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2021-02-12riscv64: define ELF_NFPREGHEADmasterKhem Raj-0/+1
ELF_NFPREG is used by some userspace applications like gdb
2021-02-10math: fix expm1f overflow thresholdSzabolcs Nagy-2/+1
the threshold was wrong so expm1f overflowed to inf a bit too early and on most targets uint32_t compare is faster than float compare so use that. this also fixes sinhf incorrectly returning nan for some values where the internal expm1f overflowed.
2021-02-10math: fix acoshf for negative inputsSzabolcs Nagy-4/+4
on some negative inputs (e.g. -0x1.1e6ae8p+5) acoshf failed to return nan. ensure that negative inputs result nan without introducing new branches. this was tried before in commit 101e6012856918440b5d7474739c3fc22a8d3b85 math: fix acoshf on negative values but that fix was wrong. there are 3 formulas used: log1p(x-1 + sqrt((x-1)*(x-1)+2*(x-1))) log(2*x - 1/(x+sqrt(x*x-1))) log(x) + 0.693147180559945309417232121458176568 the first fails on large negative inputs (may compute log1p(0) or log1p(inf)), the second one fails on some mid range or large negative inputs (may compute log(large) or log(inf)) and the last one fails on -0 (returns -inf).
2021-01-30fix possible fd leak via missing O_CLOEXEC in pthread_setname_npÉrico Rolim-1/+1
the omission of the flag here seems to have been an oversight when the function was added in 8fb28b0b3e7a5e958fb844722a4b2ef9bc244af1
2021-01-30oldmalloc: preserve errno across freeRich Felker-0/+4
as an outcome of Austin Group issue #385, future versions of the standard will require free not to alter the value of errno. save and restore it individually around the calls to madvise and munmap so that the cost is not imposed on calls to free that do not result in any syscall.
2021-01-30fix build regression in oldmallocRich Felker-1/+1
commit 8d37958d58cf36f53d5fcc7a8aa6d633da6071b2 inadvertently broke oldmalloc by having it implement __libc_malloc rather than __libc_malloc_impl.
2021-01-30preserve errno across freeRich Felker-2/+10
as an outcome of Austin Group issue #385, future versions of the standard will require free not to alter the value of errno. save and restore it individually around the calls to madvise and munmap so that the cost is not imposed on calls to free that do not result in any syscall.
2021-01-30fix inconsistent signature of __libc_start_mainRich Felker-1/+2
commit 7586360badcae6e73f04eb1b8189ce630281c4b2 removed the unused arguments from the definition of __libc_start_main, making it incompatible with the declaration at the point of call, which still passed 6 arguments. calls with mismatched function type have undefined behavior, breaking LTO and any other tooling that checks for function signature mismatch. removing the extra arguments from the point of call (crt1) is not an option for fixing this, since that would be a change in ABI surface between application and libc. adding back the extra arguments requires some care. on archs that pass arguments on the stack or that reserve argument spill space for the callee on the stack, it imposes an ABI requirement on the caller to provide such space. the modern crt1.c entry point provides such space, but originally there was arch-specific asm for the call to __libc_start_main. the last of this asm was removed in commit 6fef8cafbd0f6f185897bc87feb1ff66e2e204e1, and manual review of the code removed and its prior history was performed to check that all archs/variants passed the legacy init/fini/ldso_fini arguments.
2021-01-30fail posix_spawn file_actions operations with negative fdsRich Felker-0/+4
these functions are specified to fail with EBADF on negative fd arguments. apart from close, they are also specified to fail if the value exceeds OPEN_MAX, but as written it is not clear that this imposes any requirement when OPEN_MAX is not defined, and it's undesirable to impose a dynamic limit (via setrlimit) here since the limit at the time of posix_spawn may be different from the limit at the time of setting up the file actions. this may require revisiting later.
2021-01-14release 1.2.2v1.2.2Rich Felker-1/+52
2020-12-14fix VIDIOC_DQEVENT (v4l2) ioctl fallback for pre-5.6 kernelsRich Felker-1/+9
commit 2412638bb39eb799b2600393bbd71cca8ae96bb2 got the size of struct v4l2_event wrong and failed to account for the fact that the old struct might be either 120 bytes with time misaligned mod 8, or 128 bytes with time aligned mod 8, due to the contained union having 64-bit members whose alignment is arch-dependent. rather than adding new logic to handle the differences, use an actual stripped-down version of the structure in question to derive the ioctl number, size, and offsets.
