refactor: add a simple ramfs for rootfs. Twifs should have more specific job in future.

[lunaix-os.git] / lunaix-os / kernel / fs / ramfs / ramfs.c

diff --git a/lunaix-os/kernel/fs/ramfs/ramfs.c b/lunaix-os/kernel/fs/ramfs/ramfs.c
new file mode 100644 (file)
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+++ b/lunaix-os/kernel/fs/ramfs/ramfs.c
@@ -0,0 +1,130 @@
+/**
+ * @file ramfs.c
+ * @author Lunaixsky
+ * @brief RamFS - a file system sit in RAM
+ * @version 0.1
+ * @date 2022-08-18
+ *
+ * @copyright Copyright (c) 2022
+ *
+ */
+#include <lunaix/fs.h>
+#include <lunaix/fs/ramfs.h>
+#include <lunaix/mm/valloc.h>
+
+/*
+    A RAM FS will play a role of being a root.
+
+    This is an temporary meaure as we don't have any concrete fs
+    yet. In the near future, we will have an ISO-9660 as our first
+    fs and mount our boot medium as root. And similar thing could
+    be done when we have installed our OS into hard disk, in that
+    case, our rootfs will be something like ext2.
+
+    RamFS vs. TwiFS: Indeed, they are both fs that lives in RAM so
+    there is no foundmentally differences. However, TwiFS is designed
+    to be a 'virtual FIlesystem for KERnel space' (FIKER), so other
+    kernel sub-modules can just create node and attach their own
+    implementation of read/write, without brothering to create a
+    full featured concrete filesystem. This particularly useful for
+    kernel state exposure. In Lunaix, TwiFS is summation of procfs,
+    sysfs and kernfs in Linux world.
+
+    However, there is a smell of bad-design in the concept of TwiFS.
+    Since it tries to integrate too much responsibility. The TwiFS may
+    be replaced by more specific fs in the future.
+
+    On the other hand, RamFS is designed to be act like a dummy fs
+    that just ensure 'something there at least' and thus provide basic
+    'mountibility' for other fs.
+*/
+
+volatile static inode_t ino = 0;
+
+extern const struct v_inode_ops ramfs_inode_ops;
+
+int
+ramfs_readdir(struct v_file* file, struct dir_context* dctx)
+{
+    int i = 0;
+    struct v_dnode *pos, *n;
+    llist_for_each(pos, n, &file->dnode->children, siblings)
+    {
+        if (i++ >= dctx->index) {
+            dctx->read_complete_callback(
+              dctx, pos->name.value, pos->name.len, 0);
+            return 1;
+        }
+    }
+    return 0;
+}
+
+int
+ramfs_mkdir(struct v_inode* this, struct v_dnode* dnode)
+{
+    struct v_inode* inode = vfs_i_alloc(dnode->super_block);
+    inode->itype = VFS_IFDIR;
+
+    vfs_i_addhash(inode);
+    vfs_assign_inode(dnode, inode);
+
+    return 0;
+}
+
+int
+ramfs_create(struct v_inode* this, struct v_dnode* dnode)
+{
+    struct v_inode* inode = vfs_i_alloc(dnode->super_block);
+    inode->itype = VFS_IFFILE;
+
+    vfs_i_addhash(inode);
+    vfs_assign_inode(dnode, inode);
+
+    return 0;
+}
+
+void
+ramfs_inode_init(struct v_superblock* vsb, struct v_inode* inode)
+{
+    inode->id = ino++;
+    inode->ops = &ramfs_inode_ops;
+    inode->default_fops = &default_file_ops;
+}
+
+int
+ramfs_mount(struct v_superblock* vsb, struct v_dnode* mount_point)
+{
+    vsb->ops.init_inode = ramfs_inode_init;
+
+    struct v_inode* inode = vfs_i_alloc(vsb);
+    inode->itype = VFS_IFDIR;
+
+    vfs_i_addhash(inode);
+    vfs_assign_inode(mount_point, inode);
+
+    return 0;
+}
+
+int
+ramfs_unmount(struct v_superblock* vsb)
+{
+    return 0;
+}
+
+void
+ramfs_init()
+{
+    struct filesystem* ramfs = fsm_new_fs("ramfs", 5);
+    ramfs->mount = ramfs_mount;
+    ramfs->unmount = ramfs_unmount;
+
+    fsm_register(ramfs);
+}
+
+const struct v_inode_ops ramfs_inode_ops = { .mkdir = ramfs_mkdir,
+                                             .rmdir = default_inode_rmdir,
+                                             .dir_lookup =
+                                               default_inode_dirlookup,
+                                             .create = ramfs_create,
+                                             .open = default_inode_open,
+                                             .rename = default_inode_rename };
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