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glibc/debug/pcprofile.c
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/* Profile PC and write result to FIFO. | |
Copyright (C) 1999-2016 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) |