118 lines
3.5 KiB
C
118 lines
3.5 KiB
C
/* gprof-helper.c -- preload library to profile pthread-enabled programs
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*
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* Authors: Sam Hocevar <sam at zoy dot org>
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* Daniel Jönsson <danieljo at fagotten dot org>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the Do What The Fuck You Want To
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* Public License as published by Banlu Kemiyatorn. See
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* http://sam.zoy.org/projects/COPYING.WTFPL for more details.
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*
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* Compilation example:
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* gcc -shared -nostdlib -fPIC gprof-helper.c -o gprof-helper.so -lpthread -ldl
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*
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* Usage example:
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* LD_PRELOAD=./gprof-helper.so your_program
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*/
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#define _GNU_SOURCE
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#include <sys/time.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <dlfcn.h>
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#include <pthread.h>
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static void * wrapper_routine(void *);
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/* Original pthread function */
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static int (*pthread_create_orig)(pthread_t *__restrict,
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__const pthread_attr_t *__restrict,
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void *(*)(void *),
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void *__restrict) = NULL;
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/* Library initialization function */
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void _init(void)
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{
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pthread_create_orig = dlsym(RTLD_NEXT, "pthread_create");
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fprintf(stderr, "pthreads: using profiling hooks for gprof\n");
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if(pthread_create_orig == NULL)
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{
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char *error = dlerror();
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if(error == NULL)
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{
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error = "pthread_create is NULL";
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}
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fprintf(stderr, "%s", error);
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exit(EXIT_FAILURE);
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}
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}
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/* Our data structure passed to the wrapper */
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typedef struct wrapper_s
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{
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void * (*start_routine)(void *);
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void * arg;
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pthread_mutex_t lock;
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pthread_cond_t wait;
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struct itimerval itimer;
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} wrapper_t;
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/* The wrapper function in charge for setting the itimer value */
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static void * wrapper_routine(void * data)
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{
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/* Put user data in thread-local variables */
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void * (*start_routine)(void *) = ((wrapper_t*)data)->start_routine;
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void * arg = ((wrapper_t*)data)->arg;
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/* Set the profile timer value */
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setitimer(ITIMER_PROF, &((wrapper_t*)data)->itimer, NULL);
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/* Tell the calling thread that we don't need its data anymore */
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pthread_mutex_lock(&((wrapper_t*)data)->lock);
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pthread_cond_signal(&((wrapper_t*)data)->wait);
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pthread_mutex_unlock(&((wrapper_t*)data)->lock);
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/* Call the real function */
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return start_routine(arg);
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}
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/* Our wrapper function for the real pthread_create() */
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int pthread_create(pthread_t *__restrict thread,
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__const pthread_attr_t *__restrict attr,
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void * (*start_routine)(void *),
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void *__restrict arg)
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{
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wrapper_t wrapper_data;
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int i_return;
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/* Initialize the wrapper structure */
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wrapper_data.start_routine = start_routine;
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wrapper_data.arg = arg;
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getitimer(ITIMER_PROF, &wrapper_data.itimer);
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pthread_cond_init(&wrapper_data.wait, NULL);
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pthread_mutex_init(&wrapper_data.lock, NULL);
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pthread_mutex_lock(&wrapper_data.lock);
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/* The real pthread_create call */
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i_return = pthread_create_orig(thread,
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attr,
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&wrapper_routine,
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&wrapper_data);
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/* If the thread was successfully spawned, wait for the data
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* to be released */
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if(i_return == 0)
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{
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pthread_cond_wait(&wrapper_data.wait, &wrapper_data.lock);
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}
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pthread_mutex_unlock(&wrapper_data.lock);
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pthread_mutex_destroy(&wrapper_data.lock);
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pthread_cond_destroy(&wrapper_data.wait);
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return i_return;
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}
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