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/*
* COPYRIGHT (c) 2012 Chris Johns <chrisj@rtems.org>
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
/**
* @file
*
* @ingroup rtems_rtl
*
* @brief RTEMS Run-Time Linker Object File Unresolved Relocations Table.
*
* The unresolved relocation table holds relocations in a loaded object file
* which reference unresolved external symbols. The support is needed to allow
* dependent object files to load. In the case of dependent object files one
* will have unresolved externals until the dependent object file is also
* loaded. There is no load order that resolves this.
*
* The unresolved relocation table is a single table used by all object files
* with unresolved symbols. It made of blocks linked together where blocks are
* allocated as requiered. The table is always maintained compacted. That is as
* relocations are resolved and removed the table is compacted. The only
* pointer in the table is the object file poniter. This is used to identify
* which object the relocation belongs to. There are no linking or back
* pointers in the unresolved relocations table. The table is scanned for each
* object file's relocations. This is not fast but the table should be small
* and if it happens to grow large you have other more pressing issues to
* resolve in your application.
*
* The table holds two (2) types of records:
*
* # Symbol name strings.
* # Relocations.
*
* The symbol name a relocation references is held in a specific symbol name
* string record in the table the relocation record references. The record
* counts the number of references and the string is removed from the table
* when the reference count reaches 0. There can be many relocations
* referencing the symbol. The strings are referenced by a single 16bit
* unsigned integer which is the count of the string in the table.
*
* The section the relocation is for in the object is the section number. The
* relocation data is series of machine word sized fields:
*
* # Offset in the section.
* # Relocation info (format specific)
* # Additional format specific data.
*/
#if !defined (_RTEMS_RTL_UNRESOLVED_H_)
#define _RTEMS_RTL_UNRESOLVED_H_
#include <rtems.h>
#include "rtl-obj-fwd.h"
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
/**
* Hack to work around machine size. This needs to be cleaned up
* to better support 64bit targets.
*/
typedef uint32_t rtems_rtl_word_t;
/**
* The types of records in the blocks.
*/
typedef enum rtems_rtl_unresolved_rtype_e
{
rtems_rtl_unresolved_empty = 0, /**< The records is empty. Must always be 0 */
rtems_rtl_unresolved_name = 1, /**< The record is a name. */
rtems_rtl_unresolved_reloc = 2 /**< The record is a relocation record. */
} rtems_rtl_unresolved_rtype_t;
/**
* Unresolved externals symbol names. The names are reference counted and
* separate from the relocation records because a number of records could
* reference the same symbol name.
*/
typedef struct rtems_rtl_unresolv_name_s
{
uint16_t refs; /**< The number of references to this name. */
uint16_t length; /**< The length of this name. */
const char name[12]; /**< The symbol name. */
} rtems_rtl_unresolv_name_t;
/**
* Unresolved externals symbols require the relocation records to be held
* and references.
*/
typedef struct rtems_rtl_unresolv_reloc_s
{
rtems_rtl_obj_t* obj; /**< The relocation's object file. */
uint16_t flags; /**< Format specific flags. */
uint16_t name; /**< The symbol's name. */
uint16_t sect; /**< The target section. */
rtems_rtl_word_t rel[3]; /**< Relocation record. */
} rtems_rtl_unresolv_reloc_t;
/**
* Unresolved externals records.
*/
typedef struct rtems_rtl_unresolv_rec_s
{
rtems_rtl_unresolved_rtype_t type;
union
{
rtems_rtl_unresolv_name_t name; /**< The name, or */
rtems_rtl_unresolv_reloc_t reloc; /**< the relocation record. */
} rec;
} rtems_rtl_unresolv_rec_t;
/**
* Unresolved blocks.
*/
typedef struct rtems_rtl_unresolv_block_s
{
rtems_chain_node link; /**< Blocks are chained. */
uint32_t recs; /**< The number of records in the block. */
rtems_rtl_unresolv_rec_t rec; /**< The records. More follow. */
} rtems_rtl_unresolv_block_t;
/**
* Unresolved table holds the names and relocations.
*/
typedef struct rtems_rtl_unresolved_s
{
uint32_t marker;
size_t block_recs; /**< The records per blocks allocated. */
rtems_chain_control blocks; /**< List of blocks. */
} rtems_rtl_unresolved_t;
/**
* The iterator function used to iterate over the unresolved table.
*
* @param rec The current iterator.
* @param data The user data.
* @retval true The iterator has finished.
* @retval false The iterator has not finished. Keep iterating.
*/
typedef bool rtems_rtl_unresolved_iterator_t (rtems_rtl_unresolv_rec_t* rec,
void* data);
/**
* Open an unresolved relocation table.
*
* @param unresolv The unresolved table to open.
* @param block_records The number of records per block allocated.
* @retval true The table is open.
* @retval false The unresolved relocation table could not created. The RTL
* error has the error.
*/
bool rtems_rtl_unresolved_table_open (rtems_rtl_unresolved_t* unresolved,
size_t block_records);
/**
* Close the table and erase the blocks.
*
* @param unreolved Close the unresolved table.
*/
void rtems_rtl_unresolved_table_close (rtems_rtl_unresolved_t* unresolved);
/**
* Iterate over the table of unresolved entries.
*/
bool rtems_rtl_unresolved_interate (rtems_rtl_unresolved_iterator_t iterator,
void* data);
/**
* Add a relocation to the list of unresolved relocations.
*
* @param unresolved The unresolved symbol table.
* @param obj The object table the symbols are for.
* @param flags Format specific flags.
* @param name The symbol name the relocation references.
* @param sect The target section number the relocation references.
* @param rel The format specific relocation data.
* @retval true The relocation has been added.
* @retval false The relocation could not be added.
*/
bool rtems_rtl_unresolved_add (rtems_rtl_obj_t* obj,
const uint16_t flags,
const char* name,
const uint16_t sect,
const rtems_rtl_word_t* rel);
/**
* Resolve the unresolved symbols.
*/
void rtems_rtl_unresolved_resolve (void);
/**
* Remove a relocation from the list of unresolved relocations.
*
* @param unresolved The unresolved symbol table.
* @param obj The object table the symbols are for.
* @param esyms The exported symbol table.
* @param size The size of the table in bytes.
*/
bool rtems_rtl_unresolved_remove (rtems_rtl_obj_t* obj,
const char* name,
const uint16_t sect,
const rtems_rtl_word_t* rel);
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif
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