/*
   * Helper function for splitting a string into an argv-like array.
   */
  
  #include <linux/kernel.h>
  #include <linux/ctype.h>
  #include <linux/bug.h>
  
  static const char *skip_sep(const char *cp)
  {
  	while (*cp && isspace(*cp))
  		cp++;
  
  	return cp;
  }
  
  static const char *skip_arg(const char *cp)
  {
  	while (*cp && !isspace(*cp))
  		cp++;
  
  	return cp;
  }
  
  static int count_argc(const char *str)
  {
  	int count = 0;
  
  	while (*str) {
  		str = skip_sep(str);
  		if (*str) {
  			count++;
  			str = skip_arg(str);
  		}
  	}
  
  	return count;
  }
  
  /**
   * argv_free - free an argv
   * @argv - the argument vector to be freed
   *
   * Frees an argv and the strings it points to.
   */
  void argv_free(char **argv)
  {
  	char **p;
  	for (p = argv; *p; p++)
  		kfree(*p);
  
  	kfree(argv);
  }
  EXPORT_SYMBOL(argv_free);
  
  /**
   * argv_split - split a string at whitespace, returning an argv
   * @gfp: the GFP mask used to allocate memory
   * @str: the string to be split
   * @argcp: returned argument count
   *
   * Returns an array of pointers to strings which are split out from
   * @str.  This is performed by strictly splitting on white-space; no
   * quote processing is performed.  Multiple whitespace characters are
   * considered to be a single argument separator.  The returned array
   * is always NULL-terminated.  Returns NULL on memory allocation
   * failure.
   */
  char **argv_split(gfp_t gfp, const char *str, int *argcp)
  {
  	int argc = count_argc(str);
  	char **argv = kzalloc(sizeof(*argv) * (argc+1), gfp);
  	char **argvp;
  
  	if (argv == NULL)
  		goto out;
  
  	*argcp = argc;
  	argvp = argv;
  
  	while (*str) {
  		str = skip_sep(str);
  
  		if (*str) {
  			const char *p = str;
  			char *t;
  
  			str = skip_arg(str);
  
  			t = kstrndup(p, str-p, gfp);
  			if (t == NULL)
  				goto fail;
  			*argvp++ = t;
  		}
  	}
  	*argvp = NULL;
  
    out:
  	return argv;
  
    fail:
  	argv_free(argv);
  	return NULL;
  }
  EXPORT_SYMBOL(argv_split);