2020-12-14fix v4l2 buffer ioctl fallbacks for pre-5.6 kernelsArnd Bergmann-4/+4
commit 2412638bb39eb799b2600393bbd71cca8ae96bb2 got the size of struct v4l2_buffer wrong and omitted the tv_usec member slot from the offset list, so the ioctl numbers never matched and fallback code path was never taken. this caused the affected ioctls to fail with ENOTTY on kernels not new enough to have the native time64 ioctls.
2020-12-12sh: fix incorrect mcontext_t member namingAriadne Conill-4/+13
while the layouts match, the member member naming expected by software using mcontext_t omits the sc_ prefix.
2020-12-09use libc-internal malloc for newlocale/freelocaleRich Felker-0/+10
this is necessary for MT-fork correctness now that the code runs under locale lock. it would not be hard to avoid, but __get_locale is already using libc-internal malloc anyway. this can be reconsidered during locale overhaul later if needed.
2020-12-09drop use of pthread_once in newlocaleRich Felker-9/+7
in general, pthread_once is not compatible with MT-fork constraints (commit 167390f05564e0a4d3fcb4329377fd7743267560). here it actually no longer matters, because it's now called with a lock held, but since the lock is held it's pointless to use pthread_once.
2020-12-09lift locale lock out of internal __get_localeRich Felker-18/+19
this allows the lock to be shared with setlocale, eliminates repeated per-category lock/unlock in newlocale, and will allow the use of pthread_once in newlocale to be dropped (to be done separately).
2020-12-09fix misleading comment in strstrRich Felker-1/+1
the intent here is just to scan at least l bytes forward for the end of the haystack and at least some decent minimum to avoid doing it over and over if the needle is short, with no need to be precise. the comment erroneously stated this as an estimate for MIN when it's actually an estimate for MAX.
2020-12-08drop use of pthread_once for aio thread stack size initRich Felker-10/+8
pthread_once is not compatible with MT-fork constraints (commit 167390f05564e0a4d3fcb4329377fd7743267560) and is not needed here anyway; we already have a lock suitable for initialization. while changing this, fix a corner case where AT_MINSIGSTKSZ gives a value that's more than MINSIGSTKSZ but by a margin of less than 2048, thereby causing the size to be reduced. it shouldn't matter but the intent was to be the larger of a 2048-byte margin over the legacy fixed minimum stack requirement or a 512-byte margin over the minimum the kernel reports at runtime.
2020-12-07fix omission of non-stub pthread_mutexattr_getprotocolRich Felker-1/+1
this change should have been made when priority inheritance mutex support was added. if priority protection is also added at some point the implementation will need to change and will probably no longer be a simple bit shuffling.
2020-12-06riscv64: fix inconsistent ucontext_t struct tagDrew DeVault-2/+2
ucontext.h depends on the internal struct tag name for namespacing reasons, and the intent was always for it to be consistent across archs anyway.
2020-12-04fix failure to preserve r6 in s390x asm; per ABI it is call-savedRich Felker-0/+8
both __clone and __syscall_cp_asm failed to restore the original value of r6 after using it as a syscall argument register. the extent of breakage is not known, and in some cases may be mitigated by the only callers being internal to libc; if they used r6 but no longer needed its value after the call, they may not have noticed the problem. however at least posix_spawn (which uses __clone) was observed returning to the application with the wrong value in r6, leading to crash. since the call frame ABI already provides a place to spill registers, fixing this is just a matter of using it. in __clone, we also spuriously restore r6 in the child, since the parent branch directly returns to the caller. this takes the value from an uninitialized slot of the child's stack, but is harmless since there is no caller to return to in the child.
2020-12-03s390x: derive float_t from compiler or default to floatMarius Hillenbrand-1/+9
float_t should represent the type that is used to evaluate float expressions internally. On s390x, float_t is currently set to double. In contrast, the isa supports single-precision float operations and compilers by default evaluate float in single precision, which violates the C standard (sections 5.2.4.2.2 and 7.12 in C11/C17, to be precise). With -fexcess-precision=standard, gcc evaluates float in double precision, which aligns with the standard yet at the cost of added conversion instructions. gcc-11 will drop the special case to retrofit double precision behavior for -fexcess-precision=standard so that __FLT_EVAL_METHOD__ will be 0 on s390x in any scenario. To improve standards compliance and compatibility with future compiler direction, this patch changes the definition of float_t to be derived from the compiler's __FLT_EVAL_METHOD__.
