Add a "live" mode to ktrdump.
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Authored by jhb on Sep 25 2018, 6:07 PM.

Details

Reviewers

kib
emaste
0mp

Group Reviewers

manpages

Commits

rS339620: Add a "live" mode to ktrdump.

Summary

Support a "live" mode in ktrdump enabled via the -l flag. In this mode,
ktrdump polls the kernel's trace buffer periodiocally (currently hardcoded
as a 50 millisecond interval) and dumps any newly added entries.

While here, fix some bugs from when this was Capsicum-ized:

Use caph_limit_stream() for the output stream so that isatty() works and the output can be line-buffered (especially useful for live mode).
Use caph_limit_stderr() to permit error messages to be displayed if an error occurs after cap_enter().

Test Plan

used to debug a ptrace issue with KTR_PTRACE

Diff Detail

Repository

rS FreeBSD src repository - subversion

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Unit

Tests Not Applicable

Event Timeline

jhb created this revision.Sep 25 2018, 6:07 PM

Herald added a reviewer: manpages. · View Herald TranscriptSep 25 2018, 6:07 PM

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Harbormaster completed remote builds in B19799: Diff 48441.Sep 25 2018, 6:07 PM

kib accepted this revision.Sep 25 2018, 8:38 PM

kib added inline comments.

usr.bin/ktrdump/ktrdump.c
383 ↗	(On Diff #48441)	I suspect that some users would want a configurable interval. Also, it might make sense to compare the times between start of previous run and now, instead of introducing constant delays.

This revision is now accepted and ready to land.Sep 25 2018, 8:38 PM

jhb marked an inline comment as done.Sep 25 2018, 8:56 PM

jhb added inline comments.

usr.bin/ktrdump/ktrdump.c
383 ↗	(On Diff #48441)	I thought about making the interval configurable. I did kind of figure if someone really wants it or wants fancier logic then that could be done as a followup change. I can maybe note that in the commit log.