LinuxGuruz
  • Last 5 Forum Topics
    Replies
    Views
    Last post


The Web Only This Site
  • BOOKMARK

  • ADD TO FAVORITES

  • REFERENCES


  • MARC

    Mailing list ARChives
    - Search by -
     Subjects
     Authors
     Bodies





    FOLDOC

    Computing Dictionary




  • Text Link Ads






  • LINUX man pages
  • Linux Man Page Viewer


    The following form allows you to view linux man pages.

    Command:

    makecontext

    
    
    
    

    SYNOPSIS

           #include <ucontext.h>
    
           void makecontext(ucontext_t *ucp, void (*func)(), int argc, ...);
    
           int swapcontext(ucontext_t *oucp, ucontext_t *ucp);
    
    
    

    DESCRIPTION

           In  a System V-like environment, one has the type ucontext_t defined in
           <ucontext.h> and the four functions getcontext(3), setcontext(3), make-
           context()  and  swapcontext()  that  allow user-level context switching
           between multiple threads of control within a process.
    
           For the type and the first two functions, see getcontext(3).
    
           The makecontext() function modifies  the  context  pointed  to  by  ucp
           (which  was  obtained  from  a call to getcontext(3)).  Before invoking
           makecontext(), the caller must allocate a new stack  for  this  context
           and assign its address to ucp->uc_stack, and define a successor context
           and assign its address to ucp->uc_link.
    
           When this context is later activated (using setcontext(3)  or  swapcon-
           text())  the  function func is called, and passed the series of integer
           (int) arguments that follow argc; the caller must specify the number of
           these  arguments  in  argc.   When this function returns, the successor
           context is activated.  If the successor context pointer  is  NULL,  the
           thread exits.
    
           The  swapcontext()  function saves the current context in the structure
           pointed to by oucp, and then activates the context pointed to by ucp.
    
    
    

    RETURN VALUE

           When successful, swapcontext() does not return.   (But  we  may  return
           later,  in case oucp is activated, in which case it looks like swapcon-
           text() returns 0.)  On error, swapcontext() returns -1 and  sets  errno
           appropriately.
    
    
    

    ERRORS

           ENOMEM Insufficient stack space left.
    
    
    

    VERSIONS

           makecontext()  and  swapcontext()  are  provided in glibc since version
           2.1.
    
    
    

    CONFORMING TO

           SUSv2, POSIX.1-2001.  POSIX.1-2008 removes the specifications of  make-
           context()  and swapcontext(), citing portability issues, and recommend-
           ing that applications be rewritten to use POSIX threads instead.
    
    
    

    NOTES

           The interpretation of  ucp->uc_stack  is  just  as  in  sigaltstack(2),
    
    
    

    EXAMPLE

           The  example program below demonstrates the use of getcontext(3), make-
           context(), and swapcontext().  Running the program produces the follow-
           ing output:
    
               $ ./a.out
               main: swapcontext(&uctx_main, &uctx_func2)
               func2: started
               func2: swapcontext(&uctx_func2, &uctx_func1)
               func1: started
               func1: swapcontext(&uctx_func1, &uctx_func2)
               func2: returning
               func1: returning
               main: exiting
    
       Program source
    
           #include <ucontext.h>
           #include <stdio.h>
           #include <stdlib.h>
    
           static ucontext_t uctx_main, uctx_func1, uctx_func2;
    
           #define handle_error(msg) \
               do { perror(msg); exit(EXIT_FAILURE); } while (0)
    
           static void
           func1(void)
           {
               printf("func1: started\n");
               printf("func1: swapcontext(&uctx_func1, &uctx_func2)\n");
               if (swapcontext(&uctx_func1, &uctx_func2) == -1)
                   handle_error("swapcontext");
               printf("func1: returning\n");
           }
    
           static void
           func2(void)
           {
               printf("func2: started\n");
               printf("func2: swapcontext(&uctx_func2, &uctx_func1)\n");
               if (swapcontext(&uctx_func2, &uctx_func1) == -1)
                   handle_error("swapcontext");
               printf("func2: returning\n");
           }
    
           int
           main(int argc, char *argv[])
           {
               char func1_stack[16384];
               char func2_stack[16384];
    
    
               printf("main: swapcontext(&uctx_main, &uctx_func2)\n");
               if (swapcontext(&uctx_main, &uctx_func2) == -1)
                   handle_error("swapcontext");
    
               printf("main: exiting\n");
               exit(EXIT_SUCCESS);
           }
    
    
    

    SEE ALSO

           sigaction(2),     sigaltstack(2),     sigprocmask(2),    getcontext(3),
           sigsetjmp(3)
    
    
    

    GNU 2013-02-12 MAKECONTEXT(3)

    
    
  • MORE RESOURCE


  • Linux

    The Distributions





    Linux

    The Software





    Linux

    The News



  • MARKETING






  • Toll Free

webmaster@linuxguruz.com
Copyright © 1999 - 2016 by LinuxGuruz