2020-11-30implement reallocarrayAriadne Conill-0/+14
reallocarray is an extension introduced by OpenBSD, which introduces calloc overflow checking to realloc. glibc 2.28 introduced support for this function behind _GNU_SOURCE, while glibc 2.29 allows its usage in _DEFAULT_SOURCE.
2020-11-30implement realpath directly instead of using procfs readlinkRich Felker-23/+136
inability to use realpath in chroot/container without procfs access and at early boot prior to mount of /proc has been an ongoing issue, and it turns out realpath was one of the last remaining interfaces that needed procfs for its core functionality. during investigation while reimplementing, it was determined that there were also serious problems with the procfs-based implementation. most seriously it was unsafe on pre-O_PATH kernels, and unlike other places where O_PATH was used, the unsafety was hard or impossible to fix because O_NOFOLLOW can't be used (since the whole purpose was to follow symlinks). the new implementation is a direct one, performing readlink on each path component to resolve it. an explicit stack, as opposed to recursion, is used to represent the remaining components to be processed. the stack starts out holding just the input string, and reading a link pushes the link contents onto the stack. unlike many other implementations, this one does not call getcwd initially for relative pathnames. instead it accumulates initial .. components to be applied to the working directory if the result is still a relative path. this avoids calling getcwd (which may fail) at all when symlink traversal will eventually yield an absolute path. it also doesn't use any form of stat operation; instead it arranges for readlink to tell it when a non-directory is used in a context where a directory is needed. this minimizes the number of syscalls needed, avoids accessing inodes when the directory table suffices, and reduces the amount of code pulled in for static linking.
2020-11-29fix mallocng regression in malloc_usable_size with null argumentDominic Chen-0/+1
commit d1507646975cbf6c3e511ba07b193f27f032d108 added support for null argument in oldmalloc and was overlooked when switching to mallocng.
2020-11-29configure: do not use obsolescent form of test -a|oIssam E. Maghni-3/+3
The -a and -o operators are obsolescent and not in baseline POSIX.
2020-11-29fix segfault in lutimes when tv argument is NULLÉrico Rolim-5/+7
calling lutimes with tv=0 is valid if the application wants to set the timestamps to the current time. this commit makes it so the timespec struct is populated with values from tv only if tv != 0 and calls utimensat with times=0 if tv == 0.
2020-11-29netinet/in.h: add IP_RECVERR_4884 from linux v5.9Szabolcs Nagy-0/+1
see linux commit eba75c587e811d3249c8bd50d22bb2266ccd3c0f icmp: support rfc 4884
2020-11-29sys/fanotify.h: add new FAN_* macros from linux v5.9Szabolcs Nagy-0/+4
Update fanotify.h, see linux commit 929943b38daf817f2e6d303ea04401651fc3bc05 fanotify: add support for FAN_REPORT_NAME linux commit 83b7a59896dd24015a34b7f00027f0ff3747972f fanotify: add basic support for FAN_REPORT_DIR_FID linux commit 08b95c338e0c5a96e47f4ca314ea1e7580ecb5d7 fanotify: remove event FAN_DIR_MODIFY FAN_DIR_MODIFY that was new in v5.7 is now removed from linux uapi, but kept in musl, so we don't break api, linux cannot reuse the value anyway.
2020-11-29bits/syscall.h: add __NR_close_range from linux v5.9Szabolcs Nagy-0/+16
see linux commit 9b4feb630e8e9801603f3cab3a36369e3c1cf88d arch: wire-up close_range() linux commit 278a5fbaed89dacd04e9d052f4594ffd0e0585de open: add close_range()
2020-11-29add missing personality valuesWilliam Woodruff-0/+3
Adds two missing personality(2) personas: UNAME26 and FDPIC_FUNCPTRS. FDPIC_FUNCPTRS was also missing its corresponding PER_LINUX_FDPIC value.
2020-11-29arm fabs and sqrt: support single-precision-only fpu variantsJinliang Li-2/+2
2020-11-29fix typo in INSTALLÉrico Rolim-1/+1
"big-engian" should be "big-endian".
2020-11-23work around linux bug in readlink syscall with zero buffer sizeRich Felker-3/+17
linux fails with EINVAL when a zero buffer size is passed to the syscall. this is non-conforming because POSIX already defines EINVAL with a significantly different meaning: the target is not a symlink. since the request is semantically valid, patch it up by using a dummy buffer of length one, and truncating the return value to zero if it succeeds.
