[Buildroot] [PATCH] support/scripts/check-host-rpath: send readelf error output to oblivion

* [Buildroot] [PATCH] support/scripts/check-host-rpath: send readelf error output to oblivion
@ 2022-07-27 10:47 Thomas Petazzoni via buildroot
  2022-07-27 16:40 ` Yann E. MORIN
  2022-08-30 22:30 ` Peter Korsgaard
  0 siblings, 2 replies; 5+ messages in thread
From: Thomas Petazzoni via buildroot @ 2022-07-27 10:47 UTC (permalink / raw)
  To: Yann E. MORIN, Buildroot List, Romain Naour; +Cc: Thomas Petazzoni

Somewhere between binutils 2.35 and 2.37, some functionality was
added in readelf to parse more DWARF information. Unfortunately, as
reported in binutils bug
28981 ("https://sourceware.org/bugzilla/show_bug.cgi?id=28981"), this
feature causes a number of fairly scary warnings to be displayed when
running readelf on binaries built with Clang, such as the pre-built
rustc and rustdoc binaries part of the host-rust-bin package. It
looks like this:

readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Unrecognized form: 0x23
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Bogus end-of-siblings marker detected at offset 2f in .debug_info section
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Unrecognized form: 0x22
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Bogus end-of-siblings marker detected at offset 10b in .debug_info section
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Bogus end-of-siblings marker detected at offset 10c in .debug_info section
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Further warnings about bogus end-of-sibling markers suppressed
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Unrecognized form: 0x22
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Unrecognized form: 0x22
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Unrecognized form: 0x22
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Unrecognized form: 0x23
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Unrecognized form: 0x22
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Unrecognized form: 0x23
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Unrecognized form: 0x22
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Unrecognized form: 0x22
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Unrecognized form: 0x22
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Unrecognized form: 0x23
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Unrecognized form: 0x22
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Unrecognized form: 0x23
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: Unrecognized form: 0x22
readelf: /home/thomas/projets/buildroot/output/host/bin/rustc: Warning: DIE at offset 0x1da refers to abbreviation number 5827 which does not exist

These warnings are caused by the readelf calls done by the
support/scripts/check-host-rpath script. The annoying thing is that
once host-rust-bin has been installed in $(HOST_DIR), this warning
appears after the installation of every single host package, because
support/scripts/check-host-rpath rescans all binaries every time.

To avoid showing those scary warnings, this commit sends the error
output of readelf to /dev/null.

Of course, it would be nicer to only filter out those warnings, but
filtering the error output without merging the error output into the
standard output is tricky, so let's keep things simple. If there is
really an error, readelf will abort.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
---
 support/scripts/check-host-rpath | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/support/scripts/check-host-rpath b/support/scripts/check-host-rpath
index b27cb883f3..f36677cc96 100755
--- a/support/scripts/check-host-rpath
+++ b/support/scripts/check-host-rpath
@@ -61,7 +61,7 @@ elf_needs_rpath() {
 
     while read lib; do
         [ -e "${hostdir}/lib/${lib}" ] && return 0
-    done < <( readelf -d "${file}"                                         \
+    done < <( readelf -d "${file}" 2>/dev/null                             \
               |sed -r -e '/^.* \(NEEDED\) .*Shared library: \[(.+)\]$/!d;' \
                      -e 's//\1/;'                                          \
             )
@@ -100,7 +100,7 @@ check_elf_has_rpath() {
 	    # false.
             [[ ${dir} =~ "${perpackagedir}/"[^/]+/host/lib ]] && return 0
         done
-    done < <( readelf -d "${file}"                                              \
+    done < <( readelf -d "${file}" 2>/dev/null                                  \
               |sed -r -e '/.* \(R(UN)?PATH\) +Library r(un)?path: \[(.+)\]$/!d' \
                       -e 's//\3/;'                                              \
             )
-- 
2.37.1

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