kern: os: Add I/O tap framework

The I/O tap framework provides a way to bypass the typical device
filesystem interface for applications where more direct access would be
beneficial.

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 106 insertions, 0 deletions

diff --git a/src/sys/os/os_iotap.c b/src/sys/os/os_iotap.c
new file mode 100644
index 0000000..075b7b1
--- /dev/null
+++ b/src/sys/os/os_iotap.c
@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the project nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <sys/errno.h>
+#include <sys/queue.h>
+#include <sys/atomic.h>
+#include <os/kalloc.h>
+#include <os/iotap.h>
+#include <os/nsvar.h>
+#include <os/ns.h>
+#include <stdbool.h>
+#include <string.h>
+
+#include <sys/syslog.h>
+
+static size_t next_id = 0;
+
+iotap_t
+iotap_register(const struct iotap_desc *iotap)
+{
+    struct iotap_desc *tap;
+    struct ns_obj *obj;
+    int error;
+
+    if (iotap->name == NULL) {
+        return -EINVAL;
+    }
+
+    tap = kalloc(sizeof(*tap));
+    if (tap == NULL) {
+        return -EINVAL;
+    }
+
+    obj = kalloc(sizeof(*obj));
+    if (obj == NULL) {
+        kfree(tap);
+        return -EINVAL;
+    }
+
+    memcpy(tap, iotap, sizeof(*tap));
+    tap->id = atomic_inc_64(&next_id);
+
+    /* Copy the name */
+    tap->name = strdup(iotap->name);
+
+    /* Initialize and store */
+    ns_obj_init(obj);
+    obj->data = tap;
+    error = ns_obj_enter(NS_IOTAP, obj, iotap->name);
+
+    if (error < 0) {
+        kfree(tap);
+        kfree(obj);
+        return error;
+    }
+
+    return tap->id;
+}
+
+int
+iotap_lookup(const char *name, struct iotap_desc *dp_res)
+{
+    struct iotap_desc *tap;
+    int error;
+
+    if (name == NULL || dp_res == NULL) {
+        return -EINVAL;
+    }
+
+    /* Look up the object in the namespace */
+    error = ns_obj_lookup(NS_IOTAP, name, (void *)&tap);
+    if (error < 0) {
+        return error;
+    }
+
+    /* Copy it out to the result store */
+    *dp_res = *tap;
+    return 0;
+}