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

#define FREE(x) if(x != NULL){free(x); x = NULL;}

/* --------------------------------------------------------
   replaceAll(char *srcStr, char *patStr, char *repStr)
    Convert a string to another string in which
    every substring, matched with the given pattern,
    is replaced to the given replacement substring.
    The source string is not changed.
   Parameters
    srcstr: the source string
    patstr: the pattern substring to be matched
    repstr: replacement substring
   Returns
    the new string.
   -------------------------------------------------------- */
char *replaceAll(char *srcstr, char *patstr, char *repstr)
{
 char *str = srcstr;
 char *idx;
 char *newstr = NULL;         // new string with replaced stuff
 char *tmpstr;                // temporary pointer to a string
 char *pstr = newstr;
 int replen = strlen(repstr);
 int patlen = strlen(patstr);
 int newlen = 0;
 int counter = 0;
 int sizealloc = 0;

 if (patlen < 1)
 {
  sizealloc = strlen(srcstr) + counter*(replen - patlen) + 1;
  tmpstr = (char *) realloc(newstr, sizealloc);

  if (tmpstr == NULL)
  {
   fprintf(stderr, "ERROR: realloc failed");
   if (newstr)
    free(newstr);
   newstr = NULL;
   return NULL;
  }

  newstr = tmpstr;
  newstr = strcpy(newstr, srcstr);
  return newstr;
 }

 while (idx = strstr(str, patstr))
 {
  counter++;
  str = idx + patlen;
 }

 if (counter > 0)
 {
  str = srcstr;
  sizealloc = strlen(srcstr) + counter*(replen - patlen) + 1;
  tmpstr = (char *) realloc(newstr, sizealloc);

  if (tmpstr == NULL)
  {
   fprintf(stderr, "ERROR: realloc failed");
   if (newstr)
    free(newstr);
   newstr = NULL;
   return NULL;
  }
  newstr = tmpstr;
  pstr = newstr;

  while (idx = strstr(str, patstr))
  {
   if (idx - str > 0)
   {
    newstr = strncat(newstr, str, idx - str);
   }
   newstr = strcat(newstr, repstr);
   str = idx + patlen;
  }
 }
 else
 {
  sizealloc = strlen(srcstr) + counter*(replen - patlen) + 1;
  tmpstr = (char *) realloc(newstr, sizealloc);

  if (tmpstr == NULL)
  {
   fprintf(stderr, "ERROR: realloc failed");
   if (newstr)
    free(newstr);
   newstr = NULL;
   return NULL;
  }
  newstr = tmpstr;
  newstr = strcpy(newstr, srcstr);
 }

 return newstr;
}