[Buildroot] [PATCH v2 1/3] package/openjdk: fix installation with merged usr directories

[Ryan Barnett]

Adam/All,

On Sat, Apr 18, 2020 at 2:12 PM <aduskett at gmail.com> wrote:
>
> From: Adam Duskett <Aduskett at gmail.com>
>
> Currently, Buildroot installs the jre libraries using
> cp -dprf /build/linux-*-release/images/jre/lib/* $(TARGET_DIR)/usr/lib/
>
> However, if a system has a merged /usr directory, and there is a built kernel
> before installing OpenJDK, the installation fails because jre/lib has binary
> modules file, which causes the following error: cp: cannot overwrite directory
> '/usr/lib/modules with non-directory
>
> The obvious fix is to install the modules to /usr/lib/jvm/ and set the
> appropriate rpaths via the --with-extra-ldflags conf option. However, this fix
> does not work because the built binaries themselves do not link against
> libjava.so
>
> Indeed, running readelf on the built java binary reports the following:
> "(RUNPATH) Library runpath: [/usr/lib/jvm]" and /usr/lib/jvm/libjava.so exists.
> However, when running the Java binary on the target, the following error
> occurs: "Error: could not find libjava.so."
>
> The following is the result of "strace java" ran on the target:
> faccessat(AT_FDCWD, "/usr/lib/libjava.so", F_OK) = -1 ENOENT
> faccessat(AT_FDCWD, "/usr/jre/lib/libjava.so", F_OK) = -1 ENOENT
> newfstatat(AT_FDCWD, "/usr/lib/libjava.so", 0x7ffe7b4af8, 0) = -1 ENOENT
> newfstatat(AT_FDCWD, "/usr/lib/jvm/libjli.so", [sic] AT_SYMLINK_NOFOLLOW) = 0
>
> As seen above, the java binary searches for libjli.so in /usr/lib/jvm,
> but libjava.so has the search paths hardcoded to the following directories:
>   - /usr/lib/
>   - /usr/jre/lib/
>   - $(dirname $0)/../lib/
>
> The reason behind the hardcoded paths given by the maintainers is due to
> historical purposes for the need to support several java versions at the
> same time on a single system, and that changing the above behavior is not
> likely to ever happen.
>
> As such, most distributions such as Redhat do the following:
>   - Create the directory /usr/lib/jvm/java-$(JAVA_VERSION)/
>   - Install all directories and files found in images/jre to that directory.
>   - Symlink the binaries to in /usr/lib/jvm/java-$(JAVA_VERSION)/bin to
>     /usr/bin.
>
> However, because Buildroot does not need to support multiple versions of java
> concurrently, there is no need for the additional java-$(JAVA_VERSION)
> directory.
>
> To fix the above issue, the following changes are performed:
>   - Introduce the variable "OPENJDK_INSTALL_BASE" which points to /usr/lib/jvm
>   - Set the --with-extra-ldflags conf_opt to
>       "-Wl,-rpath,$(OPENJDK_INSTALL_BASE)/lib,-rpath,
>       $(OPENJDK_INSTALL_BASE)/lib/$(OPENJDK_JVM_VARIANT)"
>   - Run "mkdir -p $(TARGET_DIR)/usr/lib/jvm/" in the INSTALL_TARGET_CMDS step.
>   - Copy both the lib and bin directories to /usr/lib/jvm/
>   - Symlink the binaries in /usr/lib/jvm/bin/ to /usr/bin.
>
> Fixes: https://bugs.busybox.net/show_bug.cgi?id=12751
>
> Signed-off-by: Adam Duskett <Aduskett at gmail.com>
> ---
> Changes v1 -> v2:
>   - Fixed comments in openjdk.mk (Yann)
>   - Added spaces around the = sign for OPENJDK_INSTALL_BASE (Yann)
>   - Added trailing /'s for copying (Yann)
>   - Added a more complete commit message.
>
>  package/openjdk/openjdk.mk | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)

Reviewed-by: Ryan Barnett <ryan.barnett at rockwellcollins.com>
Tested-by: Ryan Barnett <ryan.barnett at rockwellcollins.com>

Built and runtime tested on x86-64 platform.

Thanks,
-Ryan

---
Ryan Barnett | Sr Systems Engineer | Commercial Avionics
COLLINS AEROSPACE
400 Collins Rd NE, Cedar Rapids, IA 52498 USA
ryan.barnett at collins.com | collinsaerospace.com

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