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

lib/libfs/CMakeLists.txt

@@ -23,7 +23,7 @@ sysroot_add_library(
 	HEADER_DIR /usr/include
 	LIB_DIR /usr/lib)
 
-target_link_libraries(libfs libmango interface::fs libc)
-target_link_libraries(libfs-static libmango interface::fs libc-core)
+target_link_libraries(libfs libmango interface::fs libc libxpc)
+target_link_libraries(libfs-static libmango interface::fs libc-core libxpc-static)
 
 set_target_properties(libfs-static PROPERTIES POSITION_INDEPENDENT_CODE FALSE)

lib/libfs/context.c

@@ -4,6 +4,12 @@
 
 #include <fs/allocator.h>
 #include <fs/context.h>
+#include <fs/dentry.h>
+#include <fs/inode.h>
+#include <fs/status.h>
+#include <fs/superblock.h>
+#include <mango/log.h>
+#include <stdio.h>
 
 BTREE_DEFINE_SIMPLE_GET(struct fs_file, unsigned long, f_node, f_id, get_file);
 BTREE_DEFINE_SIMPLE_INSERT(struct fs_file, f_node, f_id, put_file);
@@ -16,9 +22,7 @@ struct fs_context {
 	struct fs_vtable ctx_vtable;
 };
 
-struct fs_context *fs_context_create(
-	struct fs_allocator *alloc,
-	struct fs_superblock *sb)
+struct fs_context *fs_context_create(struct fs_allocator *alloc)
 {
 	struct fs_context *ctx = fs_alloc(alloc, sizeof *ctx);
 	if (!ctx) {
@@ -27,10 +31,10 @@ struct fs_context *fs_context_create(
 
 	memset(ctx, 0x0, sizeof *ctx);
 
-	ctx->ctx_sb = sb;
 	ctx->ctx_alloc = alloc;
 
 	ctx->ctx_vtable.open = fs_msg_open;
+	ctx->ctx_vtable.read = fs_msg_read;
 
 	return ctx;
 }
@@ -40,6 +44,35 @@ void fs_context_destroy(struct fs_context *ctx)
 	fs_free(ctx->ctx_alloc, ctx);
 }
 
+enum fs_status fs_context_mount_filesystem(
+	struct fs_context *ctx,
+	fs_mount_function_t func,
+	void *arg,
+	enum fs_mount_flags flags)
+{
+	if (!func) {
+		return FS_ERR_INVALID_ARGUMENT;
+	}
+
+	struct fs_superblock *sb = NULL;
+	enum fs_status status = func(ctx, arg, flags, &sb);
+	if (status != FS_SUCCESS) {
+		return status;
+	}
+
+	if (!sb) {
+		return FS_ERR_INTERNAL_FAILURE;
+	}
+
+	ctx->ctx_sb = sb;
+	return FS_SUCCESS;
+}
+
+enum fs_status fs_context_unmount_filesystem(struct fs_context *ctx)
+{
+	return FS_ERR_NOT_IMPLEMENTED;
+}
+
 struct fs_file *fs_context_open_file(struct fs_context *ctx, unsigned long id)
 {
 	struct fs_file *f = get_file(&ctx->ctx_filelist, id);
@@ -58,29 +91,104 @@ struct fs_file *fs_context_open_file(struct fs_context *ctx, unsigned long id)
 	return f;
 }
 
+struct fs_file *fs_context_get_file(struct fs_context *ctx, unsigned long id)
+{
+	return get_file(&ctx->ctx_filelist, id);
+}
+
 void fs_context_close_file(struct fs_context *ctx, struct fs_file *f)
 {
 }
 
-struct fs_dentry *fs_context_resolve_path(
-	struct fs_context *ctx,
-	const char *path)
+static size_t get_first_path_component(const char *in, char *out, size_t max)
 {
-	return NULL;
+	size_t i = 0;
+	while (i < max - 1) {
+		if (in[i] == '\0' || in[i] == '/') {
+			break;
 		}
 