2020-11-22parse v3 or future-unknown zoneinfo file versions as v2+Rich Felker-1/+1
the v1 zoneinfo format with 32-bit time is deprecated. previously, the v2 parsing code was only used if an exact match for '2' was found in the version field of the header. this was already incorrect for v3 files (trivial differences from v2 that arguably didn't merit a new version number anyway) but also failed to be future-proof.
2020-11-22explicitly prefer 64-bit/v2 zoneinfo tablesRich Felker-1/+1
since commit 38143339646a4ccce8afe298c34467767c899f51, the condition sizeof(time_t) > 4 is always true, so there is no functional change being made here. but semantically, the 64-bit tables should always be preferred now, because upstream zic (zoneinfo compiler) has quietly switched to emitting empty 32-bit tables by default, and the resulting backwards-incompatible zoneinfo files will be encountered in the wild.
2020-11-20fix regression in pthread_exitRich Felker-1/+3
commit d26e0774a59bb7245b205bc8e7d8b35cc2037095 moved the detach state transition at exit before the thread list lock was taken. this inadvertently allowed pthread_join to race to take the thread list lock first, and proceed with unmapping of the exiting thread's memory. we could fix this by just revering the offending commit and instead performing __vm_wait unconditionally before taking the thread list lock, but that may be costly. instead, bring back the old DT_EXITING vs DT_EXITED state distinction that was removed in commit 8f11e6127fe93093f81a52b15bb1537edc3fc8af, and don't transition to DT_EXITED (a value of 0, which is what pthread_join waits for) until after the lock has been taken.
2020-11-19rewrite wcsnrtombs to fix buffer overflow and other bugsRich Felker-27/+19
the original wcsnrtombs implementation, which has been largely untouched since 0.5.0, attempted to build input-length-limiting conversion on top of wcsrtombs, which only limits output length. as best I recall, this choice was made out of a mix of disdain over having yet another variant function to implement (added in POSIX 2008; not standard C) and preference not to switch things around and implement the wcsrtombs in terms of the more general new function, probably over namespace issues. the strategy employed was to impose output limits that would ensure the input limit wasn't exceeded, then finish up the tail character-at-a-time. unfortunately, none of that worked correctly. first, the logic in the wcsrtombs loop was wrong in that it could easily get stuck making no forward progress, by imposing an output limit too small to convert even one character. the character-at-a-time loop that followed was even worse. it made no effort to ensure that the converted multibyte character would fit in the remaining output space, only that there was a nonzero amount of output space remaining. it also employed an incorrect interpretation of wcrtomb's interface contract for converting the null character, thereby failing to act on end of input, and remaining space accounting was subject to unsigned wrap-around. together these errors allow unbounded overflow of the destination buffer, controlled by input length limit and input wchar_t string contents. given the extent to which this function was broken, it's plausible that most applications that would have been rendered exploitable were sufficiently broken not to be usable in the first place. however, it's also plausible that common (especially ASCII-only) inputs succeeded in the wcsrtombs loop, which mostly worked, while leaving the wildly erroneous code in the second loop exposed to particular non-ASCII inputs. CVE-2020-28928 has been assigned for this issue.
2020-11-19protect destruction of process-shared mutexes against robust list racesRich Felker-1/+5
after a non-normal-type process-shared mutex is unlocked, it's immediately available to another thread to lock, unlock, and destroy, but the first unlocking thread may still have a pointer to it in its robust_list pending slot. this means, on async process termination, the kernel may attempt to access and modify the memory that used to contain the mutex -- memory that may have been reused for some other purpose after the mutex was destroyed. setting up for this kind of race to occur is difficult to begin with, requiring dynamic use of shared memory maps, and actually hitting the race is very difficult even with a suitable setup. so this is mostly a theoretical fix, but in any case the cost is very low.
2020-11-19pthread_exit: don't __vm_wait under thread list lockRich Felker-9/+15
the __vm_wait operation can delay forward progress arbitrarily long if a thread holding the lock is interrupted by a signal. in a worst case this can deadlock. any critical section holding the thread list lock must respect lock ordering contracts and must not take any lock which is not AS-safe. to fix, move the determination of thread joinable/detached state to take place before the killlock and thread list lock are taken. this requires reverting the atomic state transition if we determine that the exiting thread is the last thread and must call exit, but that's easy to do since it's a single-threaded context with application signals blocked.
