crucible-llvm-0.9: src/Lang/Crucible/LLVM/MemModel/Strings.hs
-- TODO(#1406): Move the definitions of the deprecated imports into this module,
-- and remove the exports from MemModel.
{-# OPTIONS_GHC -Wno-warnings-deprecations #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE DeriveFunctor #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE ImplicitParams #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TupleSections #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE TypeOperators #-}
-- | Manipulating C-style null-terminated strings
module Lang.Crucible.LLVM.MemModel.Strings
( storeString
-- * Loading strings
, Mem.loadString
, Mem.loadMaybeString
, loadConcretelyNullTerminatedString
, loadProvablyNullTerminatedString
-- * String length
, Mem.strLen
, strnlen
, strlenConcreteString
, strlenConcretelyNullTerminatedString
, strlenProvablyNullTerminatedString
-- * String copying
, copyConcreteString
, copyConcretelyNullTerminatedString
, copyProvablyNullTerminatedString
-- * String duplication
, dupConcreteString
, dupConcretelyNullTerminatedString
, dupProvablyNullTerminatedString
-- * Low-level string loading primitives
-- ** 'ByteChecker'
, ControlFlow(..)
, ByteChecker(..)
, withMaxChars
-- *** For loading strings
, fullyConcreteNullTerminatedString
, concretelyNullTerminatedString
, provablyNullTerminatedString
-- *** For string length
, fullyConcreteNullTerminatedStringLength
, concretelyNullTerminatedStringLength
, provablyNullTerminatedStringLength
-- ** 'ByteLoader'
, ByteLoader(..)
, llvmByteLoader
-- ** 'loadBytes'
, loadBytes
) where
import Control.Lens ((^.), to)
import Data.Bifunctor (Bifunctor(bimap))
import Control.Monad.IO.Class (MonadIO, liftIO)
import qualified Control.Monad.State.Strict as State
import qualified Data.BitVector.Sized as BV
import Data.Functor ((<&>))
import qualified Data.Parameterized.NatRepr as DPN
import Data.Word (Word8)
import qualified Data.Vector as Vec
import qualified GHC.Stack as GHC
import qualified Lang.Crucible.Backend as LCB
import qualified Lang.Crucible.Backend.Online as LCBO
import qualified Lang.Crucible.Simulator as LCS
import qualified Lang.Crucible.LLVM.DataLayout as CLD
import qualified Lang.Crucible.LLVM.Errors.MemoryError as MemErr
import qualified Lang.Crucible.LLVM.MemModel as LCLM
import qualified Lang.Crucible.LLVM.MemModel as Mem
import qualified Lang.Crucible.LLVM.MemModel.Generic as Mem.G
import qualified Lang.Crucible.LLVM.MemModel.Partial as Partial
import qualified What4.Expr.Builder as WEB
import qualified What4.Interface as WI
import qualified What4.Protocol.Online as WPO
import qualified What4.SatResult as WS
-- | Store a null-terminated string to memory.
storeNullTerminatedString ::
forall sym bak w.
( LCB.IsSymBackend sym bak
, WI.IsExpr (WI.SymExpr sym)
, LCLM.HasPtrWidth w
, LCLM.HasLLVMAnn sym
, ?memOpts :: LCLM.MemOptions
) =>
bak ->
LCLM.MemImpl sym ->
-- | Pointer to write string to
LCLM.LLVMPtr sym w ->
-- | The bytes of the string to write (null terminator included)
Vec.Vector (WI.SymBV sym 8) ->
IO (LCLM.MemImpl sym)
storeNullTerminatedString bak mem ptr bytesBvs = do
let sym = LCB.backendGetSym bak
zeroNat <- WI.natLit sym 0
let bytes = Vec.map (Mem.LLVMValInt zeroNat) bytesBvs
let val = Mem.LLVMValArray (Mem.bitvectorType 1) bytes
let storTy = Mem.llvmValStorableType @sym val
Mem.storeRaw bak mem ptr storTy CLD.noAlignment val
-- | Store a string to memory, adding a null terminator at the end.
storeString ::
forall sym bak w.
