Add RTLD_NOLOAD support and some related changes.

* Aligned RTLD_ values with glibc for lp64
 * dlopen supports RTLD_NOLOAD flag
 * soinfo_unload calls find_library(.., RTLD_NOLOAD)
   instead of naive find_loaded_library_by_name()
 * dlopen changed to add child to caller soinfo instead
   of somain.

Bug: https://code.google.com/p/android/issues/detail?id=64069
Change-Id: I1a65f2c34f3e0edc6d2c41a2e408b58195feb640

libc/include/dlfcn.h

@@ -50,15 +50,29 @@ extern void*        dlsym(void*  handle, const char*  symbol);
 extern int          dladdr(const void* addr, Dl_info *info);
 
 enum {
+#if defined(__LP64__)
+  RTLD_NOW  = 2,
+#else
   RTLD_NOW  = 0,
+#endif
   RTLD_LAZY = 1,
 
   RTLD_LOCAL  = 0,
+#if defined(__LP64__)
+  RTLD_GLOBAL = 0x00100,
+#else
   RTLD_GLOBAL = 2,
+#endif
+  RTLD_NOLOAD = 4,
 };
 
+#if defined (__LP64__)
+#define RTLD_DEFAULT  ((void*) 0)
+#define RTLD_NEXT     ((void*) -1L)
+#else
 #define RTLD_DEFAULT  ((void*) 0xffffffff)
 #define RTLD_NEXT     ((void*) 0xfffffffe)
+#endif
 
 __END_DECLS
 

linker/dlfcn.cpp

@@ -65,10 +65,10 @@ void android_update_LD_LIBRARY_PATH(const char* ld_library_path) {
   do_android_update_LD_LIBRARY_PATH(ld_library_path);
 }
 
-void* android_dlopen_ext(const char* filename, int flags, const android_dlextinfo* extinfo)
+static void* dlopen_ext(const char* filename, int flags, const android_dlextinfo* extinfo, const void* caller_addr) {
-{
   ScopedPthreadMutexLocker locker(&g_dl_mutex);
-  soinfo* result = do_dlopen(filename, flags, extinfo);
+  soinfo* caller_soinfo = find_containing_library(caller_addr);
+  soinfo* result = do_dlopen(filename, flags, caller_soinfo, extinfo);
   if (result == NULL) {
     __bionic_format_dlerror("dlopen failed", linker_get_error_buffer());
     return NULL;
@@ -76,8 +76,14 @@ void* android_dlopen_ext(const char* filename, int flags, const android_dlextinf
   return result;
 }
 
+void* android_dlopen_ext(const char* filename, int flags, const android_dlextinfo* extinfo) {
+  void* caller_addr = __builtin_return_address(0);
+  return dlopen_ext(filename, flags, extinfo, caller_addr);
+}
+
 void* dlopen(const char* filename, int flags) {
-  return android_dlopen_ext(filename, flags, NULL);
+  void* caller_addr = __builtin_return_address(0);
+  return dlopen_ext(filename, flags, NULL, caller_addr);
 }
 
 void* dlsym(void* handle, const char* symbol) {
@@ -97,8 +103,8 @@ void* dlsym(void* handle, const char* symbol) {
   if (handle == RTLD_DEFAULT) {
     sym = dlsym_linear_lookup(symbol, &found, NULL);
   } else if (handle == RTLD_NEXT) {
-    void* ret_addr = __builtin_return_address(0);
+    void* caller_addr = __builtin_return_address(0);
-    soinfo* si = find_containing_library(ret_addr);
+    soinfo* si = find_containing_library(caller_addr);
 
     sym = NULL;
     if (si && si->next) {
@@ -151,7 +157,9 @@ int dladdr(const void* addr, Dl_info* info) {
 
 int dlclose(void* handle) {
   ScopedPthreadMutexLocker locker(&g_dl_mutex);
-  return do_dlclose(reinterpret_cast<soinfo*>(handle));
+  do_dlclose(reinterpret_cast<soinfo*>(handle));
+  // dlclose has no defined errors.
+  return 0;
 }
 
 // name_offset: starting index of the name in libdl_info.strtab

linker/linker.cpp

@@ -682,7 +682,7 @@ static int open_library(const char* name) {
   return fd;
 }
 
-static soinfo* load_library(const char* name, const android_dlextinfo* extinfo) {
+static soinfo* load_library(const char* name, int dlflags, const android_dlextinfo* extinfo) {
     // Open the file.
     int fd = open_library(name);
     if (fd == -1) {
@@ -710,6 +710,10 @@ static soinfo* load_library(const char* name, const android_dlextinfo* extinfo)
       }
     }
 
