chrpath.bbclass: strip common parent directories from rpath

Allows to use shorter TMPDIRs in corner cases, e.g. with native perl modules, having a deep directory structure.

The problem is that the original absolute rpath may be shorter than the newly generated relative rpath.

The failing rpaths were '/ab/cde/tmp/sysroots/x86_64-linux/usr/lib'
(old) and '$ORIGIN/../../../../../../../../../usr/lib' (new) for '/ab/cde/tmp/sysroots/x86_64-linux/usr/lib/perl-native/perl/5.14.3/auto/XML/Parser/Expat/Expat.so'

The new rpath is '$ORIGIN/../../../../../../..'.

The new code doesn't just compare libdir, because I guess it should also work if only parts of libdir share a parent directory with the binary.

This patch also adds a check for len(basedir) > 0, because I think basedir is empty in the cross-compile case, in which case rpath.find(basedir) would always return 0, but I'm unsure whether I understood that part of the code correctly or not.

ERROR: debugedit failed with exit code 127 (cmd was '/srv/ssd/sgw/builds/sec_flags/build/tmp/sysroots/x86_64-linux/usr/lib/rpm/bin/debugedit' -b '/srv/ssd/sgw/builds/sec_flags/build/tmp/work/i586-poky-linux' -d '/usr/src/debug' -i -l '/srv/ssd/sgw/builds/sec_flags/build/tmp/work/i586-poky-linux/eglibc/2.17-r3/debugsources.list' '/srv/ssd/sgw/builds/sec_flags/build/tmp/work/i586-poky-linux/eglibc/2.17-r3/package/usr/bin/locale')
ERROR: Function failed: split_and_strip_files
ERROR: Logfile of failure stored in: /srv/ssd/sgw/builds/sec_flags/build/tmp/work/i586-poky-linux/eglibc/2.17-r3/temp/log.do_package.26019
ERROR: Task 27 (/srv/ssd/sgw/builds/sec_flags/meta/recipes-core/eglibc/eglibc_2.17.bb, do_package) failed with exit code '1'

[YOCTO #3989]

Signed-off-by Andreas Oberritter <[email protected]>

---
v2: Fixed reassembly of libpath

  meta/classes/chrpath.bbclass |   17 +++++++++++++++--
  1 file changed, 15 insertions(+), 2 deletions(-)

meta/classes/chrpath.bbclass +15 -2

index 0c7ab77..454b587 100644
@@ -55,9 +55,22 @@ def process_dir (directory, d):
                  rpath =  os.path.normpath(rpath)
                  # If the rpath shares a root with base_prefix determine a new dynamic rpath from the
                  # base_prefix shared root
-                if rpath.find(basedir) != -1:
-                    depth = fpath.partition(basedir)[2].count('/')
+                if len(basedir) > 0 and rpath.find(basedir) != -1:
+                    relfpath = fpath.partition(basedir)[2].strip()
                      libpath = rpath.partition(basedir)[2].strip()
+                    depth = relfpath.count('/')
+                    # Compare common parent directories to reduce the length of the new rpath.
+                    # Ignore the first (empty) element.
+                    libdirs = libpath.split('/')
+                    relfdirs = relfpath.split('/')
+                    nparents = 0
+                    for i in range(1, min(len(libdirs), len(relfdirs))):
+                        if libdirs[i] != relfdirs[i]:
+                            break
+                        nparents += 1
+                    if nparents > 0:
+                        libpath = '/' + '/'.join(libdirs[i:])
+                        depth -= nparents
                  # otherwise (i.e. cross packages) determine a shared root based on the TMPDIR
                  # NOTE: This will not work reliably for cross packages, particularly in the case
                  # where your TMPDIR is a short path (i.e. /usr/poky) as chrpath cannot insert an