UBUNTU: [Debian] Fix warnings when checking for modules signatures

BugLink: https://bugs.launchpad.net/bugs/1853843
When detecting module signatures, the current approach causes
this warning for modules lacking a signature:

 /bin/bash: line 5: warning: command substitution: ignored null byte in input

My original approach used read, which works well, but for unknown
reasons causes an error from bash when by itself as the first
line in the if clause. Putting it in a no-op while loop prevents
the error, but it has the advantage of working without flooding
the build logs with warnings.

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/debian/rules.d/2-binary-arch.mk b/debian/rules.d/2-binary-arch.mk
index 070478e010f7c7e65b837017802dded9646d8c7e..2aea5e857f79da854db2ca92d68956386a80430f 100644 (file)
--- a/debian/rules.d/2-binary-arch.mk
+++ b/debian/rules.d/2-binary-arch.mk
@@ -413,12 +413,14 @@ ifneq ($(skipdbg),true)
          -name '*.ko' | while read path_module ; do \
                module="/lib/modules/$${path_module#*/lib/modules/}"; \
                if [[ -f "$(dbgpkgdir)/usr/lib/debug/$$module" ]] ; then \
-                       signature=$$(tail -c 28 "$$path_module"); \
+                       while IFS= read -r -d '' signature < <(tail -c 28 "$$path_module"); do \
+                               break; \
+                       done; \
                        $(CROSS_COMPILE)objcopy \
                                --add-gnu-debuglink=$(dbgpkgdir)/usr/lib/debug/$$module \
                                $$path_module; \
                        if grep -q CONFIG_MODULE_SIG=y $(builddir)/build-$*/.config && \
-                          [ "$$signature" = "~Module signature appended~" ]; then \
+                          [ "$$signature" = $$'~Module signature appended~\n' ]; then \
                                $(builddir)/build-$*/scripts/sign-file $(MODHASHALGO) \
                                        $(MODSECKEY) \
                                        $(MODPUBKEY) \