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From: "Andrzej Hunt via GitGitGadget" <gitgitgadget@gmail.com>
To: git@vger.kernel.org
Cc: Josh Steadmon <steadmon@google.com>,
	Andrzej Hunt <andrzej@ahunt.org>,
	Andrzej Hunt <ajrhunt@google.com>
Subject: [PATCH v3] Makefile: update 'make fuzz-all' docs to reflect modern clang
Date: Mon, 08 Mar 2021 17:14:42 +0000	[thread overview]
Message-ID: <pull.889.v3.git.1615223682911.gitgitgadget@gmail.com> (raw)
In-Reply-To: <pull.889.v2.git.1614871707845.gitgitgadget@gmail.com>

From: Andrzej Hunt <ajrhunt@google.com>

Clang no longer produces a libFuzzer.a. Instead, you can include
libFuzzer by using -fsanitize=fuzzer. Therefore we should use that in
the example command for building fuzzers.

We also add -fsanitize=fuzzer-no-link to the CFLAGS to ensure that all
the required instrumentation is added when compiling git [1], and remove
 -fsanitize-coverage=trace-pc-guard as it is deprecated.

I happen to have tested with LLVM 11 - however -fsanitize=fuzzer appears
to work in a wide range of reasonably modern clangs.

(On my system: what used to be libFuzzer.a now lives under the following
 path, which is tricky albeit not impossible for a novice such as myself
 to find:
/usr/lib64/clang/11.0.0/lib/linux/libclang_rt.fuzzer-x86_64.a )

[1] https://releases.llvm.org/11.0.0/docs/LibFuzzer.html#fuzzer-usage

Signed-off-by: Andrzej Hunt <ajrhunt@google.com>
---
    Update 'make fuzz-all' docs to reflect modern clang
    
    This version of the patch fixes the commit message as per Junio's
    feedback. Thank you!

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-889%2Fahunt%2Ffuzz-docs-v3
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-889/ahunt/fuzz-docs-v3
Pull-Request: https://github.com/gitgitgadget/git/pull/889

Range-diff vs v2:

 1:  f5b5a11966ca ! 1:  bc0d8b615410 Update 'make fuzz-all' docs to reflect modern clang
     @@ Metadata
      Author: Andrzej Hunt <ajrhunt@google.com>
      
       ## Commit message ##
     -    Update 'make fuzz-all' docs to reflect modern clang
     +    Makefile: update 'make fuzz-all' docs to reflect modern clang
      
     -    Clang no longer produces a libFuzzer.a, instead you can include
     -    libFuzzer by using -fsanitize=fuzzer. Therefore we should use
     -    that in the example command for building fuzzers.
     +    Clang no longer produces a libFuzzer.a. Instead, you can include
     +    libFuzzer by using -fsanitize=fuzzer. Therefore we should use that in
     +    the example command for building fuzzers.
      
     -    We also add -fsanitize=fuzzer-no-link to ensure that all the required
     -    instrumentation is added when compiling git [1], and remove
     +    We also add -fsanitize=fuzzer-no-link to the CFLAGS to ensure that all
     +    the required instrumentation is added when compiling git [1], and remove
           -fsanitize-coverage=trace-pc-guard as it is deprecated.
      
     -    I happen to have tested with LLVM 11 - however -fsanitize=fuzzer appears to
     -    work in a wide range of reasonably modern clangs.
     +    I happen to have tested with LLVM 11 - however -fsanitize=fuzzer appears
     +    to work in a wide range of reasonably modern clangs.
      
     -    (On my system: what used to be libFuzzer.a now lives under the following path,
     -     which is tricky albeit not impossible for a novice such as myself to find:
     +    (On my system: what used to be libFuzzer.a now lives under the following
     +     path, which is tricky albeit not impossible for a novice such as myself
     +     to find:
          /usr/lib64/clang/11.0.0/lib/linux/libclang_rt.fuzzer-x86_64.a )
      
          [1] https://releases.llvm.org/11.0.0/docs/LibFuzzer.html#fuzzer-usage


 Makefile | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index dfb0f1000fa3..f3dc2178324e 100644
--- a/Makefile
+++ b/Makefile
@@ -3299,11 +3299,11 @@ cover_db_html: cover_db
 # are not necessarily appropriate for general builds, and that vary greatly
 # depending on the compiler version used.
 #
-# An example command to build against libFuzzer from LLVM 4.0.0:
+# An example command to build against libFuzzer from LLVM 11.0.0:
 #
 # make CC=clang CXX=clang++ \
-#      CFLAGS="-fsanitize-coverage=trace-pc-guard -fsanitize=address" \
-#      LIB_FUZZING_ENGINE=/usr/lib/llvm-4.0/lib/libFuzzer.a \
+#      CFLAGS="-fsanitize=fuzzer-no-link,address" \
+#      LIB_FUZZING_ENGINE="-fsanitize=fuzzer" \
 #      fuzz-all
 #
 FUZZ_CXXFLAGS ?= $(CFLAGS)

base-commit: be7935ed8bff19f481b033d0d242c5d5f239ed50
-- 
gitgitgadget

  parent reply	other threads:[~2021-03-08 17:15 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-28 12:22 [PATCH] Update 'make fuzz-all' docs to reflect modern clang Andrzej Hunt via GitGitGadget
2021-03-01 22:39 ` Josh Steadmon
2021-03-04 15:26   ` Andrzej Hunt
2021-03-04 15:28 ` [PATCH v2] " Andrzej Hunt via GitGitGadget
2021-03-04 22:48   ` Junio C Hamano
2021-03-08 17:05     ` Andrzej Hunt
2021-03-08 18:28       ` Junio C Hamano
2021-03-10 18:50     ` Josh Steadmon
2021-03-08 17:14   ` Andrzej Hunt via GitGitGadget [this message]
2021-03-10 18:52     ` [PATCH v3] Makefile: update " Josh Steadmon

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