tools/syz-declextract: extract file_operations descriptions

Extend the clang tool to locate file_operations variables and arrays
and dump open/read/write/mmap/ioctl callbacks for each.
It also tries to extract set of ioctl commands and argument types
for them in a simple best-effort way (for now). It just locates switch
in the ioctl callback and extracts each case as a command.

3 files changed, 50 insertions, 0 deletions

diff --git a/tools/syz-declextract/testdata/include/fs.h b/tools/syz-declextract/testdata/include/fs.h
new file mode 100644
index 000000000..a5c838595
--- /dev/null
+++ b/tools/syz-declextract/testdata/include/fs.h
@@ -0,0 +1,12 @@
+// Copyright 2024 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+struct file_operations {
+	void (*open)(void);
+	void (*read)(void);
+	void (*write)(void);
+	void (*read_iter)(void);
+	void (*write_iter)(void);
+	void (*unlocked_ioctl)(unsigned int);
+	void (*mmap)(void);
+};
diff --git a/tools/syz-declextract/testdata/include/uapi/file_operations.h b/tools/syz-declextract/testdata/include/uapi/file_operations.h
new file mode 100644
index 000000000..6a2a8d259
--- /dev/null
+++ b/tools/syz-declextract/testdata/include/uapi/file_operations.h
@@ -0,0 +1,14 @@
+// Copyright 2024 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+#include "ioctl.h"
+
+#define FOO_IOCTL1		_IO('c', 1)
+#define FOO_IOCTL2		_IOR('c', 2, int)
+#define FOO_IOCTL3		_IOR('c', 3, struct foo_ioctl_arg)
+#define FOO_IOCTL4		_IOW('c', 4, struct foo_ioctl_arg)
+#define FOO_IOCTL5		_IOWR('c', 5, struct foo_ioctl_arg)
+
+struct foo_ioctl_arg {
+	int a, b;
+};
diff --git a/tools/syz-declextract/testdata/include/uapi/ioctl.h b/tools/syz-declextract/testdata/include/uapi/ioctl.h
new file mode 100644
index 000000000..fae14a74e
--- /dev/null
+++ b/tools/syz-declextract/testdata/include/uapi/ioctl.h
@@ -0,0 +1,24 @@
+// Copyright 2024 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+#define _IOC_NONE	0U
+#define _IOC_WRITE	1U
+#define _IOC_READ	2U
+
+#define _IOC_NRBITS	8
+#define _IOC_TYPEBITS	8
+#define _IOC_SIZEBITS	14
+#define _IOC_DIRBITS	2
+
+#define _IOC_NRSHIFT	0
+#define _IOC_TYPESHIFT	(_IOC_NRSHIFT+_IOC_NRBITS)
+#define _IOC_SIZESHIFT	(_IOC_TYPESHIFT+_IOC_TYPEBITS)
+#define _IOC_DIRSHIFT	(_IOC_SIZESHIFT+_IOC_SIZEBITS)
+
+#define _IOC(dir, type, nr, size) (((dir)  << _IOC_DIRSHIFT) | ((type) << _IOC_TYPESHIFT) | \
+	 ((nr)   << _IOC_NRSHIFT) | ((size) << _IOC_SIZESHIFT))
+
+#define _IO(type, nr)		_IOC(_IOC_NONE, (type), (nr), 0)
+#define _IOR(type, nr, arg)	_IOC(_IOC_READ, (type), (nr), (sizeof(arg)))
+#define _IOW(type, nr, arg)	_IOC(_IOC_WRITE, (type), (nr), (sizeof(arg)))
+#define _IOWR(type, nr, arg)	_IOC(_IOC_READ|_IOC_WRITE, (type), (nr), (sizeof(arg)))