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Mark Wielaard
df7dfab451
ELF files can share the section header string table (e_shstrndx) with the symtab .strtab section. That might in some cases save a bit of space since symbols and sections might share some (sub)strings. To handle that eu-strip just needs to not unconditionally remove the .shstrtab section (it will be properly marked as used/unused as needed). eu-unstrip needs to make sure the section names are added to the strtab if it decides to rewrite that section. Also makes sure that eu-strip won't move around a SHT_NOBITS section that has SHF_ALLOC set. Although it is allowed to move such sections around, there is no benefit. And some tools might expect no allocated section to move around, not even a nobits section. It also makes it harder to do "roundtripping" sanity checks that make sure splitting a file with eu-strip and then reconstructed with eu-unstrip produce the same ELF file (as is done in the new run-strip-strmerge.sh). Introduces a somewhat large test generator elfstrmerge.c that will hopefully turn into a more generic string table merger program. Signed-off-by: Mark Wielaard <mjw@redhat.com>
Fundamental design decision: - the sizes of external and internal types are assumed to be the same. This leaves byte ordering aside. While assuming this the code can be greatly simplified and speed increases. Since no change violating this assumption is in sight this is believed to be a worthwhile optimization. - the ABI of the backend modules is not guaranteed. Really, no guarantee whatsoever. We are enforcing this in the code. The modules and their users must match. No third-party EBL module are supported or allowed. The only reason there are separate modules is to not have the code for all architectures in all the binaries. - although the public libraries (libasm, libdw) have a stable API and are backwards ABI compatible they, and the elfutils tools, do depend on each others internals, and on internals of libelf to provide their interfaces. So they should always be upgraded in lockstep when packaging the tools and libraries separately. For one example of how to do that, see the config/elfutils.spec.