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authorMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
committerMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
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tree10027f336435511475e392454359edea8e25895d /mozglue/linker/BaseElf.h
parent49ee0794b5d912db1f95dce6eb52d781dc210db5 (diff)
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Add m-esr52 at 52.6.0
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+/* 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 BaseElf_h
+#define BaseElf_h
+
+#include "ElfLoader.h"
+#include "Elfxx.h"
+
+
+/**
+ * Base class for ELF libraries. This class includes things that will be
+ * common between SystemElfs and CustomElfs.
+ */
+class BaseElf: public LibHandle
+{
+public:
+ /**
+ * Hash function for symbol lookup, as defined in ELF standard for System V.
+ */
+ static unsigned long Hash(const char *symbol);
+
+ /**
+ * Returns the address corresponding to the given symbol name (with a
+ * pre-computed hash).
+ */
+ void *GetSymbolPtr(const char *symbol, unsigned long hash) const;
+
+ /**
+ * Returns a pointer to the Elf Symbol in the Dynamic Symbol table
+ * corresponding to the given symbol name (with a pre-computed hash).
+ */
+ const Elf::Sym *GetSymbol(const char *symbol, unsigned long hash) const;
+
+ BaseElf(const char *path, Mappable *mappable = nullptr)
+ : LibHandle(path)
+ , mappable(mappable)
+ {
+ }
+
+protected:
+ /**
+ * Inherited from LibHandle. Those are temporary and are not supposed to
+ * be used.
+ */
+ virtual void *GetSymbolPtr(const char *symbol) const;
+ virtual bool Contains(void *addr) const;
+ virtual void *GetBase() const { return GetPtr(0); }
+
+#ifdef __ARM_EABI__
+ virtual const void *FindExidx(int *pcount) const;
+#endif
+
+ virtual Mappable *GetMappable() const { return NULL; };
+
+public:
+/* private: */
+ /**
+ * Returns a pointer relative to the base address where the library is
+ * loaded.
+ */
+ void *GetPtr(const Elf::Addr offset) const
+ {
+ if (reinterpret_cast<void *>(offset) > base)
+ return reinterpret_cast<void *>(offset);
+ return base + offset;
+ }
+
+ /**
+ * Like the above, but returns a typed (const) pointer
+ */
+ template <typename T>
+ const T *GetPtr(const Elf::Addr offset) const
+ {
+ if (reinterpret_cast<void *>(offset) > base)
+ return reinterpret_cast<const T *>(offset);
+ return reinterpret_cast<const T *>(base + offset);
+ }
+
+ /* Appropriated Mappable */
+ /* /!\ we rely on this being nullptr for BaseElf instances, but not
+ * CustomElf instances. */
+ RefPtr<Mappable> mappable;
+
+ /* Base address where the library is loaded */
+ MappedPtr base;
+
+ /* Buckets and chains for the System V symbol hash table */
+ Array<Elf::Word> buckets;
+ UnsizedArray<Elf::Word> chains;
+
+/* protected: */
+ /* String table */
+ Elf::Strtab strtab;
+
+ /* Symbol table */
+ UnsizedArray<Elf::Sym> symtab;
+
+#ifdef __ARM_EABI__
+ /* ARM.exidx information used by FindExidx */
+ Array<uint32_t[2]> arm_exidx;
+#endif
+};
+
+
+/**
+ * Class for ELF libraries that already loaded in memory.
+ */
+class LoadedElf: public BaseElf
+{
+public:
+ /**
+ * Returns a LoadedElf corresponding to the already loaded ELF
+ * at the given base address.
+ */
+ static already_AddRefed<LibHandle> Create(const char *path,
+ void *base_addr);
+
+private:
+ LoadedElf(const char *path)
+ : BaseElf(path) { }
+
+ ~LoadedElf()
+ {
+ /* Avoid base's destructor unmapping something that doesn't actually
+ * belong to it. */
+ base.release();
+ ElfLoader::Singleton.Forget(this);
+ }
+
+ /**
+ * 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);
+};
+
+
+#endif /* BaseElf_h */