( LCB.IsSymBackend sym bak
, WI.IsExpr (WI.SymExpr sym)
, LCLM.HasPtrWidth w
, LCLM.HasLLVMAnn sym
, ?memOpts :: LCLM.MemOptions
) =>
bak ->
LCLM.MemImpl sym ->
-- | Pointer to write string to
LCLM.LLVMPtr sym w ->
-- | The bytes of the string to write (null terminator not included)
Vec.Vector (WI.SymBV sym 8) ->
IO (LCLM.MemImpl sym)
storeString bak mem ptr bytesBvs = do
let sym = LCB.backendGetSym bak
zeroByte <- WI.bvZero sym (DPN.knownNat @8)
let nullTerminatedBytes = Vec.snoc bytesBvs zeroByte
storeNullTerminatedString bak mem ptr nullTerminatedBytes
---------------------------------------------------------------------
-- * Loading strings
-- | Load a null-terminated string (with a concrete null terminator) from memory.
--
-- The string must contain a concrete null terminator. If a maximum number of
-- characters is provided, no more than that number of characters will be read.
-- In either case, 'loadConcretelyNullTerminatedString' will stop reading if it
-- encounters a (concretely) null terminator.
--
-- Note that the loaded string may actually be smaller than the returned list if
-- any of the symbolic bytes are equal to 0.
loadConcretelyNullTerminatedString ::
( LCB.IsSymBackend sym bak
, Mem.HasPtrWidth wptr
, Mem.HasLLVMAnn sym
, ?memOpts :: Mem.MemOptions
, GHC.HasCallStack
) =>
bak ->
Mem.MemImpl sym ->
Mem.LLVMPtr sym wptr ->
-- | Maximum number of characters to read
Maybe Int ->
IO [WI.SymBV sym 8]
loadConcretelyNullTerminatedString bak mem ptr limit =
let loader = llvmByteLoader mem in
case limit of
Nothing -> loadBytes bak mem id ptr loader concretelyNullTerminatedString
Just l ->
let byteChecker = withMaxChars l (\f -> pure (f [])) concretelyNullTerminatedString in
loadBytes bak mem (id, 0) ptr loader byteChecker
-- | Load a null-terminated string from memory.
--
-- Consults an SMT solver to check if any of the loaded bytes are known
-- to be null (0). If a maximum number of characters is provided, no
-- more than that number of charcters will be read. In either case,
-- 'loadProvablyNullTerminatedString' will stop reading if it encounters a null
-- terminator.
--
-- Note that the loaded string may actually be smaller than the returned list if
-- any of the symbolic bytes are equal to 0.
loadProvablyNullTerminatedString ::
( LCB.IsSymBackend sym bak
, sym ~ WEB.ExprBuilder scope st fs
, bak ~ LCBO.OnlineBackend solver scope st fs
, WPO.OnlineSolver solver
, Mem.HasPtrWidth wptr
, Mem.HasLLVMAnn sym
, ?memOpts :: Mem.MemOptions
, GHC.HasCallStack
) =>
bak ->
Mem.MemImpl sym ->
Mem.LLVMPtr sym wptr ->
-- | Maximum number of characters to read
Maybe Int ->
IO [WI.SymBV sym 8]
loadProvablyNullTerminatedString bak mem ptr limit =
let loader = llvmByteLoader mem in
case limit of
Nothing -> loadBytes bak mem id ptr loader provablyNullTerminatedString
Just l ->
let byteChecker = withMaxChars l (\f -> pure (f [])) provablyNullTerminatedString in
loadBytes bak mem (id, 0) ptr loader byteChecker
---------------------------------------------------------------------
-- * String length
-- | Implementation of libc @strnlen@.
strnlen ::
( LCB.IsSymBackend sym bak
, Mem.HasPtrWidth wptr
, Mem.HasLLVMAnn sym
, ?memOpts :: Mem.MemOptions
, GHC.HasCallStack
) =>
bak ->
Mem.MemImpl sym ->
-- | Pointer to null-terminated string
Mem.LLVMPtr sym wptr ->
-- | Size
--
-- If this is not concrete, this will generate an assertion failure.
WI.SymBV sym wptr ->
IO (WI.SymBV sym wptr)
strnlen bak mem ptr bound = do
case BV.asUnsigned <$> WI.asBV bound of
Nothing ->
let err = LCS.AssertFailureSimError "`strnlen` called with symbolic max length" "" in
LCB.addFailedAssertion bak err
Just b ->
let bound' = Just (fromIntegral b) in
strlenConcretelyNullTerminatedString bak mem ptr bound'
-- | @strlen@ of a concrete string.