-kern_status_t fs_context_dispatch_msg(
-	struct fs_context *ctx,
-	kern_handle_t channel,
-	struct msg_endpoint *sender,
-	struct msg_header *hdr)
-{
-	return fs_dispatch(
-		channel,
-		&ctx->ctx_vtable,
-		sender,
-		hdr,
-		NULL,
-		0,
-		ctx);
+		out[i] = in[i];
+		i++;
+	}
+
+	out[i] = '\0';
+	return i;
+}
+
+extern enum fs_status fs_context_resolve_path(
+	struct fs_context *ctx,
+	const char *path,
+	struct fs_dentry **out)
+{
+	if (!ctx->ctx_sb || !ctx->ctx_sb->s_root) {
+		return FS_ERR_NO_ENTRY;
+	}
+
+	struct fs_dentry *cur = ctx->ctx_sb->s_root;
+
+	char tok[256];
+
+	while (*path != '\0') {
+		while (*path == '/') {
+			path++;
+		}
+
+		size_t tok_len
+			= get_first_path_component(path, tok, sizeof tok);
+
+		if (!tok_len) {
+			break;
+		}
+
+		bool is_dir = *(path + tok_len) != '\0';
+
+		if (cur->d_inode->i_mode != FS_INODE_DIR) {
+			return FS_ERR_NOT_DIRECTORY;
+		}
+
+		struct fs_dentry *next = NULL;
+		enum fs_status status
+			= fs_inode_lookup(cur->d_inode, tok, &next);
+
+		if (status != FS_SUCCESS) {
+			return status;
+		}
+
+		if (!next) {
+			return FS_ERR_INTERNAL_FAILURE;
+		}
+
+		cur = next;
+
+		path += tok_len;
+	}
+
+	*out = cur;
+	return FS_SUCCESS;
+}
+
+kern_status_t fs_context_dispatch_msg(struct fs_context *ctx, xpc_msg_t *msg)
+{
+	return fs_dispatch(NULL, msg, &ctx->ctx_vtable, ctx);
+}
+
+void *fs_context_alloc(struct fs_context *ctx, size_t count)
+{
+	return fs_alloc(ctx->ctx_alloc, count);
+}
+
+void *fs_context_calloc(struct fs_context *ctx, size_t count, size_t sz)
+{
+	return fs_calloc(ctx->ctx_alloc, count, sz);
+}
+
+void *fs_context_realloc(struct fs_context *ctx, void *p, size_t count)
+{
+	return fs_realloc(ctx->ctx_alloc, p, count);
+}
+
+void fs_context_free(struct fs_context *ctx, void *p)
+{
+	fs_free(ctx->ctx_alloc, p);
 }

lib/libfs/file.c

@@ -0,0 +1,41 @@
+#include "file.h"
+
+struct fs_inode *fs_file_get_inode(const struct fs_file *f)
+{
+	return f->f_inode;
+}
+
+size_t fs_file_get_cursor(const struct fs_file *f)
+{
+	return f->f_seek;
+}
+
+enum fs_status fs_file_read(
+	struct fs_file *f,
+	struct xpc_buffer *buf,
+	size_t count)
+{
+	if (!f->f_ops || !f->f_ops->f_read) {
+		return FS_ERR_NOT_IMPLEMENTED;
+	}
+
+	off_t seek = f->f_seek;
+	enum fs_status status = f->f_ops->f_read(f, buf, count, &seek);
+	f->f_seek = seek;
+	return status;
+}
+
+enum fs_status fs_file_write(
+	struct fs_file *f,
+	struct xpc_buffer *buf,
+	size_t count)
+{
+	if (!f->f_ops || !f->f_ops->f_write) {
+		return FS_ERR_NOT_IMPLEMENTED;
+	}
+
+	off_t seek = f->f_seek;
+	enum fs_status status = f->f_ops->f_write(f, buf, count, &seek);
+	f->f_seek = seek;
+	return status;
+}

lib/libfs/file.h

@@ -3,7 +3,9 @@
 
 #include "btree.h"
 
+#include <fs/dentry.h>
 #include <fs/file.h>
+#include <fs/inode.h>
 
 struct fs_file {
 	/* id of the open file, equal to the koid of the port being used to
@@ -12,6 +14,10 @@ struct fs_file {
 	struct btree_node f_node;
 
 	const struct fs_file_ops *f_ops;
+
+	off_t f_seek;
+	struct fs_inode *f_inode;
+	struct fs_dentry *f_dent;
 };
 
 #endif

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

lib/libfs/inode.c

@@ -0,0 +1,13 @@
+#include <fs/inode.h>
+
+enum fs_status fs_inode_lookup(
+	struct fs_inode *inode,
+	const char *name,
+	struct fs_dentry **out)
+{
+	if (!inode->i_ops || !inode->i_ops->i_lookup) {
+		return FS_ERR_NOT_IMPLEMENTED;
+	}
+
+	return inode->i_ops->i_lookup(inode, name, out);
+}

lib/libfs/interface.h

@@ -2,12 +2,17 @@
 #define _FS_INTERFACE_H_
 
 #include <mango/types.h>
+#include <xpc/buffer.h>
+#include <xpc/context.h>
+#include <xpc/endpoint.h>
+#include <xpc/string.h>
 
 struct msg_endpoint;
 
 extern kern_status_t fs_msg_open(
-	const struct msg_endpoint *sender,
-	const char *path,
+	xpc_context_t *ctx,
+	const xpc_endpoint_t *sender,
+	const xpc_string_t *path,
 	int flags,
 	int *out_err,
 	void *arg);
@@ -18,4 +23,13 @@ extern kern_status_t fs_msg_close(
 	int *out_err,
 	void *arg);
 
