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* use count=0 instead of 1 for recursive mutex with only one lock referenceRich Felker2011-10-032-4/+2
| | | | | | | 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.
* sysconf for PTHREAD_KEYS_MAXRich Felker2011-10-031-1/+1
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* synchronize cond var destruction with exiting waitsRich Felker2011-10-023-0/+12
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* fix failure-to-wake in rwlock unlockRich Felker2011-10-011-1/+1
| | | | | | | | | 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).
* dlsym entry point for armRich Felker2011-10-011-0/+6
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* dynamic linker entry point for armRich Felker2011-10-011-0/+14
| | | | mildly tested, seems to work
* fix various bugs in path and error handling in execvp/fexecveRich Felker2011-09-292-18/+29
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* don't crash on null strings in printfRich Felker2011-09-281-1/+1
| | | | passing null pointer for %s is UB but lots of broken programs do it anyway
* fix excessive/insufficient wakes in __vm_unlockRich Felker2011-09-281-3/+3
| | | | | | 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).
* make getmntent_r discard long lines when it returns error, not seek backRich Felker2011-09-281-2/+1
| | | | | seeking back can be performed by the caller, but if the caller doesn't expect it, it will result in an infinite loop of failures.
* improve pshared barriersRich Felker2011-09-282-12/+14
| | | | | | | | | | | | | | eliminate the sequence number field and instead use the counter as the futex because of the way the lock is held, sequence numbers are completely useless, and this frees up a field in the barrier structure to be used as a waiter count for the count futex, which lets us avoid some syscalls in the best case. as of now, self-synchronized destruction and unmapping should be fully safe. before any thread can return from the barrier, all threads in the barrier have obtained the vm lock, and each holds a shared lock on the barrier. the barrier memory is not inspected after the shared lock count reaches 0, nor after the vm lock is released.
* next step making barrier self-sync'd destruction safeRich Felker2011-09-282-6/+18
| | | | i think this works, but it can be simplified. (next step)
* barrier destroy must also wait for threads in other processes exiting barrierRich Felker2011-09-281-0/+2
| | | | | the vm lock only waits for threads in the same process exiting. actually this fix is not enough, but it's a start...
* stupid typo (caused by rather ugly spelling in POSIX..) in aioRich Felker2011-09-281-1/+1
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* correctly handle the degenerate barrier in the pshared caseRich Felker2011-09-271-1/+1
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* fix crash in pthread_cond_wait mutex-locked checkRich Felker2011-09-271-1/+1
| | | | | | it was assuming the result of the condition it was supposed to be checking for, i.e. that the thread ptr had already been initialized by pthread_mutex_lock. use the slower call to be safe.
* fix crash in pthread_testcancel if pthread_self has not been calledRich Felker2011-09-271-1/+1
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* improve/debloat mutex unlock error checking in pthread_cond_waitRich Felker2011-09-271-3/+3
| | | | | | | we're not required to check this except for error-checking mutexes, but it doesn't hurt. the new test is actually simpler/lighter, and it also eliminates the need to later check that pthread_mutex_unlock succeeds.
* check mutex owner in pthread_cond_waitRich Felker2011-09-271-0/+3
| | | | | | | | | | when used with error-checking mutexes, pthread_cond_wait is required to fail with EPERM if the mutex is not locked by the caller. previously we relied on pthread_mutex_unlock to generate the error, but this is not valid, since in the case of such invalid usage the internal state of the cond variable has already been potentially corrupted (due to access outside the control of the mutex). thus, we have to check first.
* fix pshared barrier wrong return value.Rich Felker2011-09-271-1/+1
| | | | i set the return value but then never used it... oops!
* convert the barrier pshared option back to 0/1 values when getting itRich Felker2011-09-271-1/+1
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* improve error handling in mntent stuff...Rich Felker2011-09-271-2/+9
| | | | not sure if this is correct/ideal. it needs further attention.
