Subversion Repositories openrisc_2011-10-31

#ifndef CYGONCE_LOADER_LOADER_HXX

#define CYGONCE_LOADER_LOADER_HXX

//==========================================================================

//

//      loader.hxx

//

//      ELF dynamic loader definitions

//

//==========================================================================

//####ECOSGPLCOPYRIGHTBEGIN####

// -------------------------------------------

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//####ECOSGPLCOPYRIGHTEND####

//==========================================================================

//#####DESCRIPTIONBEGIN####

//

// Author(s):           nickg

// Contributors:        nickg

// Date:                2000-11-15

// Purpose:             Define ELF dynamic loader

// Description: The classes defined here collectively implement the

//              internal API of the ELF dynamic loader.

// Usage:       #include 

//

//####DESCRIPTIONEND####

//

//==========================================================================

#include 

#ifndef CYG_LOADER_DYNAMIC_LD

#include            // ELF data structures

#ifdef __cplusplus

#include 

#include          // assertion macros

#include 

// -------------------------------------------------------------------------

// Forward definitions

class Cyg_LoaderStream;

class Cyg_LoaderMemBlock;

class Cyg_LoaderMemAlloc;

class Cyg_LoadObject_Base;

class Cyg_LoadObject_Proc;

class Cyg_LoadObject;

class Cyg_Loader;

// -------------------------------------------------------------------------

// Error codes

#define CYG_LOADERR_NOERROR             0       // No error

#define CYG_LOADERR_NOT_ELF             1       // Not ELF format file

#define CYG_LOADERR_INVALID_CLASS       2       // Not expected file class

#define CYG_LOADERR_INVALID_BYTEORDER   3       // Not expected byte order

#define CYG_LOADERR_INVALID_VERSION     4       // Not expected ELF version

#define CYG_LOADERR_INVALID_MACHINE     5       // Not expected machine type

#define CYG_LOADERR_NO_MEMORY           6       // No memory

#define CYG_LOADERR_EOF                 7       // End of input stream

#define CYG_LOADERR_SEEK                8       // Cannot seek to stream position

#define CYG_LOADERR_INVALID_RELOC       9       // Invalid or unexpected relocation

#define CYG_LOADERR_NO_HASHTABLE        10      // No hash table in ELF file

#define CYG_LOADERR_NO_SYMTAB           11      // No symbol table in ELF file

#define CYG_LOADERR_NO_STRTAB           12      // No srting table in ELF file

#define CYG_LOADERR_NO_SYMBOL           13      // Symbol not found

// -------------------------------------------------------------------------

// Value for undefined or otherwise invalid symbol addresses.

#define CYG_LOADER_NULLSYMADDR          0

// -------------------------------------------------------------------------

// Loader Stream base class.

// This defines the interface to data streams that are ELF dynamic executable

// files.

class Cyg_LoaderStream

{

public:

    Cyg_LoaderStream();                         // Constructor

    virtual ~Cyg_LoaderStream();                // Destructor

    // The following functions are virtual and are supplied by a

    // derived class to access to data stream.

    virtual cyg_code get_byte(CYG_BYTE *val); // Get a byte from the stream

    virtual cyg_code get_data(CYG_BYTE *addr, CYG_ADDRWORD size);

    virtual cyg_code seek(CYG_ADDRWORD pos);  // seek to given position

    // The following functions all make use of the virtual functions

    // to access the data stream.

    cyg_code get_word16(CYG_WORD16 *val);       // get a 16 bit value

    cyg_code get_word32(CYG_WORD32 *val);       // get a 32 bit value

    cyg_code get_word64(CYG_WORD64 *val);       // get a 64 bit value

};

// -------------------------------------------------------------------------

// Memory allocation object. All memory allocated by the Loader is described

// by one of these.

struct Cyg_LoaderMemBlock

    : public Cyg_DNode_T

{

    void                *address;       // data address

    cyg_int32           size;           // block size

    cyg_int32           alignment;      // block alignment

    Cyg_LoaderMemAlloc  *mem;           // allocator used

    CYG_ADDRESS         actual_address; // allocator specific actual address for block

    CYG_WORD32          actual_size;    // allocator specific actual size for block

    // Convenience free() function

    void free();

};

// -------------------------------------------------------------------------

// Memory allocator base class

// This defines the interface to a memory allocator used by the loader.

class Cyg_LoaderMemAlloc

{

public:

    Cyg_LoaderMemAlloc();

    virtual ~Cyg_LoaderMemAlloc();

    // The following functions are virtual so that alternative memory

    // allocators may be implemented. The default behaviour of this

    // class is to use malloc/realloc/free to support these functions.

