Make the SDK relocatable

Hello,

this is v10 of my patch series to make the buildroot SDK (HOST_DIR) relocatable. It sanitizes the RPATH of all ELF files in the "target", "staging" and "host" tree using "patchelf --make-rpath-relative". We now use patchelf v0.9 to still support old Debian and RHEL systems.

v5 did RPATH sanitization per package after package installation into the host, staging or target tree using GLOBAL_INSTRUMENTATION_HOOKS. This approach got more and more complex and inefficient. Therefore it was abandoned in favor of global sanititation at the end of the host, staging and target build (see changes since v5).

Furthermore this patch creates the script "relocate-sdk.sh" in the top directory of the "host" tree allowing to relocate the SDK after it has been moved to a new location. It replaces the old path with the new one in all text files identified by "file --mime-type". The location is stored in "share/buildroot/sdk-location". This patch is already upstream.

Unfortunately, "qmake" uses hard-coded pathes compiled into the QT5 libraries. To overcome this problem, "qt5pase" now creates "qt.conf".

v8 now creates a relocatable SDK with "make sdk". The normal "make" only sanitizes the RPATH in the target tree.

In the meantime, various patches have been accepted. v9 will provide the rest and fixes some minor issues.

Wolfgang.

Changes since v9:

- install "relocate-sdk.sh" with "-m" and explicit target file name.
- execute the patchelf utility to check if it's working
- minor comment fixes

Changes since v8:

- patch "external-toolchain: check if a buildroot SDK has already been relocated"" dropped. The SDK is not an external toolchain and should therefore not used for that purpose.
- patches for the "sdk" target squashed together
- "sdk" now depends on "world"
- "fix-rpath" now checks if executable patchelf utility exists.
- some ninor fixes (typos, coding style, etc.).

Changes since v7:
- patchelf patches are now created with git (base on v0.9)
- the target tree is now sanitized before the overlay files are copied
- "make sdk" sanitizes the staging and host tree and adds relocate.sh
- relocate.sh does not use basism an longer
- fix-rpath now uses absolute path without rootdir for staging and target dir
- various other minor fixes (doc, indention, etc.)

Changes since v6:
- patchelf patches: update patch header with upstream commit, etc.
- ${HOST_DIR}/usr is gone which required various fixes
- Proper qt.conf.in added

Changes since v5:
- switch back to v4
- patchelf patches are now based on v0.9
- patchelf now calculates minimal relative path to the ELF file (and not to the rootdir as before).
- patchelf: neededLibFound is now passed to libFoundInRPath
- Makefile: the "host-finalize" target has been added for SDK relocation
- fix-rpath now uses variables to define the list of dirs to be pruned
- fix-rpath: the staging tree is sanitized like the target tree
- various minor fixes (typos)

Changes since v4:

- RPATH sanitation is now done per package and installation step in "pkg-generic.mk".
- After the installation step, the list of the installed files is stored in "<package-build-dir>/.br_[host|staging|target]_filelist".
- The GLOBAL_INSTRUMENTATION_HOOKS "step_sanitize_rpath" then calls "fix-rpath" to do the sanitation.
- DEPENDENCIES_HOST_PREREQ += host-patchelf is set early in the Makefile as we need it for RPATH sanitation. As soon it's available sanitation can start (currently missing some packages).
- The patchelf "file busy" issue is now worked-around differently.

Changes since v3:

- The patchelf patch implementing " --make-rpath-relative" now supports the option "--relative-to-file" instructing to use "$ORIGIN" in RPATHs. Otherwise an absolute path relative to the root directory will be used.
- The staging tree is now sanitized as well using the options "--relative-to-file" and "--no-standard-libs".
- For the "target" tree, relative RPATHs do not use "$ORIGIN" any longer. An absolute path relative to the root directory is used instead.

Changes since v2:

- provide "qt.conf" to make "qmake" relocatable
- sed now uses the separator "\" to substitute the directory path. It's one of the few characters not allowed in file names. To avoid interpreting it as escape character, the "read -r" is used.
- The paranoia substituion check is done before doing the real substituion.

Changes since v1:

- The name SDK has been chosen for the relocatabed "HOST_DIR" (instead of toolchanin).
- The patchelf version bump and patching are now done by 2 patches
- No more helper functions are used in the Makefile to call "fix-rpath" but added directly.
- The staging tree is not touched any more... until we have a good reason to do so.
- The sanitation is now performed by an optimized "fix-rpath" script.
- The relocate-sdk script is now copied for support/misc to the top directory of the host tree.

Wolfgang Grandegger (3):
core: introduce "sdk" target to make a relocatable SDK support/scripts/fix-rpath: check if the patchelf utility is executable support/scripts/fix-rpath: typo fix and unneeded ";" removed

 Makefile                  |  9 +++++++++
 support/scripts/fix-rpath | 12 ++++++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)

1.9.1

We use a separate make target to build a relocatable SDK. We first sanitize the RPATH in host tree. Next we also sanitize the staging tree. Therefore "sdk" must depend on world.

