Rework DiskDevice's read() and write() to be non-virtual wrappers.

This way subclasses only have to implement readBlock() and writeBlock().
read() and write() require that the offset and length are both divisible
by the blockSize().

VirtualFileSystem/DiskDevice.cpp

@@ -7,3 +7,39 @@ DiskDevice::DiskDevice()
 DiskDevice::~DiskDevice()
 {
 }
+
+bool DiskDevice::read(qword offset, unsigned length, byte* out) const
+{
+    ASSERT((offset % blockSize()) == 0);
+    ASSERT((length % blockSize()) == 0);
+    qword firstBlock = offset / blockSize();
+    qword endBlock = (offset + length) / blockSize();
+    ASSERT(firstBlock <= 0xffffffff);
+    ASSERT(endBlock <= 0xffffffff);
+    byte* outptr = out;
+    unsigned remainingCount = length;
+    for (unsigned bi = firstBlock; bi < endBlock; ++bi) {
+        if (!readBlock(bi, outptr))
+            return false;
+        outptr += blockSize();
+    }
+    return true;
+}
+
+bool DiskDevice::write(qword offset, unsigned length, const byte* in)
+{
+    ASSERT((offset % blockSize()) == 0);
+    ASSERT((length % blockSize()) == 0);
+    qword firstBlock = offset / blockSize();
+    qword endBlock = (offset + length) / blockSize();
+    ASSERT(firstBlock <= 0xffffffff);
+    ASSERT(endBlock <= 0xffffffff);
+    const byte* inptr = in;
+    for (unsigned bi = firstBlock; bi < endBlock; ++bi) {
+        if (!writeBlock(bi, inptr))
+            return false;
+        inptr += blockSize();
+    }
+    return true;
+}
+

VirtualFileSystem/DiskDevice.h

@@ -11,8 +11,8 @@ public:
     virtual bool readBlock(unsigned index, byte*) const = 0;
     virtual bool writeBlock(unsigned index, const byte*) = 0;
     virtual const char* className() const = 0;
-    virtual bool read(qword offset, unsigned length, byte*) const = 0;
-    virtual bool write(qword offset, unsigned length, const byte*) = 0;
+    bool read(qword offset, unsigned length, byte*) const;
+    bool write(qword offset, unsigned length, const byte*);
 
 protected:
     DiskDevice();

VirtualFileSystem/Ext2FileSystem.cpp

@@ -965,8 +965,8 @@ InodeIdentifier Ext2FileSystem::createInode(InodeIdentifier parentInode, const S
     // FIXME: Implement writing out indirect blocks!
     ASSERT(blocks.size() < EXT2_NDIR_BLOCKS);
 
-    printf("[XXX] writing %u blocks to i_block array\n", min((unsigned)EXT2_NDIR_BLOCKS, blocks.size()));
-    for (unsigned i = 0; i < min((unsigned)EXT2_NDIR_BLOCKS, blocks.size()); ++i) {
+    printf("[XXX] writing %u blocks to i_block array\n", min((size_t)EXT2_NDIR_BLOCKS, blocks.size()));
+    for (unsigned i = 0; i < min((size_t)EXT2_NDIR_BLOCKS, blocks.size()); ++i) {
         e2inode->i_block[i] = blocks[i];
     }
 

VirtualFileSystem/FileBackedDiskDevice.cpp

@@ -35,16 +35,16 @@ unsigned FileBackedDiskDevice::blockSize() const
 bool FileBackedDiskDevice::readBlock(unsigned index, byte* out) const
 {
     qword offset = index * m_blockSize;
-    return read(offset, blockSize(), out);
+    return readInternal(offset, blockSize(), out);
 }
 
 bool FileBackedDiskDevice::writeBlock(unsigned index, const byte* data)
 {
     qword offset = index * m_blockSize;
-    return write(offset, blockSize(), data);
+    return writeInternal(offset, blockSize(), data);
 }
 
-bool FileBackedDiskDevice::read(qword offset, unsigned length, byte* out) const
+bool FileBackedDiskDevice::readInternal(qword offset, unsigned length, byte* out) const
 {
 #ifndef IGNORE_FILE_LENGTH
     if (offset + length >= m_fileLength)
@@ -59,7 +59,7 @@ bool FileBackedDiskDevice::read(qword offset, unsigned length, byte* out) const
     return true;
 }
 
-bool FileBackedDiskDevice::write(qword offset, unsigned length, const byte* data)
+bool FileBackedDiskDevice::writeInternal(qword offset, unsigned length, const byte* data)
 {
 #ifndef IGNORE_FILE_LENGTH
     if (offset + length >= m_fileLength)

VirtualFileSystem/FileBackedDiskDevice.h

@@ -16,12 +16,13 @@ public:
     virtual unsigned blockSize() const override;
     virtual bool readBlock(unsigned index, byte* out) const override;
     virtual bool writeBlock(unsigned index, const byte*) override;
-    virtual bool read(qword offset, unsigned length, byte* out) const override;
-    virtual bool write(qword offset, unsigned length, const byte* data) override;
 
 private:
     virtual const char* className() const override;
 
+    bool readInternal(qword offset, unsigned length, byte* out) const;
+    bool writeInternal(qword offset, unsigned length, const byte* data);
+
     FileBackedDiskDevice(String&& imagePath, unsigned blockSize);
 
     String m_imagePath;