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90 lines
2.9 KiB
Plaintext
90 lines
2.9 KiB
Plaintext
/* An overview of the state machine from sm-malloc.cc.
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Copyright (C) 2019-2022 Free Software Foundation, Inc.
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Contributed by David Malcolm <dmalcolm@redhat.com>.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3, or (at your option)
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any later version.
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GCC is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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/* Keep this in-sync with sm-malloc.cc */
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digraph "malloc" {
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/* STATES. */
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/* Start state. */
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start;
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/* State for a pointer returned from malloc that hasn't been checked for
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NULL.
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It could be a pointer to heap-allocated memory, or could be NULL. */
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unchecked;
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/* State for a pointer that's known to be NULL. */
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null;
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/* State for a pointer to heap-allocated memory, known to be non-NULL. */
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nonnull;
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/* State for a pointer to freed memory. */
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freed;
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/* State for a pointer that's known to not be on the heap (e.g. to a local
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or global). */
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non_heap;
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/* Stop state, for pointers we don't want to track any more. */
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stop;
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/* TRANSITIONS. */
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start -> unchecked [label="on 'X=malloc(...);'"];
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start -> unchecked [label="on 'X=calloc(...);'"];
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start -> non_heap [label="on 'X=alloca(...);'"];
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start -> non_heap [label="on 'X=__builtin_alloca(...);'"];
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/* On "free". */
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start -> freed [label="on 'free(X);'"];
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unchecked -> freed [label="on 'free(X);'"];
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nonnull -> freed [label="on 'free(X);'"];
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freed -> stop [label="on 'free(X);':\n Warn('double-free')"];
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non_heap -> stop [label="on 'free(X);':\n Warn('free of non-heap')"];
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/* Handle "__attribute__((nonnull))". */
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unchecked -> nonnull [label="on 'FN(X)' with __attribute__((nonnull)):\nWarn('possible NULL arg')"];
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null -> stop [label="on 'FN(X)' with __attribute__((nonnull)):\nWarn('NULL arg')"];
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/* is_zero_assignment. */
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start -> null [label="on 'X = 0;'"];
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unchecked -> null [label="on 'X = 0;'"];
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nonnull -> null [label="on 'X = 0;'"];
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freed -> null [label="on 'X = 0;'"];
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start -> non_heap [label="on 'X = &EXPR;'"];
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/* Handle dereferences. */
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unchecked -> nonnull [label="on '*X':\nWarn('possible NULL deref')"];
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null -> stop [label="on '*X':\nWarn('NULL deref')"];
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freed -> stop [label="on '*X':\nWarn('use after free')"];
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/* on_condition. */
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unchecked -> nonnull [label="on 'X != 0'"];
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unchecked -> null [label="on 'X == 0'"];
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unchecked -> stop [label="on leak:\nWarn('leak')"];
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nonnull -> stop [label="on leak:\nWarn('leak')"];
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}
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