--
-- If any symbolic bytes are encountered, an assertion failure will be
-- generated. If a maximum number of characters is provided, no more than that
-- number of characters will be read. In either case, 'strlenConcreteString'
-- will stop reading if it encounters a null terminator.
strlenConcreteString ::
( LCB.IsSymBackend sym bak
, Mem.HasPtrWidth wptr
, Mem.HasLLVMAnn sym
, ?memOpts :: Mem.MemOptions
, GHC.HasCallStack
) =>
bak ->
Mem.MemImpl sym ->
Mem.LLVMPtr sym wptr ->
-- | Maximum number of characters to read
Maybe Int ->
IO Int
strlenConcreteString bak mem ptr limit = do
let loader = llvmByteLoader mem
case limit of
Nothing -> loadBytes bak mem 0 ptr loader fullyConcreteNullTerminatedStringLength
Just 0 -> pure 0
Just l -> do
let byteChecker = withMaxChars l pure fullyConcreteNullTerminatedStringLength
loadBytes bak mem (0, 0) ptr loader byteChecker
-- | @strlen@ of a null-terminated string (with a concrete null terminator).
--
-- The string must contain a concrete null terminator. If a maximum number of
-- characters is provided, no more than that number of characters will be read.
-- In either case, 'strlenConcretelyNullTerminatedString' will stop reading if
-- it encounters a (concretely) null terminator.
--
-- This has the same behavior as 'Lang.Crucible.LLVM.MemModel.strLen', except
-- that it supports a maximum length.
strlenConcretelyNullTerminatedString ::
( LCB.IsSymBackend sym bak
, Mem.HasPtrWidth wptr
, Mem.HasLLVMAnn sym
, ?memOpts :: Mem.MemOptions
, GHC.HasCallStack
) =>
bak ->
Mem.MemImpl sym ->
Mem.LLVMPtr sym wptr ->
-- | Maximum number of characters to read
Maybe Int ->
IO (WI.SymBV sym wptr)
strlenConcretelyNullTerminatedString bak mem ptr limit = do
let loader = llvmByteLoader mem
let sym = LCB.backendGetSym bak
z <- WI.bvZero sym ?ptrWidth
flip State.evalStateT (WI.truePred sym) $
case limit of
Nothing -> loadBytes bak mem z ptr loader concretelyNullTerminatedStringLength
Just 0 -> liftIO (WI.bvZero (LCB.backendGetSym bak) ?ptrWidth)
Just l -> do
let byteChecker = withMaxChars l pure concretelyNullTerminatedStringLength
loadBytes bak mem (z, 0) ptr loader byteChecker
-- | @strlen@ of a provably null-terminated string.
--
-- Consults an SMT solver to check if any of the loaded bytes are known
-- to be null (0). If a maximum number of characters is provided, no
-- more than that number of charcters will be read. In either case,
-- 'strlenProvablyNullTerminatedString' will stop reading if it encounters a
-- (provably) null terminator.
strlenProvablyNullTerminatedString ::
( LCB.IsSymBackend sym bak
, Mem.HasPtrWidth wptr
, Mem.HasLLVMAnn sym
, ?memOpts :: Mem.MemOptions
, GHC.HasCallStack
, sym ~ WEB.ExprBuilder scope st fs
, bak ~ LCBO.OnlineBackend solver scope st fs
, WPO.OnlineSolver solver
) =>
bak ->
Mem.MemImpl sym ->
Mem.LLVMPtr sym wptr ->
-- | Maximum number of characters to read
Maybe Int ->
IO (WI.SymBV sym wptr)
strlenProvablyNullTerminatedString bak mem ptr limit = do
let loader = llvmByteLoader mem
let sym = LCB.backendGetSym bak
z <- WI.bvZero sym ?ptrWidth
flip State.evalStateT (WI.truePred sym) $
case limit of
Nothing -> loadBytes bak mem z ptr loader provablyNullTerminatedStringLength
Just 0 -> liftIO (WI.bvZero (LCB.backendGetSym bak) ?ptrWidth)
Just l -> do
let byteChecker = withMaxChars l pure provablyNullTerminatedStringLength
loadBytes bak mem (z, 0) ptr loader byteChecker
---------------------------------------------------------------------
-- * String copying
-- | Helper, not exported
strcpyAssertDisjoint ::
( LCB.IsSymBackend sym bak
, Mem.HasPtrWidth wptr
, Mem.HasLLVMAnn sym
, ?memOpts :: Mem.MemOptions
, GHC.HasCallStack
) =>
bak ->
Mem.MemImpl sym ->
-- | Loaded bytes
Vec.Vector (WI.SymBV sym 8) ->
-- | Destination pointer
Mem.LLVMPtr sym wptr ->
-- | Source pointer
Mem.LLVMPtr sym wptr ->
IO ()
strcpyAssertDisjoint bak mem bytes dst src = do
let sym = LCB.backendGetSym bak
let len = fromIntegral (Vec.length bytes)
sz <- WI.bvLit sym ?ptrWidth (BV.mkBV ?ptrWidth len)
let heap = mem ^. to Mem.memImplHeap
let memOp =
MemErr.MemCopyOp (Just "strcpy dst", dst) (Just "strcpy src", src) sz heap
Mem.assertDisjointRegions bak memOp ?ptrWidth dst sz src sz
-- | @strcpy@ of a concrete string.
