Modify basic script to allow launching afl or libFuzzer fuzzing

tests/fuzzing/fuzz.nims

@@ -1,17 +1,89 @@
-# TODO: make this configurable when more fuzzing targets
+import strformat, strutils
-cd "discovery"
 
-if not dirExists("generated-input"):
+# Dependencies:
-  exec "nim c -r generate"
+# - afl fuzzing: afl and gcc or clang/llvm
+# - libFuzzer fuzzing: libFuzzer and clang/llvm
+# - in afl experimental modes clang/llvm is also required
+
+# TODO:
+# - switch clang / gcc option for afl
+# - afl init and persistent modes
+# - parallel fuzzing
+# - custom generate test cases from this script?
+# - rerun testcases option (or create tests from failed cases)?
+# - better cmd line parsing & and more options
+
+const aflGcc = "--cc=gcc " &
+                "--gcc.exe=afl-gcc " &
+                "--gcc.linkerexe=afl-gcc"
+const aflClang = "--cc=clang " &
+                  "--clang.exe=afl-clang " &
+                  "--clang.linkerexe=afl-clang"
+const aflClangFast = "--cc=clang " &
+                      "--clang.exe=afl-clang-fast " &
+                      "--clang.linkerexe=afl-clang-fast"
+const libFuzzerClang = "--cc=clang " &
+                        "--passC='-fsanitize=fuzzer,address' " &
+                        "--passL='-fsanitize=fuzzer,address'"
+# Can also test in debug mode obviously, but might be slower
+# Can turn on more logging, in case of libFuzzer it will get very verbose though
+const defaultFlags = "-d:release -d:chronicles_log_level=fatal " &
+                      "--hints:off --warnings:off --verbosity:0"
+const inputDir = "input" # dir for input samples
+const resultsDir = "results" # results dir (for afl)
+
+if paramCount() < 3:
+  echo "Usage: nim fuzz.nims FUZZER TARGET"
+  echo "Fuzzer options are afl or libFuzzer"
+  quit 1
+
+let
+  fuzzer = paramStr(2)
+  targetPath = paramStr(3)
+
+if not fileExists(targetPath):
+  echo "Target file does not exist"
+  quit 1
+
+let splitFile = targetPath.rsplit("/", 1)
+let workDir = splitFile[0]
+let targetNimFile = splitFile[1]
+var target = targetNimFile
+target.removeSuffix(".nim")
+cd workDir
+
+case fuzzer
+of "afl":
+  let aflOptions = &"-d:afl -d:noSignalHandler {aflGcc}"
+  let compileCmd = &"nim c {defaultFlags} {aflOptions} {target}"
+  exec compileCmd
+
+  if not dirExists(inputDir):
+    # create a input dir with one 0 file for afl
+    mkDir(inputDir)
+    withDir inputDir: exec "echo '0' > test"
+
+  var fuzzCmd: string
+  # if there is an output dir already, continue fuzzing from previous run
+  if not dirExists(resultsDir):
+    fuzzCmd = &"afl-fuzz -i {inputDir} -o {resultsDir} -M fuzzer01 -- ./{target}"
+  else:
+    fuzzCmd = &"afl-fuzz -i - -o {resultsDir} -M fuzzer01 -- ./{target}"
+  exec fuzzCmd
+
+of "libFuzzer":
+  let libFuzzerOptions = &"--noMain {libFuzzerClang}"
+  let compileCmd = &"nim c {defaultFlags} {libFuzzerOptions} {target}"
+  exec compileCmd
+
+  if not dirExists(inputDir):
+    # libFuzzer is OK with empty input dir
+    mkDir(inputDir)
+
+  # TODO: could use {resultsDir} of afl here also to reuse as corpus
+  exec &"./{target} {inputDir}"
 
-if not fileExists("fuzz"):
-  # Requires afl-gcc to be installed
-  # TODO: add + test option for clang
-  exec "nim c -d:afl -d:noSignalHandler --cc=gcc --gcc.exe=afl-gcc --gcc.linkerexe=afl-gcc fuzz"
-if dirExists("output"):
-  exec "afl-fuzz -i - -o output -M fuzzer01 -- ./fuzz"
 else:
-  exec "afl-fuzz -i generated-input -o output -M fuzzer01 -- ./fuzz"
+  echo "Invalid fuzzer option: ", fuzzer
-
+  echo "Fuzzer options are afl or libFuzzer"
-# TODO: how to add slaves for multiple cores in nimscript?
+  quit 1
-# afl-fuzz -i generated-input -o output -S fuzzer02 -- ./fuzz