library mass rename: add lttng- prefix

[ust.git] / liblttng-ust-fork / ustfork.c

diff --git a/liblttng-ust-fork/ustfork.c b/liblttng-ust-fork/ustfork.c
new file mode 100644 (file)
index 0000000..5e6acba
--- /dev/null
+++ b/liblttng-ust-fork/ustfork.c
@@ -0,0 +1,119 @@
+/*
+ * Copyright (C) 2009  Pierre-Marc Fournier
+ * Copyright (C) 2011  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 <dlfcn.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <signal.h>
+#include <sched.h>
+#include <stdarg.h>
+#include "usterr.h"
+
+#include <lttng/ust.h>
+
+struct user_desc;
+
+pid_t fork(void)
+{
+       static pid_t (*plibc_func)(void) = NULL;
+       ust_fork_info_t fork_info;
+       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");
+                       return -1;
+               }
+       }
+
+       ust_before_fork(&fork_info);
+       /* Do the real fork */
+       retval = plibc_func();
+       if (retval == 0) {
+               /* child */
+               ust_after_fork_child(&fork_info);
+       } else {
+               ust_after_fork_parent(&fork_info);
+       }
+       return retval;
+}
+
+struct ustfork_clone_info {
+       int (*fn)(void *);
+       void *arg;
+       ust_fork_info_t fork_info;
+};
+
+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->fork_info);
+       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");
+                       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.fork_info);
+               retval = plibc_func(clone_fn, child_stack, flags, &info,
+                               ptid, tls, ctid);
+               /* The child doesn't get here. */
+               ust_after_fork_parent(&info.fork_info);
+       }
+       return retval;
+}