/* =================================================================
 *
 *      objelf.c
 *
 *      An object loader for eCos
 *
 * ================================================================= 
 * ####ECOSGPLCOPYRIGHTBEGIN####
 * -------------------------------------------
 * This file is part of eCos, the Embedded Configurable Operating
 * System.
 * Copyright (C) 2005 eCosCentric Ltd.
 * 
 * eCos is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 or (at your option)
 * any later version.
 * 
 * eCos is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with eCos; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 * 
 * As a special exception, if other files instantiate templates or
 * use macros or inline functions from this file, or you compile this
 * file and link it with other works to produce a work based on this
 * file, this file does not by itself cause the resulting work to be
 * covered by the GNU General Public License. However the source code
 * for this file must still be made available in accordance with
 * section (3) of the GNU General Public License.
 * 
 * This exception does not invalidate any other reasons why a work
 * based on this file might be covered by the GNU General Public
 * License.
 *
 * -------------------------------------------
 * ####ECOSGPLCOPYRIGHTEND####
 * =================================================================
 * #####DESCRIPTIONBEGIN####
 * 
 *  Author(s):    atonizzo@lycos.com
 *  Contributors: nickg@ecoscentric.com
 *  Date:         2005-05-13
 *  Purpose:      
 *  Description:  
 *               
 * ####DESCRIPTIONEND####
 * 
 * =================================================================
 */

#include <cyg/infra/diag.h>     // For diagnostic printing.
#include <cyg/infra/cyg_ass.h>
#include <stdlib.h>
#include <string.h>

#include <pkgconf/objloader.h>

#include <cyg/objloader/elf.h>
#include <cyg/objloader/objelf.h>
#include <cyg/objloader/loader_fs.h>

cyg_uint8 *cyg_ldr_last_error;

void *cyg_ldr_malloc( size_t ) CYGBLD_ATTRIB_WEAK;
void
*cyg_ldr_malloc( size_t s )
{
    return malloc( s );
}

void cyg_ldr_free( void * ) CYGBLD_ATTRIB_WEAK;
void
cyg_ldr_free( void *s )
{
    free( s );
}

void
cyg_ldr_delete_elf_section( PELF_OBJECT p, cyg_uint32 idx )
{
    cyg_ldr_free( p->sections[idx] );
    p->sections[idx] = 0; 
}    

// Frees all the memory allocated for a particular ELF object. Also calls
//  the close() function to close files or sockets, and finally frees up
//  the ELF object altogether.
static void
cyg_ldr_free_elf_object( PELF_OBJECT p )
{
    cyg_int32 i;
        
    for ( i = 0; i < p->p_elfhdr->e_shnum + 1; i++ )
        if ( p->sections[i] )
            cyg_ldr_delete_elf_section( p, i );

    if ( p->sections != 0 )
        cyg_ldr_free( p->sections ); 

    if ( p->p_sechdr != 0 )
        cyg_ldr_free( p->p_sechdr ); 

    if ( p->p_elfhdr != 0 )
        cyg_ldr_free( p->p_elfhdr ); 

    p->close( p );    
    cyg_ldr_free( p );
}        

static cyg_uint32 
cyg_ldr_find_common_size( PELF_OBJECT p )
{
    cyg_int32 i, symtab_entries, common_size = 0;
    Elf32_Sym *p_symtab = (Elf32_Sym*)p->sections[p->hdrndx_symtab];
     
    // Total number of entries in the symbol table.
    symtab_entries = p->p_sechdr[p->hdrndx_symtab].sh_size / 
                                p->p_sechdr[p->hdrndx_symtab].sh_entsize;
    for ( i = 1; i < symtab_entries; i++ )
        if ( p_symtab[i].st_shndx == SHN_COMMON )
        {
            // In the case of an SHN_COMMON symbol the st_value field holds 
            //  alignment constraints.
            cyg_uint32 boundary = p_symtab[i].st_value - 1;

            // Calculate the next byte boundary.
            common_size = ( common_size + boundary ) & ~boundary;
            common_size += p_symtab[i].st_size;
        }    

#if CYGPKG_SERVICES_OBJLOADER_DEBUG_LEVEL > 0
    diag_printf( "common_size = %d\n", common_size );
#endif
    return common_size;
}

