platform_bionic/libc/bionic/sysprop_helpers.h
Mitch Phillips e6997d52de [GWP-ASan] Provide runtime configuration through an env var + sysprop.
This patch introduces GWP-ASan system properties and environment
variables to control the internal sampling rates of GWP-ASan. This can
be used for:

 1. "Torture testing" the system, i.e. running it under an extremely
    high sampling rate under GWP-ASan.
 2. Increasing sampling remotely to allow further crash report
    collection of rare issues.

There are three sets of system properites:
 1. libc.debug.gwp_asan.*.system_default: Default values for native
    executables and system apps.
 2. libc.debug.gwp_asan.*.app_default: Default values for non-system
    apps, and
 3. libc.debug.gwp_asan.*.<basename/app_name>: Default values for an
    individual app or native process.

There are three variables that can be changed:
 1. The allocation sampling rate (default: 2500) - using the environment
    variable GWP_ASAN_SAMPLE_RATE or the libc.debug.gwp_asan.sample_rate.*
    system property.
 2. The process sampling rate (default: 128 for system apps/processes, 1
    for opted-in apps) - using the environment variable
    GWP_ASAN_PROCESS_SAMPLING or the libc.debug.gwp_asan.process_sampling.*
    system property,
 3. The number of slots available (default: 32) - using the environment
    variable GWP_ASAN_MAX_ALLOCS or the libc.debug.gwp_asan.max_allocs.*
    system property.

If not specified, #3 will be calculated as a ratio of the default
|2500 SampleRate : 32 slots|. So, a sample rate of "1250" (i.e. twice as
frequent sampling) will result in a doubling of the max_allocs to "64".

Bug: 219651032
Test: atest bionic-unit-tests
Change-Id: Idb40a2a4d074e01ce3c4e635ad639a91a32d570f
2022-04-20 11:26:00 -07:00

45 lines
2.3 KiB
C

/*
* Copyright (C) 2021 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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*/
#pragma once
#include <stdint.h>
#include <sys/cdefs.h>
// Get the presiding config string, in the following order of priority:
// 1. Environment variables.
// 2. System properties, in the order they're specified in sys_prop_names.
// If neither of these options are specified (or they're both an empty string),
// this function returns false. Otherwise, it returns true, and the presiding
// options string is written to the `options` buffer of size `size`. If this
// function returns true, `options` is guaranteed to be null-terminated.
// `options_size` should be at least PROP_VALUE_MAX.
__LIBC_HIDDEN__ bool get_config_from_env_or_sysprops(const char* env_var_name,
const char* const* sys_prop_names,
size_t sys_prop_names_size, char* options,
size_t options_size);