* fix missing va_end in prctl syscall wrapperRich Felker2011-09-271-0/+1
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* fix clobbering of errno in get(pw|gr)([ug]id|nam) by fcloseRich Felker2011-09-272-0/+12
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* process-shared barrier support, based on discussion with bdonlanRich Felker2011-09-277-16/+102
| | | | | | | | | | | | | this implementation is rather heavy-weight, but it's the first solution i've found that's actually correct. all waiters actually wait twice at the barrier so that they can synchronize exit, and they hold a "vm lock" that prevents changes to virtual memory mappings (and blocks pthread_barrier_destroy) until all waiters are finished inspecting the barrier. thus, it is safe for any thread to destroy and/or unmap the barrier's memory as soon as pthread_barrier_wait returns, without further synchronization.
* fix incorrect allocation failure check in pthread_createRich Felker2011-09-271-1/+1
| | | | | mmap returns MAP_FAILED not 0 because some idiot thought the ability to mmap the null pointer page would be a good idea...
* another cond var fix: requeue count race conditionRich Felker2011-09-262-15/+13
| | | | | | | | | | | | | lock out new waiters during the broadcast. otherwise the wait count added to the mutex might be lower than the actual number of waiters moved, and wakeups may be lost. this issue could also be solved by temporarily setting the mutex waiter count higher than any possible real count, then relying on the kernel to tell us how many waiters were requeued, and updating the counts afterwards. however the logic is more complex, and i don't really trust the kernel. the solution here is also nice in that it replaces some atomic cas loops with simple non-atomic ops under lock.
* fix lost signals in cond varsRich Felker2011-09-263-14/+17
| | | | | | | | | | | due to moving waiters from the cond var to the mutex in bcast, these waiters upon wakeup would steal slots in the count from newer waiters that had not yet been signaled, preventing the signal function from taking any action. to solve the problem, we simply use two separate waiter counts, and so that the original "total" waiters count is undisturbed by broadcast and still available for signal.
* cleanup various minor issues reported by nszRich Felker2011-09-264-7/+8
| | | | | | | | | the changes to syscall_ret are mostly no-ops in the generated code, just cleanup of type issues and removal of some implementation-defined behavior. the one exception is the change in the comparison value, which is fixed so that 0xf...f000 (which in principle could be a valid return value for mmap, although probably never in reality) is not treated as an error return.
* redo cond vars again, use sequence numbersRich Felker2011-09-264-48/+52
| | | | | | | | | | | | | | | | | | | | | | | | testing revealed that the old implementation, while correct, was giving way too many spurious wakeups due to races changing the value of the condition futex. in a test program with 5 threads receiving broadcast signals, the number of returns from pthread_cond_wait was roughly 3 times what it should have been (2 spurious wakeups for every legitimate wakeup). moreover, the magnitude of this effect seems to grow with the number of threads. the old implementation may also have had some nasty race conditions with reuse of the cond var with a new mutex. the new implementation is based on incrementing a sequence number with each signal event. this sequence number has nothing to do with the number of threads intended to be woken; it's only used to provide a value for the futex wait to avoid deadlock. in theory there is a danger of race conditions due to the value wrapping around after 2^32 signals. it would be nice to eliminate that, if there's a way. testing showed no spurious wakeups (though they are of course possible) with the new implementation, as well as slightly improved performance.
* revert previous change in cond var waiter moveRich Felker2011-09-251-2/+6
| | | | | | using swap has a race condition: the waiters must be added to the mutex waiter count *before* they are taken off the cond var waiter count, or wake events can be lost.
* optimize cond waiter move using atomic swap instead of cas loopRich Felker2011-09-251-6/+2
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* fix logic for when wakeup is not desired on cond bcastRich Felker2011-09-251-3/+4
| | | | somehow i forgot that normal-type mutexes don't store the owner tid.
* new futex-requeue-based pthread_cond_broadcast implementationRich Felker2011-09-254-7/+69
| | | | | | this avoids the "stampede effect" where pthread_cond_broadcast would result in all waiters waking up simultaneously, only to immediately contend for the mutex and go back to sleep.