+    if ((dlflags & RTLD_NOLOAD) != 0) {
+      return NULL;
+    }
+
     // Read the ELF header and load the segments.
     if (!elf_reader.Load(extinfo)) {
         return NULL;
@@ -748,33 +752,37 @@ static soinfo *find_loaded_library_by_name(const char* name) {
   return NULL;
 }
 
-static soinfo* find_library_internal(const char* name, const android_dlextinfo* extinfo) {
+static soinfo* find_library_internal(const char* name, int dlflags, const android_dlextinfo* extinfo) {
   if (name == NULL) {
     return somain;
   }
 
   soinfo* si = find_loaded_library_by_name(name);
-  if (si != NULL) {
+
-    if (si->flags & FLAG_LINKED) {
+  // Library might still be loaded, the accurate detection
-      return si;
+  // of this fact is done by load_library
+  if (si == NULL) {
+    TRACE("[ '%s' has not been found by name.  Trying harder...]", name);
+    si = load_library(name, dlflags, extinfo);
   }
-    DL_ERR("OOPS: recursive link to \"%s\"", si->name);
+
+  if (si != NULL && (si->flags & FLAG_LINKED) == 0) {
+    DL_ERR("recursive link to \"%s\"", si->name);
     return NULL;
   }
 
-  TRACE("[ '%s' has not been loaded yet.  Locating...]", name);
+  return si;
-  return load_library(name, extinfo);
 }
 
-static soinfo* find_library(const char* name, const android_dlextinfo* extinfo) {
+static soinfo* find_library(const char* name, int dlflags, const android_dlextinfo* extinfo) {
-  soinfo* si = find_library_internal(name, extinfo);
+  soinfo* si = find_library_internal(name, dlflags, extinfo);
   if (si != NULL) {
     si->ref_count++;
   }
   return si;
 }
 
-static int soinfo_unload(soinfo* si) {
+static void soinfo_unload(soinfo* si) {
   if (si->ref_count == 1) {
     TRACE("unloading '%s'", si->name);
     si->CallDestructors();
@@ -789,7 +797,14 @@ static int soinfo_unload(soinfo* si) {
         if (d->d_tag == DT_NEEDED) {
           const char* library_name = si->strtab + d->d_un.d_val;
           TRACE("%s needs to unload %s", si->name, library_name);
-          soinfo_unload(find_loaded_library_by_name(library_name));
+          soinfo* needed = find_library(library_name, RTLD_NOLOAD, NULL);
+          if (needed != NULL) {
+            soinfo_unload(needed);
+          } else {
+            // Not found: for example if symlink was deleted between dlopen and dlclose
+            // Since we cannot really handle errors at this point - print and continue.
+            PRINT("warning: couldn't find %s needed by %s on unload.", library_name, si->name);
+          }
         }
       }
     }
@@ -801,7 +816,6 @@ static int soinfo_unload(soinfo* si) {
     si->ref_count--;
     TRACE("not unloading '%s', decrementing ref_count to %zd", si->name, si->ref_count);
   }
-  return 0;
 }
 
 void do_android_get_LD_LIBRARY_PATH(char* buffer, size_t buffer_size) {
@@ -814,8 +828,8 @@ void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path) {
   }
 }
 
-soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo) {
+soinfo* do_dlopen(const char* name, int flags, soinfo* caller, const android_dlextinfo* extinfo) {
-  if ((flags & ~(RTLD_NOW|RTLD_LAZY|RTLD_LOCAL|RTLD_GLOBAL)) != 0) {
+  if ((flags & ~(RTLD_NOW|RTLD_LAZY|RTLD_LOCAL|RTLD_GLOBAL|RTLD_NOLOAD)) != 0) {
     DL_ERR("invalid flags to dlopen: %x", flags);
     return NULL;
   }
@@ -824,20 +838,21 @@ soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo)
     return NULL;
   }
   protect_data(PROT_READ | PROT_WRITE);
-  soinfo* si = find_library(name, extinfo);
+  soinfo* si = find_library(name, flags, extinfo);
   if (si != NULL) {
     si->CallConstructors();
-    somain->add_child(si);
+    if (caller != NULL) {
+      caller->add_child(si);
+    }
   }
   protect_data(PROT_READ);
   return si;
 }
 
