No way to determine # of bytes read from InputStream

[DartBot]

This issue was originally filed by [email protected]

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InputStream provides the following method:

bool read(List<int> buffer, int offset, int len, void callback());

If the number of bytes read is equal to len, the function returns true and callback() is called. This will be the case if the number of bytes available in the stream is greater than or equal to len.

However, if fewer than len bytes are available, the function will return false (or may throw an exception as in FileInputStream). There's no way to know how many bytes were read successfully.

Consider the case where I've initialized a buffer to, say, 4K bytes, and I want to read the initial chunk of a stream. If the stream is less then 4K, I may encounter an exception and can't know how many bytes were read.

[sgjesse]

The current semantics of read are that if true is returned then all the requested bytes have been read. Otherwise the callback will be called when all requested bytes have been read. This surely is problematic as you can only get a callback when len bytes are read, so basically you cannot read unless you know how many bytes you will get.

I am currently working on changing the InputStream interface, see http://codereview.chromium.org/8318009/ (the updated interface is currently called InputStream2).

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Set owner to @sgjesse.

[sgjesse]

Added Accepted label.

[sgjesse]

The first of a number of changes to the stream interfaces landed in https://code.google.com/p/dart/source/detail?r=747.

The updates to the stream interfaces will be tracked in issue #199 going forward.

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Added Duplicate label.
Marked as being merged into #199.