// Allocates memory and loads the contents of a specific ELF section.
// Returns the address of the newly allocated memory, of 0 for any error.
cyg_int32 
*cyg_ldr_load_elf_section( PELF_OBJECT p, cyg_uint32 idx )
{
    cyg_uint32 *addr;
    
    addr = cyg_ldr_malloc( p->p_sechdr[idx].sh_size );
    CYG_ASSERT( addr != 0, "Cannot malloc() section" );
    if ( addr == 0 )
    {
        cyg_ldr_last_error = "ERROR IN MALLOC";
        return (void*)0;
    }
    p->seek( p, p->p_sechdr[idx].sh_offset );
    p->read( p, sizeof( char ), p->p_sechdr[idx].sh_size, addr );
    return addr;
}    

// Returns the starting address of a section. If the section is not already
//  loaded in memory, area for it will be allocated and the section will be
//  loaded.
cyg_int32 
*cyg_ldr_section_address( PELF_OBJECT p, cyg_uint32 idx )
{
    if ( p->sections[idx] == 0 )
        p->sections[idx] = cyg_ldr_load_elf_section( p, idx );

    return p->sections[idx];
}

void
*cyg_ldr_find_symbol( void* handle, cyg_uint8* sym_name )
{
    PELF_OBJECT p = (PELF_OBJECT)handle;
    cyg_uint8* tmp2;
    cyg_int32  i, symtab_entries;
    cyg_uint8 *p_strtab = (cyg_uint8*)p->sections[p->hdrndx_strtab];
    Elf32_Sym *p_symtab = (Elf32_Sym*)p->sections[p->hdrndx_symtab];
  
    symtab_entries = p->p_sechdr[p->hdrndx_symtab].sh_size / 
                               p->p_sechdr[p->hdrndx_symtab].sh_entsize;

    for ( i = 0; i < symtab_entries; i++ )
    {
        tmp2 = p_strtab + p_symtab[i].st_name;
        if ( !strcmp( tmp2, sym_name ) )
            return cyg_ldr_symbol_address( p, i );
    }

    // Symbol not found.
    cyg_ldr_last_error = "SYMBOL NOT FOUND";
    return 0;
}

static cyg_uint8
*cyg_ldr_sanity_check( PELF_OBJECT p )
{
    if ( ( p->p_elfhdr->e_ident[EI_MAG0] != ELFMAG0 )  || 
         ( p->p_elfhdr->e_ident[EI_MAG1] != ELFMAG1 )  ||
         ( p->p_elfhdr->e_ident[EI_MAG2] != ELFMAG2  ) || 
         ( p->p_elfhdr->e_ident[EI_MAG3] != ELFMAG3 )  || 
         ( p->p_elfhdr->e_ident[EI_CLASS] != ELFCLASS32 ) )
        return "INVALID ELF HEADER";

    // We only work with relocatable files. No dynamic linking.
    if ( p->p_elfhdr->e_type != ET_REL )
        return "NOT RELOCATABLE";
        
    // These #defines are sitting in the hal.
    if ( p->p_elfhdr->e_machine != ELF_ARCH_MACHINE_TYPE )
        return "INVALID ARCHITECTURE";

    if ( p->p_elfhdr->e_ident[EI_DATA] != ELF_ARCH_ENDIANNESS )
        return "INVALID ENDIAN";
    return 0;  }     

// Load only the ELF header and the sections header. These are the only
//  sections loaded during library initialization. All the other sections
//  will be loaded on demand when needed during the relocation process and,
//  when possible, dumped after use.
static cyg_int32 
cyg_ldr_load_sections( PELF_OBJECT p )
{
    cyg_uint8  *error_string;
    cyg_int32  idx;

    // Load the ELF header.
    p->p_elfhdr = (Elf32_Ehdr*)cyg_ldr_malloc( sizeof( Elf32_Ehdr ) );
    CYG_ASSERT( p->p_elfhdr != 0, "Cannot malloc() p->p_elfhdr" );
    if ( p->p_elfhdr == 0 )
        return -1;
    p->seek( p, 0 );
    p->read( p, sizeof( char ), sizeof( Elf32_Ehdr ), p->p_elfhdr  );
    error_string = cyg_ldr_sanity_check( p );
    if ( error_string != 0 )
    {
        cyg_ldr_last_error = "ERROR IN ELF HEADER";
        return -1;
    }    
    
