From 6c1f8e78c9205b710be7462a08c0c13392f972ad Mon Sep 17 00:00:00 2001
From: Peter Wu <peter@lekensteyn.nl>
Date: Sun, 3 Jan 2016 22:22:38 +0100
Subject: [PATCH] dump-file.py: added

Also adds G2 and G4 from @invisiblek to the tested devices list.
---
 LICENSE      |   2 +-
 README.md    |   3 ++
 dump-file.py | 105 +++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 109 insertions(+), 1 deletion(-)
 create mode 100755 dump-file.py

diff --git a/LICENSE b/LICENSE
index 4110768..fd0f82e 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,4 +1,4 @@
-Copyright (c) 2015 Peter Wu <peter@lekensteyn.nl>
+Copyright (c) 2015, 2016 Peter Wu <peter@lekensteyn.nl>
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
diff --git a/README.md b/README.md
index df33f69..09b0d6e 100644
--- a/README.md
+++ b/README.md
@@ -10,6 +10,7 @@ Contents of this repository:
    (convenience script that uses partitions.py under the hood). By default the
    largest partitions (system, cache, cust, userdata) are not dumped though.
    This can be changed with the `--max-size` option.
+ - [dump-file.py](dump-file.py) - dumps a regular file from device.
  - [protocol.md](protocol.md) - Protocol documentation.
  - [lglaf.lua](lglaf.lua) - Wireshark dissector for LG LAF protocol.
  - [scripts/](scripts/) - Miscellaneous scripts.
@@ -32,6 +33,8 @@ Tested with:
 
  - LG G3 (D855) on 64-bit Arch Linux (Python 3.5.1, pyusb 1.0.0b2, libusb 1.0.20)
  - LG G3 (D855) on 32-bit Windows XP (Python 3.4.4, LG drivers).
+ - LG G2 (VS985).
+ - LG G4 (VS986) on Linux (Python 3.5) and Windows.
 
 ## Usage
 This tool provides an interactive shell where you can execute commands in
diff --git a/dump-file.py b/dump-file.py
new file mode 100755
index 0000000..3b42e54
--- /dev/null
+++ b/dump-file.py
@@ -0,0 +1,105 @@
+#!/usr/bin/env python
+#
+# Dumps the contents of a file.
+#
+# Copyright (C) 2016 Peter Wu <peter@lekensteyn.nl>
+# Licensed under the MIT license <http://opensource.org/licenses/MIT>.
+
+from contextlib import closing, contextmanager
+import argparse, logging, os, struct, sys
+import lglaf
+
+_logger = logging.getLogger("dump-file")
+
+def read_uint32(data, offset):
+    return struct.unpack_from('<I', data, offset)[0]
+
+def get_file_size(comm, path):
+    shell_command = b'stat -t ' + path.encode('utf8') + b'\0'
+    output = comm.call(lglaf.make_request(b'EXEC', body=shell_command))[1]
+    output = output.decode('utf8')
+    if not output.startswith(path + ' '):
+        _logger.debug("Output: %r", output)
+        raise RuntimeError("Cannot get filesize for %s" % path)
+    size_bytes = output.lstrip(path + ' ').split()[0]
+    return int(size_bytes)
+
+@contextmanager
+def laf_open_ro(comm, filename):
+    filename = filename.encode('utf8') + b'\0'
+    # Open a single file in readonly mode
+    open_cmd = lglaf.make_request(b'OPEN', body=filename)
+    open_header = comm.call(open_cmd)[0]
+    fd_num = read_uint32(open_header, 4)
+    try:
+        yield fd_num
+    finally:
+        close_cmd = lglaf.make_request(b'CLSE', args=[fd_num])
+        comm.call(close_cmd)
+
+def laf_read(comm, fd_num, offset, size):
+    """Read size bytes at the given block offset."""
+    read_cmd = lglaf.make_request(b'READ', args=[fd_num, offset, size])
+    header, response = comm.call(read_cmd)
+    # Ensure that response fd, offset and length are sane (match the request)
+    assert read_cmd[4:4+12] == header[4:4+12], "Unexpected read response"
+    assert len(response) == size
+    return response
+
+# On Linux, one bulk read returns at most 16 KiB. 32 bytes are part of the first
+# header, so remove one block size (512 bytes) to stay within that margin.
+# This ensures that whenever the USB communication gets out of sync, it will
+# always start with a message header, making recovery easier.
+MAX_BLOCK_SIZE = (16 * 1024 - 512) // 512
+BLOCK_SIZE = 512
+
+def dump_file(comm, file_fd, output_file, size):
+    with open_local_writable(output_file) as f:
+        offset = 0
+        while offset < size:
+            chunksize = min(size - offset, BLOCK_SIZE * MAX_BLOCK_SIZE)
+            data = laf_read(comm, file_fd, offset // BLOCK_SIZE, chunksize)
+            f.write(data)
+            offset += chunksize
+        _logger.info("Wrote %d bytes to %s", size, output_file)
+
+def open_local_writable(path):
+    if path == '-':
+        try: return sys.stdout.buffer
+        except: return sys.stdout
+    else:
+        return open(path, "wb")
+
+parser = argparse.ArgumentParser()
+parser.add_argument("--debug", action='store_true', help="Enable debug messages")
+parser.add_argument("file", help="File path on the device")
+parser.add_argument("output_file",
+        help="Local output file (use '-' for stdout)")
+
+def main():
+    args = parser.parse_args()
+    logging.basicConfig(format='%(asctime)s %(name)s: %(levelname)s: %(message)s',
+            level=logging.DEBUG if args.debug else logging.INFO)
+
+    comm = lglaf.autodetect_device()
+    with closing(comm):
+        lglaf.try_hello(comm)
+
+        # Be careful: a too large read size will result in a hang while LAF
+        # tries to read more data, requiring a reset.
+        size = get_file_size(comm, args.file)
+        if size > 0:
+            _logger.debug("File size is %d", size)
+            with laf_open_ro(comm, args.file) as file_fd:
+                _logger.debug("Opened fd %d for file %s", file_fd, args.file)
+                dump_file(comm, file_fd, args.output_file, size)
+        else:
+            _logger.warning("Not a file or zero size, not writing file")
+
+if __name__ == '__main__':
+    try:
+        main()
+    except OSError as e:
+        # Ignore when stdout is closed in a pipe
+        if e.errno != 32:
+            raise