From 46313be8762a67d7b77d2315d3123c5f559a6734 Mon Sep 17 00:00:00 2001
From: Jean-Paul Calderone <exarkun@twistedmatrix.com>
Date: Tue, 16 May 2023 10:26:48 -0400
Subject: [PATCH] Get rid of the repeated bytesRead requests
We use `isolate` so we know exactly how far we've advanced, we can trivially
compute the correct position.
---
src/Tahoe/SDMF/Internal/Share.hs | 29 ++++++++++++-----------------
1 file changed, 12 insertions(+), 17 deletions(-)
diff --git a/src/Tahoe/SDMF/Internal/Share.hs b/src/Tahoe/SDMF/Internal/Share.hs
index e01b8b4..f62cc96 100644
--- a/src/Tahoe/SDMF/Internal/Share.hs
+++ b/src/Tahoe/SDMF/Internal/Share.hs
@@ -144,23 +144,18 @@ instance Binary Share where
encryptedPrivateKeyOffset <- getWord64be
eofOffset <- getWord64be
- pos <- bytesRead
- shareVerificationKey <- Keys.Verification <$> isolate (fromIntegral signatureOffset - fromIntegral pos) getSubjectPublicKeyInfo
-
- pos <- bytesRead
- shareSignature <- getByteString (fromIntegral hashChainOffset - fromIntegral pos)
-
- pos <- bytesRead
- shareHashChain <- isolate (fromIntegral blockHashTreeOffset - fromIntegral pos) get
-
- pos <- bytesRead
- shareBlockHashTree <- isolate (fromIntegral shareDataOffset - fromIntegral pos) get
-
- pos <- bytesRead
- shareData <- getLazyByteString (fromIntegral encryptedPrivateKeyOffset - fromIntegral pos)
-
- pos <- bytesRead
- shareEncryptedPrivateKey <- getByteString (fromIntegral eofOffset - fromIntegral pos)
+ -- This offset is not the encoded share but it's defined as being
+ -- right where we've read to. Give it a name that follows the
+ -- pattern.
+ shareVerificationOffset <- bytesRead
+
+ -- Read in the values between all those offsets.
+ shareVerificationKey <- Keys.Verification <$> isolate (fromIntegral signatureOffset - fromIntegral shareVerificationOffset) getSubjectPublicKeyInfo
+ shareSignature <- getByteString (fromIntegral hashChainOffset - fromIntegral signatureOffset)
+ shareHashChain <- isolate (fromIntegral blockHashTreeOffset - fromIntegral hashChainOffset) get
+ shareBlockHashTree <- isolate (fromIntegral shareDataOffset - fromIntegral blockHashTreeOffset) get
+ shareData <- getLazyByteString (fromIntegral encryptedPrivateKeyOffset - fromIntegral shareDataOffset)
+ shareEncryptedPrivateKey <- getByteString (fromIntegral eofOffset - fromIntegral encryptedPrivateKeyOffset)
empty <- isEmpty
unless empty (fail "Expected end of input but there are more bytes")
--
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