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* unify and overhaul timed futex waitsRich Felker2011-08-0210-53/+56
| | | | | | | | | | | | | | new features: - FUTEX_WAIT_BITSET op will be used for timed waits if available. this saves a call to clock_gettime. - error checking for the timespec struct is now inside __timedwait so it doesn't need to be duplicated everywhere. cond_timedwait still needs to duplicate it to avoid unlocking the mutex, though. - pushing and popping the cancellation handler is delegated to __timedwait, and cancellable/non-cancellable waits are unified.
* avoid accessing mutex memory after atomic unlockRich Felker2011-08-024-34/+31
| | | | | | | this change is needed to fix a race condition and ensure that it's possible to unlock and destroy or unmap the mutex as soon as pthread_mutex_lock succeeds. POSIX explicitly gives such an example in the rationale and requires an implementation to allow such usage.
* fix breakage in cancellation due to signal functions overhaulRich Felker2011-08-021-1/+7
| | | | sigaddset was not accepting SIGCANCEL as a valid signal number.
* overhaul posix semaphores to fix destructability raceRich Felker2011-08-023-27/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | the race condition these changes address is described in glibc bug report number 12674: http://sourceware.org/bugzilla/show_bug.cgi?id=12674 up until now, musl has shared the bug, and i had not been able to figure out how to eliminate it. in short, the problem is that it's not valid for sem_post to inspect the waiters count after incrementing the semaphore value, because another thread may have already successfully returned from sem_wait, (rightly) deemed itself the only remaining user of the semaphore, and chosen to destroy and free it (or unmap the shared memory it's stored in). POSIX is not explicit in blessing this usage, but it gives a very explicit analogous example with mutexes (which, in musl and glibc, also suffer from the same race condition bug) in the rationale for pthread_mutex_destroy. the new semaphore implementation augments the waiter count with a redundant waiter indication in the semaphore value itself, representing the presence of "last minute" waiters that may have arrived after sem_post read the waiter count. this allows sem_post to read the waiter count prior to incrementing the semaphore value, rather than after incrementing it, so as to avoid accessing the semaphore memory whatsoever after the increment takes place. a similar, but much simpler, fix should be possible for mutexes and other locking primitives whose usage rules are stricter than semaphores.
* fix wrong messages in gai_strerrorRich Felker2011-08-011-0/+2
| | | | i had missed the fact that a couple values were unassigned...
* port numbers should always be interpreted as decimalRich Felker2011-08-011-1/+1
| | | | | | | | | | | per POSIX and RFC 3493: If the specified address family is AF_INET, AF_INET6, or AF_UNSPEC, the service can be specified as a string specifying a decimal port number. 021 is a valid decimal number, therefore, interpreting it as octal seems to be non-conformant.
* fix crash in dns code with new stdio locking codeRich Felker2011-08-011-0/+1
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* consistency: use struct __ucontext instead of ucontext_t in prototypesRich Felker2011-07-311-1/+1
| | | | | this is necessary to avoid build errors if feature test macros are not properly defined when including ucontext.h
* fix race condition in sigqueueRich Felker2011-07-301-2/+8
| | | | | | | | | | | | | | | this race is fundamentally due to linux's bogus requirement that userspace, rather than kernelspace, fill in the siginfo structure. an intervening signal handler that calls fork could cause both the parent and child process to send signals claiming to be from the parent, which could in turn have harmful effects depending on what the recipient does with the signal. we simply block all signals for the interval between getuid and sigqueue syscalls (much like what raise() does already) to prevent the race and make the getuid/sigqueue pair atomic. this will be a non-issue if linux is fixed to validate the siginfo structure or fill it in from kernelspace.
* clean up pthread_sigmask/sigprocmask dependency orderRich Felker2011-07-302-11/+7
| | | | | | it's nicer for the function that doesn't use errno to be independent, and have the other one call it. saves some time and avoids clobbering errno.
* fix some bugs in setxid and update setrlimit to use __synccallRich Felker2011-07-302-10/+33
| | | | | | | | setrlimit is supposed to be per-process, not per-thread, but again linux gets it wrong. work around this in userspace. not only is it needed for correctness; setxid also depends on the resource limits for all threads being the same to avoid situations where temporarily unlimiting the limit succeeds in some threads but fails in others.
