gecko-dev/xpcom/io/nsFileSpecStreaming.cpp

#include "nsFileSpecStreaming.h"

#include "nsIInputStream.h"
#include "nsIOutputStream.h"
#include "nsFileStream.h"
#include "nsFileSpec.h"

#define MAX_PERSISTENT_DATA_SIZE 1000

//----------------------------------------------------------------------------------------
nsOutputStream& operator << (nsOutputStream& s, const nsFileURL& url)
//----------------------------------------------------------------------------------------
{
    return s << url.GetAsString();
}

//----------------------------------------------------------------------------------------
nsresult ReadDescriptor(
    nsIInputStream* aStream,
    nsPersistentFileDescriptor& desc)
//----------------------------------------------------------------------------------------
{
    nsInputStream inputStream(aStream);
    inputStream >> desc;
    return NS_OK;
}

//----------------------------------------------------------------------------------------
nsresult WriteDescriptor(
    nsIOutputStream* aStream,
    const nsPersistentFileDescriptor& desc)
//----------------------------------------------------------------------------------------
{
    nsOutputStream outputStream(aStream);
    outputStream << desc;
    return NS_OK;
}

//----------------------------------------------------------------------------------------
nsInputStream& operator >> (nsInputStream& s, nsPersistentFileDescriptor& d)
// reads the data from a file
//----------------------------------------------------------------------------------------
{
    char bigBuffer[MAX_PERSISTENT_DATA_SIZE + 1];
    // The first 8 bytes of the data should be a hex version of the data size to follow.
    PRInt32 bytesRead = 8;
    bytesRead = s.read(bigBuffer, bytesRead);
    if (bytesRead != 8)
        return s;
    bigBuffer[8] = '\0';
    sscanf(bigBuffer, "%x", (PRUint32*)&bytesRead);
    if (bytesRead > MAX_PERSISTENT_DATA_SIZE)
    {
        // Try to tolerate encoded values with no length header
        bytesRead = 8 + s.read(bigBuffer + 8, MAX_PERSISTENT_DATA_SIZE - 8);
    }
    else
    {
        // Now we know how many bytes to read, do it.
        bytesRead = s.read(bigBuffer, bytesRead);
    }
    d.SetData(bigBuffer, bytesRead);
    return s;
}

//----------------------------------------------------------------------------------------
nsOutputStream& operator << (nsOutputStream& s, const nsPersistentFileDescriptor& d)
// writes the data to a file
//----------------------------------------------------------------------------------------
{
    char littleBuf[9];
    PRInt32 dataSize;
    nsSimpleCharString data;
    d.GetData(data, dataSize);
    // First write (in hex) the length of the data to follow.  Exactly 8 bytes
    sprintf(littleBuf, "%0.8x", dataSize);
    s << littleBuf;
    // Now write the data itself
    s << (const char*)data;
    return s;
}