DtActionInvoke(library call) DtActionInvoke(library call)
NAME
DtActionInvoke -- invoke a CDE action
SYNOPSIS
#include <Dt/Action.h>
DtActionInvocationID DtActionInvoke(
Widget w,
char *action,
DtActionArg *args,
int argCount,
char *termOpts,
char *execHost,
char *contextDir,
int useIndicator,
DtActionCallbackProc statusUpdateCb,
XtPointer client_data);
DESCRIPTION
The DtActionInvoke function provides a way for applications to invoke desktop actions on file or buffer arguments. Applications can regis-
ter a callback for receiving action-done status and return arguments.
The actions and data types databases must be initialized and loaded (using DtInitialize(3) and DtDbLoad(3)) before DtActionInvoke can run
successfully.
The w argument is a widget that becomes the parent of any dialogs or error messages resulting from action invocation. This widget should
be a top-level application shell widget that continues to exist for the action's expected lifetime. This argument must have a non-NULL
value.
The action argument is the name of the action to be invoked. The action database may define more than one action with the same name. The
action selected for a particular invocation depends on the class, type, and number of arguments provided (as described in dtaction-
file(4)). This argument must have a non-NULL value.
The args argument is an array of action argument structures containing information about the arguments for this action invocation. If there
are no arguments, the value of args must be NULL. The items in this array are assigned to the option argument keywords referenced in the
action definition (see dtactionfile(4)). The nth item is assigned to keyword %Arg_ n%. For example, the second item is assigned to %Arg_2%.
The argCount argument is the number of action arguments provided in the array args references.
The termOpts argument is a string providing special execution information for the terminal emulator used for COMMAND actions of WINDOW_TYPE
TERMINAL or PERM_TERMINAL. (See dtactionfile(4)). This string must be quoted if it contains embedded blanks. The application uses this
string to pass on title, geometry, color and font information to the terminal emulator. This information must be in a form the expected
terminal emulator recognizes. This argument can be NULL.
The execHost argument is a string identifying a preferred execution host for this action. The execHost specified here, supersedes the list
of execution hosts defined in the action definition. If execHost is NULL, the execution host for the action is obtained from the action
definition as described in dtactionfile(4).
The contextDir argument is a string identifying a fallback working directory for the action. File name arguments are interpreted relative
to this directory, which must reside in the local file name space (for example, /usr/tmp or /net/hostb/tmp). This value is only used if
the action definition does not explicitly specify a working directory in the CWD field of the action definition. If contextDir is NULL, the
current working directory of the action is obtained from the action definition, as described in dtactionfile(4).
If the useIndicator flag is zero, DtActionInvoke does not provide any direct indication to the user that an action has been invoked. If the
useIndicator flag is non-zero, the user is notified via some activity indicator (for example, a flashing light in the front panel) that an
action has been invoked. This indication persists only until the invocation of the action completes (in other words, until the action
begins running).
The statusUpdateCb callback may be activated if the invoked actions have returnable status (for example, a TT_MSG(TT_REQUEST) returning
DtACTION_DONE ). At a minimum, a DtACTION_INVOKED status is returned when DtActionInvoked has finished processing and has completely
invoked any resulting actions, and a DtACTION_DONE or equivalent done status is returned when all actions terminate. If statusUpdateCb is
set to NULL, subsequent action status is not returned. (See Dt/Action.h - DtAction(5) for a list of all DtActionStatus codes, and see DtAc-
tionCallbackProc(3) for details on statusUpdateCb and a list of specific DtActionStatus codes it can return.)
The client_data argument is optional data to be passed to the statusUpdateCb callback when invoked.
The DtActionInvoke function searches the action database for an entry that matches the specified action name, and accepts arguments of the
class, type and count provided.
If DtActionInvoke finds a matching action, the supplied arguments are inserted into the indicated action fields. If any missing action
arguments have an associated prompt string, then a dialog box prompts the user to supply the arguments; otherwise, missing arguments are
ignored. If too many arguments are supplied to an action requiring more than a single argument, a warning dialog is posted, allowing the
action to be cancelled or continued, ignoring the extra arguments. If too many arguments are supplied to an action requiring zero or one
arguments, then that action is invoked once for each of the supplied arguments. Arguments in the DtActionArg structure that may have been
modified by the action are returned by the callback if a statusUpdateCb callback is provided. For DtActionBuffer arguments, the writable
flag acts as a hint that the buffer is allowed to be modified and returned.
The DtActionBuffer structure contains at least the following members:
void *bp location of buffer
int size size of buffer in bytes
char *type optional type of buffer
char *name optional name of buffer
Boolean writable action is allowed to modify and
return the buffer
The DtActionFile structure contains at least the following member:
char *name name of file
The DtActionArg structure contains at least the following members:
int argClass see argument class types ( ARG_CLASS
field)
DtActionFile u.file union to a DtActionFile structure
DtActionBuffer u.buffer union to a DtActionBuffer structure
where argClass is DtACTION_FILE or DtACTION_BUFFER. The action service may set argClass to DtACTION_NULLARG for action arguments returned
by a statusUpdateCb to indicate that the argument is not being updated or has been removed. DtACTION_NULLARG cannot be present in action
arguments passed to DtActionInvoke.
The DtActionInvoke function accepts a pointer to an array of DtActionArg structures describing the objects to be provided as arguments to
the action. The args structure can be modified or freed after DtActionInvoke returns.
A single call to DtActionInvoke may initiate several actions or messages. For example, if an action is given three files, but only needs
one, three instances of the action are started, one for each file. As a result, a single returned DtActionInvocationID may represent a
group of running actions, and subsequent execution management services (DtAction) calls operate on that group of actions.
