/* Profile PC and write result to FIFO.

   Copyright (C) 1999-2018 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>

/* 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)