    // Allocate an array that can hold an address to all the section of this
    //  library. This is not strictly optimal, since some sections do not
    //  need to be loaded all the time. Allocate an extra pointer for the
    //  COMMON area. 
    p->sections = cyg_ldr_malloc( ( p->p_elfhdr->e_shnum + 1 ) * 
                                                     sizeof( cyg_uint32 ) );
    CYG_ASSERT( p->sections != 0, "Cannot malloc() p->sections" );
    if ( p->sections == 0 )
    {
        cyg_ldr_last_error = "ERROR IN MALLOC";
        return -1;
    }
    memset( p->sections, 0, ( p->p_elfhdr->e_shnum + 1 ) * 
                                                     sizeof( cyg_uint32 ) );
    
    // Now that the header is loaded, load the sections header.
    p->p_sechdr = (Elf32_Shdr*)cyg_ldr_malloc( 
                             p->p_elfhdr->e_shnum * p->p_elfhdr->e_shentsize );
    CYG_ASSERT( p->p_sechdr != 0, "Cannot malloc() p->p_sechdr" );
    if ( p->p_sechdr == 0 )
    {
        cyg_ldr_last_error = "ERROR IN MALLOC";
        return -1;
    }
    p->seek( p, p->p_elfhdr->e_shoff );
    p->read( p, p->p_elfhdr->e_shentsize, p->p_elfhdr->e_shnum, p->p_sechdr );
    
    // Load the section header string table. This is a byte oriented table,
    //  so alignment is not an issue.
    idx = p->p_elfhdr->e_shstrndx;
    p->sections[idx] = cyg_ldr_load_elf_section( p, idx );
    return 0;
}

PELF_OBJECT
cyg_ldr_open_library( CYG_ADDRWORD ptr, cyg_int32 mode )
{
    Elf32_Sym *p_symtab;
    cyg_uint8 *p_shstrtab;
    PELF_OBJECT e_obj; 
    int (*fn)(void);
    cyg_int32   i, rc, symtab_entries;
    cyg_uint32  common_size;

    // In the future there might be a switch() (against 'mode') that calls an
    //  open function other than cyg_ldr_open_library_fs(). These function
    //  fetch and open a library using ftp, http or libraries that are already 
    //  in ROM.
    e_obj = cyg_ldr_open_library_fs( (cyg_uint8*)ptr );
    if ( e_obj == 0 )
        return 0;
    rc = cyg_ldr_load_sections( e_obj );
    if ( rc != 0 )
    {
        cyg_ldr_free_elf_object( e_obj );
        return 0;
    }    

    // Find the section index for the .shstrtab section. The names of the 
    //  sections are held here, and are the only way to identify them.
    p_shstrtab = (cyg_uint8*)cyg_ldr_section_address( e_obj, 
                                                 e_obj->p_elfhdr->e_shstrndx );
    if ( p_shstrtab == 0 )
    {
        cyg_ldr_free_elf_object( e_obj );
        return 0;
    }    

    // .symtab section and .strtab. We have to go through the section names
    //  to find where they are.
    for ( i = 1; i < e_obj->p_elfhdr->e_shnum; i++ )
    {
        // Now look for the index of .symtab. These are the symbols needed for 
        //  the symbol retrieval as well as relocation.
        if ( !strcmp( p_shstrtab + e_obj->p_sechdr[i].sh_name, 
                      ELF_STRING_symtab ) )
        {              
            e_obj->hdrndx_symtab = i;
            e_obj->sections[i] = cyg_ldr_load_elf_section( e_obj, i );
            if ( e_obj->sections[i] == 0 )
            {
                cyg_ldr_free_elf_object( e_obj );
                return 0;
            }    
        }    
        
        // Load the table with the names of all the symbols. We need this
        //  to compare the name of external references symbols against the
        //  names in the in the CYG_HAL_TABLE provided by the user.
        if ( !strcmp( p_shstrtab + e_obj->p_sechdr[i].sh_name, 
                      ELF_STRING_strtab ) )
        {              
            e_obj->hdrndx_strtab = i;
            e_obj->sections[i] = cyg_ldr_load_elf_section( e_obj, i );
            if ( e_obj->sections[i] == 0 )
            {
                cyg_ldr_free_elf_object( e_obj );
                return 0;
            }    
        }    
    }                                              

    CYG_ASSERT( e_obj->hdrndx_symtab != 0, "No symtab index found" );
    CYG_ASSERT( e_obj->hdrndx_strtab != 0, "No strtab index found" );

