Function find_line

src/csplit.c:562–593

   Return a pointer to the line, or NULL if it is not found in the file. */

static struct cstring *
find_line (intmax_t linenum)
{
  if (head == NULL && !load_buffer ())
    return NULL;

  if (linenum < head->start_line)
    return NULL;

  for (struct buffer_record *b = head;;)
    {
      if (linenum < b->start_line + b->num_lines)
        {
          /* The line is in this buffer. */
          struct line *l;
          idx_t offset;	/* How far into the buffer the line is. */

          l = b->line_start;
          offset = linenum - b->start_line;
          /* Find the control record. */
          while (offset >= CTRL_SIZE)
            {
              l = l->next;
              offset -= CTRL_SIZE;
            }
          return &l->starts[offset];
        }
      if (b->next == NULL && !load_buffer ())
        return NULL;
      b = b->next;		/* Try the next data block. */
    }
}

/* Return true if at least one more line is available for input. */