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       pthread_attr_setsigmask_np,  pthread_attr_getsigmask_np - set/get signal mask attribute in
       thread attributes object


       #define _GNU_SOURCE             /* See feature_test_macros(7) */
       #include <pthread.h>

       int pthread_attr_setsigmask_np(pthread_attr_t *attr,
                                      const sigset_t *sigmask);
       int pthread_attr_getsigmask_np(const pthread_attr_t *attr,
                                      sigset_t *sigmask);

       Compile and link with -pthread.


       The pthread_attr_setsigmask_np() function sets the signal mask  attribute  of  the  thread
       attributes  object  referred to by attr to the value specified in *sigmask.  If sigmask is
       specified as NULL, then any existing signal mask attribute in attr is unset.

       The pthread_attr_getsigmask_np() function returns the signal mask attribute of the  thread
       attributes  object referred to by attr in the buffer pointed to by sigmask.  If the signal
       mask  attribute  is  currently  unset,  then  this  function  returns  the  special  value
       PTHREAD_ATTR_NO_SIGMASK_NP as its result.


       The  pthread_attr_setsigmask_np() function returns 0 on success, or a nonzero error number
       on failure.

       the pthread_attr_getsigmask_np() function returns either 0 or  PTHREAD_ATTR_NO_SIGMASK_NP.
       When  0 is returned, the signal mask attribute is returned via sigmask.  A return value of
       PTHREAD_ATTR_NO_SIGMASK_NP indicates that the signal mask attribute is not set in attr.

       On error, these functions return a positive error number.


       ENOMEM (pthread_attr_setsigmask_np()) Could not allocate memory.


       These functions are provided by glibc since version 2.32.


       For an explanation of the terms used in this section, see attributes(7).

       │InterfaceAttributeValue   │
       │pthread_attr_setsigmask_np(),  │ Thread safety │ MT-Safe │
       │pthread_attr_getsigmask_np()   │               │         │


       These  functions  are  nonstandard GNU extensions; hence the suffix "_np" (nonportable) in
       the names.


       The signal mask attribute determines the signal mask that will be  assigned  to  a  thread
       created  using  the  thread  attributes object attr.  If this attribute is not set, then a
       thread created using attr will inherit a copy of the creating thread's signal mask.

       For more details on signal masks, see sigprocmask(2).  For  a  description  of  a  set  of
       macros that can be used to manipulate and inspect signals sets, see sigsetops(3).

       In  the  absence  of pthread_attr_setsigmask_np() it is possible to create a thread with a
       desired signal mask as follows:

       • The creating thread uses pthread_sigmask(3) to save its current signal mask and set  its
         mask to block all signals.

       • The  new  thread is then created using pthread_create(); the new thread will inherit the
         creating thread's signal mask.

       • The new thread sets its signal mask to the desired value using pthread_sigmask(3).

       • The creating thread restores its signal mask to the original value.

       Following the above steps, there is no possibility for the new thread to receive a  signal
       before it has adjusted its signal mask to the desired value.


       sigprocmask(2), pthread_attr_init(3), pthread_sigmask(3), pthreads(7), signals(7)


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