commit d59e50063ad708509f3ad83350be33f5612c4f54
author Dmitriy Ivanov <dimitry@google.com> Fri May 09 09:10:14 2014 -0700
committer Dmitriy Ivanov <dimitry@google.com> Wed May 14 15:16:35 2014 -0700
tree 4179117769c38d28aff06e56427f54e72e5eed6b
parent 6897b7b8b95beae120fd53e6fd15921d6420bea7

Improve detection of already loaded libraries

Linker is now able to resolve symlinked libraries correctly.

soinfo is extended to save the graph of dependencies during
load/unload. Dependencies are used only in CallConstructor.

Bug: 9741592
Change-Id: Id9c48a74c46aa89bcdf3d54ec2f8ba3d398130b1

linker/linker.h

diff --git a/linker/linker.h b/linker/linker.h
index 645498a..e5aca6e 100644
--- a/linker/linker.h
+++ b/linker/linker.h
@@ -33,8 +33,10 @@
 #include <link.h>
 #include <unistd.h>
 #include <android/dlext.h>
+#include <sys/stat.h>
 
 #include "private/libc_logging.h"
+#include "linked_list.h"
 
 #define DL_ERR(fmt, x...) \
     do { \
@@ -84,6 +86,7 @@
 #define FLAG_LINKED     0x00000001
 #define FLAG_EXE        0x00000004 // The main executable
 #define FLAG_LINKER     0x00000010 // The linker itself
+#define FLAG_NEW_SOINFO 0x40000000 // new soinfo format
 
 #define SOINFO_NAME_LEN 128
 
@@ -94,8 +97,21 @@
 #define USE_RELA 1
 #endif
 
+struct soinfo;
+
+class SoinfoListAllocator {
+public:
+  static LinkedListEntry<soinfo>* alloc();
+  static void free(LinkedListEntry<soinfo>* entry);
+private:
+  // unconstructable
+  DISALLOW_IMPLICIT_CONSTRUCTORS(SoinfoListAllocator);
+};
+
 struct soinfo {
  public:
+  typedef LinkedList<soinfo, SoinfoListAllocator> soinfo_list_t;
+ public:
   char name[SOINFO_NAME_LEN];
   const ElfW(Phdr)* phdr;
   size_t phnum;
@@ -179,17 +195,39 @@
   bool has_text_relocations;
 #endif
   bool has_DT_SYMBOLIC;
-
   void CallConstructors();
   void CallDestructors();
   void CallPreInitConstructors();
 
+  void add_child(soinfo* child);
+  void remove_all_links();
+
+  void set_st_dev(dev_t st_dev);
+  void set_st_ino(ino_t st_ino);
+  ino_t get_st_ino();
+  dev_t get_st_dev();
+
+  soinfo_list_t& get_children();
+
  private:
   void CallArray(const char* array_name, linker_function_t* functions, size_t count, bool reverse);
   void CallFunction(const char* function_name, linker_function_t function);
+
+ private:
+  // This part of the structure is only available
+  // when FLAG_NEW_SOINFO is set in this->flags.
+  unsigned int version;
+
+  dev_t st_dev;
+  ino_t st_ino;
+
+  // dependency graph
+  soinfo_list_t children;
+  soinfo_list_t parents;
+
 };
 
-extern soinfo libdl_info;
+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);