--
-- Uses 'Mem.loadString' to load the string, see that function for details.
--
-- Asserts that the regions are disjoint.
copyConcreteString ::
( LCB.IsSymBackend sym bak
, Mem.HasPtrWidth wptr
, Mem.HasLLVMAnn sym
, ?memOpts :: Mem.MemOptions
, GHC.HasCallStack
) =>
bak ->
Mem.MemImpl sym ->
-- | Destination pointer
Mem.LLVMPtr sym wptr ->
-- | Source pointer
Mem.LLVMPtr sym wptr ->
IO (Mem.MemImpl sym)
copyConcreteString bak mem dst src = do
bytes <- Mem.loadString bak mem src Nothing
let sym = LCB.backendGetSym bak
symBytes <- mapM (WI.bvLit sym WI.knownRepr . BV.word8) bytes
let bytesVec = Vec.fromList symBytes
strcpyAssertDisjoint bak mem bytesVec dst src
storeString bak mem dst (Vec.fromList symBytes)
-- | @strcpy@ of a concretely null-terminated string.
--
-- Uses 'loadConcretelyNullTerminatedString' to load the string, see that
-- function for details.
--
-- Asserts that the regions are disjoint.
copyConcretelyNullTerminatedString ::
( LCB.IsSymBackend sym bak
, Mem.HasPtrWidth wptr
, Mem.HasLLVMAnn sym
, ?memOpts :: Mem.MemOptions
, GHC.HasCallStack
) =>
bak ->
Mem.MemImpl sym ->
-- | Destination pointer
Mem.LLVMPtr sym wptr ->
-- | Source pointer
Mem.LLVMPtr sym wptr ->
-- | Maximum number of characters to read
Maybe Int ->
IO (Mem.MemImpl sym)
copyConcretelyNullTerminatedString bak mem dst src bounds = do
bytes <- loadConcretelyNullTerminatedString bak mem src bounds
let bytesVec = Vec.fromList bytes
strcpyAssertDisjoint bak mem bytesVec dst src
storeString bak mem dst bytesVec
-- | @strcpy@ of a concrete string.
--
-- Uses 'loadProvablyNullTerminatedString' to load the string, see that
-- function for details.
--
-- Asserts that the regions are disjoint.
copyProvablyNullTerminatedString ::
( LCB.IsSymBackend sym bak
, sym ~ WEB.ExprBuilder scope st fs
, bak ~ LCBO.OnlineBackend solver scope st fs
, WPO.OnlineSolver solver
, Mem.HasPtrWidth wptr
, Mem.HasLLVMAnn sym
, ?memOpts :: Mem.MemOptions
, GHC.HasCallStack
) =>
bak ->
Mem.MemImpl sym ->
-- | Destination pointer
Mem.LLVMPtr sym wptr ->
-- | Source pointer
Mem.LLVMPtr sym wptr ->
-- | Maximum number of characters to read
Maybe Int ->
IO (Mem.MemImpl sym)
copyProvablyNullTerminatedString bak mem dst src bounds = do
bytes <- loadProvablyNullTerminatedString bak mem src bounds
let bytesVec = Vec.fromList bytes
strcpyAssertDisjoint bak mem bytesVec dst src
storeString bak mem dst bytesVec
---------------------------------------------------------------------
-- * String duplication
-- | Helper function: allocate memory and store bytes for string duplication.
