Hi Mark,
I tracked down the issue to the copy in memory was actually different.
However, because dwarf_begin_elf was still providing the offset to the top cus,
I did not suspect that was the issue.
Dwarf_getfuncs did return -1, but I did not look at dwarf_errmsg.
After I ensured the copy in memory is an exact copy, everything worked.
Thanks,
-Jeff
On 8/23/21, 2:01 PM, "Mark Wielaard" <m...@klomp.org> wrote:
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Hi Jeff,
On Tue, Aug 17, 2021 at 03:40:08AM +0000, Jeff Lin via Elfutils-devel wrote:
> I’ve written code to extract function from a shared object with
> dwarf_begin api that finds the dwarf objects with the file
> descriptor using dwarf_getfuncs. However, when I tried to parse the
> same object that is loaded into memory first, dwarf_getfuncs is not
> able to get the function. In the case of accessing the object that
> is in memory, I used the following line to get the dwarf object:
>
> Elf *ehandle = elf_memory(const_cast<char *>(so_file), size);
> Dwarf *dw = dwarf_begin_elf(ehandle, DWARF_C_READ, NULL);
>
> I am able to get the offset and tag with dwarf_nextcu, but errors
> out with dwarf_getfuncs. Does anyone know why dwarf_getfuncs does
> return properly when trying to process dwarf object that was store
> in memory?
If the ELF in memory is the same as the ELF on disk I don't know why
dwarf_getfuncs would work differently. Does the callback get called?
Does dwarf_getfuncs return -1? What does dwarf_errmsg say?
Cheers,
Mark
