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NAME
ttdt_file_join - register to observe ToolTalk events on a
file
SYNOPSIS
#include <Tt/tttk.h>
Tt_pattern *ttdt_file_join(const char *pathname,
Tt_scope the_scope,
int join,
Ttdt_file_cb cb,
void *clientdata);
DESCRIPTION
The ttdt_file_join() function registers to observe Deleted,
Modified, Reverted, Moved, and Saved notices.
If join is True, ttdt_file_join() calls tt_file_join() with
a pathname argument.
The the_scope argument identifies the scope of the request.
If the_scope is TT_SCOPE_NONE, it tries TT_BOTH, and falls
back to TT_FILE_IN_SESSION if, for example, the ToolTalk
database server is not installed on the file server that
owns pathname.
The ttdt_file_join() function associates the_scope and a
copy of pathname with the Tt_patterns returned, so that
ttdt_file_quit() can access them. Thus, the caller is free
to modify or free pathname after ttdt_file_join() returns.
The clientdata argument points to arbitrary data that will
be passed into the callback unmodified.
The Ttdt_file_cb argument is a callback defined as:
Tt_message (*Ttdt_file_cb)(Tt_message msg,
Tttk_op op,
char *pathname,
void *clientdata,
int same_euid_egid,
int same_procid);
The message argument is the message. The op argument is the
operation. The pathname argument is the pathname of the
file the message is about. The clientdata argument is the
client data passed into ttdt_file_join(). The
same_euid_egid argument is True if the sender can be
trusted; otherwise it is False. The same_procid argument is
True if the sender is the same procid as the receiver; oth-
erwise it is False. A Ttdt_file_cb must return the message
if it does not consume the message. (Consuming means reply-
ing, rejecting or failing a request, and then destroying the
message.) Otherwise, it must consume the message and return
either zero or a tt_error_pointer() cast to Tt_message.
RETURN VALUE
Upon successful completion, the ttdt_file_join() function
returns a null-terminated array of Tt_pattern, which can be
passed to ttdt_file_event(3) to register for requests that
the application should handle once it begins to modify the
file; otherwise, it returns an error pointer. The applica-
tion can use tt_ptr_error(3) to extract one of the following
Tt_status values from the returned handle:
TT_ERR_DBAVAIL
The ToolTalk service could not access the Tool-
Talk database needed for this operation.
TT_ERR_DBEXIST
The ToolTalk service could not access the speci-
fied ToolTalk database in the expected place.
TT_ERR_NOMEM
There is insufficient memory available to perform
the function.
TT_ERR_NOMP
The ttsession(1) process is not running and the
ToolTalk service cannot restart it.
TT_ERR_PATH
The specified pathname included an unsearchable
directory.
APPLICATION USAGE
The null-terminated array of Tt_pattern returned by
ttdt_file_join() should be destroyed by passing the array to
ttdt_file_quit(3).
The pathname argument to Ttdt_file_cb is a copy that can be
freed using tt_free(3).
EXAMPLES
This is the typical algorithm of a Ttdt_file_cb:
Tt_message myFileCB(Tt_message msg,
Tttk_op op,
char *pathname,
int trust,
int isMe)
{
tt_free(pathname);
Tt_status status = TT_OK;
switch(op) {
case TTDT_MODIFIED:
if ((_modifiedByMe)&&(! isMe)) {
/* Hmm, the other editor either does not know or
* does not care that we are already modifying the
* file, so the last saver will win.
*/
} else {
/* Interrogate user if she ever modifies the buffer */
_modifiedByOther = 1;
XtAddCallback(myTextWidget, XmNmodifyVerifyCallback,
myTextModifyCB, 0);
}
break;
case TTDT_GET_MODIFIED:
tt_message_arg_ival_set(msg, 1, _modifiedByMe);
tt_message_reply(msg);
break;
case TTDT_SAVE:
status = mySave(trust);
if (status == TT_OK) {
tt_message_reply(msg);
} else {
tttk_message_fail(msg, status, 0, 0);
}
break;
case TTDT_REVERT:
status = myRevert(trust);
if (status == TT_OK) {
tt_message_reply(msg);
} else {
tttk_message_fail(msg, status, 0, 0);
}
break;
case TTDT_REVERTED:
if (! isMe) {
_modifiedByOther = 0;
}
break;
case TTDT_SAVED:
if (! isMe) {
_modifiedByOther = 0;
int choice = myUserChoice(myContext, myBaseFrame,
"Another tool has saved "
"this file.", 2, "Ignore",
"Revert");
switch(choice) {
case 1:
myRevert(1);
break;
}
}
break;
case TTDT_MOVED:
case TTDT_DELETED:
/* Do something appropriate */
break;
}
tttk_message_destroy(msg);
return 0;
}
SEE ALSO
tttk(5), ttdt_file_quit(3), ttdt_file_event(3),
ttdt_Get_Modified(3), ttdt_Save(3), ttdt_Revert(3),
tt_file_join(3), tt_free(3).
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