1/* Profile PC and write result to FIFO.
2 Copyright (C) 1999-2016 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1999.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <http://www.gnu.org/licenses/>. */
19
20#include <errno.h>
21#include <fcntl.h>
22#include <stdint.h>
23#include <stdlib.h>
24#include <unistd.h>
25#include <libc-internal.h>
26
27/* Nonzero if we are actually doing something. */
28static int active;
29
30/* The file descriptor of the FIFO. */
31static int fd;
32
33
34static void
35__attribute__ ((constructor))
36install (void)
37{
38 /* See whether the environment variable `PCPROFILE_OUTPUT' is defined.
39 If yes, it should name a FIFO. We open it and mark ourself as active. */
40 const char *outfile = getenv ("PCPROFILE_OUTPUT");
41
42 if (outfile != NULL && *outfile != '\0')
43 {
44 fd = open (outfile, O_RDWR | O_CREAT, 0666);
45
46 if (fd != -1)
47 {
48 uint32_t word;
49
50 active = 1;
51
52 /* Write a magic word which tells the reader about the byte
53 order and the size of the following entries. */
54 word = 0xdeb00000 | sizeof (void *);
55 if (TEMP_FAILURE_RETRY (write (fd, &word, 4)) != 4)
56 {
57 /* If even this fails we shouldn't try further. */
58 close (fd);
59 fd = -1;
60 active = 0;
61 }
62 }
63 }
64}
65
66
67static void
68__attribute__ ((destructor))
69uninstall (void)
70{
71 if (active)
72 close (fd);
73}
74
75
76void
77__cyg_profile_func_enter (void *this_fn, void *call_site)
78{
79 void *buf[2];
80
81 if (! active)
82 return;
83
84 /* Now write out the current position and that of the caller. We do
85 this now, and don't cache the because we want real-time output. */
86 buf[0] = this_fn;
87 buf[1] = call_site;
88
89 write (fd, buf, sizeof buf);
90}
91/* We don't handle entry and exit differently here. */
92strong_alias (__cyg_profile_func_enter, __cyg_profile_func_exit)
93