oss-fuzz/docs/fuzzer_environment.md

# Fuzzer environment on ClusterFuzz

Your fuzz targets will be run on a [Google Compute Engine](https://cloud.google.com/compute/) VM (Linux) with some [security restrictions](https://github.com/google/oss-fuzz/blob/master/infra/base-images/base-runner/run_minijail).

## Runtime Dependencies

You should not make any assumptions on the availability of dependent packages 
in the execution environment. Packages that are installed via
[Dockerfile](new_project_guide.md#dockerfile)
or built as part of 
[build.sh](new_project_guide.md#buildsh)
are not available on the bot runtime environment (where the fuzz targets run).

If you need these dependencies in the runtime environment, you can either
- Install the packages via Dockerfile
([example](https://github.com/google/oss-fuzz/blob/master/projects/tor/Dockerfile#L19))
and then link statically against them
([example](https://github.com/google/oss-fuzz/blob/master/projects/tor/build.sh#L40))
- Or build the dependencies statically in
[build.sh](new_project_guide.md#buildsh)
([example](https://github.com/google/oss-fuzz/blob/master/projects/ffmpeg/build.sh#L26)).

All build artifacts needed during fuzz target execution should be inside the `$OUT`
directory. Only those artifacts are archived and used on the bots. Everything else
is ignored (e.g. artifacts in `$WORK`, `$SRC`, etc) and hence is not available
in the execution environment.

You should ensure that the fuzz target works correctly by using `run_fuzzer` command 
(see instructions [here](new_project_guide.md#testing-locally)). This command uses
a clean base-runner docker container and not the base-builder docker container
created during build-time.

## argv[0]

You must not modify `argv[0]`. It is required for certain things to work correctly.

## Current working directory

You should not make any assumptions about the current working directory of your
fuzz target. If you need to load data files, please use `argv[0]` to get the
directory where your fuzz target executable is located.

## File system

Everything except `/tmp` is read-only, including the directory that your fuzz target
executable lives in.

`/dev` is also unavailable.

## Hardware

Your project should not be compiled with `-march=native` or `-mtune=native`
flags, as the build infrastructure and fuzzing machines may have different CPUs
as well as other hardware differences. You may however use `-mtune=generic`.
Add documentation about fuzzer execution environment. 2016-11-07 21:08:44 +00:00			`# Fuzzer environment on ClusterFuzz`

