copy-argv.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static char **make_copy(int argc, char **argv)
{
  size_t strlen_sum;
  char **argp;
  char *data;
  size_t len;
  int i;

  strlen_sum = 0;
  for (i = 0; i < argc; i++) strlen_sum += strlen(argv[i]) + 1;

  argp = malloc(sizeof(char *) * (argc + 1) + strlen_sum);
  if (!argp) return NULL;
  data = (char *) argp + sizeof(char *) * (argc + 1);

  for (i = 0; i < argc; i++) {
    argp[i] = data;
    len = strlen(argv[i]) + 1;
    memcpy(data, argv[i], len);
    data += len;
  }
  argp[argc] = NULL;

  return argp;
}

int main(int argc, char **argv)
{
  char **copy = make_copy(argc, argv);
  int i;

  for (i = 0; i < argc; i++) puts(copy[i]);
  free(copy);

  return 0;
}