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===========================
Sanitizer special case list
===========================
.. contents::
:local:
Introduction
============
This document describes the way to disable or alter the behavior of
sanitizer tools for certain source-level entities by providing a special
file at compile-time.
Goal and usage
==============
User of sanitizer tools, such as :doc:`AddressSanitizer`, :doc:`ThreadSanitizer`
or :doc:`MemorySanitizer` may want to disable or alter some checks for
certain source-level entities to:
* speedup hot function, which is known to be correct;
* ignore a function that does some low-level magic (e.g. walks through the
thread stack, bypassing the frame boundaries);
* ignore a known problem.
To achieve this, user may create a file listing the entities they want to
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ignore, and pass it to clang at compile-time using
``-fsanitize-blacklist`` flag. See :doc:`UsersManual` for details.
Example
=======
.. code-block:: bash
$ cat foo.c
#include <stdlib.h>
void bad_foo() {
int *a = (int*)malloc(40);
a[10] = 1;
}
int main() { bad_foo(); }
$ cat blacklist.txt
# Ignore reports from bad_foo function.
fun:bad_foo
$ clang -fsanitize=address foo.c ; ./a.out
# AddressSanitizer prints an error report.
$ clang -fsanitize=address -fsanitize-blacklist=blacklist.txt foo.c ; ./a.out
# No error report here.
Format
======
Each line contains an entity type, followed by a colon and a regular
expression, specifying the names of the entities, optionally followed by
an equals sign and a tool-specific category. Empty lines and lines starting
with "#" are ignored. The meanining of ``*`` in regular expression for entity
names is different - it is treated as in shell wildcarding. Two generic
entity types are ``src`` and ``fun``, which allow user to add, respectively,
source files and functions to special case list. Some sanitizer tools may
introduce custom entity types - refer to tool-specific docs.
.. code-block:: bash
# Lines starting with # are ignored.
# Turn off checks for the source file (use absolute path or path relative
# to the current working directory):
src:/path/to/source/file.c
# Turn off checks for a particular functions (use mangled names):
fun:MyFooBar
fun:_Z8MyFooBarv
# Extended regular expressions are supported:
fun:bad_(foo|bar)
src:bad_source[1-9].c
# Shell like usage of * is supported (* is treated as .*):
src:bad/sources/*
fun:*BadFunction*
# Specific sanitizer tools may introduce categories.
src:/special/path/*=special_sources