syscalls require as an argument the
kernel-ABI size of sigset_t, intended to allow the kernel to switch to
a larger sigset_t in the future. previously, each arch was defining
this size in syscall_arch.h, which was redundant with the definition
of _NSIG in bits/signal.h. as it's used in some not-quite-portable
application code as well, _NSIG is much more likely to be recognized
and understood immediately by someone reading the code, and it's also
shorter and less cluttered.
note that _NSIG is actually 65/129, not 64/128, but the division takes
care of throwing away the off-by-one part.
wctype_t was incorrectly "int" rather than "long" on x86_64. not only
is this an ABI incompatibility; it's also a major design flaw if we
ever wanted wctype_t to be implemented as a pointer, which would be
necessary if locales support custom character classes, since int is
too small to store a converted pointer. this commit fixes wctype_t to
be unsigned long on all archs, matching the LSB ABI; this change does
not matter for C code, but for C++ it affects mangling.
the same issue applied to wctrans_t. glibc/LSB defines this type as
const __int32_t *, but since no such definition is visible, I've just
expanded the definition, int, everywhere.
it would be nice if these types (which don't vary by arch) could be in
wctype.h, but the OB XSI requirement in POSIX that wchar.h expose some
types and functions from wctype.h precludes doing so. glibc works
around this with some hideous hacks, but trying to duplicate that
would go against the intent of musl's headers.
these structures are purely for use by trace/debug tools and tools
working with core files. the definition of fpregset_t, which was
previously here, has been removed because it was wrong; fpregset_t
should be the type used in mcontext_t, not the type used in
ptrace/core stuff.
aside from microblaze, these should be roughly correct for all archs
now. some misc junk macros and typedefs are missing, which should
probably be added for max compatibility with trace/debug tools.
it should now really match the kernel. some of the removed padding
corresponded to the difference between user and kernel sigset_t. the
space at the end was redundant with the uc_mcontext member and seems
to have been added as a result of misunderstanding glibc's definition
versus the kernel's.
unlike the previous definition, NSIG/_NSIG is supposed to be one more
than the highest signal number. adding this will allow simplifying
libc-internal code that makes signal-related syscalls, which can be
done as a later step. some apps might use it too; while this usage is
questionable, it's at least not insane.
also handle the non-GNUC case where alignment attribute is not available
by simply omitting it. this will not cause problems except for
inclusion of mcontex_t/ucontext_t in application-defined structures,
since the natural alignment of the uc_mcontext member relative to the
start of ucontext_t is already correct. and shame on whoever designed
this for making it impossible to satisfy the ABI requirements without
GNUC extensions.
apparently some other archs have sys/io.h and should not break just
because they don't have the x86 port io functions. provide a blank
bits/io.h everywhere for now.
incomplete but at least partly working. requires all files to be
compiled in the new "secure" plt model, not the old one that put plt
code in the data segment. TLS is untested but may work. invoking the
dynamic linker explicitly to load a program does not yet handle argv
correctly.
Szabolcs Nagy
Rich Felker
rofl0r