For DtACTION_BUFFER arguments, the action service first tries to type the buffer *bp using the name field (see dtdtsfile(4)). The name
field would typically contain a value resembling a file name with an optional extension describing its type. If the name field is NULL,
then the action service uses the type specified in the type field. If the type field is NULL, then the action service types the buffer *bp
by content (see dtdtsfile(4)). If the name and type fields are both non-NULL, then the action service uses the name field for typing and
ignores the type field. If the buffer pointer bp is NULL or size is equal to zero, a buffer with no contents is used in the resulting
action. If returned, the buffer pointer bp is defined, and size is equal to or greater than zero.
When necessary, DtACTION_BUFFER arguments are automatically converted to temporary files prior to actual action invocation, and reconverted
back to buffers after action termination (this is transparent to the caller). If a non-NULL name field is given, it is used in the con-
struction of the temporary file name (for example, /myhome/.dt/tmp/name). If the use of name would cause a conflict with an existing file,
or name is NULL, the action service generates a temporary file name. The permission bits on the temporary file are set according to the
writable field and the IS_EXECUTABLE attribute from the action service associated with the type field.
For DtACTION_FILE arguments, name is required.
For DtACTION_BUFFER arguments, name cannot contain slash characters.
Errors encountered are either displayed to the user in a dialog box or reported in the desktop errorlog file ($HOME/.dt/errorlog, unless
configured otherwise).
RESOURCES
This section describes the X11 resources the DtActionInvoke function recognizes. The resource class string always begins with an upper-case
letter. The corresponding resource name string begins with the lower case of the same letter. These resources can be defined for all
clients using the Action Library API by specifying *resourceName: value. For example, to set the terminal emulator to xterm(1) for all
clients, the application can use *localTerminal: xterm. The resources can also be defined on a per client basis. For example, it can use
Dtfile*localTerminal: xterm to set the terminal emulator to xterm(1) for the dtfile client only. (See dtactionfile(4)).
X11 Resources
Name Class Value Type Default
localterminal LocalTerminal string ``Dtterm''
remoteTerminals RemoteTerminals string ``Dtterm''
waitTime WaitTime number 3
LocalTerminal
Defines an alternative local terminal emulator for Command actions of WINDOW_TYPE TERMINAL or PERM_TERMINAL to use. The default
terminal emulator is dtterm(1).
RemoteTerminals
Defines a comma-separated list of host and terminal emulator pairs. When a remote COMMAND action is executed on one of the hosts
in the list, the terminal emulator associated with that host is used for that command. The list is passed to the terminal emula-
tor using the -e argument. (Thus, if another terminal emulator than dtterm is used, it must support the -e argument. See
xterm(1).
WaitTime Used to assign an alternative integer value, in seconds, to the threshold successful return time interval. If a COMMAND action of
WINDOW_TYPE TERMINAL fails, the terminal emulator may be unmapped before the user has a chance to read the standard error from
the failed command. This resource provides a workaround to this problem. If a TERMINAL window command exits before WaitTime sec-
onds have elapsed, the terminal emulator window is forced to remain open, as if it were of TYPE PERM_TERMINAL. The default value
of WaitTime is 3 seconds.
RETURN VALUE
Upon successful completion, the DtActionInvoke function returns a DtActionInvocationID. The ID can be used in subsequent execution manage-
ment services (DtAction) calls to manipulate the actions while they are running. DtActionInvocationIDs are only recycled after many have
been generated.
APPLICATION USAGE
The caller should allocate space for the array of structures describing the objects to be provided as arguments to the action. The caller
can free the memory after DtActionInvoke returns.
Since DtActionInvoke spawns subprocesses to start local actions, the caller should use waitpid(2) instead of wait(2) to distinguish between
processes started by the action service and those the caller starts.
EXAMPLES
Given the following action definition:
ACTION Edit
{
LABEL "Text Edit Action"
ARG_CLASS BUFFER, FILE
ARG_TYPE TEXT
TYPE COMMAND
WINDOW_TYPE TERMINAL
EXEC_STRING "textedit %Args%"
DESCRIPTION This action invokes the "textedit" command on
an arbitrary number of arguments. A terminal
emulator is provided for this action's I/O.
EXEC_HOST and CWD are not specified so the
defaults are used for both quantities.
}
The following call invokes the action Edit on the arguments aap supplies:
DtActionInvoke(w, "Edit", aap, 3, NULL, NULL, NULL, 1,
myCallback, myClientData);
The working directory for the action defaults to the current working directory. The execution host is the default execution host.
If the variable aap points to an array of ActionArg data structures containing the following information:
{
argClass = DtACTION_FILE;
struct {
name="/myhome/file1.txt";
} file;
}
{
argClass = DtACTION_FILE;
struct {
name="file2.txt";
} file;
}
{
argClass = DtACTION_BUFFER;
struct {
bp=(void *) myEditBuffer;
size=lengthOfMyEditBuffer;
type=NULL;
name="Doc1.txt"
writable=TRUE;
} buffer;
}
and the current working directory is /cwd, then the Edit action results in the execution string:
textedit /myhome/file1.txt /cwd/file2.txt /myhome/.dt/tmp/Doc1.txt
When the action completes, myCallback is called and the callback returns the buffer argument.
SEE ALSO
Dt/Action.h - DtAction(5), xterm(1), XtFree(3), XtMalloc(3), DtDbLoad(3), DtInitialize(3), DtActionCallbackProc(3), dtactionfile(4), dtdt-
file(4), dtdtsfile(4).
DtActionInvoke(library call)