ham_action_execute()

Add an execute action to a condition

Synopsis:

#include <ha/ham.h>

ham_action_t *ham_action_execute(
                 ham_condition_t *chdl,
                 const char *aname, 
                 const char *path, 
                 unsigned flags);

Library:

libham

Description:

The ham_action_execute() function adds an action (aname) to the specified condition. The action will execute an external program or command specified by path. The path parameter must contain the FULL path to the executable along with all parameters to be passed to it. If either the pathname or the arguments contain spaces that need to be passed on literally to the spawn call, they need to be quoted. As long as the subcomponents within the path arguments are quoted, using either of the following methods:

\'path with space\'

or

\"path with space\",

the following is allowed:

"\'path with space\' arg1 arg2 \"arg3 with space\"".

This would be parsed as

"path with space" -> path

arg1 = arg1

arg2 = arg2

arg3 = "arg3 with space".

The command line is in turn passed onto a spawn command by the HAM to create a new process that will execute the command.

The handle (chdl) is obtained either:

• from one of the ham_condition*() functions to add conditions

  or:

• by calling any of the ham_condition_handle() functions to request a handle to a specific condition.

The action is executed when the appropriate condition is triggered.

Currently the following flags are defined:

HACTIONDONOW

Tells the HAM to perform the action once immediately, in addition to performing it whenever the condition is triggered.

HREARMAFTERRESTART

Indicates that the action is to be automatically rearmed after the entity that it belongs to is restarted. By default, this flag is disabled — actions automatically get pruned across restarts of the entity. Note that if the condition that this action belongs to is pruned after a restart, this action will also be removed, regardless of the value of this flag.

HACTIONBREAKONFAIL

Indicates that if this action were to fail, and it is part of a list of actions, none of the actions following this one in the list of actions will be executed.

HACTIONKEEPONFAIL

Indicates that the action will be retained even if it fails. The default behavior is to remove failed actions. Nevertheless if the condition that this action is associated with is not retained, the action will get automatically removed.

Users can specify what will be done if an action fails. By adding action fail actions to a list associated with an action, users can determine what will be done in the case of an action failure. For every action that fails, the corresponding action fail list will be executed. Certain actions (e.g. ham_action_log() and ham_action_heartbeat_healthy()) never fail. For more details, refer to the appropriate section in the HAM API reference for the ham_action_fail_*() calls.

Returns:

A valid handle to an action to a condition, or NULL if an error occurred (errno is set).

Errors:

EBADF

Couldn't connect to the HAM.

EINVAL

The name given in aname is invalid (e.g. it contains the “/” character) or is NULL.

The connection to the HAM is invalid. This happens when the process that opened the connection (using ham_connect()) and the process that's calling ham_action_execute() aren't the same.

ENAMETOOLONG

The name given (in aname) is too long, i.e. it exceeds _POSIX_PATH_MAX (defined in <limits.h>). Note that the combined length of an entity/condition/action name is also limited by _POSIX_PATH_MAX.

ENOENT

There's no entity or condition specified by the given handle (chdl).

ENOMEM

Not enough memory to create a new handle.

In addition to the above errors, the HAM returns any error it encounters while servicing this request.

Classification:

QNX Neutrino

See also:

ham_action_notify_pulse(), ham_action_notify_signal(), ham_action_remove(), ham_action_restart(), ham_action_waitfor(), ham_condition(), ham_condition_handle()