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/* Profile PC and write result to FIFO.
Copyright (C) 1999-2019 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
<https://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)
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