kernel: Add initial VFS implementation

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

1 files changed, 123 insertions, 0 deletions

diff --git a/sys/kern/vfs_lookup.c b/sys/kern/vfs_lookup.c
new file mode 100644
index 0000000..748d5e2
--- /dev/null
+++ b/sys/kern/vfs_lookup.c
@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
+ * 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 Hyra 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/vfs.h>
+#include <vm/dynalloc.h>
+#include <string.h>
+
+/*
+ * Fetches the filename within a past at
+ * the nth index denoted by `idx'
+ *
+ * Returns memory allocated by dynalloc()
+ * containing the filename.
+ *
+ * XXX: MUST FREE RETURN VALUE WITH dynfree() WHEN
+ *      DONE!
+ */
+char *
+vfs_get_fname_at(const char *path, size_t idx)
+{
+    size_t pathlen = strlen(path);
+    size_t fname_len;
+
+    char *path_tmp = dynalloc(pathlen + 2);
+    char *ret = NULL;
+    char *start_ptr, *ptr;
+
+    /* Make one-based */
+    ++idx;
+
+    if (path_tmp == NULL) {
+        return NULL;
+    }
+
+    ptr = path_tmp;
+    memcpy(path_tmp, path, pathlen + 1);
+
+    /*
+     * We want to by default have a '/' at the end
+     * to keep the parsing logic from getting more
+     * complicated than it needs to be.
+     */
+    path_tmp[pathlen] = '/';
+    path_tmp[pathlen + 1] = '\0';
+
+    /* Skip any leading slashes */
+    while (*ptr == '/')
+        ++ptr;
+
+    start_ptr = ptr;
+
+    /* Get each filename */
+    while (*ptr != '\0') {
+        /* Handle duplicate delimiter */
+        if (*ptr == '/' && *(ptr + 1) == '/') {
+            /*
+             * Snip this delimiter and skip, the next
+             * will be read and filename returned (if of course
+             * the index is reached).
+             */
+            *(ptr++) = '\0';
+            continue;
+        }
+
+        if (*ptr == '/') {
+            *(ptr++) = '\0';
+
+            /* Continue if index not reached */
+            if ((--idx) != 0) {
+                start_ptr = ptr;
+                continue;
+            }
+
+            /* Index has been reached, start_ptr contains name */
+            fname_len = strlen(start_ptr);
+            ret = dynalloc(fname_len + 1);
+
+            if (ret != NULL) {
+                memcpy(ret, start_ptr, fname_len + 1);
+            }
+            break;
+        }
+
+        ++ptr;
+    }
+
+    dynfree(path_tmp);
+    return ret;
+}
+
+struct vnode *
+vfs_path_to_node(const char *path)
+{
+    /* TODO */
+    return NULL;
+}