--
-- Takes a vector of bytes (NOT including null terminator) and:
-- 1. Allocates memory of the appropriate size (length + 1 for null terminator)
-- 2. Stores the bytes with null terminator to the allocated memory
-- 3. Returns the new pointer and updated memory
dupFromLoadedBytes ::
( LCB.IsSymBackend sym bak
, Mem.HasPtrWidth wptr
, Mem.HasLLVMAnn sym
, ?memOpts :: Mem.MemOptions
, GHC.HasCallStack
) =>
bak ->
Mem.MemImpl sym ->
Vec.Vector (WI.SymBV sym 8) ->
String ->
CLD.Alignment ->
IO (Mem.LLVMPtr sym wptr, Mem.MemImpl sym)
dupFromLoadedBytes bak mem bytesVec displayString alignment = do
let len = fromIntegral (Vec.length bytesVec) + 1 -- +1 for null terminator
let sym = LCB.backendGetSym bak
sz <- WI.bvLit sym ?ptrWidth (BV.mkBV ?ptrWidth len)
(dst, mem') <- Mem.doMalloc bak Mem.G.HeapAlloc Mem.G.Mutable displayString mem sz alignment
mem'' <- storeString bak mem' dst bytesVec
pure (dst, mem'')
-- | @strdup@ of a concrete string.
--
-- Uses 'Mem.loadString' to load the string, see that function for details.
--
-- Allocates memory and copies the string to it, returning the new pointer.
dupConcreteString ::
( LCB.IsSymBackend sym bak
, Mem.HasPtrWidth wptr
, Mem.HasLLVMAnn sym
, ?memOpts :: Mem.MemOptions
, GHC.HasCallStack
) =>
bak ->
Mem.MemImpl sym ->
-- | Source pointer
Mem.LLVMPtr sym wptr ->
-- | Display string for allocation
String ->
-- | Alignment
CLD.Alignment ->
IO (Mem.LLVMPtr sym wptr, Mem.MemImpl sym)
dupConcreteString bak mem src displayString alignment = do
bytes <- Mem.loadString bak mem src Nothing
let sym = LCB.backendGetSym bak
symBytes <- mapM (WI.bvLit sym WI.knownRepr . BV.word8) bytes
dupFromLoadedBytes bak mem (Vec.fromList symBytes) displayString alignment
-- | @strdup@ of a concretely null-terminated string.
--
-- Uses 'loadConcretelyNullTerminatedString' to load the string, see that
-- function for details.
--
-- Allocates memory and copies the string to it, returning the new pointer.
dupConcretelyNullTerminatedString ::
( LCB.IsSymBackend sym bak
, Mem.HasPtrWidth wptr
, Mem.HasLLVMAnn sym
, ?memOpts :: Mem.MemOptions
, GHC.HasCallStack
) =>
bak ->
Mem.MemImpl sym ->
-- | Source pointer
Mem.LLVMPtr sym wptr ->
-- | Maximum number of characters to read
Maybe Int ->
-- | Display string for allocation
String ->
CLD.Alignment ->
IO (Mem.LLVMPtr sym wptr, Mem.MemImpl sym)
dupConcretelyNullTerminatedString bak mem src bounds displayString alignment = do
bytes <- loadConcretelyNullTerminatedString bak mem src bounds
dupFromLoadedBytes bak mem (Vec.fromList bytes) displayString alignment
-- | @strdup@ of a provably null-terminated string.
--
-- Uses 'loadProvablyNullTerminatedString' to load the string, see that
-- function for details.
--
-- Allocates memory and copies the string to it, returning the new pointer.
dupProvablyNullTerminatedString ::
( LCB.IsSymBackend sym bak
, sym ~ WEB.ExprBuilder scope st fs
, bak ~ LCBO.OnlineBackend solver scope st fs
, WPO.OnlineSolver solver
, Mem.HasPtrWidth wptr
, Mem.HasLLVMAnn sym
, ?memOpts :: Mem.MemOptions
, GHC.HasCallStack
) =>
bak ->
Mem.MemImpl sym ->
-- | Source pointer
Mem.LLVMPtr sym wptr ->
-- | Maximum number of characters to read
Maybe Int ->
-- | Display string for allocation
String ->
CLD.Alignment ->
IO (Mem.LLVMPtr sym wptr, Mem.MemImpl sym)
dupProvablyNullTerminatedString bak mem src bounds displayString alignment = do
bytes <- loadProvablyNullTerminatedString bak mem src bounds
dupFromLoadedBytes bak mem (Vec.fromList bytes) displayString alignment
---------------------------------------------------------------------
-- * Low-level string loading primitives
---------------------------------------------------------------------
-- ** 'ByteChecker'
-- | Whether to stop or keep going
--
-- Like Rust's @std::ops::ControlFlow@.
