commit 76ac1acdacc045cf1e56504e011dca68137dcd61
author Dmitriy Ivanov <dimitry@google.com> Wed Apr 01 14:45:10 2015 -0700
committer Dmitriy Ivanov <dimitry@google.com> Thu Apr 02 14:12:45 2015 -0700
tree 9eb3bee0f92ae74f1eba59efad4c037d50aa3dcd
parent ab7c79e22e5495a2aa171047a044ce1037e461a9

Look into local group on dlsym with RTLD_DEFAULT

  Fix dlsym to look into local group when called with
  RTLD_DEFAULT and RTLD_NEXT.

Bug: 17512583
Change-Id: I541354e89539c712af2ea4ec751e546913027084

linker/dlfcn.cpp

diff --git a/linker/dlfcn.cpp b/linker/dlfcn.cpp
index 64df7a5..479e831 100644
--- a/linker/dlfcn.cpp
+++ b/linker/dlfcn.cpp
@@ -101,16 +101,11 @@
 
   soinfo* found = nullptr;
   ElfW(Sym)* sym = nullptr;
-  if (handle == RTLD_DEFAULT) {
-    sym = dlsym_linear_lookup(symbol, &found, nullptr);
-  } else if (handle == RTLD_NEXT) {
-    void* caller_addr = __builtin_return_address(0);
-    soinfo* si = find_containing_library(caller_addr);
+  void* caller_addr = __builtin_return_address(0);
+  soinfo* caller = find_containing_library(caller_addr);
 
-    sym = nullptr;
-    if (si && si->next) {
-      sym = dlsym_linear_lookup(symbol, &found, si->next);
-    }
+  if (handle == RTLD_DEFAULT || handle == RTLD_NEXT) {
+    sym = dlsym_linear_lookup(symbol, &found, caller, handle);
   } else {
     sym = dlsym_handle_lookup(reinterpret_cast<soinfo*>(handle), &found, symbol);
   }

linker/linker.cpp

diff --git a/linker/linker.cpp b/linker/linker.cpp
index ebf125e..002a4f9 100644
--- a/linker/linker.cpp
+++ b/linker/linker.cpp
@@ -738,15 +738,21 @@
    beginning of the global solist. Otherwise the search starts at the
    specified soinfo (for RTLD_NEXT).
  */
-ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start) {
+ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* caller, void* handle) {
   SymbolName symbol_name(name);
 
-  if (start == nullptr) {
-    start = solist;
+  soinfo* start = solist;
+
+  if (handle == RTLD_NEXT) {
+    if (caller == nullptr || caller->next == nullptr) {
+      return nullptr;
+    } else {
+      start = caller->next;
+    }
   }
 
   ElfW(Sym)* s = nullptr;
-  for (soinfo* si = start; (s == nullptr) && (si != nullptr); si = si->next) {
+  for (soinfo* si = start; si != nullptr; si = si->next) {
     if ((si->get_rtld_flags() & RTLD_GLOBAL) == 0) {
       continue;
     }
@@ -758,6 +764,30 @@
     }
   }
 
+  // If not found - look into local_group unless
+  // caller is part of the global group in which
+  // case we already did it.
+  if (s == nullptr && caller != nullptr &&
+      (caller->get_rtld_flags() & RTLD_GLOBAL) == 0) {
+    soinfo* local_group_root = caller->get_local_group_root();
+
+    if (handle == RTLD_DEFAULT) {
+      start = local_group_root;
+    }
+
+    for (soinfo* si = start; si != nullptr; si = si->next) {
+      if (si->get_local_group_root() != local_group_root) {
+        break;
+      }
+
+      s = si->find_symbol_by_name(symbol_name);
+      if (s != nullptr) {
+        *found = si;
+        break;
+      }
+    }
+  }
+
   if (s != nullptr) {
     TRACE_TYPE(LOOKUP, "%s s->st_value = %p, found->base = %p",
                name, reinterpret_cast<void*>(s->st_value), reinterpret_cast<void*>((*found)->base));

linker/linker.h

diff --git a/linker/linker.h b/linker/linker.h
index bf3e7bf..ec3d8f0 100644
--- a/linker/linker.h
+++ b/linker/linker.h
@@ -351,7 +351,7 @@
 soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo);
 void do_dlclose(soinfo* si);
 
-ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start);
+ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* caller, void* handle);
 soinfo* find_containing_library(const void* addr);
 
 ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* name);