Re: [Linux-streams] Re: [PATCH] Re: export of sys_call_tabl

[David Grothe <dave@gcom.com>]

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Here is a proposed "final" patch for the streams hooks.  I think that it 
takes into account all suggestions.  I put the prototype in linux/sys.h.

This is for stock 2.4.19, and has been tested.

-- Dave

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--- arch/i386/kernel/entry.S.orig	2002-08-02 19:39:42.000000000 -0500
+++ arch/i386/kernel/entry.S	2002-10-08 15:43:08.000000000 -0500
@@ -584,8 +584,8 @@
 	.long SYMBOL_NAME(sys_capset)           /* 185 */
 	.long SYMBOL_NAME(sys_sigaltstack)
 	.long SYMBOL_NAME(sys_sendfile)
-	.long SYMBOL_NAME(sys_ni_syscall)		/* streams1 */
-	.long SYMBOL_NAME(sys_ni_syscall)		/* streams2 */
+	.long SYMBOL_NAME(sys_getpmsg)		/* streams1 */
+	.long SYMBOL_NAME(sys_putpmsg)		/* streams2 */
 	.long SYMBOL_NAME(sys_vfork)            /* 190 */
 	.long SYMBOL_NAME(sys_getrlimit)
 	.long SYMBOL_NAME(sys_mmap2)
--- kernel/sys.c.orig	2002-08-02 19:39:46.000000000 -0500
+++ kernel/sys.c	2002-10-10 15:00:45.000000000 -0500
@@ -167,6 +167,49 @@
 	return notifier_chain_unregister(&reboot_notifier_list, nb);
 }
 
+static int (*do_putpmsg) (int, void *, void *, int, int) = NULL;
+static int (*do_getpmsg) (int, void *, void *, int, int) = NULL;
+
+static DECLARE_RWSEM(streams_call_sem);
+
+long asmlinkage
+sys_putpmsg(int fd, void *ctlptr, void *datptr, int band, int flags)
+{
+	int ret = -ENOSYS;
+	down_read(&streams_call_sem);	/* should return int, but doesn't */
+	if (do_putpmsg)
+		ret = (*do_putpmsg) (fd, ctlptr, datptr, band, flags);
+	up_read(&streams_call_sem);
+	return ret;
+}
+
+long asmlinkage
+sys_getpmsg(int fd, void *ctlptr, void *datptr, int band, int flags)
+{
+	int ret = -ENOSYS;
+	down_read(&streams_call_sem);	/* should return int, but doesn't */
+	if (do_getpmsg)
+		ret = (*do_getpmsg) (fd, ctlptr, datptr, band, flags);
+	up_read(&streams_call_sem);
+	return ret;
+}
+
+int
+register_streams_calls(int (*putpmsg) (int, void *, void *, int, int),
+		       int (*getpmsg) (int, void *, void *, int, int))
+{
+	int ret = -EBUSY;
+	down_write(&streams_call_sem);	/* should return int, but doesn't */
+	if (   (putpmsg == NULL || do_putpmsg == NULL)
+	    && (getpmsg == NULL || do_getpmsg == NULL)) {
+		do_putpmsg = putpmsg;
+		do_getpmsg = getpmsg;
+		ret = 0;
+	}
+	up_write(&streams_call_sem);
+	return ret;
+}
+
 asmlinkage long sys_ni_syscall(void)
 {
 	return -ENOSYS;
@@ -1286,3 +1329,4 @@
 EXPORT_SYMBOL(unregister_reboot_notifier);
 EXPORT_SYMBOL(in_group_p);
 EXPORT_SYMBOL(in_egroup_p);
+EXPORT_SYMBOL_GPL(register_streams_calls);
--- include/linux/sys.h.orig	2002-10-11 08:59:10.000000000 -0500
+++ include/linux/sys.h	2002-10-11 09:15:04.000000000 -0500
@@ -27,4 +27,16 @@
  * These are system calls that haven't been implemented yet
  * but have an entry in the table for future expansion..
  */
+
+/*
+ * These are registration routines for system calls that are
+ * implemented by loadable modules outside of the kernel
+ * source tree.
+ */
+#if !defined(__ASSEMBLY__)
+extern int
+register_streams_calls(int (*putpmsg) (int, void *, void *, int, int),
+		       int (*getpmsg) (int, void *, void *, int, int)) ;
+
+#endif			/* __ASSEMBLY__ */
 #endif