text: /* Profile PC and write result to FIFO.
     Copyright (C) 1999-2015 Free Software Foundation, Inc.
     This file is part of the GNU C Library.
     Contributed by Ulrich Drepper <drepper@cygnus.com>, 1999.
  
     The GNU C Library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Lesser General Public
     License as published by the Free Software Foundation; either
     version 2.1 of the License, or (at your option) any later version.
  
     The GNU C Library is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Lesser General Public License for more details.
  
     You should have received a copy of the GNU Lesser General Public
     License along with the GNU C Library; if not, see
     <http://www.gnu.org/licenses/>.  */
  
  #include <errno.h>
  #include <fcntl.h>
  #include <stdint.h>
  #include <stdlib.h>
  #include <unistd.h>
  #include <libc-internal.h>
  
  /* Nonzero if we are actually doing something.  */
  static int active;
  
  /* The file descriptor of the FIFO.  */
  static int fd;
  
  
  static void
  __attribute__ ((constructor))
  install (void)
  {
    /* See whether the environment variable `PCPROFILE_OUTPUT' is defined.
       If yes, it should name a FIFO.  We open it and mark ourself as active.  */
    const char *outfile = getenv ("PCPROFILE_OUTPUT");
  
    if (outfile != NULL && *outfile != '\0')
      {
        fd = open (outfile, O_RDWR | O_CREAT, 0666);
  
        if (fd != -1)
  	{
  	  uint32_t word;
  
  	  active = 1;
  
  	  /* Write a magic word which tells the reader about the byte
  	     order and the size of the following entries.  */
  	  word = 0xdeb00000 | sizeof (void *);
  	  if (TEMP_FAILURE_RETRY (write (fd, &word, 4)) != 4)
  	    {
  	      /* If even this fails we shouldn't try further.  */
  	      close (fd);
  	      fd = -1;
  	      active = 0;
  	    }
  	}
      }
  }
  
  
  static void
  __attribute__ ((destructor))
  uninstall (void)
  {
    if (active)
      close (fd);
  }
  
  
  void
  __cyg_profile_func_enter (void *this_fn, void *call_site)
  {
    void *buf[2];
  
    if (! active)
      return;
  
    /* Now write out the current position and that of the caller.  We do
       this now, and don't cache the because we want real-time output.  */
    buf[0] = this_fn;
    buf[1] = call_site;
  
    write (fd, buf, sizeof buf);
  }
  /* We don't handle entry and exit differently here.  */
  strong_alias (__cyg_profile_func_enter, __cyg_profile_func_exit)
  