//===-- elf_common.c - Common ELF functionality -------------------*- C -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Common ELF functionality for target plugins.
// Must be included in the plugin source file AFTER omptarget.h has been
// included and macro DP(...) has been defined.
// .
//
//===----------------------------------------------------------------------===//

#if !(defined(_OMPTARGET_H_) && defined(DP))
#error Include elf_common.c in the plugin source AFTER omptarget.h has been\
 included and macro DP(...) has been defined.
#endif

#include <elf.h>
#include <libelf.h>

// Check whether an image is valid for execution on target_id
static inline int32_t elf_check_machine(__tgt_device_image *image,
    uint16_t target_id) {

  // Is the library version incompatible with the header file?
  if (elf_version(EV_CURRENT) == EV_NONE) {
    DP("Incompatible ELF library!\n");
    return 0;
  }

  char *img_begin = (char *)image->ImageStart;
  char *img_end = (char *)image->ImageEnd;
  size_t img_size = img_end - img_begin;

  // Obtain elf handler
  Elf *e = elf_memory(img_begin, img_size);
  if (!e) {
    DP("Unable to get ELF handle: %s!\n", elf_errmsg(-1));
    return 0;
  }

  // Check if ELF is the right kind.
  if (elf_kind(e) != ELF_K_ELF) {
    DP("Unexpected ELF type!\n");
    return 0;
  }
  Elf64_Ehdr *eh64 = elf64_getehdr(e);
  Elf32_Ehdr *eh32 = elf32_getehdr(e);

  if (!eh64 && !eh32) {
    DP("Unable to get machine ID from ELF file!\n");
    elf_end(e);
    return 0;
  }

  uint16_t MachineID;
  if (eh64 && !eh32)
    MachineID = eh64->e_machine;
  else if (eh32 && !eh64)
    MachineID = eh32->e_machine;
  else {
    DP("Ambiguous ELF header!\n");
    elf_end(e);
    return 0;
  }

  elf_end(e);
  return MachineID == target_id;
}