/*
* Copyright (C) 2009 Pierre-Marc Fournier
* Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*
* This 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; version 2.1 of
* the License.
*
* This 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 this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#define _GNU_SOURCE
#include <lttng/ust-dlfcn.h>
#include <unistd.h>
#include <stdio.h>
#include <signal.h>
#include <sched.h>
#include <stdarg.h>
#include <errno.h>
#include <lttng/ust.h>
pid_t fork(void)
{
static pid_t (*plibc_func)(void) = NULL;
sigset_t sigset;
pid_t retval;
if (plibc_func == NULL) {
plibc_func = dlsym(RTLD_NEXT, "fork");
if (plibc_func == NULL) {
fprintf(stderr, "libustfork: unable to find \"fork\" symbol\n");
errno = ENOSYS;
return -1;
}
}
ust_before_fork(&sigset);
/* Do the real fork */
retval = plibc_func();
if (retval == 0) {
/* child */
ust_after_fork_child(&sigset);
} else {
ust_after_fork_parent(&sigset);
}
return retval;
}
int daemon(int nochdir, int noclose)
{
static int (*plibc_func)(int nochdir, int noclose) = NULL;
sigset_t sigset;
int retval;
if (plibc_func == NULL) {
plibc_func = dlsym(RTLD_NEXT, "daemon");
if (plibc_func == NULL) {
fprintf(stderr, "libustfork: unable to find \"daemon\" symbol\n");
errno = ENOSYS;
return -1;
}
}
ust_before_fork(&sigset);
/* Do the real daemon call */
retval = plibc_func(nochdir, noclose);
if (retval == 0) {
/* child, parent called _exit() directly */
ust_after_fork_child(&sigset);
} else {
/* on error in the parent */
ust_after_fork_parent(&sigset);
}
return retval;
}
#ifdef __linux__
struct user_desc;
struct ustfork_clone_info {
int (*fn)(void *);
void *arg;
sigset_t sigset;
};
static int clone_fn(void *arg)
{
struct ustfork_clone_info *info = (struct ustfork_clone_info *) arg;
/* clone is now done and we are in child */
ust_after_fork_child(&info->sigset);
return info->fn(info->arg);
}
int clone(int (*fn)(void *), void *child_stack, int flags, void *arg, ...)
{
static int (*plibc_func)(int (*fn)(void *), void *child_stack,
int flags, void *arg, pid_t *ptid,
struct user_desc *tls, pid_t *ctid) = NULL;
/* var args */
pid_t *ptid;
struct user_desc *tls;
pid_t *ctid;
/* end of var args */
va_list ap;
int retval;
va_start(ap, arg);
ptid = va_arg(ap, pid_t *);
tls = va_arg(ap, struct user_desc *);
ctid = va_arg(ap, pid_t *);
va_end(ap);
if (plibc_func == NULL) {
plibc_func = dlsym(RTLD_NEXT, "clone");
if (plibc_func == NULL) {
fprintf(stderr, "libustfork: unable to find \"clone\" symbol.\n");
errno = ENOSYS;
return -1;
}
}
if (flags & CLONE_VM) {
/*
* Creating a thread, no need to intervene, just pass on
* the arguments.
*/
retval = plibc_func(fn, child_stack, flags, arg, ptid,
tls, ctid);
} else {
/* Creating a real process, we need to intervene. */
struct ustfork_clone_info info = { .fn = fn, .arg = arg };
ust_before_fork(&info.sigset);
retval = plibc_func(clone_fn, child_stack, flags, &info,
ptid, tls, ctid);
/* The child doesn't get here. */
ust_after_fork_parent(&info.sigset);
}
return retval;
}
#elif defined (__FreeBSD__)
pid_t rfork(int flags)
{
static pid_t (*plibc_func)(void) = NULL;
sigset_t sigset;
pid_t retval;
if (plibc_func == NULL) {
plibc_func = dlsym(RTLD_NEXT, "rfork");
if (plibc_func == NULL) {
fprintf(stderr, "libustfork: unable to find \"rfork\" symbol\n");
errno = ENOSYS;
return -1;
}
}
ust_before_fork(&sigset);
/* Do the real rfork */
retval = plibc_func();
if (retval == 0) {
/* child */
ust_after_fork_child(&sigset);
} else {
ust_after_fork_parent(&sigset);
}
return retval;
}
/*
* On BSD, no need to override vfork, because it runs in the context of
* the parent, with parent waiting until execve or exit is executed in
* the child.
*/
#else
#warning "Unknown OS. You might want to ensure that fork/clone/vfork/fork handling is complete."
#endif