From b33e85229d3ac78242d8bc597cfdaa282486743f Mon Sep 17 00:00:00 2001
From: Shea Levy <shea@shealevy.com>
Date: Wed, 13 Jul 2016 06:03:37 -0400
Subject: Make Buffered{Source,Sink} move-safe

---
 src/libutil/serialise.cc | 27 ++++++---------------------
 src/libutil/serialise.hh | 12 ++++++------
 2 files changed, 12 insertions(+), 27 deletions(-)

diff --git a/src/libutil/serialise.cc b/src/libutil/serialise.cc
index 5c45c890f7b6..776308cdf321 100644
--- a/src/libutil/serialise.cc
+++ b/src/libutil/serialise.cc
@@ -8,18 +8,9 @@
 namespace nix {
 
 
-BufferedSink::~BufferedSink()
-{
-    /* We can't call flush() here, because C++ for some insane reason
-       doesn't allow you to call virtual methods from a destructor. */
-    assert(!bufPos);
-    delete[] buffer;
-}
-
-
 void BufferedSink::operator () (const unsigned char * data, size_t len)
 {
-    if (!buffer) buffer = new unsigned char[bufSize];
+    if (!buffer) buffer = decltype(buffer)(new unsigned char[bufSize]);
 
     while (len) {
         /* Optimisation: bypass the buffer if the data exceeds the
@@ -32,7 +23,7 @@ void BufferedSink::operator () (const unsigned char * data, size_t len)
         /* Otherwise, copy the bytes to the buffer.  Flush the buffer
            when it's full. */
         size_t n = bufPos + len > bufSize ? bufSize - bufPos : len;
-        memcpy(buffer + bufPos, data, n);
+        memcpy(buffer.get() + bufPos, data, n);
         data += n; bufPos += n; len -= n;
         if (bufPos == bufSize) flush();
     }
@@ -44,7 +35,7 @@ void BufferedSink::flush()
     if (bufPos == 0) return;
     size_t n = bufPos;
     bufPos = 0; // don't trigger the assert() in ~BufferedSink()
-    write(buffer, n);
+    write(buffer.get(), n);
 }
 
 
@@ -95,21 +86,15 @@ void Source::operator () (unsigned char * data, size_t len)
 }
 
 
-BufferedSource::~BufferedSource()
-{
-    delete[] buffer;
-}
-
-
 size_t BufferedSource::read(unsigned char * data, size_t len)
 {
-    if (!buffer) buffer = new unsigned char[bufSize];
+    if (!buffer) buffer = decltype(buffer)(new unsigned char[bufSize]);
 
-    if (!bufPosIn) bufPosIn = readUnbuffered(buffer, bufSize);
+    if (!bufPosIn) bufPosIn = readUnbuffered(buffer.get(), bufSize);
 
     /* Copy out the data in the buffer. */
     size_t n = len > bufPosIn - bufPosOut ? bufPosIn - bufPosOut : len;
-    memcpy(data, buffer + bufPosOut, n);
+    memcpy(data, buffer.get() + bufPosOut, n);
     bufPosOut += n;
     if (bufPosIn == bufPosOut) bufPosIn = bufPosOut = 0;
     return n;
diff --git a/src/libutil/serialise.hh b/src/libutil/serialise.hh
index 892ec4aa36de..0139bed1cb9f 100644
--- a/src/libutil/serialise.hh
+++ b/src/libutil/serialise.hh
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <memory>
+
 #include "types.hh"
 #include "util.hh"
 
@@ -25,11 +27,10 @@ struct Sink
 struct BufferedSink : Sink
 {
     size_t bufSize, bufPos;
-    unsigned char * buffer;
+    std::unique_ptr<unsigned char[]> buffer;
 
     BufferedSink(size_t bufSize = 32 * 1024)
-        : bufSize(bufSize), bufPos(0), buffer(0) { }
-    ~BufferedSink();
+        : bufSize(bufSize), bufPos(0), buffer(nullptr) { }
 
     void operator () (const unsigned char * data, size_t len) override;
 
@@ -67,11 +68,10 @@ struct Source
 struct BufferedSource : Source
 {
     size_t bufSize, bufPosIn, bufPosOut;
-    unsigned char * buffer;
+    std::unique_ptr<unsigned char[]> buffer;
 
     BufferedSource(size_t bufSize = 32 * 1024)
-        : bufSize(bufSize), bufPosIn(0), bufPosOut(0), buffer(0) { }
-    ~BufferedSource();
+        : bufSize(bufSize), bufPosIn(0), bufPosOut(0), buffer(nullptr) { }
 
     size_t read(unsigned char * data, size_t len) override;
 
-- 
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