* add proper fuxed-based locking for stdioRich Felker2011-07-3020-46/+71
| | | | | | | | | | | | | | | | | | | | | | previously, stdio used spinlocks, which would be unacceptable if we ever add support for thread priorities, and which yielded pathologically bad performance if an application attempted to use flockfile on a key file as a major/primary locking mechanism. i had held off on making this change for fear that it would hurt performance in the non-threaded case, but actually support for recursive locking had already inflicted that cost. by having the internal locking functions store a flag indicating whether they need to perform unlocking, rather than using the actual recursive lock counter, i was able to combine the conditionals at unlock time, eliminating any additional cost, and also avoid a nasty corner case where a huge number of calls to ftrylockfile could cause deadlock later at the point of internal locking. this commit also fixes some issues with usage of pthread_self conflicting with __attribute__((const)) which resulted in crashes with some compiler versions/optimizations, mainly in flockfile prior to pthread_create.
* eliminate dependence of perror on printfRich Felker2011-07-301-10/+5
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* fix bug in synccall with no threads: lock was taken but never releasedRich Felker2011-07-301-4/+4
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* add setxid.c for new set*id() framework. missed in last commit.Rich Felker2011-07-291-0/+49
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* new attempt at making set*id() safe and robustRich Felker2011-07-2913-130/+130
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | changing credentials in a multi-threaded program is extremely difficult on linux because it requires synchronizing the change between all threads, which have their own thread-local credentials on the kernel side. this is further complicated by the fact that changing the real uid can fail due to exceeding RLIMIT_NPROC, making it possible that the syscall will succeed in some threads but fail in others. the old __rsyscall approach being replaced was robust in that it would report failure if any one thread failed, but in this case, the program would be left in an inconsistent state where individual threads might have different uid. (this was not as bad as glibc, which would sometimes even fail to report the failure entirely!) the new approach being committed refuses to change real user id when it cannot temporarily set the rlimit to infinity. this is completely POSIX conformant since POSIX does not require an implementation to allow real-user-id changes for non-privileged processes whatsoever. still, setting the real uid can fail due to memory allocation in the kernel, but this can only happen if there is not already a cached object for the target user. thus, we forcibly serialize the syscalls attempts, and fail the entire operation on the first failure. this *should* lead to an all-or-nothing success/failure result, but it's still fragile and highly dependent on kernel developers not breaking things worse than they're already broken. ideally linux will eventually add a CLONE_USERCRED flag that would give POSIX conformant credential changes without any hacks from userspace, and all of this code would become redundant and could be removed ~10 years down the line when everyone has abandoned the old broken kernels. i'm not holding my breath...
* remove ugly prng from mk*temp and just re-poll time on retryRich Felker2011-07-281-6/+5
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* eliminate mk*temp dependency on snprintfRich Felker2011-07-281-3/+4
| | | | | this helps some tiny programs be even more tiny, and barly increases code size even if both are used.
* fix for setenv bogus var argument handlingRich Felker2011-07-281-1/+1
| | | | | | | | | | | thanks to mikachu per POSIX: The setenv() function shall fail if: [EINVAL] The name argument is a null pointer, points to an empty string, or points to a string containing an '=' character.
* when resolving symbols with only weak defs, use first def, not last defRich Felker2011-07-251-0/+1
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* comment non-obvious de bruijn sequence code in int parserRich Felker2011-07-251-0/+2
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* fix resolution of weak symbols (hopefully right now) and vdsoRich Felker2011-07-241-3/+9
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* workaround for gcc's optimizer breaking dynamic symbol resolutionRich Felker2011-07-241-1/+2
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* load vdso, if present, into the dso listRich Felker2011-07-241-2/+31
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* const correctness on function pointerRich Felker2011-07-241-1/+1
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* simplify dynamic linker startupRich Felker2011-07-241-23/+17
| | | | | | instead of creating temp dso objects on the stack and moving them to the heap if dlopen/dlsym are used, use static objects to begin with, and just donate them to malloc if we no longer need them.
