The zed_strings container stores strings in an AVL, but does not
check for duplicate strings being added. Within the AVL, strings
are indexed by the string value itself. avl_add() requires the node
being added must not already exist in the tree, and will assert()
if this is not the case.
This should not cause problems in practice. ZED uses this container
in two places. In zed_conf.c, it is used to store the names of
enabled zedlets as zed scans the zedlet directory listing; duplicate
entries cannot occur here since duplicate names cannot occur within
a directory. In zed_event.c, it is used to store the environment
variables (as "NAME=VALUE" strings) that will be passed to zedlets;
duplicate strings here should never happen unless there is a bug
resulting in a duplicate nvpair or environment variable.
This commit protects against adding a duplicate to a zed_strings
container by first checking for the string being added, and removing
the previous entry should one exist. This implements a "last one
wins" policy.
This commit also changes the prototype for zed_strings_add() to allow
the string key (by which it is indexed in the AVL) to differ from
the string value. By adding zedlet environment variables using the
variable name as the key, multiple adds for the same variable name
will result in only the last value being stored.
Finally, this commit routes all additions of zedlet environment
variables through the updated _zed_event_add_var(). This ensures
all zedlet environment variable names are properly converted.
Signed-off-by: Chris Dunlap <cdunlap@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#3042
zed monitors ZFS events. When a zevent is posted, zed will run any
scripts that have been enabled for the corresponding zevent class.
Multiple scripts may be invoked for a given zevent. The zevent
nvpairs are passed to the scripts as environment variables.
Events are processed synchronously by the single thread, and there is
no maximum timeout for script execution. Consequently, a misbehaving
script can delay (or forever block) the processing of subsequent
zevents. Plans are to address this in future commits.
Initial scripts have been developed to log events to syslog
and send email in response to checksum/data/io errors and
resilver.finish/scrub.finish events. By default, email will only
be sent if the ZED_EMAIL variable is configured in zed.rc (which is
serving as a config file of sorts until a proper configuration file
is implemented).
Signed-off-by: Chris Dunlap <cdunlap@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #2
