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1998-03-11 00:42 Wolfram Gloger <wmglo@dent.med.uni-muenchen.de> * linuxthreads/manager.c: Enable resetting of the thread scheduling policy to SCHED_OTHER when the parent thread has a different one. 1998-02-01 13:51 Ulrich Drepper <drepper@cygnus.com> * sysdeps/unix/sysv/linux/bits/posix_opt.h: Define _POSIX_ASYNCHRONOUS_IO. * sysdeps/pthread/pthread.h: Define bits for Unix98 variants of mutexes. * mutex.c: Implement new mutex types. * internals.h: Include <signal.h>. * libpthread.map: Add __erno_location and __h_errno_location. * errno.c: Return pointer to variable actually in use. This might not be the one in the thread structure. * internals.h (struct _pthread_descr_struct): Add new fields p_errnop and p_h_errnop. * manager.c (__pthread_manager): Set p_errnop and p_h_errnop member of manager thread structure. (pthread_handle_create): Set p_errnop and p_h_errnop members for new thread. * pthread.c: Adapt initializer for thread structures. (__pthread_initial_thread): Set p_errnop and p_h_errnop member. (__pthread_reset_main_thread): Reset p_errnop and p_h_errnop of current thread to global variables. 1998-01-31 17:27 Ulrich Drepper <drepper@cygnus.com> * rwlock.c: New file. * Makefile (libpthread-routines): Add rwlock. * sysdeps/pthread/pthread.h: Define data structures and declare functions. * libpthread.map: Add new functions. 1997-12-18 13:50 Philip Blundell <pb@nexus.co.uk> * sysdeps/arm/pt-machine.h: New file; add ARM support. * sysdeps/arm/Implies: likewise. * README: Document it. 1997-12-13 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * signals.c: Remove unneeded initializer for sigwaited, saving a 1997-04-11 01:18 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * semaphore.c (sem_init): Set sem_spinlock only if available. 1997-12-04 01:48 Ulrich Drepper <drepper@cygnus.com> * mutex.c: Implement PTHREAD_MUTEX_CHECKERROR. * sysdeps/pthread/pthread.h: Define PTHREAD_MUTEX_CHECKERROR. * Makefile: Update from LinuxThreads 0.7. * internals.h. Likewise. * manager.c: Likewise. * mutex.c: Likewise. * pthread.c: Likewise. * signals.c: Likewise. * specific.c: Likewise. * Examples/ex3.c: Likewise. 1997-11-20 18:13 Ulrich Drepper <drepper@cygnus.com> * pthread.c (__pthread_reset_main_thread): Close pipe only if still open. 1997-10-29 05:38 Ulrich Drepper <drepper@cygnus.com> * wrapsyscall.c: Add socket functions which are also cancelation points. 1997-10-19 21:40 Wolfram Gloger <wg@wolfram.dent.med.uni-muenchen.de> * specific.c (__libc_internal_tsd_set, __libc_internal_tsd_get): New functions for fast thread specific data within libc. * internals.h: Add new array p_libc_specific to struct _pthread_descr_struct. * sysdeps/pthread/bits/libc-lock.h: Declare new functions. 1997-10-13 05:39 Ulrich Drepper <drepper@cygnus.com> * semaphore.h: Add __BEGIN_DECLS/__END_DECLS. Reported by Ralf Corsepius <corsepiu@faw.uni-ulm.de>. 1997-08-29 03:05 Ulrich Drepper <drepper@cygnus.com> * internals.h (struct _pthread_descr_struct): Add definitions for two-level specific key handling. * manager.c (pthread_handle_create): Initialize specific memory array. * specific.c: Implement two-level key handling. * weaks.c: Don't provide dummy key handling. * sysdeps/pthread/bits/libc-lock.h: Typedef __libc_lock_t (no #define). Add definition of __libc_key_t. * sysdeps/unix/sysv/linux/bits/local_lim.h: Define PTHREAD_KEYS_MAX as 1024. Add definition of _POSIX_THREAD_DESTRUCTOR_ITERATIONS and PTHREAD_DESTRUCTOR_ITERATIONS. * manager.c (pthread_handle_create): Compare mmap result with MAP_FAILED. * ptfork.c: Rename to __pthread_atfork and make old name a weak alias. * sysdeps/pthread/bits/pthread.h: Add prototype for __pthread_atfork. 