+extern kern_status_t fs_msg_read(
+	xpc_context_t *ctx,
+	const xpc_endpoint_t *sender,
+	size_t count,
+	int *out_err,
+	size_t *out_nr_read,
+	xpc_buffer_t *out_data,
+	void *arg);
+
 #endif

lib/libfs/interface/open.c

@@ -1,21 +1,53 @@
+#include "../file.h"
+
 #include <errno.h>
 #include <fs/context.h>
+#include <fs/file.h>
+#include <fs/status.h>
 
 extern kern_status_t fs_msg_open(
-	const struct msg_endpoint *sender,
-	const char *path,
+	xpc_context_t *xpc,
+	xpc_endpoint_t *sender,
+	const xpc_string_t *path,
 	int flags,
 	int *out_err,
 	void *arg)
 {
+	char path_buf[4096];
+	size_t path_len = 0;
+	kern_status_t status
+		= xpc_string_read(path, path_buf, sizeof path_buf, &path_len);
+	if (status != KERN_OK) {
+		return status;
+	}
+
 	struct fs_context *ctx = arg;
 
-	struct fs_dentry *dent = fs_context_resolve_path(ctx, path);
-	if (!dent) {
-		*out_err = ENOENT;
+	struct fs_file *f = fs_context_open_file(ctx, sender->e_port);
+	if (!f) {
+		*out_err = ENOMEM;
 		return KERN_OK;
 	}
 
+	if (f->f_inode) {
+		*out_err = EBUSY;
+		return KERN_OK;
+	}
+
+	struct fs_dentry *dent = NULL;
+	enum fs_status fs_status
+		= fs_context_resolve_path(ctx, path_buf, &dent);
+	if (fs_status != FS_SUCCESS) {
+		fs_context_close_file(ctx, f);
+		*out_err = fs_status_to_errno(status);
+		return KERN_OK;
+	}
+
+	f->f_seek = 0;
+	f->f_dent = dent;
+	f->f_inode = dent->d_inode;
+	f->f_ops = dent->d_inode->i_fops;
+
 	*out_err = SUCCESS;
 	return KERN_OK;
 }

lib/libfs/interface/read.c

@@ -0,0 +1,30 @@
+#include <errno.h>
+#include <fs/context.h>
+#include <fs/file.h>
+#include <fs/status.h>
+
+extern kern_status_t fs_msg_read(
+	xpc_context_t *xpc,
+	xpc_endpoint_t *sender,
+	size_t count,
+	int *out_err,
+	size_t *out_nr_read,
+	xpc_buffer_t *out_data,
+	void *arg)
+{
+	struct fs_context *ctx = arg;
+	struct fs_file *f = fs_context_get_file(ctx, sender->e_port);
+	if (!f) {
+		*out_err = EBADF;
+		return KERN_OK;
+	}
+
+	size_t start = fs_file_get_cursor(f);
+	enum fs_status status = fs_file_read(f, out_data, count);
+	size_t end = fs_file_get_cursor(f);
+
+	*out_err = fs_status_to_errno(status);
+	*out_nr_read = end - start;
+
+	return KERN_OK;
+}

lib/libfs/status.c

@@ -0,0 +1,25 @@
+#include <errno.h>
+#include <fs/status.h>
+
+int fs_status_to_errno(enum fs_status status)
+{
+	switch (status) {
+	case FS_SUCCESS:
+		return SUCCESS;
+	case FS_ERR_NO_ENTRY:
+		return ENOENT;
+	case FS_ERR_NO_MEMORY:
+		return ENOMEM;
+	case FS_ERR_INVALID_ARGUMENT:
+		return EINVAL;
+	case FS_ERR_NOT_IMPLEMENTED:
+		return ENOSYS;
+	case FS_ERR_IS_DIRECTORY:
+		return EISDIR;
+	case FS_ERR_NOT_DIRECTORY:
+		return ENOTDIR;
+
+	default:
+		return EINVAL;
+	}
+}