// SPDX-License-Identifier: GPL-2.0

  /*
   * Helper function for splitting a string into an argv-like array.
   */
  
  #include <linux/kernel.h>
  #include <linux/ctype.h>

  #include <linux/string.h>

  #include <linux/slab.h>

  #include <linux/export.h>

  static int count_argc(const char *str)
  {
  	int count = 0;

  	bool was_space;

  	for (was_space = true; *str; str++) {
  		if (isspace(*str)) {
  			was_space = true;
  		} else if (was_space) {
  			was_space = false;

  			count++;

  		}
  	}
  
  	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)
  {

  	argv--;
  	kfree(argv[0]);

  	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.

   *
   * The source string at `str' may be undergoing concurrent alteration via
   * userspace sysctl activity (at least).  The argv_split() implementation
   * attempts to handle this gracefully by taking a local copy to work on.

   */
  char **argv_split(gfp_t gfp, const char *str, int *argcp)
  {

  	char *argv_str;
  	bool was_space;
  	char **argv, **argv_ret;
  	int argc;
  
  	argv_str = kstrndup(str, KMALLOC_MAX_SIZE - 1, gfp);
  	if (!argv_str)
  		return NULL;
  
  	argc = count_argc(argv_str);

  	argv = kmalloc_array(argc + 2, sizeof(*argv), gfp);

  	if (!argv) {
  		kfree(argv_str);
  		return NULL;
  	}

  	*argv = argv_str;
  	argv_ret = ++argv;
  	for (was_space = true; *argv_str; argv_str++) {
  		if (isspace(*argv_str)) {
  			was_space = true;
  			*argv_str = 0;
  		} else if (was_space) {
  			was_space = false;
  			*argv++ = argv_str;

  		}
  	}

  	*argv = NULL;

  	if (argcp)
  		*argcp = argc;
  	return argv_ret;

  }
  EXPORT_SYMBOL(argv_split);