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2011-08-05fix off-by-one bug in siglongjmp that caused unpredictable behaviorRich Felker-1/+1
if saved, signal mask would not be restored unless some low signals were masked. if not saved, signal mask could be wrongly restored to uninitialized values. in any, wrong mask would be restored. i believe this function was written for a very old version of the jmp_buf structure which did not contain a final 0 field for compatibility with siglongjmp, and never updated...
2011-07-30fix race condition in sigqueueRich Felker-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.
2011-07-30clean up pthread_sigmask/sigprocmask dependency orderRich Felker-8/+4
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.
2011-06-14restore use of .type in asm, but use modern @function (vs %function)Rich Felker-0/+6
this seems to be necessary to make the linker accept the functions in a shared library (perhaps to generate PLT entries?) strictly speaking libc-internal asm should not need it. i might clean that up later.
2011-06-13remove all .size and .type directives for functions from the asmRich Felker-10/+0
these are useless and have caused problems for users trying to build with non-gnu tools like tcc's assembler.
2011-06-08implement psignal and psiginfoRich Felker-0/+20
2011-05-07overhaul implementation-internal signal protectionsRich Felker-29/+18
the new approach relies on the fact that the only ways to create sigset_t objects without invoking UB are to use the sig*set() functions, or from the masks returned by sigprocmask, sigaction, etc. or in the ucontext_t argument to a signal handler. thus, as long as sigfillset and sigaddset avoid adding the "protected" signals, there is no way the application will ever obtain a sigset_t including these bits, and thus no need to add the overhead of checking/clearing them when sigprocmask or sigaction is called. note that the old code actually *failed* to remove the bits from sa_mask when sigaction was called. the new implementations are also significantly smaller, simpler, and faster due to ignoring the useless "GNU HURD signals" 65-1024, which are not used and, if there's any sanity in the world, never will be used.
2011-04-17overhaul pthread cancellationRich Felker-12/+3
this patch improves the correctness, simplicity, and size of cancellation-related code. modulo any small errors, it should now be completely conformant, safe, and resource-leak free. the notion of entering and exiting cancellation-point context has been completely eliminated and replaced with alternative syscall assembly code for cancellable syscalls. the assembly is responsible for setting up execution context information (stack pointer and address of the syscall instruction) which the cancellation signal handler can use to determine whether the interrupted code was in a cancellable state. these changes eliminate race conditions in the previous generation of cancellation handling code (whereby a cancellation request received just prior to the syscall would not be processed, leaving the syscall to block, potentially indefinitely), and remedy an issue where non-cancellable syscalls made from signal handlers became cancellable if the signal handler interrupted a cancellation point. x86_64 asm is untested and may need a second try to get it right.
2011-04-14use a separate signal from SIGCANCEL for SIGEV_THREAD timersRich Felker-2/+3
otherwise we cannot support an application's desire to use asynchronous cancellation within the callback function. this change also slightly debloats pthread_create.c.
2011-04-08fix broken sigsetjmp on x86_64Rich Felker-7/+9
2011-04-06consistency: change all remaining syscalls to use SYS_ rather than __NR_ prefixRich Felker-3/+3
2011-03-25fix all implicit conversion between signed/unsigned pointersRich Felker-1/+1
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.
2011-03-24overhaul cancellation to fix resource leaks and dangerous behavior with signalsRich Felker-0/+2
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...
2011-03-20global cleanup to use the new syscall interfaceRich Felker-23/+10
2011-03-19syscall overhaul part two - unify public and internal syscall interfaceRich Felker-3/+3
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.
2011-03-10fix errors in sigqueue (potential information leak, wrong behavior)Rich Felker-5/+7
1. any padding in the siginfo struct was not necessarily zero-filled, so it might have contained private data off the caller's stack. 2. the uid and pid must be filled in from userspace. the previous rsyscall fix broke rsyscalls because the values were always incorrect.
2011-03-10remove useless return value checks for functions that cannot failRich Felker-3/+2
2011-03-10make sigsuspend a cancellation pointRich Felker-1/+6
2011-03-10make sigtimedwait a cancellation pointRich Felker-0/+3
2011-03-10don't fail with EINTR in sigtimedwaitRich Felker-6/+6
POSIX allows either behavior, but sigwait is not allowed to fail with EINTR, so the retry loop would have to be in one or the other anyway.
2011-03-10fix sigsuspend syscallRich Felker-1/+1
2011-03-10make sigaltstack work (missing macros in signal.h, error conditions)Rich Felker-1/+11
2011-03-09fix error handling for pthread_sigmaskRich Felker-1/+5
it must return errno, not -1, and should reject invalud values for how.
2011-03-09fix race condition in raise - just mask signalsRich Felker-9/+9
a signal handler could fork after the pid/tid were read, causing the wrong process to be signalled. i'm not sure if this is supposed to have UB or not, but raise is async-signal-safe, so it probably is allowed. the current solution is slightly expensive so this implementation is likely to be changed in the future.
2011-03-09fix raise semantics with threads.Rich Felker-1/+12
2011-02-20fix null pointer dereference introduced in last sigprocmask commitRich Felker-1/+1
2011-02-19prevent sigprocmask/pthread_sigmask from blocking implementation signalsRich Felker-3/+5
this code was wrongly disabled because the old version was trying to be too clever and didn't work. replaced it with a simple version for now.
2011-02-15Port musl to x86-64. One giant commit!Nicholas J. Kain-0/+22
2011-02-14header cleanup, conformance fixes - signalsRich Felker-6/+3
2011-02-13fix previous commit that broke sigreturn. looks like the asm is needed.Rich Felker-5/+17
2011-02-13fix omission that kept sa_restorer from being usedRich Felker-1/+1
2011-02-12initial check-in, version 0.5.0v0.5.0Rich Felker-0/+398