PTHREAD_SETASYNCCANCEL(3P)           SysV           PTHREAD_SETASYNCCANCEL(3P)



NAME
     pthread_setasynccancel - Enables or disables the asynchronous
     cancelability of the calling thread

SYNOPSIS
     #include <pthread.h>

     int pthread_setasynccancel (state)
     int state;

DESCRIPTION
     The pthread_setasynccancel function sets the calling thread's
     asynchronous cancelability state to that indicated by the state argument
     and returns the previous asynchronous cancelability state.

     The state argument specifies the new cancelability state; legal values
     are:

          CANCEL_ON Enables asynchronous cancellation

          CANCEL_OFF
                    Disables asynchronous cancellation

     By default, asynchronous cancelability is disabled, and general
     cancelability is enabled (see the pthread_setcancel(3P) function), which
     means that the thread can only be canceled at cancellation points.

     If you enable both asynchronous cancelability and general cancelability,
     the thread can be canceled at any time.

     If you disable general cancelability, the thread cannot be canceled; the
     state of asynchronous cancelability is ignored.

     You should not enable asynchronous cancelability if the thread is
     executing in a critical section, or is in another state that would be
     difficult or impossible to recover from (for example, if the thread is
     contending for a shared resource).

     The C standard functions that you can safely call with asynchronous
     cancelability enabled are the character handling functions, the
     mathematical functions, the string handling functions, and the abs(3C)
     function. The effect of calling any other C standard function with
     asynchronous cancelability enabled is unspecified.

     The character handling functions that you can safely call with
     asynchronous cancelability enabled are:

                      isalnum   isalpha   iscntrl    isdigit
                      isgraph   islower   isprint    ispunct
                      isspace   isupper   isxdigit   tolower
                      toupper

     The mathematical functions that you can safely call with asynchronous
     cancelability enabled are:

                           acos    asin   atan    atan2
                           cos     sin    tan     cosh
                           sinh    tanh   exp     frexp
                           ldexp   log    log10   modf
                           pow     sqrt   ceil    fabs
                           floor   fmod

     The string handling functions that you can safely call with asynchronous
     cancelability enabled are:

                      memcpy     memmove   strcpy    strncpy
                      strcat     strncat   memcmp    strcmp
                      strcoll    strncmp   strxfrm   memchr
                      strchr     strcspn   strpbrk   strrchr
                      strspn     strstr    strtok    memset
                      strerror   strlen

NOTES
     This interface is based on draft 4 of the IEEE P1003.4a standard, and
     will be changed to conform to the final version.

DIAGNOSTICS
     Upon successful completion, the previous value of the cancelability state
     is returned.  Otherwise, -1 is returned and errno is set to indicate the
     error.

ERRORS
     If the pthread_setasynccancel function fails, errno may be set to the
     following value:

     [EINVAL]  The specified state is not CANCEL_ON or CANCEL_OFF.

SEE ALSO
     pthread_cancel(3P), pthread_setcancel(3P)