From 2f7f4f4405d0f9fcdf3dbcbe299f00e5c3208323 Mon Sep 17 00:00:00 2001
From: Logan Chien <loganchien@google.com>
Date: Mon, 20 Feb 2017 15:57:02 +0800
Subject: [PATCH] vndk-def: Link imported symbols.

This commit resolves the library dependencies down to symbol level.  It
will traverse all undefined symbols and try to find a matching symbol
from the libraries specified in DT_NEEDED entries.  This algorithm
won't be able to find symbols for the libraries that are not built with
-Wl,--no-undefined.  Unresolved weak symbols are added to
unresolved_symbols as well.

Test: ./tests/run.py

Change-Id: I3b0f06e38f256025bb6993d5c9f3d8afc3a4bf0e
---
 .../definition-tool/tests/test_elf_linker.py  | 50 +++++++++++++++++++
 .../definition-tool/vndk_definition_tool.py   | 24 ++++++++-
 2 files changed, 73 insertions(+), 1 deletion(-)

diff --git a/vndk/tools/definition-tool/tests/test_elf_linker.py b/vndk/tools/definition-tool/tests/test_elf_linker.py
index db4c0dc30..dad176b49 100755
--- a/vndk/tools/definition-tool/tests/test_elf_linker.py
+++ b/vndk/tools/definition-tool/tests/test_elf_linker.py
@@ -163,6 +163,56 @@ class ELFLinkerTest(unittest.TestCase):
                           '/system/lib64/libdl.so'],
                          self._get_paths_from_nodes(node.deps))
 
+    def test_linked_symbols(self):
+        gb = self._create_normal_graph()
+        graph = gb.graph
+
+        # Check the unresolved symbols.
+        for lib_set in (graph.lib32, graph.lib64):
+            for lib in lib_set.values():
+                self.assertEqual(set(), lib.unresolved_symbols)
+
+        # Check the linked symbols.
+        for lib in ('lib', 'lib64'):
+            libdl = graph.map_path_to_lib('/system/' + lib + '/libdl.so')
+            libm = graph.map_path_to_lib('/system/' + lib + '/libm.so')
+            libc = graph.map_path_to_lib('/system/' + lib + '/libc.so')
+            libRS = graph.map_path_to_lib('/system/' + lib + '/libRS.so')
+            libcutils = \
+                    graph.map_path_to_lib('/system/' + lib + '/libcutils.so')
+            libEGL = graph.map_path_to_lib('/vendor/' + lib + '/libEGL.so')
+
+            # Check the linked symbols for libc.so.
+            self.assertIs(libdl, libc.linked_symbols['dlclose'])
+            self.assertIs(libdl, libc.linked_symbols['dlopen'])
+            self.assertIs(libm, libc.linked_symbols['cos'])
+            self.assertIs(libm, libc.linked_symbols['sin'])
+
+            # Check the linked symbols for libRS.so.
+            self.assertIs(libdl, libRS.linked_symbols['dlclose'])
+            self.assertIs(libdl, libRS.linked_symbols['dlopen'])
+            self.assertIs(libdl, libRS.linked_symbols['dlsym'])
+
+            # Check the linked symbols for libcutils.so.
+            self.assertIs(libdl, libcutils.linked_symbols['dlclose'])
+            self.assertIs(libdl, libcutils.linked_symbols['dlopen'])
+            self.assertIs(libc, libcutils.linked_symbols['fclose'])
+            self.assertIs(libc, libcutils.linked_symbols['fopen'])
+
+            # Check the linked symbols for libEGL.so.
+            self.assertIs(libc, libEGL.linked_symbols['fclose'])
+            self.assertIs(libc, libEGL.linked_symbols['fopen'])
+
+    def test_unresolved_symbols(self):
+        gb = GraphBuilder()
+        gb.add_lib(PT_SYSTEM, ELF.ELFCLASS64, 'libfoo', dt_needed=[],
+                   exported_symbols={'foo', 'bar'},
+                   imported_symbols={'__does_not_exist'})
+        gb.resolve()
+
+        lib = gb.graph.map_path_to_lib('/system/lib64/libfoo.so')
+        self.assertEqual({'__does_not_exist'}, lib.unresolved_symbols)
+
     def test_users(self):
         gb = self._create_normal_graph()
         graph = gb.graph
diff --git a/vndk/tools/definition-tool/vndk_definition_tool.py b/vndk/tools/definition-tool/vndk_definition_tool.py
index d44061968..c74e69b45 100755
--- a/vndk/tools/definition-tool/vndk_definition_tool.py
+++ b/vndk/tools/definition-tool/vndk_definition_tool.py
@@ -546,6 +546,8 @@ class ELFLinkData(object):
         self.deps = set()
         self.users = set()
         self.is_ndk = NDK_LIBS.is_ndk(path)
+        self.unresolved_symbols = set()
+        self.linked_symbols = dict()
 
     def add_dep(self, dst):
         self.deps.add(dst)
@@ -631,7 +633,24 @@ class ELFLinker(object):
                 if match:
                     self.add_dep(match.group(1), match.group(2))
 
+    def _find_exported_symbol(self, symbol, libs):
+        """Find the shared library with the exported symbol."""
+        for lib in libs:
+            if symbol in lib.elf.exported_symbols:
+                return lib
+        return None
+
+    def _resolve_lib_imported_symbols(self, lib, imported_libs):
+        """Resolve the imported symbols in a library."""
+        for symbol in lib.elf.imported_symbols:
+            imported_lib = self._find_exported_symbol(symbol, imported_libs)
+            if imported_lib:
+                lib.linked_symbols[symbol] = imported_lib
+            else:
+                lib.unresolved_symbols.add(symbol)
+
     def _resolve_lib_dt_needed(self, lib, resolver):
+        imported_libs = []
         for dt_needed in lib.elf.dt_needed:
             dep = resolver.resolve(dt_needed, lib.elf.dt_rpath,
                                    lib.elf.dt_runpath)
@@ -642,9 +661,12 @@ class ELFLinker(object):
                       .format(lib.path, dt_needed, candidates), file=sys.stderr)
                 continue
             lib.add_dep(dep)
+            imported_libs.append(dep)
+        return imported_libs
 
     def _resolve_lib_deps(self, lib, resolver):
-        self._resolve_lib_dt_needed(lib, resolver)
+        imported_libs = self._resolve_lib_dt_needed(lib, resolver)
+        self._resolve_lib_imported_symbols(lib, imported_libs)
 
     def _resolve_lib_set_deps(self, lib_set, resolver):
         for lib in lib_set.values():