• This patch introduces a buffered QEMUFile wrapper.  This allows QEMUFile's to be
    rate limited.  It also makes it easier to implement a QEMUFile that is
    asynchronous since the current QEMUFile API requires that all reads and writes
    be synchronous.
    
    The only real non-obvious part of the API is the "frozen" concept.  If the
    backend returns EAGAIN, the QEMUFile is said to be "frozen".  This means no
    additional output will be sent to the backend until the file is unfrozen.
    qemu_file_put_notify can be used to unfreeze a frozen file.
    
    A synchronous interface is also provided to wait for an unfreeze event.  This is
    used during the final part of live migration when the VM is no longer running.
    
    Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
    
    
    
    git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5475 c046a42c-6fe2-441c-8c8c-71466251a162
    aliguori authored
     
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  • This patch allows QEMUFile's read and write operations to return 
    negative error codes.  This is necessary to detect things like closed 
    streams during live migration.
    
    It also removes unused code for QEMUFileFD write path.  Finally, it 
    makes sure to avoid attempting to flush an output buffer if the file
    is only being used for input.  This was spotted by Uri Lublin.
    
    Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
    
    
    
    git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5474 c046a42c-6fe2-441c-8c8c-71466251a162
    aliguori authored
     
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