Rich Felker [Mon, 27 Feb 2012 23:51:02 +0000 (18:51 -0500)]
work around "signal loses thread pointer" issue with "approach 2"
this was discussed on the mailing list and no consensus on the
preferred solution was reached, so in anticipation of a release, i'm
just committing a minimally-invasive solution that avoids the problem
by ensuring that multi-threaded-capable programs will always have
initialized the thread pointer before any signal handler can run.
in the long term we may switch to initializing the thread pointer at
program start time whenever the program has the potential to access
any per-thread data.
Rich Felker [Sat, 25 Feb 2012 04:23:47 +0000 (23:23 -0500)]
replace prototype for basename in string.h with non-prototype declaration
GNU programs may expect the GNU version of basename, which has a
different prototype (argument is const-qualified) and prototype it
themselves too. of course if they're expecting the GNU behavior for
the function, they'll still run into problems, but at least this
eliminates some compile-time failures.
Rich Felker [Fri, 24 Feb 2012 02:24:56 +0000 (21:24 -0500)]
cleanup and work around visibility bug in gcc 3 that affects x86_64
in gcc 3, the visibility attribute must be placed on both the
declaration and on the definition. if it's omitted from the
definition, the compiler fails to emit the ".hidden" directive in the
assembly, and the linker will either generate textrels (if supported,
such as on i386) or refuse to link (on targets where certain types of
textrels are forbidden or impossible without further assumptions about
memory layout, such as on x86_64).
this patch also unifies the decision about when to use visibility into
libc.h and makes the visibility in the utf-8 state machine tables
based on libc.h rather than a duplicate test.
Rich Felker [Fri, 10 Feb 2012 02:24:56 +0000 (21:24 -0500)]
small fix for new pthread cleanup stuff
even if pthread_create/exit code is not linked, run flag needs to be
checked and cleanup function potentially run on pop. thus, move the
code to the module that's always linked when pthread_cleanup_push/pop
is used.
Rich Felker [Thu, 9 Feb 2012 07:33:08 +0000 (02:33 -0500)]
replace bad cancellation cleanup abi with a sane one
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.
Rich Felker [Wed, 8 Feb 2012 01:31:27 +0000 (20:31 -0500)]
protect against cancellation in dlopen
i'm not sure that it's "correct" for dlopen to block cancellation
when calling constructors for libraries it loads, but it sure seems
like the right thing. in any case, dlopen itself needs cancellation
blocked.
Rich Felker [Tue, 7 Feb 2012 18:10:30 +0000 (13:10 -0500)]
declare basename in string.h when _GNU_SOURCE is defined
note that it still will have the standards-conformant behavior, not
the GNU behavior. but at least this prevents broken code from ending
up with truncated pointers due to implicit declarations...
Rich Felker [Tue, 7 Feb 2012 17:08:27 +0000 (12:08 -0500)]
revert hacks for types of stdint.h integer constant macros
per 7.18.4: Each invocation of one of these macros shall expand to an
integer constant expression suitable for use in #if preprocessing
directives. The type of the expression shall have the same type as
would an expression of the corresponding type converted according to
the integer promotions. The value of the expression shall be that of
the argument.
the key phrase is "converted according to the integer promotions".
thus there is no intent or allowance that the expression have
smaller-than-int types.
Rich Felker [Mon, 6 Feb 2012 19:39:09 +0000 (14:39 -0500)]
add support for init/finit (constructors and destructors)
this is mainly in hopes of supporting c++ (not yet possible for other
reasons) but will also help applications/libraries which use (and more
often, abuse) the gcc __attribute__((__constructor__)) feature in "C"
code.
x86_64 and arm versions of the new startup asm are untested and may
have minor problems.
Rich Felker [Fri, 3 Feb 2012 08:16:07 +0000 (03:16 -0500)]
include dummied-out dlopen and dlsym functions for static binaries
these don't work (or do anything at all) but at least make it possible
to static link programs that insist on "having" dynamic loading
support...as long as they don't actually need to use it.
adding real support for dlopen/dlsym with static linking is going to
be significantly more difficult...
