type-layout-fuzzer.py

#!/usr/bin/env python3

# This script outputs a Swift source with randomly-generated type definitions,
# which can be used for ABI or layout algorithm fuzzing.

# TODO: generate types with generics, existentials, compositions

importrandom
importsys

maxDepth=5
maxMembers=5
typesDefined= []
classesDefined= []
nextToDefine=0
objcInterop=False

iflen(sys.argv) >=2:
ifsys.argv[1] =="--objc":
objcInterop=True
ifsys.argv[1] =="--help":
print("Usage: "+sys.argv[0] +" [--objc]", file=sys.stderr)
print("", file=sys.stderr)
print(" --objc Include ObjC-interop types", file=sys.stderr)
sys.exit(2)

random.seed()
ifobjcInterop:
print("import Foundation")
print()


defrandomTypeList(depth):
count=random.randint(0, maxMembers)
result="("
foriinrange(count):
ifi>0:
result+=", "
result+=randomTypeReference(depth+1)
result+=")"
returnresult


defrandomTypeReference(depth):
defnominal():
globaltypesDefined
allowNew=depth<maxDepth
bound=len(classesDefined) ifallowNewelselen(classesDefined) -1
which=random.randint(0, bound)
ifwhich<len(classesDefined):
returnclassesDefined[which]
newName="T"+str(len(typesDefined))

defdefineRandomRelatedType(name):
defineRandomNominalType(name, depth)

typesDefined.append((newName, defineRandomRelatedType))
returnnewName

deftuple():
returnrandomTypeList(depth+1)

defmetatype():
return"("+randomTypeReference(depth+1) +").Type"

defleaf():
leaves= ["Int", "String", "Int8", "Int16", "Int32", "Int64",
"(() -> ())", "(@convention(c) () -> ())", "AnyObject"]
ifobjcInterop:
leaves+= ["NSObject", "(@convention(block) () -> ())"]
returnrandom.choice(leaves)

ifdepth<maxDepth:
kinds= [nominal, tuple, metatype, leaf, leaf, leaf, leaf, leaf]
else:
kinds= [leaf]
returnrandom.choice(kinds)()


defdefineRandomFields(depth, basename):
numMembers=random.randint(0, maxMembers)
foriinrange(numMembers):
print(" var "+basename+str(i) +": "+
randomTypeReference(depth+1))


defdefineRandomClass(name, depth):
globalclassesDefined
classesDefined.append(name)
print("class "+name, end="")

definheritNSObject():
print(": NSObject", end="")

definheritsOtherClass():
print(": ", end="")
name="T"+str(len(typesDefined))

defdefineRandomBaseClass(name):
defineRandomClass(name, depth)

typesDefined.append((name, defineRandomBaseClass))
print(name, end="")

definheritsNothing():
pass

inheritances= [inheritsNothing]
ifdepth==0:
# The contents of classes are interesting only for top-level type
inheritances+= [inheritsOtherClass]

ifobjcInterop:
inheritances+= [inheritNSObject]
random.choice(inheritances)()

print(" {")
# Prevent errors about lack of initializers
print(" init("+name+": ()) { fatalError() }")
# The contents of classes are interesting only for top-level type
ifdepth==0:
defineRandomFields(depth, "x"+name)
print("}")
print()


defdefineRandomNominalType(name, depth=0):
defstruct():
print("struct "+name+" {")
defineRandomFields(depth, "x")
print("}")
print()

defclazz():
defineRandomClass(name, depth)

defenum():
# TODO: indirect cases
print("enum "+name+" {")

numCases=random.randint(0, maxMembers)
foriinrange(numCases):
print(" case x"+str(i) +randomTypeList(depth+1))

print("}")
print()

kinds= [struct, clazz, enum]
returnrandom.choice(kinds)()


typesDefined.append(("Generated", defineRandomNominalType))

whilenextToDefine<len(typesDefined):
name, definer=typesDefined[nextToDefine]
definer(name)
nextToDefine+=1