lib: xpc: implement support for iterating through directories

lib/libfs/context.c

@@ -92,6 +92,7 @@ struct fs_context *fs_context_create(struct fs_allocator *alloc)
 	ctx->ctx_vtable.write = fs_msg_write;
 	ctx->ctx_vtable.seek = fs_msg_seek;
 	ctx->ctx_vtable.map = fs_msg_map;
+	ctx->ctx_vtable.getdents = fs_msg_getdents;
 
 	return ctx;
 }

lib/libfs/file.c

@@ -52,3 +52,15 @@ enum fs_status fs_file_write(
 	f->f_seek = seek;
 	return status;
 }
+
+enum fs_status fs_file_readdir(struct fs_file *f, struct xpc_buffer *buf)
+{
+	if (!f->f_ops || !f->f_ops->f_readdir) {
+		return FS_ERR_NOT_IMPLEMENTED;
+	}
+
+	off_t seek = f->f_seek;
+	enum fs_status status = f->f_ops->f_readdir(f, buf, &seek);
+	f->f_seek = seek;
+	return status;
+}

lib/libfs/include/fs/file.h

@@ -19,6 +19,8 @@ struct fs_file_ops {
 		size_t,
 		off_t *);
 	enum fs_status (*f_seek)(struct fs_file *, off_t, int);
+	enum fs_status (
+		*f_readdir)(struct fs_file *, struct xpc_buffer *, off_t *);
 };
 
 extern struct fs_inode *fs_file_get_inode(const struct fs_file *f);
@@ -37,4 +39,8 @@ extern enum fs_status fs_file_write(
 	const struct xpc_buffer *buf,
 	size_t count);
 
+extern enum fs_status fs_file_readdir(
+	struct fs_file *f,
+	struct xpc_buffer *buf);
+
 #endif

lib/libfs/interface.h

@@ -27,7 +27,6 @@ extern kern_status_t fs_msg_read(
 	const xpc_endpoint_t *sender,
 	size_t count,
 	int *out_err,
-	size_t *out_nr_read,
 	xpc_buffer_t *out_data,
 	void *arg);
 extern kern_status_t fs_msg_write(
@@ -55,4 +54,11 @@ extern kern_status_t fs_msg_map(
 	kern_handle_t *out_vmo,
 	void *arg);
 
+extern kern_status_t fs_msg_getdents(
+	xpc_context_t *ctx,
+	const xpc_endpoint_t *sender,
+	int *out_err,
+	xpc_buffer_t *out_dents,
+	void *arg);
+
 #endif

lib/libfs/interface/getdents.c

@@ -0,0 +1,34 @@
+#include "../file.h"
+
+#include <errno.h>
+#include <fs/context.h>
+#include <fs/file.h>
+#include <fs/status.h>
+
+kern_status_t fs_msg_getdents(
+	xpc_context_t *xpc,
+	const xpc_endpoint_t *sender,
+	int *out_err,
+	xpc_buffer_t *out_dents,
+	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;
+	}
+
+	if (!(f->f_inode->i_mode & FS_INODE_DIR)) {
+		*out_err = ENOTDIR;
+		return KERN_OK;
+	}
+
+	size_t start = fs_file_get_cursor(f);
+	enum fs_status status = fs_file_readdir(f, out_dents);
+	size_t end = fs_file_get_cursor(f);
+
+	*out_err = fs_status_to_errno(status);
+
+	return KERN_OK;
+}

lib/libfs/interface/read.c

@@ -8,7 +8,6 @@ extern kern_status_t fs_msg_read(
 	xpc_endpoint_t *sender,
 	size_t count,
 	int *out_err,
-	size_t *out_nr_read,
 	xpc_buffer_t *out_data,
 	void *arg)
 {
@@ -24,7 +23,7 @@ extern kern_status_t fs_msg_read(
 	size_t end = fs_file_get_cursor(f);
 
 	*out_err = fs_status_to_errno(status);
-	*out_nr_read = end - start;
+	out_data->buf_len = end - start;
 
 	return KERN_OK;
 }