Move to using build-ids to tell GDB about libraries

sky/tools/update_build_id_tree.py

Index: sky/tools/update_build_id_tree.py
diff --git a/sky/tools/update_build_id_tree.py b/sky/tools/update_build_id_tree.py
new file mode 100755
index 0000000000000000000000000000000000000000..20ec3078f74006faec741d6c063c39d90599f1c2
--- /dev/null
+++ b/sky/tools/update_build_id_tree.py
@@ -0,0 +1,66 @@
+#!/usr/bin/env python
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import argparse
+import logging
+import os
+import sys
+import subprocess
+import shutil
+
+DEVNULL = open(os.devnull, 'w')
+
+def build_id_for_file(path):
+    # example output:
+    # 0+0x85e00 0ed038fdb09b296634d98e25f1f598bc4aa8fca8@0x178 png_viewer.mojo -
+    try:
+        eu_unstrip_cmd = ['eu-unstrip', '-n', '-e', path]
+        output = subprocess.check_output(eu_unstrip_cmd, stderr=DEVNULL)
+        return output.split(' ')[1].split('@')[0]
+    except subprocess.CalledProcessError, e:
+        return None
+
+
+# TODO(eseidel): This belongs as part of of the build system!
+def main():
+    logging.basicConfig(level=logging.INFO)
+    parser = argparse.ArgumentParser(
+        description='Populates a .build-id lookup tree for gdb')
+    parser.add_argument('build_dir', type=str)
+    args = parser.parse_args()
+
+    build_dir = os.path.realpath(args.build_dir)
+    if not os.path.isdir(build_dir):
+        logging.fatal('build_dir: %s is not a directory' % args.build_dir)
+        sys.exit(1)
+
+    build_id_dir = os.path.join(build_dir, '.build-id')
+    if os.path.exists(build_id_dir):
+        shutil.rmtree(build_id_dir)
+
+    for name in os.listdir(build_dir):
+        path = os.path.join(build_dir, name)
+        _, ext = os.path.splitext(name)
+        # Don't try to link both .mojo and .so as they have the same build-id.
+        if ext not in ('', '.so'):
+            continue
+        build_id = build_id_for_file(path)
+        if not build_id:
+            continue
+        # Expected location for binary with for build-id adbcdef123456 is:
+        # $BUILD/.build_id/ab/cdef123456.debug:
+        # https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html
+        build_id_path = os.path.join(build_id_dir,
+            build_id[:2], '%s.debug' % build_id[2:])
+        print build_id, build_id_path
+        print "%s -> %s" % (build_id_path, path)
+        shard_dir = os.path.dirname(build_id_path)
+        if not os.path.exists(shard_dir):
+            os.makedirs(shard_dir)
+        os.symlink(path, build_id_path)
+
+
+if __name__ == '__main__':
+    main()