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Remove a pathname from the pathname space
#include <sys/iofunc.h>
#include <sys/dispatch.h>
int resmgr_detach( dispatch_t * dpp,
int id,
unsigned flags );
- dpp
- A dispatch handle created by
dispatch_create().
- id
- The link ID that
resmgr_attach()
returned.
- flags
- Flags that affect the operation.
The possible flags (defined in <sys/dispatch.h>
and <sys/resmgr.h>) are:
- _RESMGR_DETACH_ALL —
detach the name from the namespace and invalidate all open bindings.
- _RESMGR_DETACH_CLOSE — close all bindings when
detaching.
- _RESMGR_DETACH_PATHNAME —
detach only the name from the namespace, leaving existing bindings intact.
This option is useful when you're unlinking a file or device,
and you want to remove the name, but you want processes with
open files to continue to use it until they close.
libc
Use the -l c option to
qcc
to link against this library.
This library is usually included automatically.
The resmgr_detach() function removes pathname id from the pathname space
of context dpp.
The resmgr_detach() function blocks until the RESMGR_HANDLE_T,
that's passed to the corresponding
resmgr_attach(),
isn't being used in any connection function.
The effect that this has on servers is generally minimal.
You should follow the following precautions to prevent potential deadlock situations:
- If you're using the RESMGR_HANDLE_T as an attribute,
and that attribute is locked in any of the connection callouts (i.e. open, unlink, mount, etc.),
then should unlock it before calling resmgr_detach().
This allows any pending connection requests to complete before they're
consequently invalidated.
|
If you call resmgr_detach() from within a connection function,
then the internal reference counting takes this into account and the server doesn't deadlock.
|
- If two or more resmgr_detach() requests come in simultaneously, only one of the requests is served.
The superfluous request will return with an error of -1 and errno set to ENOENT
to indicate that the detachment process has already begun, and the
entry is now invalid.
If dynamically allocated, you should release
RESMGR_HANDLE_T only after a
successful return from resmgr_detach().
- If resmgr_detach() is called and an existing client connection is established,
then the I/O callout table is redirected for that client connection.
The client will receive an error of EBADF when it uses
the fd
associated with that connection.
- 0
- Success.
- -1
- An error occurred (errno is set).
- EINVAL
- The id was never attached with
resmgr_attach().
- ENOENT
- A previous detachment request is in progress, or the id
has already been detached.
#include <sys/dispatch.h>
#include <stdio.h>
#include <stdlib.h>
int main( int argc, char **argv ) {
dispatch_t *dpp;
int id;
if ( (dpp = dispatch_create()) == NULL ) {
fprintf( stderr, "%s: Unable to allocate \
dispatch handle.\n",argv[0] );
return EXIT_FAILURE;
}
id = resmgr_attach ( … );
…
if ( resmgr_detach( dpp, id, 0) == -1 ) {
fprintf( stderr, "Failed to remove pathname \
from the pathname space.\n" );
return EXIT_FAILURE;
}
For examples using the dispatch interface, see
dispatch_create(),
message_attach(),
resmgr_attach(), and
thread_pool_create().
QNX Neutrino
Safety: | |
Cancellation point |
Yes |
Interrupt handler |
No |
Signal handler |
No |
Thread |
Yes |
dispatch_create(),
resmgr_attach()
Writing a Resource Manager
Resource Managers
chapter of Getting Started with QNX Neutrino
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