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

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;
+		}
+
+		out[i] = in[i];
+		i++;
+	}
+
+	out[i] = '\0';
+	return i;
 }
 
-kern_status_t fs_context_dispatch_msg(
+extern enum fs_status fs_context_resolve_path(
 	struct fs_context *ctx,
-	kern_handle_t channel,
-	struct msg_endpoint *sender,
-	struct msg_header *hdr)
+	const char *path,
+	struct fs_dentry **out)
 {
-	return fs_dispatch(
-		channel,
-		&ctx->ctx_vtable,
-		sender,
-		hdr,
-		NULL,
-		0,
-		ctx);
+	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);
 }