bootstrap: tar: implement readdir()

sys/bootstrap/tar.c

@@ -11,6 +11,7 @@
 #include <mango/vm.h>
 #include <stdio.h>
 #include <string.h>
+#include <sys/types.h>
 #include <xpc/buffer.h>
 
 struct tar_superblock {
@@ -148,6 +149,24 @@ static struct tar_entry *entry_get_child(
 	return NULL;
 }
 
+static struct tar_entry *entry_get_child_at(struct tar_entry *entry, size_t at)
+{
+	struct queue_entry *cur = queue_first(&entry->e_children);
+	while (cur) {
+		struct tar_entry *child
+			= QUEUE_CONTAINER(struct tar_entry, e_entry, cur);
+
+		if (at == 0) {
+			return child;
+		}
+
+		at--;
+		cur = queue_next(cur);
+	}
+
+	return NULL;
+}
+
 static const struct fs_dentry_ops dentry_ops = {};
 
 static enum fs_status dir_lookup(
@@ -189,7 +208,7 @@ static enum fs_status file_read(
 
 	char *src = (char *)entry->e_data + offset;
 	size_t w;
-	xpc_buffer_write(buf, src, count, &w);
+	xpc_buffer_write(buf, 0, src, count, &w);
 
 	offset += w;
 	*seek = offset;
@@ -197,10 +216,66 @@ static enum fs_status file_read(
 	return FS_SUCCESS;
 }
 
+static enum fs_status dir_readdir(
+	struct fs_file *f,
+	xpc_buffer_t *out,
+	off_t *seek)
+{
+	off_t offset = *seek;
+	struct tar_entry *entry = entry_from_inode(fs_file_get_inode(f));
+	if (!entry) {
+		return FS_ERR_BAD_STATE;
+	}
+
+	size_t bytes_written = 0;
+	size_t available = xpc_buffer_capacity(out);
+
+	while (1) {
+		struct tar_entry *child = entry_get_child_at(entry, offset);
+		if (!child) {
+			break;
+		}
+
+		struct dentry dent = {0};
+
+		size_t name_len = strlen(child->e_dentry.d_name);
+		size_t to_write
+			= offsetof(struct dentry, d_name) + name_len + 1;
+		if (to_write > available) {
+			break;
+		}
+
+		dent.d_reclen = to_write;
+		kern_iovec_t iov[] = {
+			IOVEC(&dent, offsetof(struct dentry, d_name)),
+			IOVEC(child->e_dentry.d_name, name_len + 1),
+		};
+		size_t tmp = 0;
+		kern_status_t status
+			= xpc_buffer_writev(out, bytes_written, iov, 2, &tmp);
+		if (status != KERN_OK) {
+			break;
+		}
+
+		bytes_written += tmp;
+		available -= tmp;
+		offset++;
+	}
+
+	*seek = offset;
+	out->buf_len = bytes_written;
+
+	return FS_SUCCESS;
+}
+
 static const struct fs_file_ops file_ops = {
 	.f_read = file_read,
 };
 
+static const struct fs_file_ops dir_ops = {
+	.f_readdir = dir_readdir,
+};
+
 static const struct fs_inode_ops file_inode_ops = {
 	.i_lookup = NULL,
 };
@@ -224,6 +299,7 @@ static struct tar_entry *create_dir_entry(
 	entry->e_inode.i_sb = &sb->sb_base;
 	entry->e_inode.i_mode = FS_INODE_DIR;
 	entry->e_inode.i_ops = &dir_inode_ops;
+	entry->e_inode.i_fops = &dir_ops;
 
 	entry->e_dentry.d_sb = &sb->sb_base;
 	entry->e_dentry.d_ops = &dentry_ops;