Added fuzzing tests

.gitignore

@@ -1,3 +1,10 @@
+nimcache/
+snappycpp/
+
 master
 *.exe
-*.a
+*.a
+
+# Fuzzer-generated files
+crash-*
+

snappy.nim

@@ -1,7 +1,7 @@
 import
   stew/ranges/ptr_arith,
   faststreams/[inputs, outputs, buffers, multisync],
-  snappy/utils
+  snappy/[types, utils]
 
 const
   tagLiteral* = 0x00
@@ -11,10 +11,8 @@ const
 
   inputMargin = 16 - 1
 
-type
-  SnappyError* = object of CatchableError
-  UnexpectedEofError* = object of SnappyError
-  MalformedSnappyData* = object of SnappyError
+export
+  types
 
 # PutUvarint encodes a uint64 into buf and returns the number of bytes written.
 proc putUvarint(s: OutputStream, x: uint64) =

snappy/framing.nim

@@ -1,8 +1,11 @@
 import
-  ../snappy, ../snappy/utils,
-  ../tests/openarrays_snappy as oas,
   faststreams/[inputs, outputs, multisync],
-  stew/endians2
+  stew/endians2,
+  ../snappy, utils, types,
+  ../tests/openarrays_snappy as oas
+
+export
+  types
 
 {.compile: "crc32c.c".}
 # TODO: we don't have a native implementation of CRC32C algorithm yet.
@@ -63,7 +66,7 @@ proc uncompressFramedStream*(input: InputStream, output: OutputStream) {.fsMulti
 
         if uncompressedLen <= 0:
           raise newException(MalformedSnappyData, "Failed to decompress content")
-          
+
         if not checkCrcAndAppend(Sync output, uncompressedData.toOpenArray(0, uncompressedLen-1), crc):
           raise newException(MalformedSnappyData, "Content CRC checksum failed")
 
@@ -88,11 +91,14 @@ proc uncompressFramedStream*(input: InputStream, output: OutputStream) {.fsMulti
   finally:
     close output
 
-proc framingFormatUncompress*(input: openarray[byte]): seq[byte] =
+proc framingFormatUncompress*(input: InputStream): seq[byte] =
   var output = memoryOutput()
-  uncompressFramedStream unsafeMemoryInput(input), output
+  uncompressFramedStream input, output
   return output.getOutput
 
+proc framingFormatUncompress*(input: openarray[byte]): seq[byte] =
+  framingFormatUncompress unsafeMemoryInput(input)
+
 proc processFrame*(output: OutputStream, dst: var openArray[byte], src: openArray[byte]) =
   let
     crc = masked_crc32c(src[0].unsafeAddr, src.len.uint)

snappy/types.nim

@@ -0,0 +1,5 @@
+type
+  SnappyError* = object of CatchableError
+  UnexpectedEofError* = object of SnappyError
+  MalformedSnappyData* = object of SnappyError
+

tests/fuzzing/.gitignore

@@ -0,0 +1,3 @@
+corpus/
+nimcache/
+

tests/fuzzing/collect_corpus.nim

@@ -0,0 +1,37 @@
+import
+  os,
+  ../../snappy,
+  ../../snappy/framing
+
+let
+  fuzzingDir = getAppDir()
+  dataDir = fuzzingDir / ".." / "data"
+
+  corpusDir = fuzzingDir / "corpus"
+  blockFormatCorpusDir = corpusDir / "block_format"
+  framingFormatCorpusDir = corpusDir / "framing_format"
+
+removeDir corpusDir
+createDir blockFormatCorpusDir
+createDir framingFormatCorpusDir
+
+for kind, file in walkDir(dataDir):
+  if kind != pcFile:
+    continue
+
+  let size = getFileSize(file)
+  if size > 50000:
+    continue
+
+  let
+    fileContents = cast[seq[byte]](readFile(file))
+    fileName = splitFile(file).name
+    blockFileName = changeFileExt(fileName, "snappy")
+    framingFileName = changeFileExt(fileName, "fsnappy")
+
+  writeFile(blockFormatCorpusDir / blockFileName,
+            snappy.encode(fileContents))
+
+  writeFile(framingFormatCorpusDir / framingFileName,
+            framingFormatCompress(fileContents))
+

tests/fuzzing/fuzz_block_format.nim

@@ -0,0 +1,13 @@
+import
+  testutils/fuzzing,
+  ../../snappy
+
+test:
+  block:
+    try:
+      let decoded = snappy.decode(payload)
+      let encoded = snappy.encode(decoded)
+      doAssert encoded == payload
+    except SnappyError:
+      discard
+

tests/fuzzing/fuzz_framing_format.nim

@@ -0,0 +1,17 @@
+import
+  faststreams/inputs, testutils/fuzzing,
+  ../../snappy/framing
+
+test:
+  block:
+    try:
+      let input = unsafeMemoryInput(payload)
+      let decoded = framingFormatUncompress(input)
+      if input.len.get > 0:
+        break
+
+      let encoded = framingFormatCompress(decoded)
+      doAssert encoded == payload
+    except SnappyError:
+      discard
+

tests/fuzzing/run_fuzzing_test.nims

@@ -0,0 +1,23 @@
+import
+  os, strformat,
+  confutils, testutils/fuzzing_engines
+
+type
+  SnappyFormat = enum
+    block_format
+    framing_format
+
+cli do (format {.argument.}: SnappyFormat,
+        fuzzer = libFuzzer):
+  let
+    fuzzingDir = thisDir()
+    fuzzingFile = fuzzingDir / "fuzz_" & addFileExt($format, "nim")
+    corpusDir = fuzzingDir / "corpus" / $format
+
+  let
+    collectCorpusNim = fuzzingDir / "collect_corpus.nim"
+    fuzzNims = fuzzingDir / ".." / ".." / ".." / "nim-testutils" / "testutils" / "fuzzing" / "fuzz.nims"
+
+  exec &"""nim c -r "{collectCorpusNim}""""
+  exec &"""nim "{fuzzNims}" {fuzzer} "{fuzzingFile}" "{corpusDir}" """
+