tagging a shared library with checksum

Question

How can I tag ELF libs with build IDs? I downloaded a precompiled library that has a sha1 sum in it:

user@localhost ~/tmp $ file foo.so.0
foo.so.0: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, BuildID[sha1]=0x7e3374eb34cafb69d3dca8b126f4aa33d44bb465, stripped

user@localhost ~/tmp $ ldd foo.so.0
linux-vdso.so.1 (0x00007fff955b1000)
libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f436d3c9000)
libc.so.6 => /lib64/libc.so.6 (0x00007f436d022000)
/lib64/ld-linux-x86-64.so.2 (0x0000003000000000)

score 0 · Answer 1 · edited Apr 22 '13 at 07:52

From http://fedoraproject.org/wiki/RolandMcGrath/BuildID

ld: new option --build-id:

This adds an option to ld to synthesize a .note.gnu.build-id section with type SHT_NOTE and flags SHF_ALLOC (read-only data), that contains an ELF note header and the build ID bits. This then goes into the link as if it were part of the first object file (so it may be placed or merged by the linker script). The build ID bits are determined as the very last thing ld does before writing out the linked file. You can give --build-id=style chose md5, uuid (128 random bits), or 0xabcdef (your chosen bytes in hex). Just --build-id defaults to md5, which computes an 128-bit MD5 signature based all the ELF header bits and section contents in the file--i.e., an ID that is unique among the set of meaningful contents for ELF files and identical when the output file would otherwise have been identical.

The Linux binutils-2.17.50.0.17 release includes this, in f8test1.

Please include the relevant parts of the page you link to in the actual answer. If the page ever gets moved your answer will become useless. — ChrisF, Apr 21 '13 at 19:15
Rather than just copy the text, it would be better to explain it. — ChrisF, Apr 21 '13 at 19:42

tagging a shared library with checksum

1 Answers1