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2011-04-01use bss instead of mmap for main thread's pthread thread-specific dataRich Felker-9/+4
this simplifies code and removes a failure case
2011-04-01remove obsolete and useless useconds_t typeRich Felker-2/+2
2011-04-01fix misspelled PTHREAD_CANCELED constantRich Felker-1/+1
2011-04-01use a_store to set cancel flag in pthread_cancel, to ensure a barrierRich Felker-1/+1
2011-03-31simplify pthread_key_deleteRich Felker-1/+1
calling this function on an uninitialized key value is UB, so there is no need to check that the table pointer was initialized.
2011-03-31greatly simplify pthread_key_create (~20% size reduction)Rich Felker-10/+9
2011-03-30avoid all malloc/free in timer creation/destructionRich Felker-29/+20
instead of allocating a userspace structure for signal-based timers, simply use the kernel timer id. we use the fact that thread pointers will always be zero in the low bit (actually more) to encode integer timerid values as pointers. also, this change ensures that the timer_destroy syscall has completed before the library timer_destroy function returns, in case it matters.
2011-03-30optimize timer creation and possibly protect against some minor racesRich Felker-16/+19
the major idea of this patch is not to depend on having the timer pointer delivered to the signal handler, and instead use the thread pointer to get the callback function address and argument. this way, the parent thread can make the timer_create syscall while the child thread is starting, and it should never have to block waiting for the barrier.
2011-03-30avoid crash on stupid but allowable usage of pthread_mutex_unlockRich Felker-1/+3
unlocking an unlocked mutex is not UB for robust or error-checking mutexes, so we must avoid calling __pthread_self (which might crash due to lack of thread-register initialization) until after checking that the mutex is locked.
2011-03-30rename __simple_malloc.c to lite_malloc.c - yes this affects behavior!Rich Felker-0/+0
why does this affect behavior? well, the linker seems to traverse archive files starting from its current position when resolving symbols. since calloc.c comes alphabetically (and thus in sequence in the archive file) between __simple_malloc.c and malloc.c, attempts to resolve the "malloc" symbol for use by calloc.c were pulling in the full malloc.c implementation rather than the __simple_malloc.c implementation. as of now, lite_malloc.c and malloc.c are adjacent in the archive and in the correct order, so malloc.c should never be used to resolve "malloc" unless it's already needed to resolve another symbol ("free" or "realloc").
2011-03-30streamline mutex unlock to remove a useless branch, use a_store to unlockRich Felker-2/+6
this roughly halves the cost of pthread_mutex_unlock, at least for non-robust, normal-type mutexes. the a_store change is in preparation for future support of archs which require a memory barrier or special atomic store operation, and also should prevent the possibility of the compiler misordering writes.
2011-03-30cheap special-case optimization for normal mutexesRich Felker-0/+4
cycle-level benchmark on atom cpu showed typical pthread_mutex_lock call dropping from ~120 cycles to ~90 cycles with this change. benefit may vary with compiler options and version, but this optimization is very cheap to make and should always help some.
2011-03-29reorder timer initialization so that timer_create does not depend on freeRich Felker-9/+17
this allows small programs which only create times, but never delete them, to use simple_malloc instead of the full malloc.
2011-03-29revert mutex "optimization" that turned out to be worseRich Felker-1/+1
2011-03-29implement POSIX timersRich Felker-0/+143
this implementation is superior to the glibc/nptl implementation, in that it gives true realtime behavior. there is no risk of timer expiration events being lost due to failed thread creation or failed malloc, because the thread is created as time creation time, and reused until the timer is deleted.
2011-03-29major improvements to cancellation handlingRich Felker-8/+19
- there is no longer any risk of spoofing cancellation requests, since the cancel flag is set in pthread_cancel rather than in the signal handler. - cancellation signal is no longer unblocked when running the cancellation handlers. instead, pthread_create will cause any new threads created from a cancellation handler to unblock their own cancellation signal. - various tweaks in preparation for POSIX timer support.
2011-03-29some preliminaries for adding POSIX timersRich Felker-0/+4
2011-03-29fix tempnam name generation, and a small bug in tmpnam on retry limitRich Felker-21/+20
2011-03-29make tmpfile fail after exceeding max tries.Rich Felker-2/+6
2011-03-29fix tmpnam to generate better names, not depend on non-ISO-C symbolsRich Felker-25/+17
2011-03-29fix messed-up errno if remove fails for a non-EISDIR reasonRich Felker-2/+2
2011-03-29learned something new - remove is supposed to support directories on POSIXRich Felker-1/+3
2011-03-28revert some more spin optimizations that turned out to be pessimizationsRich Felker-4/+3
2011-03-28fix broken spinlock due to miscompilationRich Felker-1/+1
actually this trick also seems to have made the uncontended case slower.
2011-03-28remove useless field in pthread struct (wasted a good bit of space)Rich Felker-1/+0
2011-03-28fix getc - the classic error of trying to store EOF+0-255 in a char type..Rich Felker-3/+3
2011-03-28major stdio overhaul, using readv/writev, plus other changesRich Felker-281/+258
the biggest change in this commit is that stdio now uses readv to fill the caller's buffer and the FILE buffer with a single syscall, and likewise writev to flush the FILE buffer and write out the caller's buffer in a single syscall. making this change required fundamental architectural changes to stdio, so i also made a number of other improvements in the process: - the implementation no longer assumes that further io will fail following errors, and no longer blocks io when the error flag is set (though the latter could easily be changed back if desired) - unbuffered mode is no longer implemented as a one-byte buffer. as a consequence, scanf unreading has to use ungetc, to the unget buffer has been enlarged to hold at least 2 wide characters. - the FILE structure has been rearranged to maintain the locations of the fields that might be used in glibc getc/putc type macros, while shrinking the structure to save some space. - error cases for fflush, fseek, etc. should be more correct. - library-internal macros are used for getc_unlocked and putc_unlocked now, eliminating some ugly code duplication. __uflow and __overflow are no longer used anywhere but these macros. switch to read or write mode is also separated so the code can be better shared, e.g. with ungetc. - lots of other small things.