    // Allocate memory of the supplied size and alignment.

    // size      - size in bytes

    // alignment - alignment expressed as a power of 2

    //             defaults to 8 byte alignment

    virtual Cyg_LoaderMemBlock *alloc( cyg_int32 size,

                                       cyg_int32 alignment = 8);

    // Reallocate block

    // block    - block to reallocate

    // size     - new size in bytes

    // alignment - new alignment, -1 if old alignment is to be used.

    virtual Cyg_LoaderMemBlock *realloc( Cyg_LoaderMemBlock *block,

                                         cyg_int32 size,

                                         cyg_int32 alignment = -1);

    // Free a previously allocated memory segment.

    virtual void free( Cyg_LoaderMemBlock *block );

};

// -------------------------------------------------------------------------

// Cyg_LoaderMemBlock convenience free() function implementation.

inline void Cyg_LoaderMemBlock::free() { mem->free(this); };

// -------------------------------------------------------------------------

// A loaded object

class Cyg_LoadObject_Base

    : public Cyg_DNode_T

{

    friend class Cyg_Loader;

protected:

    // The following fields come from the constructor arguments

    cyg_uint32          mode;           // mode flags

    Cyg_LoaderMemAlloc  *memalloc;      // Memory allocator

    // The following fields are derived from the ELF header

    Elf32_Word          e_type;         // File type

    Elf32_Addr          e_entry;        // Executable entry point

    // The following fields are derived from the PT_DYNAMIC segment in

    // the program header. These fields are named after the DT_ tags

    // that their values are derived from.

    Elf32_Word          flags;          // flags from DT_FLAGS

    Elf32_Word          soname;         // name of module, if defined

    Elf_Hash            *hash;          // address of hash table

    Elf32_Word          *bucket;        // derived bucket array address

    Elf32_Word          *chain;         // derived chain array address

    // String table

    unsigned char       *strtab;        // address of table

    Elf32_Word          strsize;        // size of table in bytes

    // Symbol table

    Elf32_Sym           *symtab;        // address of table

    Elf32_Word          syment;         // size of entry

    // PTL and GOT

    Elf32_Addr          pltgot;         // address of PLT and/or GOT

    // PLT relocation entries

    Elf32_Addr          jmprel;         // address of relocation table

    Elf32_Word          pltrelsz;       // size of jmprel table in bytes

    Elf32_Word          pltrel;         // type of table entries: DT_REL

                                        //   or DT_RELA

    // Relocation table with implicit addends

    Elf32_Rel           *rel;           // table address

    Elf32_Word          relsize;        // table size in bytes

    Elf32_Word          relent;         // size of entry

    // Relocation table with explicit addends

    Elf32_Rela          *rela;          // table address

    Elf32_Word          relasize;       // table size in bytes

    Elf32_Word          relaent;        // size of entry

    // Init and Fini support

    Elf32_Addr          init;           // address of init function

    Elf32_Addr          fini;           // address of fini function

    Elf32_Addr          *init_array;    // address of init array

    Elf32_Word          init_array_sz;  // size of init array

    Elf32_Addr          *fini_array;    // address of fini array

    Elf32_Word          fini_array_sz;  // size of fini array

    Elf32_Addr          *pre_init_array;   // address of pre_init array

    Elf32_Word          pre_init_array_sz; // size of pre_init array

    Elf32_Dyn           *dynamic;       // address of _DYNAMIC section

    CYG_ADDRESS         base;           // base address used in address and

                                        // relocation calcualtions

    Cyg_CList_T segs;      // chain of loaded segments

    cyg_code            error;          // most recent error code

    // private functions

    void parse_dynamic( Elf32_Dyn *dynamic );

    // Translate a symbol from its symbol table index into its

    // actual address

    CYG_ADDRESS get_sym_addr_from_ix( Elf32_Word sym );

    // Get a symbol from this object's symbol table.

    Elf32_Sym *get_sym( Elf32_Word ix );

    // Get a name from this object's string table.

    char *get_name( Elf32_Word offset );

    // Look up the name in the hash table and return its symbol

    // table entry, or NULL if not found.

    Elf32_Sym *hash_lookup( const char *name );

    // Look up the name in the hash table and return its absolute

    // address or CYG_LOADER_NULLSYMADDR if it is not found.

    CYG_ADDRESS hash_lookup_addr( const char *name );

    // Standard ELF-defined hash function for symbol table.

    static unsigned long elf_hash( const unsigned char *name );

public:

    // Constructor - reads and allocates the executable.

