/* $Id: ldrELF.cpp $ */
/** @file
 * IPRT - Binary Image Loader, Executable and Linker Format (ELF).
 */

/*
 * Copyright (C) 2006-2020 Oracle Corporation
 *
 * This file is part of VirtualBox Open Source Edition (OSE), as
 * available from http://www.virtualbox.org. This file is free software;
 * you can redistribute it and/or modify it under the terms of the GNU
 * General Public License (GPL) as published by the Free Software
 * Foundation, in version 2 as it comes in the "COPYING" file of the
 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
 *
 * The contents of this file may alternatively be used under the terms
 * of the Common Development and Distribution License Version 1.0
 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
 * VirtualBox OSE distribution, in which case the provisions of the
 * CDDL are applicable instead of those of the GPL.
 *
 * You may elect to license modified versions of this file under the
 * terms and conditions of either the GPL or the CDDL or both.
 */


/*********************************************************************************************************************************
*   Header Files                                                                                                                 *
*********************************************************************************************************************************/
#define LOG_GROUP RTLOGGROUP_LDR
#include <iprt/ldr.h>
#include "internal/iprt.h"

#include <iprt/alloc.h>
#include <iprt/assert.h>
#include <iprt/dbg.h>
#include <iprt/string.h>
#include <iprt/log.h>
#include <iprt/err.h>
#include <iprt/formats/elf32.h>
#include <iprt/formats/elf64.h>
#include <iprt/formats/elf-i386.h>
#include <iprt/formats/elf-amd64.h>
#include "internal/ldr.h"
#include "internal/dbgmod.h"



/*********************************************************************************************************************************
*   Defined Constants And Macros                                                                                                 *
*********************************************************************************************************************************/
/** Finds an ELF symbol table string. */
#define ELF_STR(pHdrs, iStr)        ((pHdrs)->Rel.pStr + (iStr))
/** Finds an ELF symbol table string. */
#define ELF_DYN_STR(pHdrs, iStr)    ((pHdrs)->Dyn.pStr + (iStr))
/** Finds an ELF section header string. */
#define ELF_SH_STR(pHdrs, iStr)     ((pHdrs)->pShStr + (iStr))



/*********************************************************************************************************************************
*   Internal Functions                                                                                                           *
*********************************************************************************************************************************/
#ifdef LOG_ENABLED
static const char *rtldrElfGetShdrType(uint32_t iType);
static const char *rtldrElfGetPhdrType(uint32_t iType);
#endif


/* Select ELF mode and include the template. */
#define ELF_MODE            32
#define Elf_Reloc           Elf_Rel
#include "ldrELFRelocatable.cpp.h"
#undef ELF_MODE
#undef Elf_Reloc


#define ELF_MODE            64
#define Elf_Reloc           Elf_Rela
#include "ldrELFRelocatable.cpp.h"
#undef ELF_MODE
#undef Elf_Reloc


#ifdef LOG_ENABLED

/**
 * Gets the section type.
 *
 * @returns Pointer to read only string.
 * @param   iType       The section type index.
 */
static const char *rtldrElfGetShdrType(uint32_t iType)
{
    switch (iType)
    {
        RT_CASE_RET_STR(SHT_NULL);
        RT_CASE_RET_STR(SHT_PROGBITS);
        RT_CASE_RET_STR(SHT_SYMTAB);
        RT_CASE_RET_STR(SHT_STRTAB);
        RT_CASE_RET_STR(SHT_RELA);
        RT_CASE_RET_STR(SHT_HASH);
        RT_CASE_RET_STR(SHT_DYNAMIC);
        RT_CASE_RET_STR(SHT_NOTE);
        RT_CASE_RET_STR(SHT_NOBITS);
        RT_CASE_RET_STR(SHT_REL);
        RT_CASE_RET_STR(SHT_SHLIB);
        RT_CASE_RET_STR(SHT_DYNSYM);
        default:
            return "";
    }
}

/**
 * Gets the program header type.
 *
 * @returns Pointer to read only string.
 * @param   iType       The section type index.
 */
static const char *rtldrElfGetPhdrType(uint32_t iType)
{
    switch (iType)
    {
        RT_CASE_RET_STR(PT_NULL);
        RT_CASE_RET_STR(PT_LOAD);
        RT_CASE_RET_STR(PT_DYNAMIC);
        RT_CASE_RET_STR(PT_INTERP);
        RT_CASE_RET_STR(PT_NOTE);
        RT_CASE_RET_STR(PT_SHLIB);
        RT_CASE_RET_STR(PT_PHDR);
        RT_CASE_RET_STR(PT_TLS);
        RT_CASE_RET_STR(PT_GNU_EH_FRAME);
        RT_CASE_RET_STR(PT_GNU_STACK);
        RT_CASE_RET_STR(PT_GNU_RELRO);
        RT_CASE_RET_STR(PT_GNU_PROPERTY);
        default:
            return "";
    }
}

#endif /* LOG_ENABLED*/


/**
 * Open an ELF image.
 *
 * @returns iprt status code.
 * @param   pReader     The loader reader instance which will provide the raw image bits.
 * @param   fFlags      Reserved, MBZ.
 * @param   enmArch     Architecture specifier.
 * @param   phLdrMod    Where to store the handle.
 * @param   pErrInfo    Where to return extended error information. Optional.
 */
DECLHIDDEN(int) rtldrELFOpen(PRTLDRREADER pReader, uint32_t fFlags, RTLDRARCH enmArch, PRTLDRMOD phLdrMod, PRTERRINFO pErrInfo)
{
    const char *pszLogName = pReader->pfnLogName(pReader); NOREF(pszLogName);

    /*
     * Read the ident to decide if this is 32-bit or 64-bit
     * and worth dealing with.
     */
    uint8_t e_ident[EI_NIDENT];
    int rc = pReader->pfnRead(pReader, &e_ident, sizeof(e_ident), 0);
    if (RT_FAILURE(rc))
        return rc;

    if (    e_ident[EI_MAG0] != ELFMAG0
        ||  e_ident[EI_MAG1] != ELFMAG1
        ||  e_ident[EI_MAG2] != ELFMAG2
        ||  e_ident[EI_MAG3] != ELFMAG3
        ||  (   e_ident[EI_CLASS] != ELFCLASS32
             && e_ident[EI_CLASS] != ELFCLASS64)
       )
        return RTERRINFO_LOG_SET_F(pErrInfo, VERR_BAD_EXE_FORMAT,
                                   "%s: Unsupported/invalid ident %.*Rhxs", pszLogName, sizeof(e_ident), e_ident);

    if (e_ident[EI_DATA] != ELFDATA2LSB)
        return RTERRINFO_LOG_SET_F(pErrInfo, VERR_LDRELF_ODD_ENDIAN,
                                   "%s: ELF endian %x is unsupported", pszLogName, e_ident[EI_DATA]);

    if (e_ident[EI_CLASS] == ELFCLASS32)
        rc = rtldrELF32Open(pReader, fFlags, enmArch, phLdrMod, pErrInfo);
    else
        rc = rtldrELF64Open(pReader, fFlags, enmArch, phLdrMod, pErrInfo);
    return rc;
}