lib: fs: implement mounting filesystems; reading, writing from files

lib/libfs/include/fs/context.h

@@ -2,30 +2,54 @@
 #define FS_CONTEXT_H_
 
 #include <rosetta/fs.h>
+#include <xpc/msg.h>
 
 struct fs_file;
+struct fs_dentry;
 struct fs_context;
 struct fs_allocator;
 struct fs_superblock;
 
-extern struct fs_context *fs_context_create(
-	struct fs_allocator *alloc,
-	struct fs_superblock *sb);
+enum fs_mount_flags {
+	FS_MOUNT_READONLY = 0x01u,
+};
+
+typedef enum fs_status (*fs_mount_function_t)(
+	struct fs_context *,
+	void *arg,
+	enum fs_mount_flags,
+	struct fs_superblock **);
+
+extern struct fs_context *fs_context_create(struct fs_allocator *alloc);
 extern void fs_context_destroy(struct fs_context *ctx);
 
+extern enum fs_status fs_context_mount_filesystem(
+	struct fs_context *ctx,
+	fs_mount_function_t func,
+	void *arg,
+	enum fs_mount_flags flags);
+extern enum fs_status fs_context_unmount_filesystem(struct fs_context *ctx);
+
 extern struct fs_file *fs_context_open_file(
 	struct fs_context *ctx,
 	unsigned long id);
+extern struct fs_file *fs_context_get_file(
+	struct fs_context *ctx,
+	unsigned long id);
 extern void fs_context_close_file(struct fs_context *ctx, struct fs_file *f);
 
-extern struct fs_dentry *fs_context_resolve_path(
+extern enum fs_status fs_context_resolve_path(
 	struct fs_context *ctx,
-	const char *path);
+	const char *path,
+	struct fs_dentry **out);
 
 extern kern_status_t fs_context_dispatch_msg(
 	struct fs_context *ctx,
-	kern_handle_t channel,
-	struct msg_endpoint *sender,
-	struct msg_header *hdr);
+	xpc_msg_t *msg);
+
+extern void *fs_context_alloc(struct fs_context *ctx, size_t count);
+extern void *fs_context_calloc(struct fs_context *ctx, size_t count, size_t sz);
+extern void *fs_context_realloc(struct fs_context *ctx, void *p, size_t count);
+extern void fs_context_free(struct fs_context *ctx, void *p);
 
 #endif

lib/libfs/include/fs/dentry.h

@@ -13,6 +13,7 @@ struct fs_dentry {
 	struct fs_superblock *d_sb;
 	const struct fs_dentry_ops *d_ops;
 	void *d_fsdata;
+	char *d_name;
 };
 
 #endif

lib/libfs/include/fs/file.h

@@ -5,11 +5,31 @@
 #include <stddef.h>
 
 struct fs_file;
+struct xpc_buffer;
 
 struct fs_file_ops {
-	ssize_t (*f_read)(struct fs_file *, void *, size_t);
-	ssize_t (*f_write)(struct fs_file *, const void *, size_t);
-	off_t (*f_seek)(struct fs_file *, off_t, int);
+	enum fs_status (*f_read)(
+		struct fs_file *,
+		struct xpc_buffer *,
+		size_t,
+		off_t *);
+	enum fs_status (*f_write)(
+		struct fs_file *,
+		const struct xpc_buffer *,
+		size_t,
+		off_t *);
+	enum fs_status (*f_seek)(struct fs_file *, off_t, int);
 };
 
+extern struct fs_inode *fs_file_get_inode(const struct fs_file *f);
+extern size_t fs_file_get_cursor(const struct fs_file *f);
+extern enum fs_status fs_file_read(
+	struct fs_file *f,
+	struct xpc_buffer *buf,
+	size_t count);
+extern enum fs_status fs_file_write(
+	struct fs_file *f,
+	struct xpc_buffer *buf,
+	size_t count);
+
 #endif

lib/libfs/include/fs/inode.h

@@ -1,17 +1,37 @@
 #ifndef FS_INODE_H_
 #define FS_INODE_H_
 
+#include <fs/status.h>
+#include <stddef.h>
+
 struct fs_inode;
 struct fs_dentry;
 struct fs_superblock;
+struct fs_file_ops;
+
+enum fs_inode_mode {
+	FS_INODE_REG = 0x01u,
+	FS_INODE_DIR = 0x02u,
+};
 
 struct fs_inode_ops {
-	int (*i_lookup)(struct fs_inode *, struct fs_dentry *);
+	enum fs_status (*i_lookup)(
+		struct fs_inode *,
+		const char *,
+		struct fs_dentry **);
 };
 
 struct fs_inode {
+	enum fs_inode_mode i_mode;
 	struct fs_superblock *i_sb;
 	const struct fs_inode_ops *i_ops;
+	const struct fs_file_ops *i_fops;
+	size_t i_size;
 };
 
+extern enum fs_status fs_inode_lookup(
+	struct fs_inode *inode,
+	const char *name,
+	struct fs_dentry **out);
+
 #endif

lib/libfs/include/fs/status.h

@@ -0,0 +1,18 @@
+#ifndef FS_STATUS_H_
+#define FS_STATUS_H_
+
+enum fs_status {
+	FS_SUCCESS = 0,
+	FS_ERR_NO_ENTRY,
+	FS_ERR_NO_MEMORY,
+	FS_ERR_INVALID_ARGUMENT,
+	FS_ERR_NOT_IMPLEMENTED,
+	FS_ERR_IS_DIRECTORY,
+	FS_ERR_NOT_DIRECTORY,
+	FS_ERR_BAD_STATE,
+	FS_ERR_INTERNAL_FAILURE,
+};
+
+extern int fs_status_to_errno(enum fs_status status);
+
+#endif