* some preliminaries for vdso clock supportRich Felker2011-07-233-7/+35
| | | | | | | | these changes also make it so clock_gettime(CLOCK_REALTIME, &ts) works even on pre-2.6 kernels, emulated via the gettimeofday syscall. there is no cost for the fallback check, as it falls under the error case that already must be checked for storing the error code in errno, but which would normally be hidden inside __syscall_ret.
* check for fd exhaustion in forkptyRich Felker2011-07-221-2/+15
| | | | | | | we cannot report failure after forking, so the idea is to ensure prior to fork that fd 0,1,2 exist. this will prevent dup2 from possibly hitting a resource limit and failing in the child process. fcntl rather than dup2 is used prior to forking to avoid race conditions.
* incorrect check for open failure in openpty functionRich Felker2011-07-221-1/+1
| | | | -1, not 0, indicates failure
* socket headers macro adjustment - workaround for buggy programsRich Felker2011-07-212-2/+2
| | | | some program was undefining AF_NETLINK and thereby breaking AF_ROUTE...
* fix errno value when fdopendir is given an invalid file descriptorRich Felker2011-07-211-1/+4
| | | | this resolves an issue reported by Vasiliy Kulikov
* ensure in fork that child gets its own new robust mutex listRich Felker2011-07-161-0/+1
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* fix logic error in freadRich Felker2011-07-161-6/+1
| | | | | | | | fread was calling f->read without checking that the file was in reading mode. this could: 1. crash, if f->read was a null pointer 2. cause unwanted blocking on a terminal already at eof 3. allow reading on a write-only file
* fix various bugs in new integer parser frameworkRich Felker2011-07-145-10/+15
| | | | | | | | | | 1. my interpretation of subject sequence definition was wrong. adjust parser to conform to the standard. 2. some code for handling tail overflow case was missing (forgot to finish writing it). 3. typo (= instead of ==) caused ERANGE to wrongly behave like EINVAL
* fix wcsto[iu]max with high charactersRich Felker2011-07-142-4/+2
| | | | | | | | stopping without letting the parser see a stop character prevented getting a result. so treat all high chars as the null character and pass them into the parser. also eliminated ugly tmp var using compound literals.
* new restartable integer parsing framework.Rich Felker2011-07-146-156/+197
| | | | | | | | | this fixes a number of bugs in integer parsing due to lazy haphazard wrapping, as well as some misinterpretations of the standard. the new parser is able to work character-at-a-time or on whole strings, making it easy to support the wide functions without unbounded space for conversion. it will also be possible to update scanf to use the new parser.
* gb18030 support in iconv (only from, not to)Rich Felker2011-07-122-2/+1887
| | | | | also support (and restrict to subsets) older chinese sets, and explicitly refuse to convert to cjk (since there's no code for it yet)
* "implement" getnetbyaddr and getnetbynameRich Felker2011-07-121-0/+12
| | | | | these are useless legacy functions but some old software contains cruft that expects them to exist...
* legacy japanese charset support in iconv (only from, not to)Rich Felker2011-07-122-0/+597
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* simplify iconv and support more legacy codepagesRich Felker2011-07-123-352/+331
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* add missing signalfd flagsRich Felker2011-07-091-0/+3
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* printf: "if a precision is specified, the '0' flag shall be ignored."Rich Felker2011-07-041-1/+1
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* zero precision with zero value should not inhibit prefix/width printingRich Felker2011-07-041-1/+4
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* printf("%#x",0) should print 0 not 0x0Rich Felker2011-07-041-1/+1
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* iconv was not returning -1 on most failureRich Felker2011-07-031-0/+2
| | | | | this broke most uses of iconv in real-world programs, especially glib's iconv wrappers.
* 0.7.12 release notes v0.7.12Rich Felker2011-07-031-0/+16
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* fix dlopen UB due to longjmp/volatile rules violationRich Felker2011-07-011-1/+1
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* res_search symbol, aliased to res_query for now (better than nothing)Rich Felker2011-06-301-0/+3
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* simple rpath support (no token expansion yet) for dynamic linkerRich Felker2011-06-301-2/+8
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* fill in junk in stropts.hRich Felker2011-06-301-1/+123
| | | | | | STREAMS are utterly useless as far as I can tell, but some software was apparently broken by the presence of stropts.h but lack of macros it's supposed to define...
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