LINKER_USE_RPATH=ORIGIN

Use Linux specific linker trick to allow relocation
of built tree.

relative rpath

use $ORIGIN to reference libraries in other modules
by relative path.

fix rel. RPATH

configure/CONFIG_BASE

@@ -44,6 +44,8 @@ FULLPATHNAME     = $(PERL) $(TOOLS)/fullPathName.pl
 TAPTOJUNIT       = $(PERL) $(TOOLS)/tap-to-junit-xml.pl
 GENVERSIONHEADER = $(PERL) $(TOOLS)/genVersionHeader.pl $(QUIET_FLAG) $(QUESTION_FLAG)
 
+MAKERPATH = $(PYTHON) $(TOOLS)/makeRPath.py
+
 #---------------------------------------------------------------
 # tools for installing libraries and products
 INSTALL = $(PERL) $(TOOLS)/installEpics.pl $(QUIET_FLAG)

configure/CONFIG_COMMON

@@ -38,6 +38,8 @@ BUILD_ARCHS = $(EPICS_HOST_ARCH) $(CROSS1) $(CROSS2)
 # otherwise override this in os/CONFIG_SITE.<host_arch>.Common
 PERL = perl -CSD
 
+PYTHON = python
+
 #-------------------------------------------------------
 # Check configure/RELEASE file for consistency
 CHECK_RELEASE_YES = checkRelease

configure/CONFIG_SITE

@@ -169,10 +169,17 @@ EPICS_SITE_VERSION =
 GCC_PIPE = NO
 
 # Set RPATH when linking executables and libraries.
-#  Must be either YES or NO.  If you set this to NO you must also provide a
+#  Must be either YES, NO, or ORIGIN.  If you set this to NO you must also provide a
 #  way for Base executables to find their shared libraries when they are
 #  run at build-time, e.g. set the LD_LIBRARY_PATH environment variable.
+#  ORIGIN is Linux specific.
 LINKER_USE_RPATH = YES
 
+# Only used when LINKER_USE_RPATH=ORIGIN
+# The build time root of the relocatable tree.
+# Linking to libraries under this root directory will be relative.
+# Linking to libraries outside of this root will be absolute.
+LINKER_ORIGIN_ROOT = $(INSTALL_LOCATION)
+
 # Overrides for the settings above may appear in a CONFIG_SITE.local file
 -include $(CONFIG)/CONFIG_SITE.local

configure/RULES_BUILD

@@ -194,6 +194,13 @@ ifeq ($(EPICS_HOST_ARCH),$(T_A))
 	$(info Warning: RELEASE file consistency checks have been disabled)
 endif
 
+# $(FINAL_DIR) signals eventual install locations to makeRPath script
+$(TESTPRODNAME): FINAL_DIR=.
+$(PRODNAME): FINAL_DIR=$(INSTALL_BIN)
+$(TESTSHRLIBNAME): FINAL_DIR=.
+$(SHRLIBNAME): FINAL_DIR=$(INSTALL_SHRLIB)
+$(LOADABLE_SHRLIBNAME): FINAL_DIR=$(INSTALL_SHRLIB)
+
 #---------------------------------------------------------------
 #  The order of the following rules is
 #  VERY IMPORTANT !!!!

configure/os/CONFIG.Common.linuxCommon

@@ -25,11 +25,13 @@ STATIC_LDLIBS_YES= -Wl,-Bdynamic
 
 # Set runtime path for shared libraries if USE_RPATH=YES and STATIC_BUILD=NO
 SHRLIBDIR_RPATH_LDFLAGS_YES_NO = $(SHRLIB_DEPLIB_DIRS:%=-Wl,-rpath,%)
+SHRLIBDIR_RPATH_LDFLAGS_ORIGIN_NO = $(shell $(MAKERPATH) -O '\$$ORIGIN' -F $(FINAL_DIR) -R $(LINKER_ORIGIN_ROOT) $(SHRLIB_DEPLIB_DIRS))
 SHRLIBDIR_LDFLAGS += \
     $(SHRLIBDIR_RPATH_LDFLAGS_$(LINKER_USE_RPATH)_$(STATIC_BUILD))
 
 # Set runtime path for products if USE_RPATH=YES and STATIC_BUILD=NO
 PRODDIR_RPATH_LDFLAGS_YES_NO = $(PROD_DEPLIB_DIRS:%=-Wl,-rpath,%)
+PRODDIR_RPATH_LDFLAGS_ORIGIN_NO = $(shell $(MAKERPATH) -O '\$$ORIGIN' -F $(FINAL_DIR) -R $(LINKER_ORIGIN_ROOT) $(PROD_DEPLIB_DIRS))
 PRODDIR_LDFLAGS += \
     $(PRODDIR_RPATH_LDFLAGS_$(LINKER_USE_RPATH)_$(STATIC_BUILD))
 

src/tools/Makefile

@@ -39,6 +39,8 @@ PERL_SCRIPTS += tap-to-junit-xml.pl
 PERL_SCRIPTS += useManifestTool.pl
 PERL_SCRIPTS += genVersionHeader.pl
 
+PERL_SCRIPTS += makeRPath.py
+
 HTMLS = style.css
 HTMLS += EPICS/Getopts.html
 HTMLS += EPICS/Path.html

src/tools/makeRPath.py

@@ -0,0 +1,33 @@
+#!/usr/bin/env python
+
+from __future__ import print_function
+
+import sys
+import os
+
+from argparse import ArgumentParser
+
+if os.environ.get('EPICS_DEBUG_RPATH','')=='YES':
+    sys.stderr.write('%s'%sys.argv)
+
+P = ArgumentParser()
+P.add_argument('-F','--final',default=os.getcwd(), help='Final install location for ELF file')
+P.add_argument('-R','--root',default='/')
+P.add_argument('-O', '--origin', default='$ORIGIN')
+P.add_argument('path', nargs='*')
+args = P.parse_args()
+
+fdir = os.path.abspath(args.final)
+
+output = []
+for path in args.path:
+    path = os.path.abspath(path)
+
+    if args.root and os.path.relpath(path, args.root).startswith('../'):
+        pass # absolute rpath
+    else:
+        path = os.path.relpath(path, fdir)
+
+    output.append('-Wl,-rpath,'+os.path.join(args.origin, path))
+
+print(' '.join(output))