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authorMichael I. Bushnell <mib@gnu.org>1993-12-03 01:55:28 +0000
committerMichael I. Bushnell <mib@gnu.org>1993-12-03 01:55:28 +0000
commit99be20e0687fff63642da6f753f56427b0ba4efc (patch)
treec1b1f0232ced47ea8af822351e3a3ec62b3e475b
parenta7a6a6d433f7386ca80bec0290fc6ea6bf283dcc (diff)
Initial revision
-rw-r--r--libiohelp/get_conch.c58
1 files changed, 58 insertions, 0 deletions
diff --git a/libiohelp/get_conch.c b/libiohelp/get_conch.c
new file mode 100644
index 00000000..4e2467b6
--- /dev/null
+++ b/libiohelp/get_conch.c
@@ -0,0 +1,58 @@
+/*
+ Copyright (C) 1993 Free Software Foundation
+
+ This program is free software; you can redistribute it and/or
+ modify it under the terms of the GNU General Public License as
+ published by the Free Software Foundation; either version 2, or (at
+ your option) any later version.
+
+ This program is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
+
+#include <libioserver.h>
+
+/* The conch must be locked when calling this routine. */
+error_t
+_libioserver_internal_get_conch (struct conch *c)
+{
+ struct shared *user_sh;
+ int error = 0;
+
+ again:
+ user_sh = c->holder_shared_page;
+
+ if (user_sh)
+ {
+ spin_lock (&user_sh->lock);
+ switch (user_sh->conch_status)
+ {
+ case USER_HAS_CONCH:
+ user_sh->conch_status = USER_RELEASE_CONCH;
+ /* fall through ... */
+ case USER_RELEASE_CONCH:
+ spin_unlock (&user_sh->lock);
+ condition_wait (&c->wait, &c->lock);
+ /* Anything can have happened */
+ goto again;
+
+ case USER_COULD_HAVE_CONCH:
+ user_sh->conch_status = USER_HAS_NOT_CONCH;
+ spin_unlock (&user_sh->lock);
+ error = fetch_shared_data (c->holder);
+ break;
+
+ case USER_HAS_NOT_CONCH:
+ spin_unlock (&user_sh->lock);
+ break;
+ }
+ }
+ c->holder = 0;
+ c->holder_shared_page = 0;
+ return error;
+}