path: root/src/exit
AgeCommit message (Collapse)AuthorLines
2012-08-25add c11 quick_exit and at_quick_exit functionsRich Felker-0/+44
2012-08-19fix bug whereby most atexit-registered functions got skippedRich Felker-3/+2
2012-06-19stdio: handle file position correctly at program exitRich Felker-3/+5
for seekable files, posix imposed requirements on the offset of the underlying open file description after a stream is closed. this was correctly handled (as a side effect of the unconditional fflush call) when streams were explicitly closed by fclose, but was not handled correctly at program exit time, where fflush(0) was being used. the weak symbol hackery is to pull in __stdio_exit if either of __toread or __towrite is used, but avoid calling it twice so we don't have to keep extra state. the new __stdio_exit is a streamlined fflush variant that avoids performing any unnecessary operations and which never unlocks the files or open file list, so we can be sure no other threads write new data to a stream's buffer after it's already flushed.
2012-06-14reorder exit code to defer stdio flush until after dtorsRich Felker-4/+1
this is required in case dtors use stdio. also remove the old comments; one was cruft from when the code used to be using function pointers and conditional calls, and has little motivation now that we're using weak symbols. the other was just complaining about having to support dtors even though the cost was made essentially zero in the non-use case by the way it's done here.
2012-06-02ensure that abort always worksRich Felker-0/+2
Per POSIX, "The abort() function shall cause abnormal process termination to occur, unless the signal SIGABRT is being caught and the signal handler does not return." If SIGABRT is blocked or if a signal handler is installed and does return, abort is still required to cause abnormal program termination. We cannot use a_crash() to do this, since a SIGILL handler could also be installed (and might even longjmp out of the abort, not expecting to be invoked from within abort), nor can we rely on resetting the signal handler and re-raising the signal (this has race conditions in multi-threaded programs). On the other hand, SIGKILL is a perfectly safe, unblockable way to obtain abnormal program termination, and it requires no ugly loop-and-retry logic.
2012-05-10remove __lock dependency from exitRich Felker-2/+4
there's no sense in using a powerful lock in exit, because it will never be unlocked. a thread that arrives at exit while exit is already in progress just needs to hang forever. use the pause syscall for this because it's cheap and easy and universally available.
2012-04-24ditch the priority inheritance locks; use malloc's version of lockRich Felker-9/+9
i did some testing trying to switch malloc to use the new internal lock with priority inheritance, and my malloc contention test got 20-100 times slower. if priority inheritance futexes are this slow, it's simply too high a price to pay for avoiding priority inversion. maybe we can consider them somewhere down the road once the kernel folks get their act together on this (and perferably don't link it to glibc's inefficient lock API)... as such, i've switch __lock to use malloc's implementation of lightweight locks, and updated all the users of the code to use an array with a waiter count for their locks. this should give optimal performance in the vast majority of cases, and it's simple. malloc is still using its own internal copy of the lock code because it seems to yield measurably better performance with -O3 when it's inlined (20% or more difference in the contention stress test).
2011-10-14add dummy __cxa_finalizeRich Felker-0/+4
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..
2011-10-14support __cxa_atexit, and registering atexit functions from atexit handlersRich Felker-7/+26
mildly tested; may have bugs. the locking should be updated not to use spinlocks but that's outside the scope of this one module.
2011-10-14simplify atexit and fflush-on-exit handlingRich Felker-8/+8
2011-04-06consistency: change all remaining syscalls to use SYS_ rather than __NR_ prefixRich Felker-2/+2
2011-03-28major stdio overhaul, using readv/writev, plus other changesRich Felker-1/+1
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.
2011-03-19syscall overhaul part two - unify public and internal syscall interfaceRich Felker-3/+2
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.
2011-02-12initial check-in, version 0.5.0v0.5.0Rich Felker-0/+111