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From f6bc8fb3d26892ba1a84ba2df76beedd51998dd2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20P=C3=ADsa=C5=99?= <>
Date: Mon, 29 Jan 2018 16:34:17 +0100
Subject: [PATCH] hints/linux: Add -lphtread to lddlflags
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Passing -z defs to linker flags causes perl to fail to build if threads are

gcc  -shared -Wl,-z,relro -Wl,-z,defs -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -L/usr/local/lib -fstack-protector-strong Bzip2.o  -o ../../lib/auto/Compress/Raw/Bzip2/  \
   -L/usr/lib64 -lbz2 "-L../.." -lperl   \

Bzip2.o: In function `deRef':
/builddir/build/BUILD/perl-5.26.1/cpan/Compress-Raw-Bzip2/Bzip2.xs:256: undefined reference to `pthread_getspecific'

The reason is Bzip2.xs calls dTHX macro included from thread.h via perl.h that
expands to pthread_getspecific() function call that is defined in pthread
library. But the pthread library is not explicitly linked to (see the
gcc command). This is exactly what -z defs linker flag enforces.

Underlinking ELFs can be dangerous because in case of versioned
symbols it can cause run-time binding to an improper version symbol or
even to an symbold from different library.

This patch fixes hints for Linux by adding -lpthreads to lddlflags. It
also adds -shared there because adds it only hints return
lddlflags empty.


Signed-off-by: Petr Písař <>
 hints/ | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hints/ b/hints/
index 3f38ea07f1..9ec3bc02ef 100644
--- a/hints/
+++ b/hints/
@@ -353,12 +353,16 @@ if [ -f /etc/synoinfo.conf -a -d /usr/syno ]; then
     echo "$libswanted" >&4
+# Flags needed to produce shared libraries.
 # This script UU/usethreads.cbu will get 'called-back' by Configure
 # after it has prompted the user for whether to use threads.
 cat > UU/usethreads.cbu <<'EOCBU'
 case "$usethreads" in
         ccflags="-D_REENTRANT -D_GNU_SOURCE $ccflags"
+        lddlflags="-lpthread $lddlflags"
         if echo $libswanted | grep -v pthread >/dev/null
             set `echo X "$libswanted "| sed -e 's/ c / pthread c /'`