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Re: [patch 1/3] Extend __libdw_open_file and elf_begin as *_at_offset


On Tue, 25 Feb 2014 23:12:04 +0100, Mark Wielaard wrote:
> I rather not extend the libelf interface if possible. The various libelf
> implementations are already a little diverged. Lets not unnecessarily
> make the divergence even bigger.

I was aware of this issue but I had no other idea.


> If possible, could you mmap the file at
> the offset directly and use elf_memory() instead?

No, I cannot.  strace-ing eu-stack shows:

open("/proc/10797/mem", O_RDONLY)       = 4
mmap(NULL, 28672, PROT_READ|PROT_WRITE, MAP_PRIVATE, 4, 0x400000) = -1 ENODEV (No such device)
pread(4, "\177ELF...", 64, 4194304) = 64

It is not due to a bit inappropriate PROT_WRITE there, with a standalone
testcase ENODEV is there same:

open("/proc/19126/mem", O_RDONLY)       = 3
mmap(NULL, 4096, PROT_READ, MAP_PRIVATE, 3, 0x400000) = -1 ENODEV (No such device)


Thanks,
Jan

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