| 1 | |
| 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 |
|
| 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))
|
| 26 | static void die(const char *msg)
|
| 27 | {
|
| 28 | fputs(msg, stderr);
|
| 29 | exit(EXIT_FAILURE);
|
| 30 | }
|
| 31 |
|
| 32 | int 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 |
|
| 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 | }
|