[Buildroot] [PATCH v3] download: fix file:// BR2_PRIMARY_SITE (download cache)

[Thomas Petazzoni <thomas.petazzoni@bootlin.com>]

Hello,

On Wed, 15 Aug 2018 16:44:34 -0700, Hollis Blanchard wrote:
> wget is the only downloader currently usable with BR2_PRIMARY_SITE, and that
> doesn't work at all for file:// URLs. The symptoms are these:
> 
> 	support/download/dl-wrapper -c '2.4.47' -d '/PATH/build/sw/source/attr' -D '/PATH/build/sw/source' -f 'attr-2.4.47.src.tar.gz' -H 'package/attr//attr.hash' -n 'attr-2.4.47' -N 'attr' -o '/PATH/build/sw/source/attr/attr-2.4.47.src.tar.gz'  -u file\|urlencode+file:///NFS/buildroot_dl_cache/attr -u file\|urlencode+file:///NFS/buildroot_dl_cache -u http+http://download.savannah.gnu.org/releases/attr -u http\|urlencode+http://sources.buildroot.net/attr -u http\|urlencode+http://sources.buildroot.net  --
> 	file:///NFS/buildroot_dl_cache/attr/attr-2.4.47.src.tar.gz: Unsupported scheme `file'.
> 	ERROR: attr-2.4.47.src.tar.gz has wrong sha256 hash:
> 	ERROR: expected: 25772f653ac5b2e3ceeb89df50e4688891e21f723c460636548971652af0a859
> 	ERROR: got     : e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
> 	ERROR: Incomplete download, or man-in-the-middle (MITM) attack
> 
> In the case of custom Linux kernel versions, this is fatal, because there isn't
> necessarily a hash file to indicate that wget's empty tarball is wrong.
> 
> This seems to have been broken by commit c8ef0c03b0b, because:
> 1. BR2_PRIMARY_SITE always appends "urlencode" (package/pkg-download.mk)
> 2. Anything with the "|urlencode" suffix in $uri will end up using wget due to
>    the backend case wildcarding.
> 3. The wget backend rejects file:/// URLs ("unsupported scheme"), and we end up
>    with an empty .tar.gz file in the downloads directory.
> 
> Fix that by shell-extracting the backend name from the left of "|". I'm not
> positive if all URLs will have a "|", so this code only looks for a "|" left of
> the "+".
> 
> Signed-off-by: Hollis Blanchard <hollis_blanchard@mentor.com>
> Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
> Tested-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
> 
> ---
> Changes from v2: add quoting around the variable expansion.

Applied to master, thanks.

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com