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authorGravatar Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>2019-02-05 22:15:44 +0100
committerGravatar Thomas Petazzoni <thomas.petazzoni@bootlin.com>2019-10-27 14:52:44 +0100
commitd4d4056e63a9fa09d1ac0ecb390d4c677ebbb45d (patch)
treea2cc7e28107cc0eac9db33e8cfee55cddb7f2986 /toolchain
parentccc9e05990a44d8db5825c07ed61d405ebb40caa (diff)
downloadbuildroot-d4d4056e63a9fa09d1ac0ecb390d4c677ebbb45d.tar.gz
buildroot-d4d4056e63a9fa09d1ac0ecb390d4c677ebbb45d.tar.bz2
toolchain/toolchain-external: restrict copying of dynamic loader to ld*.so.*
Commit 32bec8ee2fb00c6750fa842bbb0eb79b0c081fa2 ("toolchain-external: copy ld*.so* for all C libraries") changed (among other things) the glob pattern to catch the dynamic loader from ld*.so.* to ld*.so* thus now matching files like 'ld-2.20.so' in addition to files like 'ld.so.1'. However, there is no apparent reason why that change was made. It is not explicitly mentioned in the commit message as to why that would be needed, nor is clear based on the rest of the changes in that commit. But it turns out that it causes too many files to be copied with some toolchains. In most toolchains, the structure looks like this: -rwxr-xr-x 1 tdescham tdescham 834364 Feb 16 21:23 output/target/lib/ld-2.16.so lrwxrwxrwx 1 tdescham tdescham 10 Feb 16 21:23 output/target/lib/ld.so.1 -> ld-2.16.so So, a symlink 'ld.so.1' which points to another file. Applications would have 'ld.so.1' (the link) encoded as program interpreter (readelf -l <program>, see INTERP entry) The patterns like 'ld*.so*' are passed as argument to copy_toolchain_lib_root which is defined in toolchain/helpers.mk. This macro copy_toolchain_lib_root will find all files/links matching the pattern. If a match is a regular file, it is simply copied. If it is a symbolic link, the link is copied and then the logic is recursively repeated on the link destination. That destination could either again be a link or a regular file. In the first case we recurse again, in the latter we stop and continue with the next match of the pattern. The problem this patch is solving is when a toolchain does not have this structure with a link and a real file, but rather two actual files: -rwxr-xr-x 1 tdescham tdescham 170892 Feb 16 21:55 output/target/lib/ld-2.20.so -rwxr-xr-x 1 tdescham tdescham 170892 Feb 16 21:55 output/target/lib/ld.so.1 In this case the pattern 'ld*.so*' would find two regular file matches and copy both. On the other hand, the pattern 'ld*.so.*' would only find the 'ld.so.1' file and copy just that. This saves about 170K in rootfs size. Closer inspection reveals that this particular toolchain has more such dedoubled symbolic links, e.g. the standard pattern of 'usr/lib/libfoo.so -> libfoo.so.1 -> libfoo.so.1.0.2' is not present, and each of these three components are real files. In any case, it is obvious that the toolchain itself is 'broken'. That being said, because we have the logic that recursively resolves symbolic links, TOOLCHAIN_EXTERNAL_LIBS really only needs to contain the "initial" name of the library to be copied. Therefore, revert the glob pattern back to what it was. Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com> [Thomas: improve the commit log with the additional details from Thomas] Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Diffstat (limited to 'toolchain')
-rw-r--r--toolchain/toolchain-external/pkg-toolchain-external.mk2
1 files changed, 1 insertions, 1 deletions
diff --git a/toolchain/toolchain-external/pkg-toolchain-external.mk b/toolchain/toolchain-external/pkg-toolchain-external.mk
index 5147da0104..7dfd2bf1bd 100644
--- a/toolchain/toolchain-external/pkg-toolchain-external.mk
+++ b/toolchain/toolchain-external/pkg-toolchain-external.mk
@@ -112,7 +112,7 @@ endif
# Definitions of the list of libraries that should be copied to the target.
#
-TOOLCHAIN_EXTERNAL_LIBS += ld*.so* libgcc_s.so.* libatomic.so.*
+TOOLCHAIN_EXTERNAL_LIBS += ld*.so.* libgcc_s.so.* libatomic.so.*
ifneq ($(BR2_SSP_NONE),y)
TOOLCHAIN_EXTERNAL_LIBS += libssp.so.*