2020-11-11lift child restrictions after multi-threaded forkRich Felker-4/+170
as the outcome of Austin Group tracker issue #62, future editions of POSIX have dropped the requirement that fork be AS-safe. this allows but does not require implementations to synchronize fork with internal locks and give forked children of multithreaded parents a partly or fully unrestricted execution environment where they can continue to use the standard library (per POSIX, they can only portably use AS-safe functions). up until recently, taking this allowance did not seem desirable. however, commit 8ed2bd8bfcb4ea6448afb55a941f4b5b2b0398c0 exposed the extent to which applications and libraries are depending on the ability to use malloc and other non-AS-safe interfaces in MT-forked children, by converting latent very-low-probability catastrophic state corruption into predictable deadlock. dealing with the fallout has been a huge burden for users/distros. while it looks like most of the non-portable usage in applications could be fixed given sufficient effort, at least some of it seems to occur in language runtimes which are exposing the ability to run unrestricted code in the child as part of the contract with the programmer. any attempt at fixing such contracts is not just a technical problem but a social one, and is probably not tractable. this patch extends the fork function to take locks for all libc singletons in the parent, and release or reset those locks in the child, so that when the underlying fork operation takes place, the state protected by these locks is consistent and ready for the child to use. locking is skipped in the case where the parent is single-threaded so as not to interfere with legacy AS-safety property of fork in single-threaded programs. lock order is mostly arbitrary, but the malloc locks (including bump allocator in case it's used) must be taken after the locks on any subsystems that might use malloc, and non-AS-safe locks cannot be taken while the thread list lock is held, imposing a requirement that it be taken last.
2020-11-11convert malloc use under libc-internal locks to use internal allocatorRich Felker-0/+41
this change lifts undocumented restrictions on calls by replacement mallocs to libc functions that might take these locks, and sets the stage for lifting restrictions on the child execution environment after multithreaded fork. care is taken to #define macros to replace all four functions (malloc, calloc, realloc, free) even if not all of them will be used, using an undefined symbol name for the ones intended not to be used so that any inadvertent future use will be caught at compile time rather than directed to the wrong implementation.
2020-11-11give libc access to its own malloc even if public malloc is interposedRich Felker-1/+43
allowing the application to replace malloc (since commit c9f415d7ea2dace5bf77f6518b6afc36bb7a5732) has brought multiple headaches where it's used from various critical sections in libc components. for example: - the thread-local message buffers allocated for dlerror can't be freed at thread exit time because application code would then run in the context of a non-existant thread. this was handled in commit aa5a9d15e09851f7b4a1668e9dbde0f6234abada by queuing them for free later. - the dynamic linker has to be careful not to pass memory allocated at early startup time (necessarily using its own malloc) to realloc or free after redoing relocations with the application and all libraries present. bugs in this area were fixed several times, at least in commits 0c5c8f5da6e36fe4ab704bee0cd981837859e23f and 2f1f51ae7b2d78247568e7fdb8462f3c19e469a4 and possibly others. - by calling the allocator from contexts where libc-internal locks are held, we impose undocumented requirements on alternate malloc implementations not to call into any libc function that might attempt to take these locks; if they do, deadlock results. - work to make fork of a multithreaded parent give the child an unrestricted execution environment is blocked by lock order issues as long as the application-provided allocator can be called with libc-internal locks held. these problems are all fixed by giving libc internals access to the original, non-replaced allocator, for use where needed. it can't be used everywhere, as some interfaces like str[n]dup, open_[w]memstream, getline/getdelim, etc. are required to provide the called memory obtained as if by (the public) malloc. and there are a number of libc interfaces that are "pure library" code, not part of some internal singleton, and where using the application's choice of malloc implementation is preferable -- things like glob, regex, etc. one might expect there to be significant cost to static-linked programs, pulling in two malloc implementations, one of them mostly-unused, if malloc is replaced. however, in almost all of the places where malloc is used internally, care has been taken already not to pull in realloc/free (i.e. to link with just the bump allocator). this size optimization carries over automatically. the newly-exposed internal allocator functions are obtained by renaming the actual definitions, then adding new wrappers around them with the public names. technically __libc_realloc and __libc_free could be aliases rather than needing a layer of wrapper, but this would almost surely break certain instrumentation (valgrind) and the size and performance difference is negligible. __libc_calloc needs to be handled specially since calloc is designed to work with either the internal or the replaced malloc. as a bonus, this change also eliminates the longstanding ugly dependency of the static bump allocator on order of object files in libc.a, by making it so there's only one definition of the malloc function and having it in the same source file as the bump allocator.
