From bd0f4401deb80eca14a31fce22ed30e64583c965 Mon Sep 17 00:00:00 2001
From: Eugene Kim <ek@harmony.one>
Date: Tue, 12 Feb 2019 11:28:18 -0800
Subject: [PATCH] =?UTF-8?q?DYLD=5FLIBRARY=5FPATH=20=E2=86=92=20DYLD=5FFALL?=
 =?UTF-8?q?BACK=5FLIBRARY=5FPATH?=
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DYLD_LIBRARY_PATH has a “look here first before usual places” semantics,
in order to let users use an alternative version of a shared library.
On the other side, DYLD_FALLBACK_LIBRARY_PATH has a “look here if not
found in usual places” semantics, in order to let users specify
additional locations where a shared library is found.

In our case, if a binary refers to a common shared library found in
usual places, we want to use it; we simply want to specify additional
locations where BLS/MCL/OpenSSL libraries are found.  So it is more
appropriate to use DYLD_FALLBACK_LIBRARY_PATH.

This also fixes a nasty symbol table mismatch, which is the main reason
for this change: Certain commonly used shared libraries - such as
libJPEG.dylib, co-located within the ImageIO framework and expected by
the main ImageIO library – are often also found in Homebrew or MacPorts
root (/opt/local//lib for MacPort).  If DYLD_LIBRARY_PATH included
/opt/local/lib for OpenSSL, many system programs linked against ImageIO
will erroneously pick up libJPEG.dylib in /opt/local/lib, which lacks
certain internal symbols that the framework version has.  Using
DYLD_FALLBACK_LIBRARY_PATH makes dyld honor the full path to the
framework version of libJPEG, which is hardcoded in the main ImageIO
framework library.
---
 README.md                        | 2 +-
 scripts/setup_bls_build_flags.sh | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 4b315fcd3..983d09bd8 100644
--- a/README.md
+++ b/README.md
@@ -19,7 +19,7 @@ export CGO_CFLAGS="-I$GOPATH/src/github.com/harmony-one/bls/include -I$GOPATH/sr
 export CGO_LDFLAGS="-L$GOPATH/src/github.com/harmony-one/bls/lib -L/usr/local/opt/openssl/lib"
 export LD_LIBRARY_PATH=$GOPATH/src/github.com/harmony-one/bls/lib:$GOPATH/src/github.com/harmony-one/mcl/lib:/usr/local/opt/openssl/lib
 export LIBRARY_PATH=$LD_LIBRARY_PATH
-export DYLD_LIBRARY_PATH=$LD_LIBRARY_PATH
+export DYLD_FALLBACK_LIBRARY_PATH=$LD_LIBRARY_PATH
 
 mkdir -p $HOME/<path_of_your_choice>/src/github.com/harmony-one
 
diff --git a/scripts/setup_bls_build_flags.sh b/scripts/setup_bls_build_flags.sh
index eb0115c18..c65e9c7f4 100644
--- a/scripts/setup_bls_build_flags.sh
+++ b/scripts/setup_bls_build_flags.sh
@@ -16,6 +16,6 @@ case $OS in
       export CGO_CFLAGS="-I${BLS_DIR}/include -I${MCL_DIR}/include -I${OPENSSL_DIR}/include"
       export CGO_LDFLAGS="-L${BLS_DIR}/lib -L${OPENSSL_DIR}/lib"
       export LD_LIBRARY_PATH=${BLS_DIR}/lib:${MCL_DIR}/lib:${OPENSSL_DIR}/lib
-      export DYLD_LIBRARY_PATH=$LD_LIBRARY_PATH
+      export DYLD_FALLBACK_LIBRARY_PATH=$LD_LIBRARY_PATH
       ;;
 esac