1 files changed, 159 insertions, 0 deletions
diff --git a/mozglue/linker/CustomElf.h b/mozglue/linker/CustomElf.h
new file mode 100644
index 0000000000..5ecc7da085
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+++ b/mozglue/linker/CustomElf.h
@@ -0,0 +1,159 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef CustomElf_h
+#define CustomElf_h
+
+#include "ElfLoader.h"
+#include "BaseElf.h"
+#include "Logging.h"
+#include "Elfxx.h"
+
+/**
+ * Library Handle class for ELF libraries we don't let the system linker
+ * handle.
+ */
+class CustomElf: public BaseElf, private ElfLoader::link_map
+{
+  friend class ElfLoader;
+  friend class SEGVHandler;
+public:
+  /**
+   * Returns a new CustomElf using the given file descriptor to map ELF
+   * content. The file descriptor ownership is stolen, and it will be closed
+   * in CustomElf's destructor if an instance is created, or by the Load
+   * method otherwise. The path corresponds to the file descriptor, and flags
+   * are the same kind of flags that would be given to dlopen(), though
+   * currently, none are supported and the behaviour is more or less that of
+   * RTLD_GLOBAL | RTLD_BIND_NOW.
+   */
+  static already_AddRefed<LibHandle> Load(Mappable *mappable,
+                                               const char *path, int flags);
+
+  /**
+   * Inherited from LibHandle/BaseElf
+   */
+  virtual ~CustomElf();
+
+protected:
+  virtual Mappable *GetMappable() const;
+
+public:
+  /**
+   * Shows some stats about the Mappable instance. The when argument is to be
+   * used by the caller to give an identifier of the when the stats call is
+   * made.
+   */
+  virtual void stats(const char *when) const;
+
+  /**
+   * Returns the instance, casted as BaseElf. (short of a better way to do
+   * this without RTTI)
+   */
+  virtual BaseElf *AsBaseElf() { return this; }
+
+private:
+  /**
+   * Scan dependent libraries to find the address corresponding to the
+   * given symbol name. This is used to find symbols that are undefined
+   * in the Elf object.
+   */
+  void *GetSymbolPtrInDeps(const char *symbol) const;
+
+  /**
+   * Private constructor
+   */
+  CustomElf(Mappable *mappable, const char *path)
+  : BaseElf(path, mappable)
+  , link_map()
+  , init(0)
+  , fini(0)
+  , initialized(false)
+  , has_text_relocs(false)
+  { }
+
+  /**
+   * Loads an Elf segment defined by the given PT_LOAD header.
+   * Returns whether this succeeded or failed.
+   */
+  bool LoadSegment(const Elf::Phdr *pt_load) const;
+
+  /**
+   * Initializes the library according to information found in the given
+   * PT_DYNAMIC header.
+   * Returns whether this succeeded or failed.
+   */
+  bool InitDyn(const Elf::Phdr *pt_dyn);
+
+  /**
+   * Apply .rel.dyn/.rela.dyn relocations.
+   * Returns whether this succeeded or failed.
+   */
+  bool Relocate();
+
+  /**
+   * Apply .rel.plt/.rela.plt relocations.
+   * Returns whether this succeeded or failed.
+   */
+  bool RelocateJumps();
+
+  /**
+   * Call initialization functions (.init/.init_array)
+   * Returns true;
+   */
+  bool CallInit();
+
+  /**
+   * Call destructor functions (.fini_array/.fini)
+   * Returns whether this succeeded or failed.
+   */
+  void CallFini();
+
+  /**
+   * Call a function given a pointer to its location.
+   */
+  void CallFunction(void *ptr) const
+  {
+    /* C++ doesn't allow direct conversion between pointer-to-object
+     * and pointer-to-function. */
+    union {
+      void *ptr;
+      void (*func)(void);
+    } f;
+    f.ptr = ptr;
+    DEBUG_LOG("%s: Calling function @%p", GetPath(), ptr);
+    f.func();
+  }
+
+  /**
+   * Call a function given a an address relative to the library base
+   */
+  void CallFunction(Elf::Addr addr) const
+  {
+    return CallFunction(GetPtr(addr));
+  }
+
+  /* List of dependent libraries */
+  std::vector<RefPtr<LibHandle> > dependencies;
+
+  /* List of .rel.dyn/.rela.dyn relocations */
+  Array<Elf::Reloc> relocations;
+
+  /* List of .rel.plt/.rela.plt relocation */
+  Array<Elf::Reloc> jumprels;
+
+  /* Relative address of the initialization and destruction functions
+   * (.init/.fini) */
+  Elf::Addr init, fini;
+
+  /* List of initialization and destruction functions
+   * (.init_array/.fini_array) */
+  Array<void *> init_array, fini_array;
+
+  bool initialized;
+
+  bool has_text_relocs;
+};
+
+#endif /* CustomElf_h */