    Cyg_LoadObject_Base();

    Cyg_LoadObject_Base( Cyg_LoaderStream& stream,

                         cyg_uint32 mode,

                         Cyg_LoaderMemAlloc *mem );

    ~Cyg_LoadObject_Base();                          // Destructor

    inline cyg_code get_error() { return error; };

    // Translate a symbol into its address.

    void *symbol( const char *name );

    // Start this executable running

    cyg_code exec(int argc, char **argv, char **envv);

};

#endif // __cplusplus

#endif // CYG_LOADER_DYNAMIC_LD

// -------------------------------------------------------------------------

// All the following files should have suitable ifdefs so that only

// one actually provides content.

#include         // MIPS ELF support

#include          // ARM ELF support

#include         // i386 ELF support

#include          // PowerPC ELF support

//#include        // Sparc ELF support

//#include           // SH ELF support

// -------------------------------------------------------------------------

#ifndef CYG_LOADER_DYNAMIC_LD

#ifdef __cplusplus

class Cyg_LoadObject :

    public Cyg_LoadObject_Proc

{

    Cyg_LoaderMemBlock  *block;

public:

    inline Cyg_LoadObject()

        : Cyg_LoadObject_Proc()

        {

        };

    inline Cyg_LoadObject( Cyg_LoaderStream& stream,

                    cyg_uint32 mode,

                    Cyg_LoaderMemAlloc *mem,

                    Cyg_LoaderMemBlock *ablock = NULL)

        : Cyg_LoadObject_Proc( stream, mode, mem )

        {

            block = ablock;

        };

    inline ~Cyg_LoadObject() {};

    Cyg_LoaderMemBlock *get_block() { return block; };

    // Apply dynamic relocations to the executable

    void relocate();

    // Apply PLT relocations

    void relocate_plt();

};

// -------------------------------------------------------------------------

// Main loader class

class Cyg_Loader

{

    // current error code.

    cyg_code            error;

    // Default memory allocator.

    Cyg_LoaderMemAlloc  *mem_default;

    // Load object for main program

    Cyg_LoadObject      *main;

    // List of loaded executables, including the main

    // program and all libraries.

    Cyg_CList_T loadlist;

public:

    Cyg_Loader( Cyg_LoaderMemAlloc *mem);       // Constructor

    ~Cyg_Loader();                              // Destructor

    // Load an object and all its dependencies.

    cyg_code load( Cyg_LoaderStream& stream,

                   cyg_uint32 mode,

                   Cyg_LoadObject **object);

    // Close an object and remove it from memory

    cyg_code close( Cyg_LoadObject *object );

    // Translate current error code into a string.

    const char *error_string( );

    // Look up a symbol

    Elf32_Sym *hash_lookup( const char *name );

    // look up a named symbol in loadlist and return its

    // address relocated to its load address.

    CYG_ADDRESS hash_lookup_addr( const char *name );

    // Static pointer to loader object

    static Cyg_Loader *loader;

};

//==========================================================================

// Memory based loader stream

class Cyg_LoaderStream_Mem

    : public Cyg_LoaderStream

{

    CYG_ADDRESS         base;

    CYG_ADDRESS         pos;

    CYG_ADDRESS         end;

public:

    Cyg_LoaderStream_Mem( const void *addr, cyg_int32 size );

    ~Cyg_LoaderStream_Mem();                // Destructor

    cyg_code get_byte(CYG_BYTE *val); // Get a byte from the stream

    cyg_code get_data(CYG_BYTE *addr, CYG_ADDRWORD size);

    cyg_code seek(CYG_ADDRWORD pos);  // seek to given position

};

//==========================================================================

// Fileio based loader stream

#ifdef CYGPKG_IO_FILEIO

class Cyg_LoaderStream_File

    : public Cyg_LoaderStream

{

    int         fd;

public:

    Cyg_LoaderStream_File( int afd );

    ~Cyg_LoaderStream_File();                // Destructor

    cyg_code get_byte(CYG_BYTE *val); // Get a byte from the stream

    cyg_code get_data(CYG_BYTE *addr, CYG_ADDRWORD size);

    cyg_code seek(CYG_ADDRWORD pos);  // seek to given position

};

#endif

// -------------------------------------------------------------------------

#endif // __cplusplus

#endif // CYG_LOADER_DYNAMIC_LD

// -------------------------------------------------------------------------

#endif // ifndef CYGONCE_LOADER_LOADER_HXX

// EOF loader.hxx