the preprocessor can reliably determine the signedness of wchar_t.
L'\0' is used for 0 in the expressions so that, if the underlying type
of wchar_t is long rather than int, the promoted type of the
expression will match the type of wchar_t.
this type was removed back in 5243e5f160 ,
because it was removed from the XSI specs.
however some apps use it.
since it's in the POSIX reserved namespace, we can expose it
unconditionally.
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.
arm eabi requires this symbol for static C++ dtors.
usually it is provided by libstdc++, but when a C++ program
doesn't use the std lib (free-standing), the libc has to provide
it.
this was encountered while building transmission, which
depends on such a C++ library (libutp).
this function is nearly identical to __cxa_atexit, but it has the
order of argumens swapped for "performance reasons".
see page 25 of
http://infocenter.arm.com/help/topic/com.arm.doc.ihi0043d/IHI0043D_rtabi.pdf
there are other aeabi specific C++ support functions missing, but
it is not clear yet that GCC makes use of them so we omit them for
the moment.
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.
with these changes, the members/types of mcontext_t and related stuff
should closely match the glibc definitions. unlike glibc, however, the
definitions here avoid using typedefs as much as possible and work
directly with the underlying types, to minimize namespace pollution
from signal.h in the default (_BSD_SOURCE) profile.
this is a first step in improving compatibility with applications
which poke at context/register information -- mainly debuggers, trace
utilities, etc. additional definitions in ucontext.h and other headers
may be needed later.
if feature test macros are used to request a conforming namespace,
mcontext_t is replaced with an opaque structure of the equivalent size
and alignment; conforming programs cannot examine its contents anyway.
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.
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.
put some macros that do not differ between architectures in the
main header and remove from bits.
restructure mips header so it has the same structure as the others.
despite documentation that makes it sound a lot different, the only
ABI-constraint difference between TLS variants II and I seems to be
that variant II stores the initial TLS segment immediately below the
thread pointer (i.e. the thread pointer points to the end of it) and
variant I stores the initial TLS segment above the thread pointer,
requiring the thread descriptor to be stored below. the actual value
stored in the thread pointer register also tends to have per-arch
random offsets applied to it for silly micro-optimization purposes.
with these changes applied, TLS should be basically working on all
supported archs except microblaze. I'm still working on getting the
necessary information and a working toolchain that can build TLS
binaries for microblaze, but in theory, static-linked programs with
TLS and dynamic-linked programs where only the main executable uses
TLS should already work on microblaze.
alignment constraints have not yet been heavily tested, so it's
possible that this code does not always align TLS segments correctly
on archs that need TLS variant I.
currently, only i386 is tested. x86_64 and arm should probably work.
the necessary relocation types for mips and microblaze have not been
added because I don't understand how they're supposed to work, and I'm
not even sure if it's defined yet on microblaze. I may be able to
reverse engineer the requirements out of gcc/binutils output.
I'm not 100% sure that Linux's O_PATH meets the POSIX requirements for
O_SEARCH, but it seems very close if not perfect. and old kernels
ignore it, so O_SEARCH will still work as desired as long as the
caller has read permissions to the directory.
now public syscall.h only exposes __NR_* and SYS_* constants and the
variadic syscall function. no macros or inline functions, no
__syscall_ret or other internal details, no 16-/32-bit legacy syscall
renaming, etc. this logic has all been moved to src/internal/syscall.h
with the arch-specific parts in arch/$(ARCH)/syscall_arch.h, and the
amount of arch-specific stuff has been reduced to a minimum.
changes still need to be reviewed/double-checked. minimal testing on
i386 and mips has already been performed.
while musl itself requires a c99 compiler, some applications insist on
being compiled with c89 compilers, and use of "inline" in the headers
was breaking them. much of this had been avoided already by just
skipping the inline keyword in pre-c99 compilers or modes, but this
new unified solution is cleaner and may/should result in better code
generation in the default gcc configuration.
this is needed to match the underlying "ABI" standards. it's not
really an ABI issue since the binary representations are the same, but
having the wrong type can lead to errors when the type arising from a
difference-of-pointers expression does not match the defined type of
ptrdiff_t. most of the problems affect C++, not C.
