Use build id to lookup debug symbols for libc >= 2.31

[robbert1978]

I found that they use "build id" from version 2.31

[dp1]

While preparing #282 I remember testing something similar to this, but I would get some empty files for libcs older than 2.34. I'll check if this is really the case later today or tomorrow

[robbert1978]

While preparing #282 I remember testing something similar to this, but I would get some empty files for libcs older than 2.34. I'll check if this is really the case later today or tomorrow
This is before I used your code

I changed "2.34" to "2.31" and it worked for me

[dp1]

@robbert1978 While the change seems to work for the specific libc you're testing, it also causes a few regressions:

Files:
libc6_2.31-0ubuntu9_amd64.so
  libc6_2.31-0ubuntu9_amd64.so: 19383256 bytes -> 2029224 bytes
  libc.so.6: 19383256 bytes -> 2029224 bytes
libc6_2.33-0ubuntu5_i386.so
  libc6_2.33-0ubuntu5_i386.so: 12343416 bytes -> 2059156 bytes
  libc.so.6: 12343416 bytes -> 2059156 bytes
libc6_2.32-0ubuntu3.2_i386.so
  libc6_2.32-0ubuntu3.2_i386.so: 11649236 bytes -> 2055092 bytes
  libc.so.6: 11649236 bytes -> 2055092 bytes
libc6_2.31-0ubuntu9.9_i386.so
  libc.so.6: 2020588 bytes -> 7070572 bytes
  libc6_2.31-0ubuntu9.9_i386.so: 2020588 bytes -> 7070572 bytes
libc6_2.32-0ubuntu3_i386.so
  libc.so.6: 11649172 bytes -> 2055092 bytes
  libc6_2.32-0ubuntu3_i386.so: 11649172 bytes -> 2055092 bytes
libc6_2.31-0ubuntu9.7_i386.so
  libc.so.6: 17014256 bytes -> 2020556 bytes
  libc6_2.31-0ubuntu9.7_i386.so: 17014256 bytes -> 2020556 bytes
libc6_2.32-0ubuntu3_amd64.so
  libc.so.6: 13759760 bytes -> 1995896 bytes
  libc6_2.32-0ubuntu3_amd64.so: 13759760 bytes -> 1995896 bytes
libc6_2.31-0ubuntu9.9_amd64.so
  libc.so.6: 2029592 bytes -> 7459456 bytes
  libc6_2.31-0ubuntu9.9_amd64.so: 2029592 bytes -> 7459456 bytes
libc6_2.31-0ubuntu9_i386.so
  libc.so.6: 16996364 bytes -> 2018664 bytes
  libc6_2.31-0ubuntu9_i386.so: 16996364 bytes -> 2018664 bytes
Total: 0 new files, 0 deleted files, 18 modified files
Warnings:
warning: failed detecting libc version (is the libc an Ubuntu glibc?): failed finding version string: 159 
warning: failed unstripping libc: eu-unstrip exited with failure: exit status: 1: 140 -23
warning: failed unstripping libc: libc deb error: failed to find file in data.tar: 58 +30 -2
Total: 357 +30 -25

Notice how some libcs shrunk down in size, since they don't have symbols anymore after this change - the ones I'm more worried about are libc6_2.31-0ubuntu9_amd64.so and libc6_2.32-0ubuntu3_amd64.so, since 32bit challenges are relatively rare.

I suspect some extra logic, maybe even just trying both ways, is needed

[YsielX]

So is there any way to unstrip libc for versions above 2.34?

[robbert1978]

So is there any way to unstrip libc for versions above 2.34?

Check my small tool, I've tested it with libc 2.35 and 2.37. Maybe it will useful for you.