Dear Mark, Mark Wielaard wrote on 08.08.2015 00:35: > On Thu, Aug 06, 2015 at 05:14:25PM +0200, Kai Wasserbäch wrote: >>> Could you compile the following with: >>> gcc -g -lelf -o elfrel elfrel.c >> >> this does not work for several reasons: >> 1. I certainly need -std=c99 for the inline initialisation of the >> counter in the for() statement. > > Ah, yes, this system has gcc 5.1 which defaults to gnu11.
ah, ok. GCC 5.x is currently in unstable and still needs to migrate to testing.
>> 2. *section (first used in »gelf_getshdr(section, §ion_header)«) isn't
>> defined/filled anywhere:
>> [...]
>> Long story short: did you paste the entire/correct code?
>
> Drat, so sorry. I must have copy/pasted an earlier version, that didn't
> even compile.
No problem. I'm just not familiar with libelf's API and didn't have time to read
the documentation to fix the bug by myself (or at least attempt that).
> Attached is a version I double checked, that includes one
> extra check (the size of the .text section).
Here you go (first the output when elfrel is linked against libelf1:
$ for i in 794488_elfs/libelf*/dump.elf.*; do ./elfrel $i; done
file: 794488_elfs/libelf1/dump.elf.EL5kJT
.text code size: 24
Nothing found
file: 794488_elfs/libelf1/dump.elf.J4EnbO
.text code size: 11c
symbols: 5
1: not global or undefined
2: not global or undefined
3: not global or undefined
4: not global or undefined
5: 0
relocations: 2
0: 10, SCRATCH_RSRC_DWORD1
1: 200000081,
file: 794488_elfs/libelfg0/dump.elf.7NnBvc
.text code size: 24
Nothing found
file: 794488_elfs/libelfg0/dump.elf.ahPsJJ
.text code size: 11c
symbols: 5
1: not global or undefined
2: not global or undefined
3: not global or undefined
4: not global or undefined
5: 0
relocations: 2
0: 10, SCRATCH_RSRC_DWORD1
1: 200000081,
file: 794488_elfs/libelfg0/dump.elf.DYTjdO
.text code size: 28
Nothing found
file: 794488_elfs/libelfg0/dump.elf.Lke6Xg
.text code size: 38
Nothing found
Now linked with libelfg0:
$ for i in 794488_elfs/libelf*/dump.elf.*; do ./elfrel_elfg0 $i; done
file: 794488_elfs/libelf1/dump.elf.EL5kJT
.text code size: 24
Nothing found
file: 794488_elfs/libelf1/dump.elf.J4EnbO
.text code size: 11c
symbols: 5
1: not global or undefined
2: not global or undefined
3: not global or undefined
4: not global or undefined
5: 0
relocations: 2
0: 10, SCRATCH_RSRC_DWORD1
1: 2c, SCRATCH_RSRC_DWORD0
file: 794488_elfs/libelfg0/dump.elf.7NnBvc
.text code size: 24
Nothing found
file: 794488_elfs/libelfg0/dump.elf.ahPsJJ
.text code size: 11c
symbols: 5
1: not global or undefined
2: not global or undefined
3: not global or undefined
4: not global or undefined
5: 0
relocations: 2
0: 10, SCRATCH_RSRC_DWORD1
1: 2c, SCRATCH_RSRC_DWORD0
file: 794488_elfs/libelfg0/dump.elf.DYTjdO
.text code size: 28
Nothing found
file: 794488_elfs/libelfg0/dump.elf.Lke6Xg
.text code size: 38
Nothing found
And there *IS* a difference vs. your output: for you the relocations in
794488_elfs/libelf1/dump.elf.J4EnbO look fine, for me the second relocation is
botched with libelf1 while it works with libelfg0.
libelf1:
relocations: 2
0: 10, SCRATCH_RSRC_DWORD1
1: 200000081,
libelfg0:
relocations: 2
0: 10, SCRATCH_RSRC_DWORD1
1: 2c, SCRATCH_RSRC_DWORD0
I also went ahead and checked Michel's information, that 0.159-4.2 worked. And
indeed, if I link elfrel with that older libelf1 I get a good looking relocation
section again:
$ for i in 794488_elfs/libelf*/dump.elf.*; do ./elfrel_elf1-old $i; done
file: 794488_elfs/libelf1/dump.elf.EL5kJT
.text code size: 24
Nothing found
file: 794488_elfs/libelf1/dump.elf.J4EnbO
.text code size: 11c
symbols: 5
1: not global or undefined
2: not global or undefined
3: not global or undefined
4: not global or undefined
5: 0
relocations: 2
0: 10, SCRATCH_RSRC_DWORD1
1: 2c, SCRATCH_RSRC_DWORD0
file: 794488_elfs/libelfg0/dump.elf.7NnBvc
.text code size: 24
Nothing found
file: 794488_elfs/libelfg0/dump.elf.ahPsJJ
.text code size: 11c
symbols: 5
1: not global or undefined
2: not global or undefined
3: not global or undefined
4: not global or undefined
5: 0
relocations: 2
0: 10, SCRATCH_RSRC_DWORD1
1: 2c, SCRATCH_RSRC_DWORD0
file: 794488_elfs/libelfg0/dump.elf.DYTjdO
.text code size: 28
Nothing found
file: 794488_elfs/libelfg0/dump.elf.Lke6Xg
.text code size: 38
Nothing found
If you want to take a look at Debian's builds of libelf{g0,1}, check out:
- libelfg0 (0.8.13-5):
<https://packages.debian.org/stretch/amd64/libelfg0/download> (working)
- libelf1 (0.159-4.2):
<http://snapshot.debian.org/package/elfutils/0.159-4.2/#libelf1_0.159-4.2>
(working)
- libelf1 (0.163-4):
<https://packages.debian.org/stretch/amd64/libelf1/download> (failing)
In case the versions change on packages.debian.org, snapshot.debian.org is your
friend. ;-)
Let me know, if you need something else.
Cheers,
Kai
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