X-Git-Url: https://git.liburcu.org/?a=blobdiff_plain;f=libustfork%2Fustfork.c;fp=libustfork%2Fustfork.c;h=ecc39e38ca78c3e413de26da20c99367b2c50554;hb=e8300fb7111bd3686d8b863db0c661ae491ee6ae;hp=0000000000000000000000000000000000000000;hpb=761547672693a192995b72ad69b41d079636de3a;p=ust.git

diff --git a/libustfork/ustfork.c b/libustfork/ustfork.c
new file mode 100644
index 0000000..ecc39e3
--- /dev/null
+++ b/libustfork/ustfork.c
@@ -0,0 +1,143 @@
+/* Copyright (C) 2009  Pierre-Marc Fournier
+ *
+ * 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; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * 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 <ust/ust.h>
+#include <sched.h>
+#include <stdarg.h>
+#include <ust/tracectl.h>
+#include "usterr.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, "libcwrap: unable to find fork\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;
+}
+
+int execve(const char *filename, char *const argv[], char *const envp[])
+{
+	static int (*plibc_func)(const char *filename, char *const argv[], char *const envp[]) = NULL;
+
+	pid_t retval;
+
+	if(plibc_func == NULL) {
+		plibc_func = dlsym(RTLD_NEXT, "execve");
+		if(plibc_func == NULL) {
+			fprintf(stderr, "libinterfork: unable to find execve\n");
+			return -1;
+		}
+	}
+
+	ust_potential_exec();
+
+	retval = plibc_func(filename, argv, envp);
+
+	return retval;
+}
+
+struct interfork_clone_info {
+	int (*fn)(void *);
+	void *arg;
+	ust_fork_info_t fork_info;
+};
+
+static int clone_fn(void *arg)
+{
+	struct interfork_clone_info *info = (struct interfork_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;
+
+	/* varargs */
+	pid_t *ptid;
+	struct user_desc *tls;
+	pid_t *ctid;
+
+	int retval;
+
+	va_list ap;
+
+	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, "libinterfork: unable to find clone\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 interfork_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;
+}