2011-03-25match glibc/lsb cancellation abi on i386Rich Felker-0/+36
glibc made the ridiculous choice to use pass-by-register calling convention for these functions, which is impossible to duplicate directly on non-gcc compilers. instead, we use ugly asm to wrap and convert the calling convention. presumably this works with every compiler anyone could potentially want to use.
2011-03-25fix all implicit conversion between signed/unsigned pointersRich Felker-48/+44
sadly the C language does not specify any such implicit conversion, so this is not a matter of just fixing warnings (as gcc treats it) but actual errors. i would like to revisit a number of these changes and possibly revise the types used to reduce the number of casts required.
2011-03-24simplify and optimize FILE lock handlingRich Felker-14/+14
2011-03-24prepare pthread_spin_unlock for archs that need memory barriersRich Felker-1/+2
2011-03-24optimize contended case for pthread_spin_trylockRich Felker-1/+2
2011-03-24optimize spinlock spinRich Felker-1/+1
2011-03-24fix non-atomicity of putsRich Felker-1/+5
2011-03-24overhaul cancellation to fix resource leaks and dangerous behavior with signalsRich Felker-13/+43
this commit addresses two issues: 1. a race condition, whereby a cancellation request occurring after a syscall returned from kernelspace but before the subsequent CANCELPT_END would cause cancellable resource-allocating syscalls (like open) to leak resources. 2. signal handlers invoked while the thread was blocked at a cancellation point behaved as if asynchronous cancellation mode wer in effect, resulting in potentially dangerous state corruption if a cancellation request occurs. the glibc/nptl implementation of threads shares both of these issues. with this commit, both are fixed. however, cancellation points encountered in a signal handler will not be acted upon if the signal was received while the thread was already at a cancellation point. they will of course be acted upon after the signal handler returns, so in real-world usage where signal handlers quickly return, it should not be a problem. it's possible to solve this problem too by having sigaction() wrap all signal handlers with a function that uses a pthread_cleanup handler to catch cancellation, patch up the saved context, and return into the cancellable function that will catch and act upon the cancellation. however that would be a lot of complexity for minimal if any benefit...
2011-03-23very cheap double-free checks in mallocRich Felker-0/+4
2011-03-20global cleanup to use the new syscall interfaceRich Felker-238/+180
2011-03-19if returning errno value directly from a syscall, we need to negate it.Rich Felker-3/+3
2011-03-19syscall overhaul part two - unify public and internal syscall interfaceRich Felker-31/+53
with this patch, the syscallN() functions are no longer needed; a variadic syscall() macro allows syscalls with anywhere from 0 to 6 arguments to be made with a single macro name. also, manually casting each non-integer argument with (long) is no longer necessary; the casts are hidden in the macros. some source files which depended on being able to define the old macro SYSCALL_RETURNS_ERRNO have been modified to directly use __syscall() instead of syscall(). references to SYSCALL_SIGSET_SIZE and SYSCALL_LL have also been changed. x86_64 has not been tested, and may need a follow-up commit to fix any minor bugs/oversights.
2011-03-19remove comment cruft that got left behind in x86_64 syscall.sRich Felker-1/+0
2011-03-19overhaul syscall interfaceRich Felker-13/+67
this commit shuffles around the location of syscall definitions so that we can make a syscall() library function with both SYS_* and __NR_* style syscall names available to user applications, provides the syscall() library function, and optimizes the code that performs the actual inline syscalls in the library itself. previously on i386 when built as PIC (shared library), syscalls were incurring bus lock (lock prefix) overhead at entry and exit, due to the way the ebx register was being loaded (xchg instruction with a memory operand). now the xchg takes place between two registers. further cleanup to arch/$(ARCH)/syscall.h is planned.
2011-03-18various legacy and linux-specific stuffRich Felker-0/+5
this commit is part of an effort to make more of busybox work out-of-the-box.
2011-03-18implement [v]swprintfRich Felker-1/+61
2011-03-17implement wprintf family of functionsRich Felker-0/+387
this implementation is extremely ugly and inefficient, but it avoids a good deal of code duplication and bloat. it may be cleaned up later to eliminate the remaining code duplication and some of the warts, but i don't really care about its performance. note that swprintf is not yet implemented.
2011-03-17fix broken wmemchr (unbounded search)Rich Felker-1/+1
2011-03-17implement robust mutexesRich Felker-10/+83
some of this code should be cleaned up, e.g. using macros for some of the bit flags, masks, etc. nonetheless, the code is believed to be working and correct at this point.
2011-03-17avoid function call to pthread_self in mutex unlockRich Felker-1/+1
if the mutex was previously locked, we can assume pthread_self was already called at the time of locking, and thus that the thread pointer is initialized.
2011-03-17reorder mutex struct fields to make room for pointers (upcoming robust mutexes)Rich Felker-1/+3
the layout has been chosen so that pointer slots 3 and 4 fit between the integer slots on 32-bit archs, and come after the integer slots on 64-bit archs.
2011-03-17unify lock and owner fields of mutex structureRich Felker-8/+6
this change is necessary to free up one slot in the mutex structure so that we can use doubly-linked lists in the implementation of robust mutexes.
2011-03-17optimize contended normal mutex case; add int compare-and-swap atomicRich Felker-1/+1