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Re: BLODA detection code in latest snapshot
On 29/02/2012 10:01 AM, Corinna Vinschen wrote:
On Feb 29 09:51, Ryan Johnson wrote:
Sure. That's what I'd do also, but we're both familiar with the bloda. I
was thinking more of users sending problem reports. Telling them to
attach the output of `cygcheck -svrb' would give us useful information
even if they don't (yet) know what the bloda is let alone whether
they're affected by it. Sort of like how we could ask users having
strange problems to check for a second cygwin1.dll in their path... but
it's easier to just ask for cygcheck output and check that. As a bonus,
it would catch times where someone (*cough* me *cough*) thinks they're
bloda free and so doesn't check for it before reporting a problem.
On 27/02/2012 7:26 AM, Corinna Vinschen wrote:
I've just uploaded a new snapshot "2012-02-27 12:04:23 UTC". It
contains two code snippets which are supposed to help diagnosing BLODA
If you set the environment variable CYGWIN to "detect_bloda" and then
start a Cygwin process (bash or so), then Cygwin will detect two types
Would it be a good idea to update the FAQ's bloda entry with this
info? Sure, it's probably going to give occasional false positives
and/or negatives, but it would definitely catch the obvious cases
and give a quick test for claims of bloda-free systems. You'd almost
want a new cygcheck -b option that could fork off a process or two
with detect_bloda active and capture any output that results.
Of course I will document this at one point. So far I just didn't.
I doubt that the cygcheck -b would be useful, though. Just call
$ export CYGWIN=detect_bloda some_executable
and you get what you want.
Heck, if we really wanted to go whole-hog, we could add an option to
check for dlls in $PATH that have base collisions. Once cygcheck
supported both those checks, the fork failure error message could even
tell users to run cygcheck before reporting a problem.
Actually, now that I think about it, we could just make cygwin list any
base collisions among dlls used by a failed forkee and point to the FAQ
entry on rebaseall. The info is at our fingertips (dll::preferred_base)
and in the absence of base collisions we could spawn a process to check
for bloda, whose output (if non-empty) is highly likely to be relevant.
The latency of a single spawn is nothing compared to ten failed fork
attempts, so it wouldn't make cygwin any slower. Between those two
checks, an intelligent user could deal with the vast majority of fork
failures without ever invoking the mailing list. No change to cygcheck
needed at that point.
Of course, SHTDI and I won't be able to until the semester ends, but it
should be just a few hours' work.
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