data ControlFlow a b
= Continue a
| Break b
deriving Functor
-- NB: 'first' is used in this module
instance Bifunctor ControlFlow where
bimap l r =
\case
Continue x -> Continue (l x)
Break x -> Break (r x)
-- | Compute a result from a symbolic byte, and check if the load should
-- continue to the next byte.
--
-- Used to:
--
-- * Check if the byte is concrete ('fullyConcreteNullTerminatedString')
-- * Check if the byte is concretely a null terminator
-- ('concretelyNullTerminatedString')
-- * Check if a byte is known by a solver to be a null terminator ('nullTerminatedString')
-- * Check if we have surpassed a length limit ('withMaxChars')
--
-- Note that it is relatively common for @a@ to be a function @[b] -> [b]@. This
-- is used to build up a snoc-list.
newtype ByteChecker m sym bak a b
= ByteChecker { runByteChecker :: bak -> a -> Mem.LLVMPtr sym 8 -> m (ControlFlow a b) }
-- Helper, not exported
ptrToBv8 ::
LCB.IsSymBackend sym bak =>
bak ->
Mem.LLVMPtr sym 8 ->
IO (WI.SymBV sym 8)
ptrToBv8 bak bytePtr = do
let err = LCS.AssertFailureSimError "Found pointer instead of byte when loading string" ""
Partial.ptrToBv bak err bytePtr
-- | 'ByteChecker' for adding a maximum character length.
withMaxChars ::
MonadIO m =>
GHC.HasCallStack =>
LCB.IsSymBackend sym bak =>
Functor m =>
-- | Maximum number of bytes to load
Int ->
-- | What to do when the maximum is reached
(a -> m b) ->
ByteChecker m sym bak a b ->
ByteChecker m sym bak (a, Int) b
withMaxChars limit done checker =
ByteChecker $ \bak (acc, i) bytePtr ->
runByteChecker checker bak acc bytePtr >>=
\case
Break r -> pure (Break r)
Continue r ->
if i + 1 >= limit
then Break <$> done r
else pure (Continue (r, i + 1))
---------------------------------------------------------------------
-- *** For loading strings
-- | 'ByteChecker' for loading concrete strings.
--
-- Currently unused internally, but analogous with
-- 'Lang.Crucible.LLVM.MemModel.loadString'. In fact, it would be good to define
-- that function in terms of this one. However, this is blocked on TODO(#1406).
fullyConcreteNullTerminatedString ::
MonadIO m =>
GHC.HasCallStack =>
LCB.IsSymBackend sym bak =>
ByteChecker m sym bak ([Word8] -> [Word8]) [Word8]
fullyConcreteNullTerminatedString =
ByteChecker $ \bak acc bytePtr -> do
byte <- liftIO (ptrToBv8 bak bytePtr)
case BV.asUnsigned <$> WI.asBV byte of
Just 0 -> pure (Break (acc []))
Just c -> do
let c' = toEnum @Word8 (fromInteger c)
pure (Continue (\l -> acc (c' : l)))
Nothing -> do
let msg = "Symbolic value encountered when loading a string"
liftIO (LCB.addFailedAssertion bak (LCS.Unsupported GHC.callStack msg))
-- | 'ByteChecker' for loading symbolic strings with a concrete null terminator.
--
-- Used in 'loadConcretelyNullTerminatedString'.
concretelyNullTerminatedString ::
MonadIO m =>
GHC.HasCallStack =>
LCB.IsSymBackend sym bak =>
ByteChecker m sym bak ([WI.SymBV sym 8] -> [WI.SymBV sym 8]) [WI.SymBV sym 8]
concretelyNullTerminatedString =
ByteChecker $ \bak acc bytePtr -> do
byte <- liftIO (ptrToBv8 bak bytePtr)
if isConcreteNullTerminator byte
then pure (Break (acc []))
else pure (Continue (\l -> acc (byte : l)))
where
isConcreteNullTerminator symByte =
case BV.asUnsigned <$> WI.asBV symByte of
Just 0 -> True
_ -> False
-- | 'ByteChecker' for loading symbolic strings with a provably-null terminator.
