[Buildroot] [PATCH v4 2/3] pkg-generic: prevent _SITE URLs with a trailing slash

[Luca Ceresoli]

A trailing slash in FOO_SITE is useless, since Buildroot automatically adds
a slash between FOO_SITE and the filename as appropriate.

Moreover it is potentially harmful, which led to introducing a workaround
to strip them:

    commit 1cbffbd015106ea90fe49e27433375769dc1035b
    Author: Shawn J. Goff <shawn7400 at gmail.com>
    Date:   Fri Apr 12 09:40:30 2013 +0000

        eliminate double slashes caused by FOO_SITE ending in a slash

        When a FOO_SITE variable ends in a slash and gets joined with a
        FOO_SOURCE variable like $(FOO_SITE)/$(FOO_SOURCE), the resulting URI
        has a double slash. While double-slashes are fine in unix paths, they
        are reserved in URIs - the part following '//' must be an authority.

So let's ban trailing slashes entirely. They have all been removed in
a 7b0e757fb85fd, now add a check to error out loudly in case a new one
is added.

Example commands to test this check:

  $ make busybox-dirclean busybox-source
  rm -Rf /home/murray/devel/buildroot/output/build/busybox-1.23.2
  busybox-1.23.2.tar.bz2: OK (md5: 7925683d7dd105aabe9b6b618d48cc73)
  busybox-1.23.2.tar.bz2: OK (sha1: 7f37193cb249f27630e0b2a2c6c9bbb7b1d24c16)
  $
  $ make BUSYBOX_SITE=http://www.busybox.net/downloads/ busybox-dirclean busybox-source
  rm -Rf /home/murray/devel/buildroot/output/build/busybox-1.23.2
  BUSYBOX_SITE (http://www.busybox.net/downloads/) cannot have a trailing slash
  make[1]: *** [/home/murray/devel/buildroot/output/build/busybox-1.23.2/.stamp_downloaded] Error 1
  make: *** [_all] Error 2
  $

Signed-off-by: Luca Ceresoli <luca at lucaceresoli.net>
Cc: Arnout Vandecappelle <arnout at mind.be>
Cc: Baruch Siach <baruch at tkos.co.il>

---

Changed v3 -> v4:
 - Completely reimplement with make code, not shell code (Arnout actually
   wrote this patch, I was the typing monkey).
 - Slightly improve commit log and fix typos (Baruch, me).

Changed v2 -> v3:
 - Simplify the check logic removing a useless "&& true".
 - Expand commit log message. This is a pretty important change, so it
   should be well justified.
---
 package/pkg-generic.mk | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/package/pkg-generic.mk b/package/pkg-generic.mk
index 5201fca..de2fb07 100644
--- a/package/pkg-generic.mk
+++ b/package/pkg-generic.mk
@@ -847,6 +847,10 @@ endif
 	$(1)-source \
 	$(1)-source-check
 
+ifeq ($$(patsubst %/,ERROR,$$($(2)_SITE)),ERROR)
+$$(error $(2)_SITE ($$($(2)_SITE)) cannot have a trailing slash)
+endif
+
 endif # $(2)_KCONFIG_VAR
 endef # inner-generic-package
 
-- 
1.9.1