[committed] analyzer: add sm-fd.dot
Checks
Commit Message
Add a .dot file to document the file descriptor state machine.
gcc/analyzer/ChangeLog:
* sm-fd.dot: New file.
Signed-off-by: David Malcolm <dmalcolm@redhat.com>
---
gcc/analyzer/sm-fd.dot | 109 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 109 insertions(+)
create mode 100644 gcc/analyzer/sm-fd.dot
new file mode 100644
@@ -0,0 +1,109 @@
+/* An overview of the state machine from sm-fd.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-dot.cc */
+
+digraph "fd" {
+
+ /* STATES. */
+
+ /* Start state. */
+ start;
+
+ /* States representing a file descriptor that hasn't yet been
+ checked for validity after opening, for three different
+ access modes. */
+ unchecked_read_write;
+ unchecked_read_only;
+ unchecked_write_only;
+
+ /* States for representing a file descriptor that is known to be valid (>=
+ 0), for three different access modes. */
+ valid_read_write;
+ valid_read_only;
+ valid_write_only;
+
+ /* State for a file descriptor that is known to be invalid (< 0). */
+ invalid;
+
+ /* State for a file descriptor that has been closed. */
+ closed;
+
+ /* State for a file descriptor that we do not want to track anymore . */
+ stop;
+
+ /* TRANSITIONS. */
+
+ /* On "open". */
+ start -> unchecked_read_only [label="on 'X = open(..., O_RDONLY);'"];
+ start -> unchecked_write_only [label="on 'X = open(..., O_WRONLY);'"];
+ start -> unchecked_read_write [label="on 'X = open(..., ...);'"];
+
+ /* On "creat". */
+ start -> unchecked_write_only [label="on 'X = create(...);'"];
+
+ /* On "close". */
+ start -> closed [label="on 'close(X);'"];
+ unchecked_read_write -> closed [label="on 'close(X);'"];
+ unchecked_read_only -> closed [label="on 'close(X);'"];
+ unchecked_write_only -> closed [label="on 'close(X);'"];
+ valid_read_write -> closed [label="on 'close(X);'"];
+ valid_read_only -> closed [label="on 'close(X);'"];
+ valid_write_only -> closed [label="on 'close(X);'"];
+ constant_fd -> closed [label="on 'close(X);'"];
+ closed -> stop [label="on 'close(X);':\nWarn('double close')"];
+
+ /* On "read". */
+ closed -> closed [label="on 'read(X);':\nWarn('use after close')"];
+ unchecked_read_write -> unchecked_read_write [label="on 'read(X);:\nWarn('use without check')'"];
+ unchecked_read_only -> unchecked_read_only [label="on 'read(X);:\nWarn('use without check')'"];
+ unchecked_write_only -> unchecked_write_only [label="on 'read(X);:\nWarn('use without check')'"];
+ valid_write_only -> valid_write_only [label="on 'read(X);:\nWarn('access mode mismatch')'"];
+
+ /* On "write". */
+ closed -> closed [label="on 'write(X);':\nWarn('use after close')"];
+ unchecked_read_write -> unchecked_read_write [label="on 'write(X);:\nWarn('use without check')'"];
+ unchecked_read_only -> unchecked_read_only [label="on 'write(X);:\nWarn('use without check')'"];
+ unchecked_write_only -> unchecked_write_only [label="on 'write(X);:\nWarn('use without check')'"];
+ valid_read_only -> valid_read_only [label="on 'write(X);:\nWarn('access mode mismatch')'"];
+
+ /* On "dup". */
+ closed -> closed [label="on 'dup(X);':\nWarn('use after close')"];
+ /* plus stuff for the new fd. */
+
+ /* On "pipe". */
+ start -> valid_read_write [label="when 'pipe()' succeeds"];
+
+ /* on_condition. */
+ unchecked_read_write -> valid_read_write [label="on 'X >= 0'"];
+ unchecked_read_only -> valid_read_only [label="on 'X >= 0'"];
+ unchecked_write_only -> valid_write_only [label="on 'X >= 0'"];
+ unchecked_read_write -> invalid [label="on 'X < 0'"];
+ unchecked_read_only -> invalid [label="on 'X < 0'"];
+ unchecked_write_only -> invalid [label="on 'X < 0'"];
+
+ /* Leaks. */
+ unchecked_read_write -> stop [label="on leak:\nWarn('leak')"];
+ unchecked_read_only -> stop [label="on leak:\nWarn('leak')"];
+ unchecked_write_only -> stop [label="on leak:\nWarn('leak')"];
+ valid_read_write -> stop [label="on leak:\nWarn('leak')"];
+ valid_read_only -> stop [label="on leak:\nWarn('leak')"];
+ valid_write_only -> stop [label="on leak:\nWarn('leak')"];
+}