--
-- Used in 'loadSymbolicString'.
provablyNullTerminatedString ::
MonadIO m =>
GHC.HasCallStack =>
LCB.IsSymBackend sym bak =>
sym ~ WEB.ExprBuilder scope st fs =>
bak ~ LCBO.OnlineBackend solver scope st fs =>
WPO.OnlineSolver solver =>
ByteChecker m sym bak ([WI.SymBV sym 8] -> [WI.SymBV sym 8]) [WI.SymBV sym 8]
provablyNullTerminatedString =
ByteChecker $ \bak acc bytePtr -> liftIO $ do
byte <- ptrToBv8 bak bytePtr
let sym = LCB.backendGetSym bak
isNullTerm <- isProvablyNullTerminator bak sym byte
if isNullTerm
then pure (Break (acc []))
else pure (Continue (\l -> acc (byte : l)))
-- Helper, not exported
isProvablyNullTerminator ::
GHC.HasCallStack =>
LCB.IsSymBackend sym bak =>
sym ~ WEB.ExprBuilder scope st fs =>
bak ~ LCBO.OnlineBackend solver scope st fs =>
WPO.OnlineSolver solver =>
bak ->
sym ->
WI.SymBV sym 8 ->
IO Bool
isProvablyNullTerminator bak sym symByte =
case BV.asUnsigned <$> WI.asBV symByte of
Just 0 -> pure True
Just _ -> pure False
_ ->
LCBO.withSolverProcess bak (pure False) $ \proc -> do
z <- WI.bvZero sym (WI.knownNat @8)
p <- WI.notPred sym =<< WI.bvEq sym z symByte
WPO.checkSatisfiable proc "isProvablyNullTerminator" p <&>
\case
WS.Unsat () -> True
WS.Sat () -> False
WS.Unknown -> False
---------------------------------------------------------------------
-- *** For string length
-- | 'ByteChecker' for @strlen@ of concrete strings.
fullyConcreteNullTerminatedStringLength ::
MonadIO m =>
GHC.HasCallStack =>
LCB.IsSymBackend sym bak =>
ByteChecker m sym bak Int Int
fullyConcreteNullTerminatedStringLength =
ByteChecker $ \bak acc bytePtr -> do
byte <- liftIO (ptrToBv8 bak bytePtr)
case BV.asUnsigned <$> WI.asBV byte of
Just 0 -> pure (Break acc)
Just _ -> pure (Continue $! acc + 1)
Nothing -> do
let msg = "Symbolic value encountered when loading a string"
liftIO (LCB.addFailedAssertion bak (LCS.Unsupported GHC.callStack msg))
-- Helper, not exported
symStringLength ::
MonadIO m =>
State.MonadState (WI.Pred sym) m =>
GHC.HasCallStack =>
Mem.HasPtrWidth wptr =>
LCB.IsSymBackend sym bak =>
-- | How to check if a predicate is false
(bak -> WI.Pred sym -> m Bool) ->
ByteChecker m sym bak (WI.SymBV sym wptr) (WI.SymBV sym wptr)
symStringLength predIsFalse =
ByteChecker $ \bak len bytePtr -> do
byte <- liftIO (ptrToBv8 bak bytePtr)
keepGoing <- State.get
let sym = LCB.backendGetSym bak
byteWasNonNull <- liftIO (WI.bvIsNonzero sym byte)
keepGoing' <- liftIO (WI.andPred sym keepGoing byteWasNonNull)
stopHere <- predIsFalse bak keepGoing'
if stopHere
then pure (Break len)
else do
State.put keepGoing'
lenPlusOne <- liftIO (WI.bvAdd sym len =<< WI.bvOne sym ?ptrWidth)
Continue <$> liftIO (WI.bvIte sym keepGoing' lenPlusOne len)
-- | 'ByteChecker' for @strlen@ of strings with a concrete null terminator.
concretelyNullTerminatedStringLength ::
MonadIO m =>
State.MonadState (WI.Pred sym) m =>
GHC.HasCallStack =>
Mem.HasPtrWidth wptr =>
LCB.IsSymBackend sym bak =>
ByteChecker m sym bak (WI.SymBV sym wptr) (WI.SymBV sym wptr)
concretelyNullTerminatedStringLength =
symStringLength (\_bak p -> pure (WI.asConstantPred p == Just False))
-- | 'ByteChecker' for @strlen@ for strings with a provably-null terminator.
