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1 | /* gprof-helper.c -- preload library to profile pthread-enabled programs |
2 | * | |
3 | * Authors: Sam Hocevar <sam at zoy dot org> | |
4 | * Daniel Jönsson <danieljo at fagotten dot org> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the Do What The Fuck You Want To | |
8 | * Public License as published by Banlu Kemiyatorn. See | |
9 | * http://sam.zoy.org/projects/COPYING.WTFPL for more details. | |
10 | * | |
11 | * Compilation example: | |
12 | * gcc -shared -fPIC gprof-helper.c -o gprof-helper.so -lpthread -ldl | |
13 | * | |
14 | * Usage example: | |
15 | * LD_PRELOAD=./gprof-helper.so your_program | |
16 | */ | |
17 | ||
18 | #include <sys/time.h> | |
19 | #include <stdio.h> | |
20 | #include <stdlib.h> | |
21 | #include <dlfcn.h> | |
22 | #include <pthread.h> | |
23 | ||
24 | static void * wrapper_routine(void *); | |
25 | ||
26 | /* Original pthread function */ | |
27 | static int (*pthread_create_orig)(pthread_t *__restrict, | |
28 | __const pthread_attr_t *__restrict, | |
29 | void *(*)(void *), | |
30 | void *__restrict) = NULL; | |
31 | ||
32 | /* Library initialization function */ | |
33 | void wooinit(void) __attribute__((constructor)); | |
34 | ||
35 | void wooinit(void) | |
36 | { | |
37 | pthread_create_orig = dlsym(RTLD_NEXT, "pthread_create"); | |
38 | fprintf(stderr, "pthreads: using profiling hooks for gprof\n"); | |
39 | if(pthread_create_orig == NULL) | |
40 | { | |
41 | char *error = dlerror(); | |
42 | if(error == NULL) | |
43 | { | |
44 | error = "pthread_create is NULL"; | |
45 | } | |
46 | fprintf(stderr, "%s\n", error); | |
47 | exit(EXIT_FAILURE); | |
48 | } | |
49 | } | |
50 | ||
51 | /* Our data structure passed to the wrapper */ | |
52 | typedef struct wrapper_s | |
53 | { | |
54 | void * (*start_routine)(void *); | |
55 | void * arg; | |
56 | ||
57 | pthread_mutex_t lock; | |
58 | pthread_cond_t wait; | |
59 | ||
60 | struct itimerval itimer; | |
61 | ||
62 | } wrapper_t; | |
63 | ||
64 | /* The wrapper function in charge for setting the itimer value */ | |
65 | static void * wrapper_routine(void * data) | |
66 | { | |
67 | /* Put user data in thread-local variables */ | |
68 | void * (*start_routine)(void *) = ((wrapper_t*)data)->start_routine; | |
69 | void * arg = ((wrapper_t*)data)->arg; | |
70 | ||
71 | /* Set the profile timer value */ | |
72 | setitimer(ITIMER_PROF, &((wrapper_t*)data)->itimer, NULL); | |
73 | ||
74 | /* Tell the calling thread that we don't need its data anymore */ | |
75 | pthread_mutex_lock(&((wrapper_t*)data)->lock); | |
76 | pthread_cond_signal(&((wrapper_t*)data)->wait); | |
77 | pthread_mutex_unlock(&((wrapper_t*)data)->lock); | |
78 | ||
79 | /* Call the real function */ | |
80 | return start_routine(arg); | |
81 | } | |
82 | ||
83 | /* Our wrapper function for the real pthread_create() */ | |
84 | int pthread_create(pthread_t *__restrict thread, | |
85 | __const pthread_attr_t *__restrict attr, | |
86 | void * (*start_routine)(void *), | |
87 | void *__restrict arg) | |
88 | { | |
89 | wrapper_t wrapper_data; | |
90 | int i_return; | |
91 | ||
92 | /* Initialize the wrapper structure */ | |
93 | wrapper_data.start_routine = start_routine; | |
94 | wrapper_data.arg = arg; | |
95 | getitimer(ITIMER_PROF, &wrapper_data.itimer); | |
96 | pthread_cond_init(&wrapper_data.wait, NULL); | |
97 | pthread_mutex_init(&wrapper_data.lock, NULL); | |
98 | pthread_mutex_lock(&wrapper_data.lock); | |
99 | ||
100 | /* The real pthread_create call */ | |
101 | i_return = pthread_create_orig(thread, | |
102 | attr, | |
103 | &wrapper_routine, | |
104 | &wrapper_data); | |
105 | ||
106 | /* If the thread was successfully spawned, wait for the data | |
107 | * to be released */ | |
108 | if(i_return == 0) | |
109 | { | |
110 | pthread_cond_wait(&wrapper_data.wait, &wrapper_data.lock); | |
111 | } | |
112 | ||
113 | pthread_mutex_unlock(&wrapper_data.lock); | |
114 | pthread_mutex_destroy(&wrapper_data.lock); | |
115 | pthread_cond_destroy(&wrapper_data.wait); | |
116 | ||
117 | return i_return; | |
118 | } | |
119 |