Update fuzzer_environment.md 2018-11-27 22:36:44 +00:00			`Your fuzz targets will be run on a [Google Compute Engine](https://cloud.google.com/compute/) VM (Linux) with some [security restrictions](https://github.com/google/oss-fuzz/blob/master/infra/base-images/base-runner/run_minijail).`
Add documentation about fuzzer execution environment. 2016-11-07 21:08:44 +00:00
Update fuzzer_environment.md 2017-02-07 16:39:14 +00:00			`## Runtime Dependencies`
Update fuzzer_environment.md 2017-01-10 20:44:14 +00:00
			`You should not make any assumptions on the availability of dependent packages`
Fix typos and clarify grammar and word choice throughout the OSS-Fuzz docs. (#363) 2017-02-08 03:15:53 +00:00			`in the execution environment. Packages that are installed via`
[infra] Update documentation (new coverage screenshots + some cleanup), follow-up #1839). 2018-10-01 15:13:41 +00:00			`[Dockerfile](new_project_guide.md#dockerfile)`
Tidy up #360 even more 2017-02-07 17:14:23 +00:00			`or built as part of`
[infra] Update documentation (new coverage screenshots + some cleanup), follow-up #1839). 2018-10-01 15:13:41 +00:00			`[build.sh](new_project_guide.md#buildsh)`
Fix typos and clarify grammar and word choice throughout the OSS-Fuzz docs. (#363) 2017-02-08 03:15:53 +00:00			`are not available on the bot runtime environment (where the fuzz targets run).`
Tidy up #360 even more 2017-02-07 17:14:23 +00:00
			`If you need these dependencies in the runtime environment, you can either`
Fix typos and clarify grammar and word choice throughout the OSS-Fuzz docs. (#363) 2017-02-08 03:15:53 +00:00			`- Install the packages via Dockerfile`
Tidy up #360 even more 2017-02-07 17:14:23 +00:00			`([example](https://github.com/google/oss-fuzz/blob/master/projects/tor/Dockerfile#L19))`
			`and then link statically against them`
			`([example](https://github.com/google/oss-fuzz/blob/master/projects/tor/build.sh#L40))`
			`- Or build the dependencies statically in`
[infra] Update documentation (new coverage screenshots + some cleanup), follow-up #1839). 2018-10-01 15:13:41 +00:00			`[build.sh](new_project_guide.md#buildsh)`
Tidy up #360 even more 2017-02-07 17:14:23 +00:00			`([example](https://github.com/google/oss-fuzz/blob/master/projects/ffmpeg/build.sh#L26)).`
[docs] Add more explicit documentation regarding build dependencies. (#360) 2017-02-07 16:43:34 +00:00
Fix typos and clarify grammar and word choice throughout the OSS-Fuzz docs. (#363) 2017-02-08 03:15:53 +00:00			All build artifacts needed during fuzz target execution should be inside the `$OUT`
Tidy up #360 even more 2017-02-07 17:14:23 +00:00			`directory. Only those artifacts are archived and used on the bots. Everything else`
			is ignored (e.g. artifacts in `$WORK`, `$SRC`, etc) and hence is not available
			`in the execution environment.`
Update fuzzer_environment.md 2017-01-14 20:20:48 +00:00
Update fuzzer_environment.md 2017-02-07 16:39:14 +00:00			You should ensure that the fuzz target works correctly by using `run_fuzzer` command
Update fuzzer_environment.md 2017-01-14 20:20:48 +00:00			`(see instructions [here](new_project_guide.md#testing-locally)). This command uses`
			`a clean base-runner docker container and not the base-builder docker container`
			`created during build-time.`
Update fuzzer_environment.md 2017-01-10 20:44:14 +00:00
Update fuzzer_environment.md 2017-01-20 19:55:22 +00:00			`## argv[0]`

Minor proposal (on string #35) (#1289) 2018-04-02 05:28:18 +00:00			You must not modify `argv[0]`. It is required for certain things to work correctly.
Update fuzzer_environment.md 2017-01-20 19:55:22 +00:00
Add documentation about fuzzer execution environment. 2016-11-07 21:08:44 +00:00			`## Current working directory`

Update fuzzer_environment.md 2016-11-26 23:59:29 +00:00			`You should not make any assumptions about the current working directory of your`
Update fuzzer_environment.md 2017-01-06 07:41:38 +00:00			fuzz target. If you need to load data files, please use `argv[0]` to get the
			`directory where your fuzz target executable is located.`
Add documentation about fuzzer execution environment. 2016-11-07 21:08:44 +00:00
Update fuzzer_environment.md 2016-11-29 19:47:37 +00:00			`## File system`
Add documentation about fuzzer execution environment. 2016-11-07 21:08:44 +00:00
Update fuzzer_environment.md 2017-01-06 07:41:38 +00:00			Everything except `/tmp` is read-only, including the directory that your fuzz target
Update fuzzer_environment.md 2017-01-10 20:44:14 +00:00			`executable lives in.`
Add documentation about fuzzer execution environment. 2016-11-07 21:08:44 +00:00
Update fuzzer_environment.md 2016-12-09 16:49:42 +00:00			`/dev` is also unavailable.

[docs] Add note regarding -march/-mtune flags as suggested in #752. (#753) 2017-08-01 16:31:29 +00:00			`## Hardware`

			Your project should not be compiled with `-march=native` or `-mtune=native`
			`flags, as the build infrastructure and fuzzing machines may have different CPUs`
			as well as other hardware differences. You may however use `-mtune=generic`.