Sanitizing staging is not really needed, in the sense that any rpath in there is simply not going to be used. We want to sanitize staging for the following reasons:

- To avoid leaking references to the original output directory. This way, we can validate that the SDK is relocatable by running a simple "grep -r ${BASE_DIR} ${HOST_DIR}". Obviously RPATH sanitization is not sufficient (e.g. also the references to source files have to be stripped), but it's a step in the right direction. This reason is obviously only relevant for the SDK.

- To make sure that when an executable is copied to target that it actually executes correctly. Since within Buildroot we never copy stuff from staging to target, this is clearly only relevant for the SDK.

Finally we install the script "relocate-sdk.sh" into the top directory of the SDK (HOST_DIR) and the SDK location path is stored in the file "HOST_DIR/share/buildroot/sdk-location"-

---
 Makefile | 9 +++++++++
 1 file changed, 9 insertions(+)

index d4faa02..f9ff963 100644
@@ -552,6 +552,14 @@ prepare: $(BUILD_DIR)/buildroot-config/auto.conf
 .PHONY: world
 world: target-post-image
 
+.PHONY: sdk
+sdk: world
+	@$(call MESSAGE,"Rendering the SDK relocatable")
+	$(TOPDIR)/support/scripts/fix-rpath host
+	$(TOPDIR)/support/scripts/fix-rpath staging
+	install -m 755 $(TOPDIR)/support/misc/relocate-sdk.sh $(HOST_DIR)/relocate-sdk.sh
+	echo $(HOST_DIR) > $(HOST_DIR)/share/buildroot/sdk-location
+
 # Compatibility symlink in case a post-build script still uses $(HOST_DIR)/usr
 $(HOST_DIR)/usr: $(HOST_DIR)
 	@ln -snf . $@

@@ -1001,6 +1009,7 @@ help:
 	@echo 'Build:'
 	@echo '  all                    - make world'
 	@echo '  toolchain              - build toolchain'
+	@echo '  sdk                    - build relocatable SDK'
 	@echo
 	@echo 'Configuration:'
 	@echo '  menuconfig             - interactive curses-based configurator'

1.9.1

---
 support/scripts/fix-rpath | 8 ++++++++
 1 file changed, 8 insertions(+)

index f7c70b7..f92e601 100755
@@ -45,6 +45,9 @@ Environment:
 
     TOOLCHAIN_EXTERNAL_DOWNLOAD_INSTALL_DIR
                  (default HOST_DIR/opt/ext-toolchain)
+
+Returns:         0 if success or 1 in case of error
+
 EOF
 }
 

@@ -60,6 +63,11 @@ main() {
     local find_args=( )
     local sanitize_extra_args=( )
 
+    if ! "${PATCHELF}" --version > /dev/null 2>&1; then
+	echo "Error: can't execute patchelf utility '${PATCHELF}'"
+	exit 1
+    fi
+
     case "${tree}" in
         host)
             rootdir="${HOST_DIR}"

1.9.1

---
 support/scripts/fix-rpath | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

index f92e601..15705a3 100755
@@ -27,7 +27,7 @@ Description:
 
     Sanitization behaves the same whatever the kind of the processed tree,
     but the resulting RPATH differs. The rpath sanitization is done using
-    "patchelf --make-rpath-relazive".
+    "patchelf --make-rpath-relative".
 
 Arguments:
 

@@ -81,7 +81,7 @@ main() {
                 find_args+=( "-path" "${TOOLCHAIN_EXTERNAL_DOWNLOAD_INSTALL_DIR}" "-prune" "-o" )
 
             for excludepath in ${HOST_EXCLUDEPATHS}; do
-                find_args+=( "-path" "${HOST_DIR}""${excludepath}" "-prune" "-o" );
+                find_args+=( "-path" "${HOST_DIR}""${excludepath}" "-prune" "-o" )
             done
 
             # do not process the patchelf binary but a copy to work-around "file in use"

1.9.1

Hello,

Thanks a lot, I've applied those remaining 3 patches!

I would like to take this opportunity to thank you for your patience and your dedication in pushing this SDK topic. It's been long overdue in Buildroot, and the fact that you have taken all comments into account and sent quickly new iterations was really instrumental to getting the all thing finally merged. So: many thanks!

Best regards,

Thomas

Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

Yes, from me as well - Thanks a lot!

Bye, Peter Korsgaard

And me - thanks again!

Do you happen to go to ELC-E in October, or to FOSDEM in February? It would be
nice to meet at a BR developer meeting.

Regards,
Arnout

Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint:  7493 020B C7E3 8618 8DEC 222C 82EB F404 F9AC 0DDF

Hello Arnout, Peter and Thomas,

Am 23.07.2017 um 14:58 schrieb Arnout Vandecappelle:

You are welcome! Great that "make sdk" is now mainline! It's useful for my/our project as well. Thank you for the fruitful discussions and for keeping buildroot up-to-date and robust.

No plans so far. In case I'm around I would be glad to meet you.

Wolfgang.