text: // SPDX-License-Identifier: GPL-2.0+
  /* getline.c -- Replacement for GNU C library function getline
   *
   * Copyright (C) 1993, 1996, 2001, 2002 Free Software Foundation, Inc.
   */
  
  /* Written by Jan Brittenson, bson@gnu.ai.mit.edu.  */
  
  #include <assert.h>
  #include <stdio.h>
  
  /* Always add at least this many bytes when extending the buffer.  */
  #define MIN_CHUNK 64
  
  /* Read up to (and including) a TERMINATOR from STREAM into *LINEPTR
     + OFFSET (and null-terminate it). *LINEPTR is a pointer returned from
     malloc (or NULL), pointing to *N characters of space.  It is realloc'd
     as necessary.  Return the number of characters read (not including the
     null terminator), or -1 on error or EOF.
     NOTE: There is another getstr() function declared in <curses.h>.  */
  static int getstr(char **lineptr, size_t *n, FILE *stream,
  		  char terminator, size_t offset)
  {
  	int nchars_avail;	/* Allocated but unused chars in *LINEPTR.  */
  	char *read_pos;		/* Where we're reading into *LINEPTR. */
  	int ret;
  
  	if (!lineptr || !n || !stream)
  		return -1;
  
  	if (!*lineptr) {
  		*n = MIN_CHUNK;
  		*lineptr = malloc(*n);
  		if (!*lineptr)
  			return -1;
  	}
  
  	nchars_avail = *n - offset;
  	read_pos = *lineptr + offset;
  
  	for (;;) {
  		register int c = getc(stream);
  
  		/* We always want at least one char left in the buffer, since we
  		   always (unless we get an error while reading the first char)
  		   NUL-terminate the line buffer.  */
  
  		assert(*n - nchars_avail == read_pos - *lineptr);
  		if (nchars_avail < 2) {
  			if (*n > MIN_CHUNK)
  				*n *= 2;
  			else
  				*n += MIN_CHUNK;
  
  			nchars_avail = *n + *lineptr - read_pos;
  			*lineptr = realloc(*lineptr, *n);
  			if (!*lineptr)
  				return -1;
  			read_pos = *n - nchars_avail + *lineptr;
  			assert(*n - nchars_avail == read_pos - *lineptr);
  		}
  
  		if (c == EOF || ferror (stream)) {
  			/* Return partial line, if any.  */
  			if (read_pos == *lineptr)
  				return -1;
  			else
  				break;
  		}
  
  		*read_pos++ = c;
  		nchars_avail--;
  
  		if (c == terminator)
  			/* Return the line.  */
  			break;
  	}
  
  	/* Done - NUL terminate and return the number of chars read.  */
  	*read_pos = '\0';
  
  	ret = read_pos - (*lineptr + offset);
  	return ret;
  }
  
  int getline (char **lineptr, size_t *n, FILE *stream)
  {
  	return getstr(lineptr, n, stream, '\n', 0);
  }
  