Resolve unresolved externals when loading object files.

Object files that depend on each other will cause an unresolved
external. The change lets object files load with unresolved
externals and will resolve them when the object file with the
external is loaded.

A common table of symbol strings and relocation records is maintained.
The symbol string is shared by each object file that is unresolved.
Each relocation record that references the symbol is held. The table
is a series of small blocks that compact as symbols are resolved. The
number of symbols left unresolved is typically small this design avoids
fragmentation of the heap memory.

1 files changed, 26 insertions, 10 deletions

diff --git a/rtl.h b/rtl.h
index 03d15e2..9c33b50 100644
--- a/rtl.h
+++ b/rtl.h
@@ -22,13 +22,11 @@
 #include <rtems.h>
 #include <rtems/chain.h>
 
-// #include <rtems/rtl/rtl-elf.h>
-
 #include <rtl-allocator.h>
 #include <rtl-fwd.h>
-#include <rtl-elf.h>
 #include <rtl-obj.h>
 #include <rtl-obj-cache.h>
+#include <rtl-unresolved.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -48,13 +46,18 @@ extern "C" {
  * files or in an archive. Object files in an archive are referenced by
  * specifing 'archive:object' format. For example 'libfoo.a:bar.o'.
  */
-  
+
 /**
  * The number of buckets in the global symbol table.
  */
 #define RTEMS_RTL_SYMS_GLOBAL_BUCKETS (32)
 
 /**
+ * The number of relocation record per block in the unresolved table.
+ */
+#define RTEMS_RTL_UNRESOLVED_BLOCK_SIZE (64)
+
+/**
  * The global debugger interface variable.
  */
 extern struct r_debug _rtld_debug;
@@ -69,7 +72,7 @@ extern void _rtld_debug_state (void);
  * The type of constructor/destructor function.
  */
 typedef void (*rtems_rtl_cdtor_t)(void);
-  
+
 /**
  * The global RTL data. This structure is allocated on the heap when the first
  * call to the RTL is made and never released.
@@ -85,6 +88,7 @@ struct rtems_rtl_data_s
   rtems_chain_control    objects;        /**< List if loaded object files. */
   const char*            paths;          /**< Search paths for archives. */
   rtems_rtl_symbols_t    globals;        /**< Global symbol table. */
+  rtems_rtl_unresolved_t unresolved;     /**< Unresolved symbols. */
   rtems_rtl_obj_t*       base;           /**< Base object file. */
   rtems_rtl_obj_cache_t  symbols;        /**< Symbols object file cache. */
   rtems_rtl_obj_cache_t  strings;        /**< Strings object file cache. */
@@ -111,6 +115,15 @@ rtems_rtl_data_t* rtems_rtl_data (void);
 rtems_rtl_symbols_t* rtems_rtl_global_symbols (void);
 
 /**
+ * Get the RTL resolved table with out locking. This call assmes the RTL
+ * is locked.
+ *
+ * @return rtems_rtl_unresolv_t* The RTL unresolved symbols and reloc records.
+ * @retval NULL The RTL data is not initialised.
+ */
+rtems_rtl_unresolved_t* rtems_rtl_unresolved (void);
+
+/**
  * Get the RTL symbols, strings, or relocations object file caches. This call
  * assmes the RTL is locked.
  *
@@ -171,21 +184,24 @@ rtems_rtl_obj_t* rtems_rtl_find_obj (const char* name);
  * Load an object file into memory relocating it. It will not be resolved
  * against other symbols in other object files or the base image.
  *
- * The name can be a file name for an ELF object file or it can be encoded to
+ * The name can be a file name for an object file or it can be encoded to
  * reference an archive of object modules (static library). This encoding is
  * specific to RTEMS and allows dependences to specify an archive without the
  * searching overhead normally incurred by linkers locating object files in an
  * archive. The file name format rules are:
  *
- *  1. Absolute file references a specific ELF format file in that specific
- *     location on the file system.
- *  2. Relative file references an ELF format file in the search path.
+ *  1. Absolute file references a specific object file in the architecture
+ *     specific location on the file system.
+ *
+ *  2. Relative file references an object format file in the search path.
+ *
  *  3. Absolute archive and file reference to a specific location in the file
  *     system. The archive and file are encoded as 'archive:file [@offset]'
  *     where 'archive' is a valid file at the absolute path in the file system,
  *     and 'file' is a contained in the archive, and optionally an offset to
  *     the 'file' in the 'archive'. If no offset is provided the archive is
  *     searched.
+ *
  *  4. Relative archive and file in the search path. The encoding is the same
  *     as described in item 3 of this list.
  *
@@ -215,7 +231,7 @@ bool rtems_rtl_unload_object (rtems_rtl_obj_t* obj);
  * @param obj The object file.
  */
 void rtems_rtl_run_ctors (rtems_rtl_obj_t* obj);
-  
+
 /**
  * Get the last error message clearing it. This operation locks the run time
  * linker and therefore keeps the RTL thread safe.