2020-11-11drop use of getdelim/stdio in dynamic linkerRich Felker-5/+22
the only place stdio was used here was for reading the ldso path file, taking advantage of getdelim to automatically allocate and resize the buffer. the motivation for use here was that, with shared libraries, stdio is already available anyway and free to use. this has long been a nuisance to users because getdelim's use of realloc here triggered a valgrind bug, but removing it doesn't really fix that; on some archs even calling the valgrind-interposed malloc at this point will crash. the actual motivation for this change is moving towards getting rid of use of application-provided malloc in parts of libc where it would be called with libc-internal locks held, leading to the possibility of deadlock if the malloc implementation doesn't follow unwritten rules about which libc functions are safe for it to call. since getdelim is required to produce a pointer as if by malloc (i.e. that can be passed to reallor or free), it necessarily must use the public malloc. instead of performing a realloc loop as the path file is read, first query its size with fstat and allocate only once. this produces slightly different truncation behavior when racing with writes to a file, but neither behavior is or could be made safe anyway; on a live system, ldso path files should be replaced by atomic rename only. the change should also reduce memory waste.
2020-11-11dlerror: don't gratuitously hold freebuf_queue lock while freeingRich Felker-5/+8
thread-local buffers allocated for dlerror need to be queued for free at a later time when the owning thread exits, since malloc may be replaced by application code and the exiting context is not valid to call application code from. the code to process queue of pending frees, introduced in commit aa5a9d15e09851f7b4a1668e9dbde0f6234abada, gratuitously held the lock for the entire duration of queue processing, updating the global queue pointer after each free, despite there being no logical requirement that all frees finish before another thread can access the queue. instead, immediately claim the whole queue for freeing and release the lock, then walk the list and perform frees without the lock held. the change is unlikely to make any meaningful difference to performance, but it eliminates one point where the allocator is called under an internal lock. since the allocator may be application-provided, such calls are undesirable because they allow application code to impede forward progress of libc functions in other threads arbitrarily long, and to induce deadlock if it calls a libc function that requires the same lock. the change also eliminates a lock ordering consideration that's an impediment upcoming work with multithreaded fork.
2020-11-11fix vector types in aarch64 register file structuresRich Felker-3/+3
the ABI type for the vector registers in fpregset_t, struct fpsimd_context, and struct user_fpsimd_struct is __uint128_t, which was presumably originally not used because it's a nonstandard type, but its existence is mandated by the aarch64 psABI. use of the wrong type here broke software using these structures, and encouraged incorrect fixes with casts rather than reinterpretation of representation.
2020-10-30fix erroneous pthread_cond_wait mutex waiter count logic due to typoRich Felker-1/+1
introduced in commit 27b2fc9d6db956359727a66c262f1e69995660aa.
2020-10-30fix missing-wake regression in pthread_cond_waitRich Felker-0/+5
the reasoning in commit 2d0bbe6c788938d1332609c014eeebc1dff966ac was not entirely correct. while it's true that setting the waiters flag ensures that the next unlock will perform a wake, it's possible that the wake is consumed by a mutex waiter that has no relationship with the condvar wait queue being processed, which then takes the mutex. when that thread subsequently unlocks, it sees no waiters, and leaves the rest of the condvar queue stuck. bring back the waiter count adjustment, but skip it for PI mutexes, for which a successful lock-after-waiting always sets the waiters bit. if future changes are made to bring this same waiters-bit contract to all lock types, this can be reverted.
2020-10-28add support for SIGEV_THREAD_ID timersJames Y Knight-5/+19
This is like SIGEV_SIGNAL, but targeted to a particular thread's tid, rather than the process.
2020-10-28fix sem_close unmapping of still-referenced semaphoreRich Felker-3/+5
sem_open is required to return the same sem_t pointer for all references to the same named semaphore when it's opened more than once in the same process. thus we keep a table of all the mapped semaphores and their reference counts. the code path for sem_close checked the reference count, but then proceeded to unmap the semaphore regardless of whether the count had reached zero. add an immediate unlock-and-return for the nonzero refcnt case so the property of performing the munmap syscall after releasing the lock can be preserved.