1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #ifndef CRAZY_LINKER_LIBRARY_LIST_H
6 #define CRAZY_LINKER_LIBRARY_LIST_H
7 
8 #include <link.h>
9 
10 #include "crazy_linker_error.h"
11 #include "crazy_linker_search_path_list.h"
12 #include "elf_traits.h"
13 
14 // This header contains definitions related to the global list of
15 // library views maintained by the crazy linker. Each library view
16 // points to either a crazy library, or a system one.
17 
18 namespace crazy {
19 
20 class SharedLibrary;
21 class LibraryView;
22 
23 // The list of all shared libraries loaded by the crazy linker.
24 // IMPORTANT: This class is not thread-safe!
25 class LibraryList {
26  public:
27   LibraryList();
28   ~LibraryList();
29 
30   // Find a library in the list by its base name.
31   // |base_name| must not contain a directory separator.
32   LibraryView* FindLibraryByName(const char* base_name);
33 
34   // Lookup for a given |symbol_name|, starting from |from_lib|
35   // then through its dependencies in breadth-first search order.
36   // On failure, returns NULL.
37   void* FindSymbolFrom(const char* symbol_name, LibraryView* from_lib);
38 
39   // Return the address of a visible given symbol. Used to implement
40   // the dlsym() wrapper. Returns NULL on failure.
41   void* FindAddressForSymbol(const char* symbol_name);
42 
43   // Find a SharedLibrary that contains a given address, or NULL if none
44   // could be found. This simply scans all libraries.
45   LibraryView* FindLibraryForAddress(void* address);
46 
47 #ifdef __arm__
48   // Find the base address of the .ARM.exidx section corresponding
49   // to the address |pc|, as well as the number of 8-byte entries in
50   // the table into |*count|. Used to implement the wrapper for
51   // dl_unwind_find_exidx().
52   _Unwind_Ptr FindArmExIdx(void* pc, int* count);
53 #else
54   typedef int (*PhdrIterationCallback)(dl_phdr_info* info,
55                                        size_t info_size,
56                                        void* data);
57 
58   // Loop over all loaded libraries and call the |cb| callback
59   // on each iteration. If the function returns 0, stop immediately
60   // and return its value. Used to implement the wrapper for
61   // dl_iterate_phdr().
62   int IteratePhdr(PhdrIterationCallback callback, void* data);
63 #endif
64 
65   // Try to load a library, possibly at a fixed address.
66   // On failure, returns NULL and sets the |error| message.
67   LibraryView* LoadLibrary(const char* path,
68                            int dlopen_flags,
69                            uintptr_t load_address,
70                            off_t file_offset,
71                            SearchPathList* search_path_list,
72                            Error* error);
73 
74   // Unload a given shared library. This really decrements the library's
75   // internal reference count. When it reaches zero, the library's
76   // destructors are run, its dependencies are unloaded, then the
77   // library is removed from memory.
78   void UnloadLibrary(LibraryView* lib);
79 
80   // Used internally by the wrappers only.
81   void AddLibrary(LibraryView* lib);
82 
83  private:
84   LibraryList(const LibraryList&);
85   LibraryList& operator=(const LibraryList&);
86 
87   void ClearError();
88 
89   // The list of all known libraries.
90   Vector<LibraryView*> known_libraries_;
91 
92   LibraryView* FindKnownLibrary(const char* name);
93 
94   // The list of all libraries loaded by the crazy linker.
95   // This does _not_ include system libraries present in known_libraries_.
96   SharedLibrary* head_;
97 
98   size_t count_;
99   bool has_error_;
100   char error_buffer_[512];
101 };
102 
103 }  // namespace crazy
104 
105 #endif  // CRAZY_LINKER_LIBRARY_LIST_H