LXR linux/arch/mips/tools/elf-entry.c

   1// SPDX-License-Identifier: GPL-2.0
   2#include <byteswap.h>
   3#include <elf.h>
   4#include <endian.h>
   5#include <inttypes.h>
   6#include <stdint.h>
   7#include <stdio.h>
   8#include <stdlib.h>
   9#include <string.h>
  10
  11#ifdef be32toh
  12/* If libc provides [bl]e{32,64}toh() then we'll use them */
  13#elif BYTE_ORDER == LITTLE_ENDIAN
  14# define be32toh(x)     bswap_32(x)
  15# define le32toh(x)     (x)
  16# define be64toh(x)     bswap_64(x)
  17# define le64toh(x)     (x)
  18#elif BYTE_ORDER == BIG_ENDIAN
  19# define be32toh(x)     (x)
  20# define le32toh(x)     bswap_32(x)
  21# define be64toh(x)     (x)
  22# define le64toh(x)     bswap_64(x)
  23#endif
  24
  25__attribute__((noreturn))
  26static void die(const char *msg)
  27{
  28        fputs(msg, stderr);
  29        exit(EXIT_FAILURE);
  30}
  31
  32int main(int argc, const char *argv[])
  33{
  34        uint64_t entry;
  35        size_t nread;
  36        FILE *file;
  37        union {
  38                Elf32_Ehdr ehdr32;
  39                Elf64_Ehdr ehdr64;
  40        } hdr;
  41
  42        if (argc != 2)
  43                die("Usage: elf-entry <elf-file>\n");
  44
  45        file = fopen(argv[1], "r");
  46        if (!file) {
  47                perror("Unable to open input file");
  48                return EXIT_FAILURE;
  49        }
  50
  51        nread = fread(&hdr, 1, sizeof(hdr), file);
  52        if (nread != sizeof(hdr)) {
  53                perror("Unable to read input file");
  54                fclose(file);
  55                return EXIT_FAILURE;
  56        }
  57
  58        if (memcmp(hdr.ehdr32.e_ident, ELFMAG, SELFMAG)) {
  59                fclose(file);
  60                die("Input is not an ELF\n");
  61        }
  62
  63        switch (hdr.ehdr32.e_ident[EI_CLASS]) {
  64        case ELFCLASS32:
  65                switch (hdr.ehdr32.e_ident[EI_DATA]) {
  66                case ELFDATA2LSB:
  67                        entry = le32toh(hdr.ehdr32.e_entry);
  68                        break;
  69                case ELFDATA2MSB:
  70                        entry = be32toh(hdr.ehdr32.e_entry);
  71                        break;
  72                default:
  73                        fclose(file);
  74                        die("Invalid ELF encoding\n");
  75                }
  76
  77                /* Sign extend to form a canonical address */
  78                entry = (int64_t)(int32_t)entry;
  79                break;
  80
  81        case ELFCLASS64:
  82                switch (hdr.ehdr32.e_ident[EI_DATA]) {
  83                case ELFDATA2LSB:
  84                        entry = le64toh(hdr.ehdr64.e_entry);
  85                        break;
  86                case ELFDATA2MSB:
  87                        entry = be64toh(hdr.ehdr64.e_entry);
  88                        break;
  89                default:
  90                        fclose(file);
  91                        die("Invalid ELF encoding\n");
  92                }
  93                break;
  94
  95        default:
  96                fclose(file);
  97                die("Invalid ELF class\n");
  98        }
  99
 100        printf("0x%016" PRIx64 "\n", entry);
 101        fclose(file);
 102        return EXIT_SUCCESS;
 103}
 104