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

          The pthread_attr_setsigmask_np() function returns 0 on suc-
          cess, 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 sig-
          nal 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.

               (pthread_attr_setsigmask_np()) Could not allocate mem-

          These functions are provided by glibc since version 2.32.


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          For an explanation of the terms used in this section, see
          attributes(7).  allbox; lbw30 lb lb l l l.
          Interface Attribute Value T{ pthread_attr_setsigmask_np(),
          pthread_attr_getsigmask_np() T}   Thread safety  MT-Safe

          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 creat-
          ing 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 manipu-
          late and inspect signals sets, see sigsetops(3).

          In the absence of pthread_attr_setsigmask_np() it is possi-
          ble to create a thread with a desired signal mask as fol-

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

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

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

          +o The creating thread restores its signal mask to the origi-
            nal 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)

          This page is part of release 5.10 of the Linux man-pages
          project.  A description of the project, information about
          reporting bugs, and the latest version of this page, can be
          found at

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