Emerge of oracle-jdk-bin expects a tarred, gzipped file. However, the Oracle JDK webpage, http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html, supplies them as a gzipped file, gz. The hash digests have been calculated for this file. Any attempt to unzip the file, convert it to a tarred gzip results in a different size and digest. This makes it impossible to emerge oracle-jdk-bin unless one manually edits the Manifest file to reflect the size and digests of the tarrged, gzip archive.
Here is the output generated by editing the name "jdk-8u66-linux-x64.gz" to "jdk-8u66-linux-x64.tar.gz" >>> Emerging (1 of 1) dev-java/oracle-jdk-bin-1.8.0.66::gentoo * jdk-8u66-linux-x64.tar.gz SHA256 SHA512 WHIRLPOOL size ;-) ... [ ok ] >>> Unpacking source... >>> Unpacking jdk-8u66-linux-x64.tar.gz to /var/tmp/portage/dev-java/oracle-jdk-bin-1.8.0.66/work gzip: /var/tmp/portage/dev-java/oracle-jdk-bin-1.8.0.66/distdir/jdk-8u66-linux-x64.tar.gz: Permission denied tar: This does not look like a tar archive tar: Exiting with failure status due to previous errors As you can see, the gzipped file is passing checksum OK, but given that isn't actually a tarred file, the unpack phase fails.
This sounds a lot like bug #560198. Every .gz on that page has a .tar before it. Fix your browser. The error you just posted has nothing to do with the name or the content. It says permission denied. Please ensure the file is readable by Portage when you move it to distfiles.
Chrome is known to rename files on download, and also puts overly restrictive permissions on downloaded files. You will need to manually adjust the downloaded file.
