kldmempeek.c

/*
 * kldmempeek.c
 *
 * Author: Szymon Urbaś <szymon.urbas@aol.com>
 *
 * Description: Take a hexdump-like peek at a module's bytes. It is very
 *              platform specific and _probably_ works _only_ under FreeBSD.
 *
 * License: the MIT (X11) License
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/linker.h>
#include <fcntl.h>
#include <errno.h>
#include <err.h>

int main(int argc, char *argv[])
{
  struct kld_file_stat st;
  int fd, openfd;
  unsigned i, j;
  unsigned char *p;
  void *addr;
  unsigned cols = 15;

  if (argc < 2){
    errx(1, "usage: kldmempeek <module> [cols]");
    return 1;
  }

  if (argc > 2){
    cols = atoi(argv[2]);
  }

  if ((fd = kldfind(argv[1])) < 0){
    err(1, "can't find module %s", argv[1]);
    return 1;
  }

  st.version = sizeof(struct kld_file_stat);

  if (kldstat(fd, &st) == -1){
    err(1, "kldstat");
    return 1;
  }

  openfd = open(st.pathname, O_RDONLY);

  printf("module %s:\n\n", st.pathname);
  printf("  id: %d, fd: %d\n", st.id, fd);
  printf("  refs: %d\n", st.refs);
  printf("  size: %zu bytes (0x%zx)\n", st.size, st.size);
  printf("  address: %p\n\n", st.address);

  addr = mmap(NULL, st.size, PROT_READ, MAP_PRIVATE, openfd, 0);

  if (addr == MAP_FAILED){
    err(1, "mmap failed");
    return 1;
  }

  p = addr;
  for (i = 0; i < st.size; i += cols){
    printf("  ");
    for (j = 0; j < cols; j++){
      printf("%.2x", *(p + j));
      if (j % 4 == 3)
        printf("  ");
      else
        printf(" ");
    }
    printf("    ");
    for (j = 0; j < cols; j++){
      if (isprint(*(p + j))){
        printf("%c", *(p + j));
      } else {
        printf(".");
      }
    }
    printf("\n");
    p += cols;
  }

  munmap(addr, st.size);

  close(fd);

  return 0;
}