Coding an ELF Parser

To help summarize some of what we have learned, I have included some simple code that will print the program headers and section names of a 32-bit ELF executable. Many more examples of ELF-related code (and much more interesting ones) will be shown throughout this book:

/* elfparse.c – gcc elfparse.c -o elfparse */
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <elf.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <stdint.h>
#include <sys/stat.h>
#include <fcntl.h>

int main(int argc, char **argv)
{
   int fd, i;
   uint8_t *mem;
   struct stat st;
   char *StringTable, *interp;
   
   Elf32_Ehdr *ehdr;
   Elf32_Phdr *phdr;
   Elf32_Shdr *shdr;

   if (argc < 2) {
      printf("Usage: %s <executable>\n", argv[0]);
      exit(0);
   }

   if ((fd = open(argv[1], O_RDONLY)) < 0) {
      perror("open");
      exit(-1);
   }
   
   if (fstat(fd, &st) <...