1997-08-22 19:04 Richard Henderson <rth@cygnus.com> sysdeps/sparc -> sysdeps/sparc/sparc32 sysdeps/sparc64 -> sysdeps/sparc/sparc64 * internals.h: Change definition of THREAD_SELF to be an expression, not a statement that did a return. * sysdeps/alpha/pt-machine.h (THREAD_SELF): Update accordingly. * sysdeps/sparc/sparc32/pt-machine.h (THREAD_SELF, INIT_THREAD_SELF): Follow Solaris and use a "system reserved" register (%g6) to hold the thread descriptor. * sysdeps/sparc/sparc64/pt-machine.h: Likewise. 1997-08-03 00:09 Ulrich Drepper <drepper@cygnus.com> * mutex.c: Correct pthread_once. Patch by Xavier Leroy. * sysdeps/pthread/pthread.h: Add prototype for __pthread_once. * sysdeps/pthread/bits/pthread.h: Add macros for __libc_once. * semaphore.c: Include spinlock.h only when needed. * specific.c (__pthread_setsepcific, __pthread_getspecific): Reject keys for entries not in use. * weaks.c: Implement key handling functions for real. 1997-06-29 01:04 Richard Henderson <richard@gnu.ai.mit.edu> Initial sparc64-linux support: * linuxthreads/sysdeps/sparc64/Implies: New file. * linuxthreads/sysdeps/sparc64/pt-machine.h: Likewise. 1997-06-29 00:48 Ulrich Drepper <drepper@cygnus.com> * semaphore.c: Include spinlock.h at correct place. Patch by HJ Lu. 1997-06-13 10:06 Richard Henderson <rth@tamu.edu> The Great Bit File Move: * sysdeps/alpha/semaphorebits.h: -> .../bits/semaphore.h. * sysdeps/powerpc/semaphorebits.h: Likewise. * sysdeps/pthread/cmpxchg/semaphorebits.h: Likewise. * sysdeps/pthread/no-cmpxchg/semaphorebits.h: Likewise. * sysdeps/pthread/libc-lock.h: -> bits/ * sysdeps/pthread/stdio-lock.h: Likewise. * sysdeps/unix/sysv/linux/local_lim.h: Likewise. * sysdeps/unix/sysv/linux/posix_opt.h: Likewise. * semaphore.h: Likewise. * sysdeps/pthread/pthread.h: Likewise. * lockfile.c: <foo.h> -> <bits/foo.h>. * semaphore.h: Likewise. * Makefile: (headers): foo.h -> bits/foo.h. * sysdeps/pthread/Makefile: Likewise. 1997-04-11 01:18 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * semaphore.c (sem_init): Set sem_spinlock only if available. * sysdeps/m68k/pt-machine.h (testandset, __compare_and_swap): Fix asm constraints. 1997-04-09 03:00 Ulrich Drepper <drepper@cygnus.com> Update from LinuxThreads 0.6. * attr.c (pthread_attr_getdetachstate): Use __sched_get_priority_max and __sched_get_priority_min instead of names without `__'. * manager.c: Rewrite large parts to implement opaque pthread_t. * cancel.c: Adapt for opaque pthread_t type. * condvar.c: Likewise. * errno.c: Likewise. * join.c: Likewise. * mutex.c: Likewise. * pthread.c: Likewise. * signals.c: Likewise. * specific.c: Likewise. * restart.h: Likewise. * queue.h: Likewise. * Examples/ex3.c: Likewise. * Examples/ex4.c: Likewise. * sysdeps/pthread/pthread.h: Likewise. * pthread.c: Accumulate time for all threads in thread manager. * semaphore.c: Implement fallback implementation for architectures sometimes missing compare-exchange operations. * cancel.c (pthread_cancel): Validate handle argument. * join.c (pthread_join): Likewise. (pthread_detach): Likewise. * signals.c (pthread_kill): Likewise. * spinlock.h (acquire): Use __sched_yield not sched_yield. * queue.h (enqueue): Enqueue thread according to priority. * internals.c (struct pthread_start_args): New struct for passing args to cloning function. (struct _pthread): Rename to _pthread_descr_struct and adapt for opaque pthread_t. * Examples/Makefile (clean): Pass -f option to rm. * sysdeps/i386/pt-machine.h: Add check for compare-exchange instruction and define TEST_FOR_COMPARE_AND_SWAP. * sysdeps/i386/i486/pt-machine.h: Removed. * sysdeps/unix/sysv/linux/local_lim.h (PTHREAD_THREADS_MAX): Increase to 1024. 1997-04-04 16:38 Ulrich Drepper <drepper@cygnus.com> * restart.h (suspend): Clear p_signal before suspending. (suspend_with_cancellation): Likewise. Patch by Xavier Leroy <Xavier.Leroy@inria.fr>. * weaks.c: Make __pthread_key_create return 1. * sysdeps/pthread/libc-lock.h: Define __libc_key_create, __libc_getspecific, __libc_setspecific, and __libc_key_t. * sysdeps/pthread/stdio-lock.h: Don't care for implementation not using libio. 