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. */ |
28 | static int active; |
29 | |
30 | /* The file descriptor of the FIFO. */ |
31 | static int fd; |
32 | |
33 | |
34 | static void |
35 | __attribute__ ((constructor)) |
36 | install (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 | |
67 | static void |
68 | __attribute__ ((destructor)) |
69 | uninstall (void) |
70 | { |
71 | if (active) |
72 | close (fd); |
73 | } |
74 | |
75 | |
76 | void |
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. */ |
92 | strong_alias (__cyg_profile_func_enter, __cyg_profile_func_exit) |
93 | |