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https://issues.apache.org/jira/browse/WSCOMMONS-424?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andreas Veithen resolved WSCOMMONS-424.
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Resolution: Fixed
Fix Version/s: Axiom 1.2.8
Assignee: Andreas Veithen
Fixed BufferUtils#doesDataHandlerExceedLimit. It now uses the following
strategy:
1) If the data source implementation uses the new optional SizeAwareDataSource
interface, the result of the getSize method is used.
2) If the data source is a FileDataSource, the size is determined from the file
size, without actually opening and reading the file.
3) If the data source is a javax.mail.util.ByteArrayDataSource,
ByteArrayInputStream#available is used to determine the size.
4) In all other cases, DataHandler#writeTo is invoked with a special
OutputStream implementation that triggers an exception when the limit is
exceeded. This avoids the issue with DataHandlers constructed from Objects and
also keeps the overhead low for other data sources, independently of their
actual size.
In addition, the new SizeAwareDataSource interface has been added to Axiom's
ByteArrayDataSource.
> BufferUtils#doesDataHandlerExceedLimit needs review
> ---------------------------------------------------
>
> Key: WSCOMMONS-424
> URL: https://issues.apache.org/jira/browse/WSCOMMONS-424
> Project: WS-Commons
> Issue Type: Bug
> Components: AXIOM
> Reporter: Andreas Veithen
> Assignee: Andreas Veithen
> Fix For: Axiom 1.2.8
>
>
> The code in BufferUtils#doesDataHandlerExceedLimit has several issues and
> should be reviewed:
> 1) The code never closes the InputStream requested from the DataSource. This
> might have unexpected consequences if the DataSource is a FileDataSource.
> 2) The code assumes that there are DataSources that can only be read once.
> Indeed the code in BufferUtils#getInputStream throws an exception if the
> input stream returned from the DataSource doesn't support mark ("Stream does
> not support mark, Cannot read the stream as DataSource will be consumed.").
> This is plain wrong, because by definition a DataSource can be read several
> times (this is the very reason for the existence of this interface). If there
> are DataSource implementations that can be "consumed", i.e. read only once,
> they need to be fixed.
> 3) The code assumes that the end of stream is reached when
> InputStream#available() returns 0. This is wrong.
> 4) doesDataHandlerExceedLimit tries to establish a lower bound on the
> DataSource size by reading data from it. This is suboptimal, because in most
> cases this can be achieved without actually reading a single byte from the
> data source:
> * If the DataSource is a FileDataSource, it is possible to get the File
> object and the size of the DataSource can be determined from the file size.
> This is much less costly than to open the file and read data from it.
> * InputStream#available() can always be used to get a lower limit on the
> stream size. For a ByteArrayDataSource this actually returns the size
> directly.
> * InputStream#skip can be used to advance in the stream without reading from
> it.
> Only if the InputStream implementation returned by the DataSource neither
> implements available nor skip (this is possible), it is necessary to actually
> read the data.
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