public int read()

in src/main/java/org/apache/commons/io/input/UnsynchronizedBufferedInputStream.java [306:375]
59 lines of code
23 McCabe index (conditional complexity)

    public int read(final byte[] dest, int offset, final int length) throws IOException {
        // Use local ref since buf may be invalidated by an unsynchronized
        // close()
        byte[] localBuf = buffer;
        if (localBuf == null) {
            throw new IOException("Stream is closed");
        }
        // avoid int overflow
        if (offset > dest.length - length || offset < 0 || length < 0) {
            throw new IndexOutOfBoundsException();
        }
        if (length == 0) {
            return 0;
        }
        final InputStream localIn = inputStream;
        if (localIn == null) {
            throw new IOException("Stream is closed");
        }

        int required;
        if (pos < count) {
            /* There are bytes available in the buffer. */
            final int copylength = count - pos >= length ? length : count - pos;
            System.arraycopy(localBuf, pos, dest, offset, copylength);
            pos += copylength;
            if (copylength == length || localIn.available() == 0) {
                return copylength;
            }
            offset += copylength;
            required = length - copylength;
        } else {
            required = length;
        }

        while (true) {
            final int read;
            /*
             * If we're not marked and the required size is greater than the buffer, simply read the bytes directly bypassing the buffer.
             */
            if (markPos == IOUtils.EOF && required >= localBuf.length) {
                read = localIn.read(dest, offset, required);
                if (read == IOUtils.EOF) {
                    return required == length ? IOUtils.EOF : length - required;
                }
            } else {
                if (fillBuffer(localIn, localBuf) == IOUtils.EOF) {
                    return required == length ? IOUtils.EOF : length - required;
                }
                // localBuf may have been invalidated by fillBuffer()
                if (localBuf != buffer) {
                    localBuf = buffer;
                    if (localBuf == null) {
                        throw new IOException("Stream is closed");
                    }
                }

                read = count - pos >= required ? required : count - pos;
                System.arraycopy(localBuf, pos, dest, offset, read);
                pos += read;
            }
            required -= read;
            if (required == 0) {
                return length;
            }
            if (localIn.available() == 0) {
                return length - required;
            }
            offset += read;
        }
    }