nim-eth/tests/fuzzing/fuzztest.nim

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import streams, posix, strutils, chronicles, macros, stew/ranges/ptr_arith
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template fuzz(body) =
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# For code we want to fuzz, SIGSEGV is needed on unwanted exceptions.
# However, this is only needed when fuzzing with afl.
when defined(standalone):
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try:
body
except Exception as e:
error "Fuzzer input created exception", exception=e.name, trace=e.repr, msg=e.msg
discard kill(getpid(), SIGSEGV)
else:
body
proc readStdin*(): seq[byte] =
# Read input from stdin (fastest for AFL)
let s = newFileStream(stdin)
if s.isNil:
error "Error opening stdin"
discard kill(getpid(), SIGSEGV)
# We use binary files as with hex we can get lots of "not hex" failures
var input = s.readAll()
s.close()
# Remove newline if it is there
input.removeSuffix
result = cast[seq[byte]](input)
proc NimMain() {.importc: "NimMain".}
# The default init, gets redefined when init template is used.
template initImpl(): untyped =
when defined(standalone):
discard
else:
proc fuzzerInit(): cint {.exportc: "LLVMFuzzerInitialize".} =
NimMain()
return 0
template init*(body: untyped) =
when defined(standalone):
template initImpl(): untyped = fuzz: `body`
else:
template initImpl() =
proc fuzzerInit(): cint {.exportc: "LLVMFuzzerInitialize".} =
NimMain()
`body`
return 0
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template test*(body: untyped): untyped =
mixin initImpl
initImpl()
when defined(standalone):
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var payload {.inject.} = readStdin()
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fuzz: `body`
else:
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proc fuzzerCall(data: ptr byte, len: csize):
cint {.exportc: "LLVMFuzzerTestOneInput".} =
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template payload(): auto =
makeOpenArray(data, len)
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`body`