lib/strsep.c

/* Copyright (C) 2004, 2007, 2009-2026 Free Software Foundation, Inc.

   Written by Yoann Vandoorselaere <yoann@prelude-ids.org>.

   This file is free software: you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as
   published by the Free Software Foundation; either version 2.1 of the
   License, or (at your option) any later version.

   This file is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

/* Specification.  */
#include <string.h>

char *
strsep (char **stringp, const char *delim)
{
  char *start = *stringp;

  if (start == NULL)
    return NULL;

  /* Optimize the case of no delimiters.  */
  if (delim[0] == '\0')
    {
      *stringp = NULL;
      return start;
    }

  char *ptr;
  /* Optimize the case of one delimiter.  */
  if (delim[1] == '\0')
    ptr = strchr (start, delim[0]);
  else
    /* The general case.  */
    ptr = strpbrk (start, delim);

  if (ptr == NULL)
    {
      *stringp = NULL;
      return start;
    }

  *ptr = '\0';
  *stringp = ptr + 1;

  return start;
}