kern: vfs: Add namei() prototype function

Introduce a namei() prototype function to build upon when implementing
core namei() logic. The prototype simply implemenets the path parsing
and mimicks a UNIX-like (shell) namei output.

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

1 files changed, 91 insertions, 0 deletions

diff --git a/src/sys/os/vfs_namei.c b/src/sys/os/vfs_namei.c
new file mode 100644
index 0000000..8727965
--- /dev/null
+++ b/src/sys/os/vfs_namei.c
@@ -0,0 +1,91 @@
+/*
+ * 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.
+ */
+
+/*
+ * Description: File lookup algorithm
+ * Author: Ian Marco Moffett
+ */
+
+#include <sys/errno.h>
+#include <sys/syslog.h>
+#include <sys/mount.h>
+#include <sys/limits.h>
+#include <sys/namei.h>
+#include <string.h>
+
+int
+namei(struct nameidata *ndp)
+{
+    struct mount *mp = NULL;
+    char namebuf[NAME_MAX];
+    const char *p, *pcur;
+    size_t len, i = 0;
+    int error;
+
+    if (ndp == NULL) {
+        return -EINVAL;
+    }
+
+    if ((p = ndp->path) == NULL) {
+        printf("namei: path is NULL\n");
+        return -EINVAL;
+    }
+
+    error = mount_lookup("/", &mp);
+    if (error < 0) {
+        printf("namei: failed to get rootfs\n");
+        return error;
+    }
+
+    printf("namei: f: %s\n", ndp->path);
+    printf("namei: d: /\n", ndp->path);
+
+    pcur = p;
+    while (*pcur != '\0') {
+        /* Get out of the slashes */
+        while (*pcur == '/')
+            ++pcur;
+
+        p = pcur;
+
+        /* Go back to the start */
+        memset(namebuf, 0, sizeof(namebuf));
+        while (*pcur != '/' && *pcur != '\0') {
+            namebuf[i++] = *pcur++;
+
+            if (i > sizeof(namebuf) - 1) {
+                return -ENAMETOOLONG;
+            }
+        }
+
+        i = 0;
+        printf("namei: n %s\n", namebuf);
+    }
+    return 0;
+}