On 04/10/2014 08:29 PM, Mark Wielaard wrote:
I like the helper function, but I think it is a little more low-level
than what we normally provide. We should at least (also) have a
dwarf_get_alt () that returns a Dwarf *.
This would just return the stored Dwarf *, and not attempt to open any
files?
Yes. dwarf_getalt () would just return the set Dwarf *alt (or NULL when
none was set).
Okay, I will include this in a revision of the patch.
We could add them at the ELF layer, but then we'd have to iterate over
all the ELF section headers in each of these functions. The section
header array in libdw avoids this. I'm also not sure where to put such
convenience functions.
Yeah, I might be designing things. You are right having it in libdw and
using the debug section array is the right thing to use. I am mostly
concerned about the naming because I think this functionality is at a
different level than the rest.
So what about dwarf_elf_debugaltlink or even dwarf_elf_gnu_debugaltlink
as a name? This shows the relationship to the underlying ELF data.
libebl? But I currently don't use that, and I
think some downstreams assign send-class status to it.
libebl is strictly for internal use, not for public functions.
The utility functions could just be part of libdw, just like the dwfl
functions are, just with a slightly different naming convention (let the
bike-shedding begin).
BTW. I don't know what assigning send-class status means.
Typo for "second-class". :)
I would make build_id_len the return value. Then you can return:
- 0 No debugaltlink found.
- > 0 Length of build_id, success.
- < 0 Error.
Hmm, I wonder if the interface is similar enough to read(2) so that the
tri-state return value isn't a problem. Usually, it's problematic
because callers are tempted to treat the result as boolean, interpreting
-1 as success.
The tri-state return value pattern is used with more libdw functions, so
I don't think it will surprise our users. Especially not if we properly
document it :)
Okay, I will make this change as well.
--
Florian Weimer / Red Hat Product Security Team