    // Now look for symbols in the COMMON area. The COMMON symbols are a 
    //  special case, because the area they reside in must be sized up
    //  and allocated separately from the other sections, which appear in
    //  the sections header and can be read out of the library itself.
    // Extra room in the 'sections' array has already been allocated to hold 
    //  the pointer to the commons area.
    common_size = cyg_ldr_find_common_size( e_obj ); 
    if ( common_size != 0 )
    {
        cyg_uint32 com_shndx = e_obj->p_elfhdr->e_shnum;
        cyg_int32  com_offset = 0;
        
        e_obj->sections[com_shndx] = (cyg_uint32*)cyg_ldr_malloc( common_size );
        CYG_ASSERT( e_obj->sections[com_shndx] != 0, 
                    "Cannot malloc() the COMMONS" );
   
        if ( e_obj->sections[com_shndx] == 0 )
        {
            cyg_ldr_free_elf_object( e_obj );
            return 0;
        }    

        // Now find all the symbols in the SHN_COMMON area and make 
        //  them  point to the newly allocated COM area.
        symtab_entries = e_obj->p_sechdr[e_obj->hdrndx_symtab].sh_size / 
                              e_obj->p_sechdr[e_obj->hdrndx_symtab].sh_entsize;
        p_symtab = (Elf32_Sym*)e_obj->sections[e_obj->hdrndx_symtab];
    
#if CYGPKG_SERVICES_OBJLOADER_DEBUG_LEVEL > 1
        diag_printf( "Num   Value   Size Ndx Name\n" ); 
#endif
        for ( i = 1; i < symtab_entries; i++ )
        {
#if CYGPKG_SERVICES_OBJLOADER_DEBUG_LEVEL > 1
            cyg_uint8 *p_strtab = (cyg_uint8*)cyg_ldr_section_address( e_obj, 
                                                        e_obj->hdrndx_strtab );
#endif        
            if ( p_symtab[i].st_shndx == SHN_COMMON )
            {             
                cyg_uint32 boundary = p_symtab[i].st_value - 1;
                // Calculate the next byte boundary.
                com_offset = ( com_offset + boundary ) & ~boundary;
                p_symtab[i].st_shndx = com_shndx;
                p_symtab[i].st_value = com_offset;
                com_offset += p_symtab[i].st_size;
            }
    
#if CYGPKG_SERVICES_OBJLOADER_DEBUG_LEVEL > 1
            diag_printf( "%03d  %08X %04X %03d %s\n", 
                         i, 
                         p_symtab[i].st_value,
                         p_symtab[i].st_size,
                         p_symtab[i].st_shndx,
                         p_strtab + p_symtab[i].st_name );
#endif        
        }    
    }

#if CYGPKG_SERVICES_OBJLOADER_DEBUG_LEVEL > 0
    cyg_ldr_print_section_data( e_obj );
#if CYGPKG_SERVICES_OBJLOADER_DEBUG_LEVEL > 1
    cyg_ldr_print_symbol_names( e_obj );
#endif    
#endif    

    for ( i = 1; i < e_obj->p_elfhdr->e_shnum; i++ )
    {
        // Find all the '.rel' or '.rela' sections and relocate them.
        if ( ( e_obj->p_sechdr[i].sh_type == SHT_REL ) ||
                                  ( e_obj->p_sechdr[i].sh_type == SHT_RELA ) )
        {
            // Load and relocate the section.
            rc = cyg_ldr_relocate_section( e_obj, i );
            if ( rc < 0 )
            { 
#if CYGPKG_SERVICES_OBJLOADER_DEBUG_LEVEL > 0
                ELFDEBUG( "Relocation unsuccessful\n" );
#endif
                cyg_ldr_free_elf_object( e_obj );
                return 0;
            }    
        }    
    }    

    // Synch up the caches before calling any function in the library.
    cyg_ldr_flush_cache();

    // Run the library initialization code.
    fn = cyg_ldr_find_symbol( e_obj, "library_open" );
    if ( fn != 0 )
        fn();
    return ((void*)e_obj);
}

cyg_uint8
*cyg_ldr_error( void )
{
    cyg_uint8* p = cyg_ldr_last_error;
    cyg_ldr_last_error = NULL;
    return p;
}

void cyg_ldr_close_library( void* handle )
{
    void (*fn)(void);

    PELF_OBJECT p = (PELF_OBJECT)handle;
    fn = cyg_ldr_find_symbol( p, "library_close" );
    if ( fn != 0 )
        fn();

    cyg_ldr_free_elf_object( p );
    p = 0;
}

