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

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;
 }