the kernel wrongly expects the cmsg length field to be size_t instead
of socklen_t. in order to work around the issue, we have to impose a
length limit and copy to a local buffer. the length limit should be
more than sufficient for any real-world use; these headers are only
used for passing file descriptors and permissions between processes
over unix sockets.
on arm, the location of the saved-signal-mask flag and mask were off
by one between sigsetjmp and siglongjmp, causing incorrect behavior
restoring the signal mask. this is because the siglongjmp code assumed
an extra slot was in the non-sig jmp_buf for the flag, but arm did not
have this. now, the extra slot is removed for all archs since it was
useless.
also, arm eabi requires jmp_buf to have 8-byte alignment. we achieve
that using long long as the type rather than with non-portable gcc
attribute tags.
on old kernels, there's no way to detect errors; we must assume
negative syscall return values are pgrp ids. but if the F_GETOWN_EX
fcntl works, we can get a reliable answer.
this is actually rather ugly, and would get even uglier if we ever
want to support further feature test macros. at some point i may
factor the bits headers into separate files for C base, POSIX base,
and nonstandard extensions (the only distinctions that seem to matter
now) and then the logic for which to include can go in the main header
rather than being duplicated for each arch. the downside of this is
that it would result in more files having to be opened during
compilation, so as long as the ugliness does not grow, i'm inclined to
leave it alone for now.
fcntl values 1024 and up are universal, arch-independent. later I'll
add some of the other linux-specific ones for notify, leases, pipe
size, etc. here too.
DECIMAL_DIG is not the same as LDBL_DIG
type_DIG is the maximimum number of decimal digits that can survive a
round trip from decimal to type and back to decimal.
DECIMAL_DIG is the minimum number of decimal digits required in order
for any floating point type to survive the round trip to decimal and
back, and it is generally larger than LDBL_DIG. since the exact
formula is non-trivial, and defining it larger than necessary may be
legal but wasteful, just define the right value in bits/float.h.
the old abi was intended to duplicate glibc's abi at the expense of
being ugly and slow, but it turns out glib was not even using that abi
except on non-gcc-compatible compilers (which it doesn't even support)
and was instead using an exceptions-in-c/unwind-based approach whose
abi we could not duplicate anyway without nasty dwarf2/unwind
integration.
the new abi is copied from a very old glibc abi, which seems to still
be supported/present in current glibc. it avoids all unwinding,
whether by sjlj or exceptions, and merely maintains a linked list of
cleanup functions to be called from the context of pthread_exit. i've
made some care to ensure that longjmp out of a cleanup function should
work, even though it is not required to.
this change breaks abi compatibility with programs which were using
pthread cancellation, which is unfortunate, but that's why i'm making
the change now rather than later. considering that most pthread
features have not been usable until recently anyway, i don't see it as
a major issue at this point.
it's a keyword in c++ (wtf). i'm not sure this is the cleanest
solution; it might be better to avoid ever defining __NEED_wchar_t on
c++. but in any case, this works for now.
actually this is just to avoid gcc being stupid and refusing to inline
the function version, even when the size cost is essentially identical
whether it's inlined or not.
the arm syscall abi requires 64-bit arguments to be aligned on an even
register boundary. these new macros facilitate meeting the abi
requirement without imposing significant ugliness on the code.
really wchar_t should never vary, but the ARM EABI defines it as an
unsigned 32-bit int instead of a signed one, and gcc follows this
nonsense. thus, to give a conformant environment, we have to follow
(otherwise L""[0] and L'\0' would be 0U rather than 0, but the
application would be unaware due to a mismatched definition for
WCHAR_MIN and WCHAR_MAX, and Bad Things could happen with respect to
signed/unsigned comparisons, promotions, etc.).
fortunately no rules are imposed by the C standard on the relationship
between wchar_t and wint_t, and WEOF has type wint_t, so we can still
make wint_t always-signed and use -1 for WEOF.
this port assumes eabi calling conventions, eabi linux syscall
convention, and presence of the kernel helpers at 0xffff0f?0 needed
for threads support. otherwise it makes very few assumptions, and the
code should work even on armv4 without thumb support, as well as on
systems with thumb interworking. the bits headers declare this a
little endian system, but as far as i can tell the code should work
equally well on big endian.
some small details are probably broken; so far, testing has been
limited to qemu/aboriginal linux.
