[PATCH 1/5] mmap_notify: new subsystem for tracking the changes of memory mappings

[Masatake YAMATO]

This subsystem is a spin-off of the mmap_cache subsystem.

The mmap_cache subsystem had two features: (1) tracking the change of
a memory mapping, and (2) maintaining the cache of memory mapping.

mmap_notify is a subsystem specialized to provide feature (2).
unwind-libdw itself has the feature (1). It needs only (2).

* mmap_notify.h: New file.
* mmap_notify.c: New file.

Signed-off-by: Masatake YAMATO <yamato at redhat.com>
---
 Makefile.am   |  2 ++
 mmap_notify.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 mmap_notify.h | 39 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 95 insertions(+)
 create mode 100644 mmap_notify.c
 create mode 100644 mmap_notify.h

diff --git a/Makefile.am b/Makefile.am
index c616e7c7..ba896db9 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -191,6 +191,8 @@ strace_SOURCES =	\
 	mknod.c		\
 	mmap_cache.c	\
 	mmap_cache.h	\
+	mmap_notify.c	\
+	mmap_notify.h	\
 	mmsghdr.c	\
 	mount.c		\
 	mpers_type.h	\
diff --git a/mmap_notify.c b/mmap_notify.c
new file mode 100644
index 00000000..57de09c3
--- /dev/null
+++ b/mmap_notify.c
@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2018 The strace developers.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "mmap_notify.h"
+
+struct mmap_notify_client {
+	mmap_notify_fn fn;
+	void *data;
+	struct mmap_notify_client *next;
+};
+
+static struct mmap_notify_client *clients;
+
+void
+mmap_notify_register_client(mmap_notify_fn fn, void * data)
+{
+	struct mmap_notify_client *client = xmalloc(sizeof(*client));
+	client->fn = fn;
+	client->data = data;
+	client->next = clients;
+	clients = client;
+}
+
+void
+mmap_notify_report (struct tcb *tcp)
+{
+	struct mmap_notify_client *client;
+
+	for (client = clients; client; client = client->next)
+		client->fn(tcp, client->data);
+}
diff --git a/mmap_notify.h b/mmap_notify.h
new file mode 100644
index 00000000..fe89bb7b
--- /dev/null
+++ b/mmap_notify.h
@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2018 The strace developers.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef STRACE_MMAP_NOTIFY_H
+#define STRACE_MMAP_NOTIFY_H
+
+#include "defs.h"
+
+typedef void (*mmap_notify_fn)(struct tcb *, void *);
+
+extern void
+mmap_notify_register_client(mmap_notify_fn, void *);
+
+extern void
+mmap_notify_report (struct tcb *);
+#endif /* !STRACE_MMAP_NOTIFY_H */
-- 
2.14.3