provablyNullTerminatedStringLength ::
MonadIO m =>
State.MonadState (WI.Pred sym) m =>
GHC.HasCallStack =>
LCB.IsSymBackend sym bak =>
Mem.HasPtrWidth wptr =>
sym ~ WEB.ExprBuilder scope st fs =>
bak ~ LCBO.OnlineBackend solver scope st fs =>
WPO.OnlineSolver solver =>
ByteChecker m sym bak (WI.SymBV sym wptr) (WI.SymBV sym wptr)
provablyNullTerminatedStringLength =
symStringLength $ \bak p ->
case WI.asConstantPred p of
Just b -> pure b
_ ->
liftIO $ LCBO.withSolverProcess bak (pure False) $ \proc -> do
WPO.checkSatisfiable proc "provablyNullTerminatedStringLength" p <&>
\case
WS.Unsat () -> True
WS.Sat () -> False
WS.Unknown -> False
---------------------------------------------------------------------
-- ** 'ByteLoader'
-- | Load a byte from memory.
--
-- The only 'ByteLoader' defined here is 'llvmByteLoader', but Macaw users will
-- most often want one based on @doReadMemModel@.
newtype ByteLoader m sym bak wptr
= ByteLoader { runByteLoader :: bak -> Mem.LLVMPtr sym wptr -> m (Mem.LLVMPtr sym 8) }
-- | A 'ByteLoader' for LLVM memory based on 'Mem.doLoad'.
llvmByteLoader ::
( LCB.IsSymBackend sym bak
, Mem.HasPtrWidth wptr
, Mem.HasLLVMAnn sym
, ?memOpts :: Mem.MemOptions
, GHC.HasCallStack
, MonadIO m
) =>
Mem.MemImpl sym ->
ByteLoader m sym bak wptr
llvmByteLoader mem =
ByteLoader $ \bak ptr -> do
let i1 = Mem.bitvectorType 1
let p8 = Mem.LLVMPointerRepr (DPN.knownNat @8)
liftIO (Mem.doLoad bak mem ptr i1 p8 CLD.noAlignment)
---------------------------------------------------------------------
-- * 'loadBytes'
-- | Load a sequence of bytes, one at a time.
--
-- Used to implement 'loadConcretelyNullTerminatedString' and
-- 'loadSymbolicString'. Highly customizable via 'ByteLoader' and 'ByteChecker'.
loadBytes ::
forall m a b sym bak wptr.
( LCB.IsSymBackend sym bak
, Mem.HasPtrWidth wptr
, Mem.HasLLVMAnn sym
, ?memOpts :: Mem.MemOptions
, GHC.HasCallStack
, MonadIO m
) =>
bak ->
Mem.MemImpl sym ->
-- | Initial accumulator
a ->
-- | Pointer to load from
Mem.LLVMPtr sym wptr ->
-- | How to load a byte from memory
ByteLoader m sym bak wptr ->
-- | How to check if we should continue loading the next byte
ByteChecker m sym bak a b ->
m b
loadBytes bak mem = go
where
sym = LCB.backendGetSym bak
go ::
a ->
Mem.LLVMPtr sym wptr ->
ByteLoader m sym bak wptr ->
ByteChecker m sym bak a b ->
m b
go acc ptr loader checker = do
byte <- runByteLoader loader bak ptr
runByteChecker checker bak acc byte >>=
\case
Break result -> pure result
Continue acc' -> do
-- It is important that safety assertions for later loads can use
-- the assumption that earlier bytes were nonzero, see #1463 or
-- `crucible-llvm-cli/test-data/T1463-read-bytes.cbl` for details.
prevByteWasNonNull <-
liftIO (WI.notPred sym =<< Mem.ptrIsNull sym (WI.knownNat @8) byte)
loc <- liftIO (WI.getCurrentProgramLoc sym)
let assump = LCB.BranchCondition loc Nothing prevByteWasNonNull
liftIO (LCB.addAssumption bak assump)
ptr' <- liftIO (Mem.doPtrAddOffset bak mem ptr =<< WI.bvOne sym Mem.PtrWidth)
go acc' ptr' loader checker