From f92e6d0979190347796329a66b76fd9b16ad22a5 Mon Sep 17 00:00:00 2001
From: Niels Lohmann <mail@nlohmann.me>
Date: Sun, 8 May 2022 17:06:23 +0200
Subject: [PATCH] :memo: address review comments

---
 tests/fuzzing.md | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/tests/fuzzing.md b/tests/fuzzing.md
index 3ac696a59e..cfbf4f2499 100644
--- a/tests/fuzzing.md
+++ b/tests/fuzzing.md
@@ -1,12 +1,12 @@
 # Fuzz testing
 
 Each parser of the library (JSON, BJData, BSON, CBOR, MessagePack, and UBJSON) can be fuzz tested. Currently,
-[LibFuzzer](https://llvm.org/docs/LibFuzzer.html) and [afl++](https://github.com/AFLplusplus/AFLplusplus) are supported.
+[libFuzzer](https://llvm.org/docs/LibFuzzer.html) and [afl++](https://github.com/AFLplusplus/AFLplusplus) are supported.
 
 ## Corpus creation
 
 For most effective fuzzing, a [corpus](https://llvm.org/docs/LibFuzzer.html#corpus) should be provided. A corpus is a
-directory with some simple  input files that cover several features of the parser and is hence a good starting point
+directory with some simple input files that cover several features of the parser and is hence a good starting point
 for mutations.
 
 ```shell
@@ -16,18 +16,19 @@ unzip v$TEST_DATA_VERSION.zip
 rm v$TEST_DATA_VERSION.zip
 for FORMAT in json bjdata bson cbor msgpack ubjson
 do
-  rm -fr mkdir corpus_$FORMAT
+  rm -fr corpus_$FORMAT
   mkdir corpus_$FORMAT
   find json_test_data-$TEST_DATA_VERSION -size -5k -name "*.$FORMAT" -exec cp "{}" "corpus_$FORMAT" \;
 done
 rm -fr json_test_data-$TEST_DATA_VERSION
 ```
 
-The generated corpus can be used with both LibFuzzer and afl++.
+The generated corpus can be used with both libFuzzer and afl++. The remainder of this documentation assumes the corpus
+directories have been created in the `tests` directory.
 
-## LibFuzzer
+## libFuzzer
 
-To use LibFuzzer, you need to pass `-fsanitize=fuzzer` as `FUZZER_ENGINE`:
+To use libFuzzer, you need to pass `-fsanitize=fuzzer` as `FUZZER_ENGINE`. In the `tests` directory, call
 
 ```shell
 make fuzzers FUZZER_ENGINE="-fsanitize=fuzzer"
@@ -36,14 +37,15 @@ make fuzzers FUZZER_ENGINE="-fsanitize=fuzzer"
 This creates a fuzz tester binary for each parser that supports these
 [command line options](https://llvm.org/docs/LibFuzzer.html#options).
 
-Note the compiler provided by Xcode (AppleClang) does not contain libFuzzer. Please install Clang via Homebrew calling
-`brew install llvm` and add `CXX=$(brew --prefix llvm)/bin/clang` to the `make` call:
+In case your default compiler is not a Clang compiler that includes libFuzzer (Clang 6.0 or later), you need to set the
+`CXX` variable accordingly. Note the compiler provided by Xcode (AppleClang) does not contain libFuzzer. Please install
+Clang via Homebrew calling `brew install llvm` and add `CXX=$(brew --prefix llvm)/bin/clang` to the `make` call:
 
 ```shell
 make fuzzers FUZZER_ENGINE="-fsanitize=fuzzer" CXX=$(brew --prefix llvm)/bin/clang
 ```
 
-Then pass the corpus directory as command-line argument:
+Then pass the corpus directory as command-line argument (assuming it is located in `tests`):
 
 ```shell
 ./parse_cbor_fuzzer corpus_cbor
@@ -55,13 +57,13 @@ a file starting with `crash-`.
 ## afl++
 
 To use afl++, you need to pass `-fsanitize=fuzzer` as `FUZZER_ENGINE`. It will be replaced by a `libAFLDriver.a` to
-re-use the same code written for LibFuzzer with afl++. Furthermore, set `afl-clang-fast++` as compiler.
+re-use the same code written for libFuzzer with afl++. Furthermore, set `afl-clang-fast++` as compiler.
 
 ```shell
 CXX=afl-clang-fast++ make fuzzers FUZZER_ENGINE="-fsanitize=fuzzer" 
 ```
 
-Then the fuzzer is called like this:
+Then the fuzzer is called like this in the `tests` directory:
 
 ```shell
 afl-fuzz -i corpus_cbor -o out  -- ./parse_cbor_fuzzer 
@@ -76,4 +78,4 @@ The library is further fuzz-tested 24/7 by Google's [OSS-Fuzz project](https://g
 the same `fuzzers` target as above and also relies on the `FUZZER_ENGINE` variable. See the used
 [build script](https://github.com/google/oss-fuzz/blob/master/projects/json/build.sh) for more information.
 
-In case the build at OSS-Fuzz fails, and issue will be created automatically.
+In case the build at OSS-Fuzz fails, an issue will be created automatically.