1997-03-19 15:13 Miguel de Icaza <miguel@nuclecu.unam.mx> * sysdeps/sparc/pt-machine (RELEASE): Fix. 1997-03-01 07:55 Geoff Keating <geoffk@ozemail.com.au> * sysdeps/powerpc/Implies: Added. * sysdeps/powerpc/pt-machine.h: Added. * sysdeps/powerpc/semaphorebits.h: Added. 1997-01-22 01:22 Ulrich Drepper <drepper@cygnus.com> * linuxtheads/pthread.c (__pthread_initial_thread): Correct initializer. (__pthread_manager_thread): Likewise. Reported by Andreas Jaeger. 1997-01-18 22:15 Richard Henderson <rth@tamu.edu> Since sigset_t no longer fits in a register, we can't pass in the thread's initial mask so easily. Take this opportunity to simplify the clone implementation by only accepting a single void* argument. * linuxthreads/manager.c (__pthread_manager): Put thread vitals in the thread struct instead of as arguments through clone. (pthread_start_thread): Look for them there. * linuxthreads/internals.h (struct _pthread): Add p_initial_fn, p_initial_fn_arg, p_initial_mask. Fix __pthread_manager proto. * linuxthreads/pthread.c (pthread_initialize_manager): Revise clone invocation.
156 lines
4.9 KiB
Groff
156 lines
4.9 KiB
Groff
.TH PTHREAD_CANCEL 3 LinuxThreads
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.XREF pthread_setcancelstate
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.XREF pthread_setcanceltype
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.XREF pthread_testcancel
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.SH NAME
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pthread_cancel, pthread_setcancelstate, pthread_setcanceltype, pthread_testcancel \- thread cancellation
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.SH SYNOPSIS
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#include <pthread.h>
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int pthread_cancel(pthread_t thread);
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int pthread_setcancelstate(int state, int *oldstate);
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int pthread_setcanceltype(int type, int *oldtype);
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void pthread_testcancel(void);
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.SH DESCRIPTION
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Cancellation is the mechanism by which a thread can terminate the
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execution of another thread. More precisely, a thread can send a
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cancellation request to another thread. Depending on its settings, the
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target thread can then either ignore the request, honor it
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immediately, or defer it till it reaches a cancellation point.
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When a thread eventually honors a cancellation request, it performs as
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if !pthread_exit(PTHREAD_CANCELED)! has been called at that point:
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all cleanup handlers are executed in reverse order, finalization
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functions for thread-specific data are called, and finally the thread
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stops executing with the return value !PTHREAD_CANCELED!. See
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!pthread_exit!(3) for more information.
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!pthread_cancel! sends a cancellation request to the thread denoted
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by the |thread| argument.