Rich Felker [Thu, 2 Feb 2012 05:11:29 +0000 (00:11 -0500)]
make stdio open, read, and write operations cancellation points
it should be noted that only the actual underlying buffer flush and
fill operations are cancellable, not reads from or writes to the
buffer. this behavior is compatible with POSIX, which makes all
cancellation points in stdio optional, and it achieves the goal of
allowing cancellation of a thread that's "stuck" on IO (due to a
non-responsive socket/pipe peer, slow/stuck hardware, etc.) without
imposing any measurable performance cost.
Rich Felker [Tue, 24 Jan 2012 05:22:27 +0000 (00:22 -0500)]
make gcc wrapper support -shared correctly
it was previously attempting to link start files as part of shared
objects. this is definitely wrong and depending on the platform and
linker could range from just adding extraneous junk to introducing
textrels to making linking fail entirely.
Rich Felker [Sun, 22 Jan 2012 22:19:37 +0000 (17:19 -0500)]
fix cancellation failure in single-threaded programs
even a single-threaded program can be cancellable, e.g. if it's called
pthread_cancel(pthread_self()). the correct predicate to check is not
whether multiple threads have been invoked, but whether pthread_self
has been invoked.
Rich Felker [Fri, 20 Jan 2012 16:14:27 +0000 (11:14 -0500)]
fix dynamic linker not to depend on DYNAMIC ptr in 0th entry of GOT
this fixes an issue using gold instead of gnu ld for linking. it also
should eliminate the need of the startup code to even load/pass the
got address to the dynamic linker.
based on patch submitted by sh4rm4 with minor cosmetic changes.
Rich Felker [Thu, 19 Jan 2012 04:28:48 +0000 (23:28 -0500)]
alias basename to glibc name for it, to meet abi goals
note that regardless of the name used, basename is always conformant.
it never takes on the bogus gnu behavior, unlike glibc where basename
is nonconformant when declared manually without including libgen.h.
Rich Felker [Thu, 17 Nov 2011 04:59:28 +0000 (23:59 -0500)]
fix issue with excessive mremap syscalls on realloc
CHUNK_SIZE macro was defined incorrectly and shaving off at least one
significant bit in the size of mmapped chunks, resulting in the test
for oldlen==newlen always failing and incurring a syscall. fortunately
i don't think this issue caused any other observable behavior; the
definition worked correctly for all non-mmapped chunks where its
correctness matters more, since their lengths are always multiples of
the alignment.
Rich Felker [Sat, 15 Oct 2011 04:28:49 +0000 (00:28 -0400)]
don't define wchar_t on c++
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.
Rich Felker [Sat, 15 Oct 2011 03:31:04 +0000 (23:31 -0400)]
add dummy __cxa_finalize
musl's dynamic linker does not support unloading dsos, so there's
nothing for this function to do. adding the symbol in case anything
depends on its presence..
Rich Felker [Mon, 10 Oct 2011 02:51:03 +0000 (22:51 -0400)]
fix F_GETOWN return value handling
the fcntl syscall can return a negative value when the command is
F_GETOWN, and this is not an error code but an actual value. thus we
must special-case it and avoid calling __syscall_ret to set errno.
this fix is better than the glibc fix (using F_GETOWN_EX) which only
works on newer kernels and is more complex.
Rich Felker [Mon, 3 Oct 2011 04:19:05 +0000 (00:19 -0400)]
simplify robust mutex unlock code path
right now it's questionable whether this change is an improvement or
not, but if we later want to support priority inheritance mutexes, it
will be important to have the code paths unified like this to avoid
major code duplication.
Rich Felker [Mon, 3 Oct 2011 04:09:08 +0000 (00:09 -0400)]
use count=0 instead of 1 for recursive mutex with only one lock reference
this simplifies the code paths slightly, but perhaps what's nicer is
that it makes recursive mutexes fully reentrant, i.e. locking and
unlocking from a signal handler works even if the interrupted code was
in the middle of locking or unlocking.
Rich Felker [Sat, 1 Oct 2011 13:11:35 +0000 (09:11 -0400)]
fix failure-to-wake in rwlock unlock
a reader unlocking the lock need only wake one waiter (necessarily a
writer, but a writer unlocking the lock must wake all waiters
(necessarily readers). if it only wakes one, the remainder can remain
blocked indefinitely, or at least until the first reader unlocks (in
which case the whole lock becomes serialized and behaves as a mutex
rather than a read lock).
there is no need to send a wake when the lock count does not hit zero,
but when it does, all waiters must be woken (since all with the same
sign are eligible to obtain the lock).