-int do_dlclose(soinfo* si) {
+void do_dlclose(soinfo* si) {
   protect_data(PROT_READ | PROT_WRITE);
-  int result = soinfo_unload(si);
+  soinfo_unload(si);
   protect_data(PROT_READ);
-  return result;
 }
 
 #if defined(USE_RELA)
@@ -1435,6 +1450,10 @@ void soinfo::CallDestructors() {
 
   // DT_FINI should be called after DT_FINI_ARRAY if both are present.
   CallFunction("DT_FINI", fini_func);
+
+  // This is needed on second call to dlopen
+  // after library has been unloaded with RTLD_NODELETE
+  constructors_called = false;
 }
 
 void soinfo::add_child(soinfo* child) {
@@ -1811,7 +1830,7 @@ static bool soinfo_link_image(soinfo* si, const android_dlextinfo* extinfo) {
         memset(g_ld_preloads, 0, sizeof(g_ld_preloads));
         size_t preload_count = 0;
         for (size_t i = 0; g_ld_preload_names[i] != NULL; i++) {
-            soinfo* lsi = find_library(g_ld_preload_names[i], NULL);
+            soinfo* lsi = find_library(g_ld_preload_names[i], 0, NULL);
             if (lsi != NULL) {
                 g_ld_preloads[preload_count++] = lsi;
             } else {
@@ -1829,7 +1848,7 @@ static bool soinfo_link_image(soinfo* si, const android_dlextinfo* extinfo) {
         if (d->d_tag == DT_NEEDED) {
             const char* library_name = si->strtab + d->d_un.d_val;
             DEBUG("%s needs %s", si->name, library_name);
-            soinfo* lsi = find_library(library_name, NULL);
+            soinfo* lsi = find_library(library_name, 0, NULL);
             if (lsi == NULL) {
                 strlcpy(tmp_err_buf, linker_get_error_buffer(), sizeof(tmp_err_buf));
                 DL_ERR("could not load library \"%s\" needed by \"%s\"; caused by %s",

linker/linker.h

@@ -231,8 +231,8 @@ extern soinfo* get_libdl_info();
 
 void do_android_get_LD_LIBRARY_PATH(char*, size_t);
 void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path);
-soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo);
+soinfo* do_dlopen(const char* name, int flags, soinfo* caller, const android_dlextinfo* extinfo);
-int do_dlclose(soinfo* si);
+void do_dlclose(soinfo* si);
 
 ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start);
 soinfo* find_containing_library(const void* addr);

tests/Android.mk

@@ -266,6 +266,18 @@ build_type := target
 build_target := SHARED_LIBRARY
 include $(LOCAL_PATH)/Android.build.mk
 
+# -----------------------------------------------------------------------------
+# Library used by dlfcn tests
+# -----------------------------------------------------------------------------
+libtest_simple_src_files := \
+    dlopen_testlib_simple.cpp
+
+module := libtest_simple
+build_type := target
+build_target := SHARED_LIBRARY
+include $(LOCAL_PATH)/Android.build.mk
+
+
 # -----------------------------------------------------------------------------
 # Library used by atexit tests
 # -----------------------------------------------------------------------------

tests/dlfcn_test.cpp

@@ -50,6 +50,18 @@ TEST(dlfcn, dlsym_in_self) {
   ASSERT_EQ(0, dlclose(self));
 }
 
+TEST(dlfcn, dlopen_noload) {
+  void* handle = dlopen("libtest_simple.so", RTLD_NOW | RTLD_NOLOAD);
+  ASSERT_TRUE(handle == NULL);
+  handle = dlopen("libtest_simple.so", RTLD_NOW);
+  void* handle2 = dlopen("libtest_simple.so", RTLD_NOW | RTLD_NOLOAD);
+  ASSERT_TRUE(handle != NULL);
+  ASSERT_TRUE(handle2 != NULL);
+  ASSERT_TRUE(handle == handle2);
+  ASSERT_EQ(0, dlclose(handle));
+  ASSERT_EQ(0, dlclose(handle2));
+}
+
 TEST(dlfcn, dlopen_failure) {
   void* self = dlopen("/does/not/exist", RTLD_NOW);
   ASSERT_TRUE(self == NULL);

tests/dlopen_testlib_simple.cpp

@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdlib.h>
+
+uint32_t dlopen_testlib_taxicab_number = 1729;
+
+bool dlopen_testlib_simple_func() {
+  return true;
+}