Hexdump tool to "copy-paste" binaries into a shell. Useful for root-me.org VM challenges.

hexdump_tool_by_yandros.c

/* Hexdump tool to "copy-paste" binaries into a shell.
 * Useful for root-me.org VM challenges.
 * Compile with:
 * $ cc -std=c99 -o slice slice.c
 *
 * By Yandros (https://www.root-me.org/Yandros)
 */
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

#define DEFAULT_BUFSIZE 200

#define NAME argv[1]

#define PREFIX "printf \""
#define SUFFIX "\" >> %s\n", NAME

#define failwith(s) \
 do { close(fd); perror(s); exit(EXIT_FAILURE); } while(0)

int main(int argc, char * argv[]) {
 if (argc != 2 && argc != 3) {
   fprintf(stderr, "Usage:\t%s filename [bufsize]\n", argv[0]);
   exit(EXIT_FAILURE);
 }
 size_t bufsize =
   argc == 3 ?
     atoi(argv[2]) :
     DEFAULT_BUFSIZE;
 fprintf(stderr, "Dumping '%s'...\n", argv[1]);
 int fd = open(argv[1], O_RDONLY);
 if (fd == -1) {
   perror("open");
   exit(EXIT_FAILURE);
 }
 struct stat file_stat;
 if (fstat(fd, &file_stat) == -1)
   failwith("fstat");
 fprintf(stderr, "Length = %ld bytes.\n", file_stat.st_size);
 uintptr_t addr = (uintptr_t) mmap(NULL, file_stat.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 if ((void *)addr == MAP_FAILED)
   failwith("mmap");
 printf("touch %s\n", NAME);
 printf("chmod +x %s\n", NAME);
 int len;
 for(len = file_stat.st_size; len > 0; len -= bufsize) {
   size_t size = (len > bufsize ? bufsize : len);
   printf(PREFIX);
   for (size_t i = 0; i < size; ++i) {
     printf("\\x%02x", ((char *) addr)[i] & 0xff);
   }
   printf(SUFFIX);
   addr += bufsize;
 }
 printf("./%s\n", NAME);
 if (munmap((void *)(addr + len - file_stat.st_size), file_stat.st_size) == -1)
   failwith("munmap");
 close(fd);
 return EXIT_SUCCESS;
}