Re: [RFC][PATCH] /proc/pid/maps doesn't match "ipcs -m" shmid

From: Albert Cahalan
Date: Thu Jun 07 2007 - 12:43:52 EST


On 6/7/07, Badari Pulavarty <pbadari@xxxxxxxxxx> wrote:

BTW, I agree with Eric that its would be nice to use shmid as part
of name instead of forcing to be as inode number. It should be
possible for pmap to workout shmid from "key" or name. Isn't it ?

It is not at all nice.

1. it's incompatible ABI breakage
2. where will you put the key then, in the inode? :-)

Changing to "SYSVID%d" is no good either. Look, people
are ***parsing*** this stuff in /proc. The /proc filesystem
is not some random sandbox to be playing in.

Before you go messing with it, note that the device number
also matters. (it's per-boot dynamic, but that's OK)
That's how one knows that /SYSV00000000 is not just
a regular file; sadly these didn't get a non-/ prefix.
(and no you can't fix that now; it's way too late)

Next time you feel like breaking an ABI, mind putting
"LET'S BREAK AN ABI!" in the subject of your email?

BTW, I suspect this kind of thing also breaks:
a. fuser, lsof, and other resource usage display tools
b. various obscure emulators (similar to valgrind)
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