* fix ABA race in cond vars, improve them overallRich Felker2011-09-233-11/+12
| | | | | | | | | | | | | | | | | | | | | previously, a waiter could miss the 1->0 transition of block if another thread set block to 1 again after the signal function set block to 0. we now use the caller's thread id as a unique token to store in block, which no other thread will ever write there. this ensures that if block still contains the tid, no signal has occurred. spurious wakeups will of course occur whenever there is a spurious return from the futex wait and another thread has begun waiting on the cond var. this should be a rare occurrence except perhaps in the presence of interrupting signal handlers. signal/bcast operations have been improved by noting that they need not avoid inspecting the cond var's memory after changing the futex value. because the standard allows spurious wakeups, there is no way for an application to distinguish between a spurious wakeup just before another thread called signal/bcast, and the deliberate wakeup resulting from the signal/bcast call. thus the woken thread must assume that the signalling thread may still be waiting to act on the cond var, and therefore it cannot destroy/unmap the cond var.
* fix deadlock in condition wait whenever there are multiple waitersRich Felker2011-09-224-5/+18
| | | | | it's amazing none of the conformance tests i've run even bothered to check whether something so basic works...
* protect against/handle cancellation reading shadow passwordsRich Felker2011-09-211-1/+11
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* make dns lookups (and thus getaddrinfo) cancellableRich Felker2011-09-211-4/+11
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* use poll rather than select in dns lookups (also clock_gettime)Rich Felker2011-09-211-12/+10
| | | | | | | | | | if the file descriptor resource limit has been increased past FD_SETSIZE, this is actually a security issue; we could write past the end of the fd_set object. using poll makes it a non-issue, and simplifies the code at the same time. also, use clock_gettime instead of gettimeofday, for reduced bloat and better entropy.
* avoid setting FILE lock count when not using flockfileRich Felker2011-09-211-1/+1
| | | | | | | for now this is just a tiny optimization, but later if we support cancellation from __stdio_read and __stdio_write, it will be necessary for the recusrive lock count to be zero in order for these functions to know they are responsible for unlocking the FILE on cancellation.
* update syscalls with off_t arguments to handle argument alignment, if neededRich Felker2011-09-216-8/+8
| | | | | | 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.
* fix statvfs.c to match new fsid_t definitionRich Felker2011-09-201-1/+1
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* fix the definition of struct statvfs to match lsb abiRich Felker2011-09-192-19/+46
| | | | | at the same time, make struct statfs match the traditional definition and make it more useful, especially the fsid_t stuff.
* fix incorrect long double parameters on arm (and other future ports)Rich Felker2011-09-191-0/+12
| | | | | this was the cause of crashes in printf when attempting to print floating point values.
* initial commit of the arm portRich Felker2011-09-188-0/+136
| | | | | | | | | | | | | 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.
* disable dynamic linking/loading code in static libc builds, for nowRich Felker2011-09-181-0/+2
| | | | | it does not work, but some configure scripts will falsely detect support then generate programs that crash when they call dlopen.
* overhaul clone syscall wrappingRich Felker2011-09-188-62/+108
| | | | | | | | | | | | | | | | | | | | several things are changed. first, i have removed the old __uniclone function signature and replaced it with the "standard" linux __clone/clone signature. this was necessary to expose clone to applications anyway, and it makes it easier to port __clone to new archs, since it's now testable independently of pthread_create. secondly, i have removed all references to the ugly ldt descriptor structure (i386 only) from the c code and pthread structure. in places where it is needed, it is now created on the stack just when it's needed, in assembly code. thus, the i386 __clone function takes the desired thread pointer as its argument, rather than an ldt descriptor pointer, just like on all other sane archs. this should not affect applications since there is really no way an application can use clone with threads/tls in a way that doesn't horribly conflict with and clobber the underlying implementation's use. applications are expected to use clone only for creating actual processes, possibly with new namespace features and whatnot.
* dummy implementation of set_thread_areaRich Felker2011-09-171-0/+6
| | | | | | | | eventually we may have a working "generic" implementation for archs that don't need anything special. in any case, the goal of having stubs like this is to allow early testing of new ports before all the details needed for threads have been filled in. more functions like this will follow.
* fix assumptions that char is signedRich Felker2011-09-161-2/+2
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* fix more instances of old a_xchg (use new a_swap name)Rich Felker2011-09-163-3/+3
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