The InputStream.read(byte[]) method may return partial read results

PROBLEM:

The EpubCheck class tries to read the header with the following code:

FileInputStream epubIn = new FileInputStream(epubFile);
byte[] header = new byte[58];
if (epubIn.read(header) != header.length) {
  report.error(null, 0, "cannot read header");
}

This does not take into account that the read method does not warrant that a 
number of bytes equal with the array length will be read, it can return after 
reading one byte for example, the application being responsible to call read 
again for the rest of the array.

Here it is a fragment from the InputStream.read() javadoc:

***
Reads some number of bytes from the input stream and stores them into the 
buffer array b. The number of bytes actually read is returned as an integer. 
This method blocks until input data is available, end of file is detected, or 
an exception is thrown.

If the length of b is zero, then no bytes are read and 0 is returned; 
otherwise, there is an attempt to read at least one byte. If no byte is 
available because the stream is at the end of the file, the value -1 is 
returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[0], the next one into b[1], and so 
on. The number of bytes read is, at most, equal to the length of b. Let k be 
the number of bytes actually read; these bytes will be stored in elements b[0] 
through b[k-1], leaving elements b[k] through b[b.length-1] unaffected.
***

Original issue reported on code.google.com by georgebina76 on 17 Feb 2011 at 8:30

daniel782 / epubcheck

The InputStream.read(byte[]) method may return partial read results #97