#include <stdio.h>#include <stdlib.h>#include <math.h>#define BUFSZ (1 << 22)#ifdef WIN32// whateverstatic double drand48() {  double r = rand() / (double)RAND_MAX;  return r;}long lrand48() {	long l = 0;	int i;	for (i = 0; i < 32; i++) {		l = l ^ (l << 2) ^ (l << 1) ^ rand();	}	return l;}#endif#ifdef _WIN32#define XD3_WIN32 1#else#define XD3_POSIX 1#endif#define XD3_MAIN 1#define main notmain#define EXTERNAL_COMPRESSION 0#define XD3_USE_LARGEFILE64 1#include "xdelta3.c"#undef maindouble error_prob   = 0.0001;usize_t mean_change  = 100;xoff_t total_change = 0;xoff_t total_size   = 0;usize_t max_change   = 0;usize_t num_change   = 0;static usize_tedist (usize_t mean, usize_t max){  double mean_d = mean;  double erand  = log (1.0 / drand48 ());  usize_t x = (usize_t) (mean_d * erand + 0.5);  return (x < max) ? (x > 0 ? x : 1) : max;}void modify (char *buf, usize_t size){  usize_t bufpos = 0, j;  usize_t last_end = 0;  for (;; /* bufpos and j are incremented in the inner loop */)    {      /* The size of the next modification. */      usize_t next_size = edist (mean_change, 1 << 31);      /* The expected interval of such a change. */      double expect_interval = ((double) next_size * (1.0 - error_prob)) / error_prob;      /* The number of bytes until the next modification. */      usize_t next_mod  = edist ((usize_t)expect_interval, 1 << 31);      if (next_size + next_mod + bufpos > size) { break; }      if (max_change < next_size) { max_change = next_size; }      bufpos += next_mod;      fprintf (stderr, "COPY: %I64u-%I64u (%u)\n", 		  total_size + (xoff_t)last_end, 		  total_size + (xoff_t)bufpos, 		  bufpos - last_end);      fprintf (stderr, "ADD:  %I64u-%I64u (%u) is change %u\n", 		  total_size + (xoff_t)bufpos, 		  total_size + (xoff_t)(bufpos + next_size),		  next_size, num_change);      total_change += next_size;      num_change   += 1;      for (j = 0; j < next_size; j += 1, bufpos += 1)	{	  buf[bufpos] = (char)(lrand48 () >> 3);	}      last_end = bufpos;    }  fprintf (stderr, "COPY: %I64u-%I64u (%u)\n", 	  total_size + last_end, 	  total_size + size, size - last_end);  total_size += size;}int main(int argc, char **argv){  main_file inp, out;  char *buf = malloc(BUFSZ);  int c, ret;  main_file_init(&inp);  main_file_init(&out);  option_force = 1;  if (argc > 5)    {      fprintf (stderr, "usage: badcopy [byte_error_prob [mean_error_size]]\n");      return 1;    }  if (argc > 4) { mean_change = atoi (argv[4]); }  if (argc > 3) { error_prob  = atof (argv[3]); }  fprintf (stderr, "mean change = %u; error_prob = %0.10f\n", mean_change, error_prob);  if ((ret = main_file_open (&inp, argv[1], XO_READ)) != 0) {	  return 1;  }  if ((ret = main_file_open (&out, argv[2], XO_WRITE)) != 0) {	  return 1;  }  if (error_prob < 0.0 || error_prob > 1.0)    {      fprintf (stderr, "warning: error probability out of range\n");      return 1;    }  do    {		if ((ret = main_file_read (&inp, buf, BUFSZ, &c, "read failed")) != 0) {			return 1;		}        if (c == 0) { break; }        modify (buf, c);		if ((ret = main_file_write (&out, buf, c, "write failed")) != 0) {			return 1;		}    }  while (c == BUFSZ);  if ((ret = main_file_close (&out)))    {      return 1;    }  fprintf (stderr, "add_prob %f; %u adds; total_change %u of %u bytes; add percentage %f; max add size %u\n",	   error_prob, num_change, total_change, total_size, (double) total_change / (double) total_size, max_change);  return 0;}