Add WebRTC code freshness version string.

This CL adds a string to the resulting WebRTC library (trying to make
sure the version string will be there no matter how WebRTC is packaged).

This CL should be followed by some process to regularly and
automatically update the version string.

No-Try: True
No-Presubmit: True
Bug: webrtc:12159
Change-Id: I9143aeae2cd54d0d4048c138772888100d7873cb
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/191223
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32825}

BUILD.gn

@@ -88,6 +88,9 @@ if (!build_with_chromium) {
         ]
       }
     }
+    if (target_os == "android") {
+      deps += [ "tools_webrtc:binary_version_check" ]
+    }
   }
 }
 

call/BUILD.gn

@@ -8,6 +8,14 @@
 
 import("../webrtc.gni")
 
+rtc_library("version") {
+  sources = [
+    "version.cc",
+    "version.h",
+  ]
+  visibility = [ ":*" ]
+}
+
 rtc_library("call_interfaces") {
   sources = [
     "audio_receive_stream.cc",
@@ -254,6 +262,7 @@ rtc_library("call") {
     ":rtp_receiver",
     ":rtp_sender",
     ":simulated_network",
+    ":version",
     ":video_stream_api",
     "../api:array_view",
     "../api:callfactory_api",

call/call.cc

@@ -31,6 +31,7 @@
 #include "call/receive_time_calculator.h"
 #include "call/rtp_stream_receiver_controller.h"
 #include "call/rtp_transport_controller_send.h"
+#include "call/version.h"
 #include "logging/rtc_event_log/events/rtc_event_audio_receive_stream_config.h"
 #include "logging/rtc_event_log/events/rtc_event_rtcp_packet_incoming.h"
 #include "logging/rtc_event_log/events/rtc_event_rtp_packet_incoming.h"
@@ -624,6 +625,10 @@ Call::Call(Clock* clock,
   RTC_DCHECK(config.trials != nullptr);
   RTC_DCHECK(worker_thread_->IsCurrent());
 
+  // Do not remove this call; it is here to convince the compiler that the
+  // WebRTC source timestamp string needs to be in the final binary.
+  LoadWebRTCVersionInRegister();
+
   call_stats_->RegisterStatsObserver(&receive_side_cc_);
 
   module_process_thread_->process_thread()->RegisterModule(

call/version.cc

@@ -0,0 +1,25 @@
+/*
+ *  Copyright (c) 2020 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "call/version.h"
+
+namespace webrtc {
+
+// The timestamp is always in UTC.
+const char* const kSourceTimestamp = "WebRTC source stamp 2020-12-14T14:30:00";
+
+void LoadWebRTCVersionInRegister() {
+  // Using volatile to instruct the compiler to not optimize `p` away even
+  // if it looks unused.
+  const char* volatile p = kSourceTimestamp;
+  static_cast<void>(p);
+}
+
+}  // namespace webrtc

call/version.h

@@ -0,0 +1,25 @@
+/*
+ *  Copyright (c) 2020 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef CALL_VERSION_H_
+#define CALL_VERSION_H_
+
+// LoadWebRTCVersionInRegistry is a helper function that loads the pointer to
+// the WebRTC version string into a register. While this function doesn't do
+// anything useful, it is needed in order to avoid that compiler optimizations
+// remove the WebRTC version string from the final binary.
+
+namespace webrtc {
+
+void LoadWebRTCVersionInRegister();
+
+}  // namespace webrtc
+
+#endif  // CALL_VERSION_H_

tools_webrtc/BUILD.gn

@@ -0,0 +1,18 @@
+# Copyright (c) 2020 The WebRTC project authors. All Rights Reserved.
+#
+# Use of this source code is governed by a BSD-style license
+# that can be found in the LICENSE file in the root of the source
+# tree. An additional intellectual property rights grant can be found
+# in the file PATENTS.  All contributing project authors may
+# be found in the AUTHORS file in the root of the source tree.
+
+if (target_os == "android") {
+  action("binary_version_check") {
+    testonly = true
+    script = "binary_version_check.py"
+    deps = [ "../sdk/android:libjingle_peerconnection_so" ]
+    inputs = [ "$root_out_dir/libjingle_peerconnection_so.so" ]
+    outputs = [ "$root_out_dir/webrtc_binary_version_check" ]
+    args = [ "libjingle_peerconnection_so.so" ]
+  }
+}

tools_webrtc/binary_version_check.py

@@ -0,0 +1,34 @@
+# Copyright (c) 2020 The WebRTC project authors. All Rights Reserved.
+#
+# Use of this source code is governed by a BSD-style license
+# that can be found in the LICENSE file in the root of the source
+# tree. An additional intellectual property rights grant can be found
+# in the file PATENTS.  All contributing project authors may
+# be found in the AUTHORS file in the root of the source tree.
+
+import re
+import subprocess
+import sys
+
+WEBRTC_VERSION_RE = re.compile(
+    r'WebRTC source stamp [0-9]{4}-[0-9]{2}-[0-9]{2}T[0-9]{2}:[0-9]{2}:[0-9]{2}'
+)
+
+
+if __name__ == '__main__':
+    args = sys.argv
+    if len(args) != 2:
+        print('Usage: binary_version_test.py <FILE_NAME>')
+        exit(1)
+    filename = sys.argv[1]
+    output = subprocess.check_output(['strings', filename])
+    strings_in_binary = output.decode('utf-8').splitlines()
+    for symbol in strings_in_binary:
+        if WEBRTC_VERSION_RE.match(symbol):
+            with open('webrtc_binary_version_check', 'w') as f:
+                f.write(symbol)
+            exit(0)
+    print('WebRTC source timestamp not found in "%s"' % filename)
+    print('Check why "kSourceTimestamp" from call/version.cc is not linked '
+          '(or why it has been optimized away by the compiler/linker)')
+    exit(1)

