On Thu, Jul 12, 2001 at 04:34:45PM -0400, Roland McGrath wrote:
> I didn't look closely, but now I am thinking twice. If the data is small
> enough to fit inline, and you use a separate reply stub, then you can send
> it without copying. That ought to be the common case.
This would be what you want. I can't say I like it. Maybe if we were to
use a seperate reply stub in auth_getids as well, we might use the same code
again. Otherwise I am afraid we have two slightly different versions of the
macros. (The argument why to use a seperate reply stub for auth_getids is
the same as for auth_server_authenticate, we can avoid a copy).
Thanks,
Marcus
--- auth.c Thu Jul 12 22:52:53 2001
+++ auth.c.new Thu Jul 12 23:11:05 2001
@@ -27,6 +27,7 @@
#include <hurd/ports.h>
#include <hurd/ihash.h>
#include <idvec.h>
+#include <sys/mman.h>
#include <assert.h>
#include <argp.h>
#include <error.h>
@@ -82,18 +83,57 @@ auth_port_to_handle (auth_t auth)
/* id management. */
-inline void idvec_copyout (struct idvec *idvec, uid_t **ids, uid_t *nids)
+inline int idvec_copyout (struct idvec *idvec, uid_t **ids, uid_t *nids)
{
if (idvec->num > *nids)
- *ids = idvec->ids;
+ {
+ *ids = mmap (0, idvec->num * sizeof (**ids), PROT_READ|PROT_WRITE,
+ MAP_ANON, 0, 0);
+ if (*ids == (uid_t *) -1)
+ return errno;
+ }
+ memcpy (*ids, idvec->ids, idvec->num * sizeof (**ids));
+ *nids = idvec->num;
+
+ return 0;
+}
+
+#define C(auth, ids) if (! err) \
+ err = idvec_copyout (&auth->ids, ids, n##ids)
+#define OUTIDS(auth) { C (auth, euids); C (auth, egids); \
+ C (auth, auids); C (auth, agids); }
+#define D(ids) *ids##_saved = *ids
+#define SAVEIDS uid_t D (euids), D (egids), D (auids), D (agids)
+#define F(ids) if (*ids != ids##_saved) \
+ munmap (*ids, *n##ids * sizeof (uid_t))
+#define FREEIDS { F (euids); F (egids); F (auids); F (agids); }
+
+/* In auth_server_authenticate, we use a reply stub to avoid copying
+ small inlined data twice. */
+inline int idvec_copyout_reply (struct idvec *idvec, uid_t **ids, uid_t *nids)
+{
+ if (idvec->num > *nids)
+ {
+ *ids = mmap (0, idvec->num * sizeof (**ids), PROT_READ|PROT_WRITE,
+ MAP_ANON, 0, 0);
+ if (*ids == (uid_t *) -1)
+ return errno;
+ memcpy (*ids, idvec->ids, idvec->num * sizeof (**ids));
+ }
else
- memcpy (*ids, idvec->ids, idvec->num * sizeof *ids);
+ *ids = idvec->ids;
+
*nids = idvec->num;
+ return 0;
}
-#define C(auth, ids) idvec_copyout (&auth->ids, ids, n##ids)
-#define OUTIDS(auth) (C (auth, euids), C (auth, egids), \
- C (auth, auids), C (auth, agids))
+#define C_R(auth, ids) if (! err) \
+ err = idvec_copyout_reply (&auth->ids, ids, n##ids)
+#define OUTIDS_R(auth) { C_R (auth, euids); C_R (auth, egids); \
+ C_R (auth, auids); C_R (auth, agids); }
+#define F_R(idsr) if (*idsr != user->idsr.ids) \
+ munmap (*idsr, *n##idsr * sizeof (uid_t))
+#define FREEIDS_R { F_R (euids); F_R (egids); F_R (auids); F_R (agids); }
/* Implement auth_getids as described in <hurd/auth.defs>. */
kern_return_t
@@ -107,12 +147,17 @@ S_auth_getids (struct authhandle *auth,
uid_t **agids,
u_int *nagids)
{
+ int err = 0;
+ SAVEIDS;
+
if (! auth)
return EOPNOTSUPP;
-
+
OUTIDS (auth);
-
- return 0;
+ if (err)
+ FREEIDS;
+
+ return err;
}
/* Implement auth_makeauth as described in <hurd/auth.defs>. */
@@ -358,6 +403,7 @@ S_auth_server_authenticate (struct authh
uid_t **agids,
u_int *nagids)
{
+ error_t err = 0;
struct pending *u;
struct authhandle *user;
@@ -392,7 +438,6 @@ S_auth_server_authenticate (struct authh
/* No pending user RPC for this port.
Create a pending server RPC record. */
struct pending s;
- error_t err;
err = ihash_add (pending_servers, rendezvous, &s, &s.locp);
if (! err)
@@ -418,17 +463,21 @@ S_auth_server_authenticate (struct authh
user = s.user;
}
- /* Extract the ids. We must use a separate reply stub so
- we can deref the user auth handle after the reply uses its
- contents. */
+ OUTIDS_R (user);
+ if (err)
+ FREEIDS_R;
+
+ /* Extract the ids. We use a separate reply stub to avoid copying
+ small data twice. For this to work we must keep the user reference
+ until the reply stub did its work. */
auth_server_authenticate_reply (reply, reply_type, 0,
- user->euids.ids, user->euids.num,
- user->auids.ids, user->auids.num,
- user->egids.ids, user->egids.num,
- user->agids.ids, user->agids.num);
+ *euids, *neuids,
+ *auids, *nauids,
+ *egids, *negids,
+ *agids, *nagids);
ports_port_deref (user);
mach_port_deallocate (mach_task_self (), rendezvous);
- return MIG_NO_REPLY;
+ return err;
}
--
`Rhubarb is no Egyptian god.' Debian http://www.debian.org [EMAIL PROTECTED]
Marcus Brinkmann GNU http://www.gnu.org [EMAIL PROTECTED]
[EMAIL PROTECTED]
http://www.marcus-brinkmann.de
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