gcc/analyzer/sm-file.dot

/* An overview of the state machine from sm-file.cc.
   Copyright (C) 2022 Free Software Foundation, Inc.
   Contributed by David Malcolm <dmalcolm@redhat.com>.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.

GCC 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
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

/* Keep this in-sync with sm-file.cc  */

digraph "file" {

  /* STATES. */

  /* Start state.  */
  start;

  /* State for a FILE * returned from fopen that hasn't been checked for
     NULL.
     It could be an open stream, or could be NULL.  */
  unchecked;

  /* State for a FILE * that's known to be NULL.  */
  null;

  /* State for a FILE * that's known to be a non-NULL open stream.  */
  nonnull;

  /* State for a FILE * that's had fclose called on it.  */
  closed;

  /* Stop state, for a FILE * we don't want to track any more.  */
  stop;

  /* TRANSITIONS. */

  /* On "fopen".  */
  start -> unchecked [label="on 'X = fopen(...);'"];

  /* On "fclose".  */
  start -> closed [label="on 'close(X);'"];
  /* TODO: is it safe to call fclose (NULL) ? */
  unchecked -> closed [label="on 'close(X);'"];
  null -> closed [label="on 'close(X);'"];
  nonnull -> closed [label="on 'close(X);'"];
  closed -> stop [label="on 'close(X);':\nWarn('double fclose')"];

  /* on_condition.  */
  unchecked -> nonnull [label="on 'X != 0'"];
  unchecked -> null [label="on 'X == 0'"];

  /* Leaks.  */
  unchecked -> stop [label="on leak:\nWarn('leak')"];
  nonnull -> stop [label="on leak:\nWarn('leak')"];
}