tools_webrtc/version_updater/update_version.py

@@ -0,0 +1,153 @@
+#!/usr/bin/env python
+# Copyright (c) 2020 The WebRTC project authors. All Rights Reserved.
+#
+# Use of this source code is governed by a BSD-style license
+# that can be found in the LICENSE file in the root of the source
+# tree. An additional intellectual property rights grant can be found
+# in the file PATENTS.  All contributing project authors may
+# be found in the AUTHORS file in the root of the source tree.
+
+"""Script to auto-update the WebRTC source version in call/version.cc"""
+
+import argparse
+import datetime
+import logging
+import os
+import re
+import subprocess
+import sys
+
+
+def FindSrcDirPath():
+    """Returns the abs path to the src/ dir of the project."""
+    src_dir = os.path.dirname(os.path.abspath(__file__))
+    while os.path.basename(src_dir) != 'src':
+        src_dir = os.path.normpath(os.path.join(src_dir, os.pardir))
+    return src_dir
+
+
+UPDATE_BRANCH_NAME = 'webrtc_version_update'
+CHECKOUT_SRC_DIR = FindSrcDirPath()
+
+
+def _RemovePreviousUpdateBranch():
+    active_branch, branches = _GetBranches()
+    if active_branch == UPDATE_BRANCH_NAME:
+        active_branch = 'master'
+    if UPDATE_BRANCH_NAME in branches:
+        logging.info('Removing previous update branch (%s)',
+                     UPDATE_BRANCH_NAME)
+        subprocess.check_call(['git', 'checkout', active_branch])
+        subprocess.check_call(['git', 'branch', '-D', UPDATE_BRANCH_NAME])
+    logging.info('No branch to remove')
+
+
+def _GetBranches():
+    """Returns a tuple (active, branches).
+
+    'active' is a string with name of the currently active branch, while
+     'branches' is the list of all branches.
+    """
+    lines = subprocess.check_output(['git', 'branch']).splitlines()
+    branches = []
+    active = ''
+    for line in lines:
+        if '*' in line:
+            # The assumption is that the first char will always be the '*'.
+            active = line[1:].strip()
+            branches.append(active)
+        else:
+            branch = line.strip()
+            if branch:
+                branches.append(branch)
+    return active, branches
+
+
+def _CreateUpdateBranch():
+    logging.info('Creating update branch: %s', UPDATE_BRANCH_NAME)
+    subprocess.check_call(['git', 'checkout', '-b', UPDATE_BRANCH_NAME])
+
+
+def _UpdateWebRTCVersion(filename):
+    with open(filename) as f:
+        content = f.read()
+    d = datetime.datetime.utcnow()
+    # pylint: disable=line-too-long
+    new_content = re.sub(
+        r'WebRTC source stamp [0-9]{4}-[0-9]{2}-[0-9]{2}T[0-9]{2}:[0-9]{2}:[0-9]{2}',
+        r'WebRTC source stamp %02d-%02d-%02dT%02d:%02d:%02d' % (d.year,
+                                                                d.month,
+                                                                d.day,
+                                                                d.hour,
+                                                                d.minute,
+                                                                d.second),
+        content,
+        flags=re.MULTILINE)
+    # pylint: enable=line-too-long
+    with open(filename, 'w') as f:
+        f.write(new_content)
+
+
+def _IsTreeClean():
+    stdout = subprocess.check_output(['git', 'status', '--porcelain'])
+    if len(stdout) == 0:
+        return True
+    return False
+
+
+def _LocalCommit():
+    logging.info('Committing changes locally.')
+    d = datetime.datetime.utcnow()
+    commit_msg = ('Update WebRTC code version (%02d-%02d-%02dT%02d:%02d:%02d).'
+                  '\n\nBugs: None')
+    commit_msg = commit_msg % (d.year, d.month, d.day, d.hour, d.minute,
+                               d.second)
+    subprocess.check_call(['git', 'add', '--update', '.'])
+    subprocess.check_call(['git', 'commit', '-m', commit_msg])
+
+
+def _UploadCL(commit_queue_mode):
+    """Upload the committed changes as a changelist to Gerrit.
+
+  commit_queue_mode:
+    - 2: Submit to commit queue.
+    - 1: Run trybots but do not submit to CQ.
+    - 0: Skip CQ, upload only.
+  """
+    cmd = ['git', 'cl', 'upload', '--force', '--bypass-hooks',
+           '--cc=""', '--bypass-watchlist']
+    if commit_queue_mode >= 2:
+        logging.info('Sending the CL to the CQ...')
+        cmd.extend(['--use-commit-queue'])
+    elif commit_queue_mode >= 1:
+        logging.info('Starting CQ dry run...')
+        cmd.extend(['--cq-dry-run'])
+    subprocess.check_call(cmd)
+
+
+def main():
+    logging.basicConfig(level=logging.INFO)
+    p = argparse.ArgumentParser()
+    p.add_argument('--clean',
+                   action='store_true',
+                   default=False,
+                   help='Removes any previous local update branch.')
+    opts = p.parse_args()
+
+    if opts.clean:
+        _RemovePreviousUpdateBranch()
+
+    version_filename = os.path.join(CHECKOUT_SRC_DIR, 'call', 'version.cc')
+    _CreateUpdateBranch()
+    _UpdateWebRTCVersion(version_filename)
+    if _IsTreeClean():
+        logging.info("No WebRTC version change detected, skipping CL.")
+    else:
+        _LocalCommit()
+        logging.info('Uploading CL...')
+        _UploadCL(1)
+    return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main())