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!pthread_setcancelstate! changes the cancellation state for the
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calling thread -- that is, whether cancellation requests are ignored
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or not. The |state| argument is the new cancellation state: either
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!PTHREAD_CANCEL_ENABLE! to enable cancellation, or
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!PTHREAD_CANCEL_DISABLE! to disable cancellation (cancellation
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requests are ignored). If |oldstate| is not !NULL!, the previous
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cancellation state is stored in the location pointed to by |oldstate|,
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and can thus be restored later by another call to
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!pthread_setcancelstate!.
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!pthread_setcanceltype! changes the type of responses to cancellation
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requests for the calling thread: asynchronous (immediate) or deferred.
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The |type| argument is the new cancellation type: either
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!PTHREAD_CANCEL_ASYNCHRONOUS! to cancel the calling thread as soon as
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the cancellation request is received, or !PTHREAD_CANCEL_DEFERRED! to
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keep the cancellation request pending until the next cancellation
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point. If |oldtype| is not !NULL!, the previous
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cancellation state is stored in the location pointed to by |oldtype|,
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and can thus be restored later by another call to
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!pthread_setcanceltype!.
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Threads are always created by !pthread_create!(3) with cancellation
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enabled and deferred. That is, the initial cancellation state is
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!PTHREAD_CANCEL_ENABLE! and the initial type is
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!PTHREAD_CANCEL_DEFERRED!.
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Cancellation points are those points in the program execution where a
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test for pending cancellation requests is performed and cancellation
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is executed if positive. The following POSIX threads functions
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are cancellation points:
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!pthread_join!(3)
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.br
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!pthread_cond_wait!(3)
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.br
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!pthread_cond_timedwait!(3)
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.br
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!pthread_testcancel!(3)
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.br
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!sem_wait!(3)
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.br
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!sigwait!(3)
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All other POSIX threads functions are guaranteed not to be
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cancellation points. That is, they never perform cancellation in
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deferred cancellation mode.
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!pthread_testcancel! does nothing except testing for pending
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cancellation and executing it. Its purpose is to introduce explicit
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checks for cancellation in long sequences of code that do not call
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cancellation point functions otherwise.
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.SH "RETURN VALUE"
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!pthread_cancel!, !pthread_setcancelstate! and
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!pthread_setcanceltype! return 0 on success and a non-zero error code
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on error.
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.SH ERRORS
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!pthread_cancel! returns the following error code on error:
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.RS
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.TP
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!ESRCH!
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no thread could be found corresponding to that specified by the |thread| ID.
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.RE
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!pthread_setcancelstate! returns the following error code on error:
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.RS
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.TP
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!EINVAL!
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the |state| argument is not !PTHREAD_CANCEL_ENABLE! nor
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!PTHREAD_CANCEL_DISABLE!
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.RE
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!pthread_setcanceltype! returns the following error code on error:
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.RS
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.TP
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!EINVAL!
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the |type| argument is not !PTHREAD_CANCEL_DEFERRED! nor
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!PTHREAD_CANCEL_ASYNCHRONOUS!
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.RE
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.SH AUTHOR
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Xavier Leroy <Xavier.Leroy@inria.fr>
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.SH "SEE ALSO"
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!pthread_exit!(3),
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!pthread_cleanup_push!(3),
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!pthread_cleanup_pop!(3).
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.SH BUGS
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POSIX specifies that a number of system calls (basically, all
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system calls that may block, such as !read!(2), !write!(2), !wait!(2),
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etc.) and library functions that may call these system calls (e.g.
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!fprintf!(3)) are cancellation points. LinuxThreads is not yet
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integrated enough with the C library to implement this, and thus none
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of the C library functions is a cancellation point.
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For system calls at least, there is a workaround. Cancellation
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requests are transmitted to the target thread by sending it a
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signal. That signal will interrupt all blocking system calls, causing
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them to return immediately with the !EINTR! error. So, checking for
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cancellation during a !read! system call, for instance, can be
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achieved as follows:
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.RS
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.ft 3
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.nf
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.sp
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pthread_testcancel();
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retcode = read(fd, buffer, length);
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pthread_testcancel();
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.ft
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.LP
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.RE
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.fi
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