1 files changed, 339 insertions, 0 deletions
diff --git a/lib/tar/src/iterator.c b/lib/tar/src/iterator.c
new file mode 100644
index 0000000..9a6b9f7
--- /dev/null
+++ b/lib/tar/src/iterator.c
@@ -0,0 +1,339 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * iterator.c
+ *
+ * Copyright (C) 2023 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "tar/tar.h"
+#include "sqfs/error.h"
+#include "util/util.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+
+typedef struct {
+	dir_iterator_t base;
+	tar_header_decoded_t current;
+	istream_t *stream;
+	int state;
+
+	/* File I/O wrapper related */
+	bool locked;
+
+	sqfs_u64 record_size;
+	sqfs_u64 file_size;
+	sqfs_u64 offset;
+
+	size_t padding;
+	size_t last_chunk;
+	bool last_sparse;
+} tar_iterator_t;
+
+typedef struct {
+	istream_t base;
+
+	tar_iterator_t *parent;
+
+	sqfs_u8 buffer[4096];
+} tar_istream_t;
+
+static bool is_sparse_region(const tar_iterator_t *tar, sqfs_u64 *count)
+{
+	const sparse_map_t *it;
+
+	*count = tar->file_size - tar->offset;
+	if (tar->current.sparse == NULL)
+		return false;
+
+	for (it = tar->current.sparse; it != NULL; it = it->next) {
+		if (tar->offset >= it->offset) {
+			sqfs_u64 diff = tar->offset - it->offset;
+
+			if (diff < it->count) {
+				*count = it->count - diff;
+				return false;
+			}
+		}
+	}
+
+	for (it = tar->current.sparse; it != NULL; it = it->next) {
+		if (tar->offset < it->offset) {
+			sqfs_u64 diff = it->offset - tar->offset;
+
+			if (diff < *count)
+				*count = diff;
+		}
+	}
+
+	return true;
+}
+
+static int data_available(tar_iterator_t *tar, sqfs_u64 want, sqfs_u64 *out)
+{
+	sqfs_u64 avail = tar->stream->buffer_used - tar->stream->buffer_offset;
+
+	if ((want > avail) &&
+	    ((tar->stream->buffer_offset > 0) || avail == 0)) {
+		if (istream_precache(tar->stream)) {
+			tar->state = SQFS_ERROR_IO;
+			return -1;
+		}
+
+		if (tar->stream->buffer_used == 0 && tar->stream->eof) {
+			tar->state = SQFS_ERROR_CORRUPTED;
+			return -1;
+		}
+
+		avail = tar->stream->buffer_used;
+	}
+
+	*out = avail <= want ? avail : want;
+	return 0;
+}
+
+/*****************************************************************************/
+
+static const char *strm_get_filename(istream_t *strm)
+{
+	return ((tar_istream_t *)strm)->parent->current.name;
+}
+
+static int strm_precache(istream_t *strm)
+{
+	tar_istream_t *tar = (tar_istream_t *)strm;
+	sqfs_u64 diff;
+
+	tar->parent->offset += tar->parent->last_chunk;
+
+	if (!tar->parent->last_sparse) {
+		tar->parent->stream->buffer_offset += tar->parent->last_chunk;
+		tar->parent->record_size -= tar->parent->last_chunk;
+	}
+
+	if (tar->parent->offset >= tar->parent->file_size)
+		goto out_eof;
+
+	if (is_sparse_region(tar->parent, &diff)) {
+		if (diff > sizeof(tar->buffer))
+			diff = sizeof(tar->buffer);
+
+		strm->buffer = tar->buffer;
+		strm->buffer_used = diff;
+		tar->parent->last_chunk = diff;
+		tar->parent->last_sparse = true;
+
+		memset(tar->buffer, 0, diff);
+	} else {
+		if (data_available(tar->parent, diff, &diff))
+			goto out_eof;
+
+		strm->buffer = tar->parent->stream->buffer +
+			tar->parent->stream->buffer_offset;
+		strm->buffer_used = diff;
+		tar->parent->last_chunk = diff;
+		tar->parent->last_sparse = false;
+	}
+
+	return 0;
+out_eof:
+	strm->eof = true;
+	strm->buffer_used = 0;
+	strm->buffer = tar->buffer;
+	tar->parent->locked = false;
+	return tar->parent->state < 0 ? -1 : 0;
+}
+
+static void strm_destroy(sqfs_object_t *obj)
+{
+	tar_istream_t *tar = (tar_istream_t *)obj;
+
+	tar->parent->locked = false;
+	sqfs_drop(tar->parent);
+	free(tar);
+}
+
+/*****************************************************************************/
+
+static int it_next(dir_iterator_t *it, dir_entry_t **out)
+{
+	tar_iterator_t *tar = (tar_iterator_t *)it;
+	dir_entry_t *ent;
+	int ret;
+
+	*out = NULL;
+	if (tar->locked)
+		return SQFS_ERROR_SEQUENCE;
+
+	if (tar->state != 0)
+		return tar->state;
+retry:
+	if (tar->record_size > 0) {
+		ret = istream_skip(tar->stream, tar->record_size);
+		if (ret)
+			goto fail;
+	}
+
+	if (tar->padding > 0) {
+		ret = istream_skip(tar->stream, tar->padding);
+		if (ret)
+			goto fail;
+	}
+
+	clear_header(&(tar->current));
+	ret = read_header(tar->stream, &(tar->current));
+	if (ret != 0)
+		goto fail;
+
+	tar->offset = 0;
+	tar->last_chunk = 0;
+	tar->last_sparse = false;
+	tar->record_size = tar->current.record_size;
+	tar->file_size = tar->current.actual_size;
+	tar->padding = tar->current.record_size % 512;
+	if (tar->padding > 0)
+		tar->padding = 512 - tar->padding;
+
+	if (tar->current.unknown_record)
+		goto retry;
+
+	if (canonicalize_name(tar->current.name) != 0) {
+		tar->state = SQFS_ERROR_CORRUPTED;
+		return tar->state;
+	}
+
+	ent = calloc(1, sizeof(*ent) + strlen(tar->current.name) + 1);
+	if (ent == NULL) {
+		tar->state = SQFS_ERROR_ALLOC;
+		return tar->state;
+	}
+
+	ent->mtime = tar->current.mtime;
+	ent->rdev = tar->current.devno;
+	ent->uid = tar->current.uid;
+	ent->gid = tar->current.gid;
+	ent->mode = tar->current.mode;
+	strcpy(ent->name, tar->current.name);
+
+	if (tar->current.is_hard_link) {
+		ent->mode = (S_IFLNK | 0777);
+		ent->flags |= DIR_ENTRY_FLAG_HARD_LINK;
+	}
+
+	if (S_ISREG(ent->mode))
+		ent->size = tar->current.actual_size;
+
+	*out = ent;
+	return 0;
+fail:
+	tar->state = ret < 0 ? SQFS_ERROR_IO : 1;
+	return tar->state;
+}
+
+static int it_read_link(dir_iterator_t *it, char **out)
+{
+	tar_iterator_t *tar = (tar_iterator_t *)it;
+
+	*out = NULL;
+	if (tar->locked)
+		return SQFS_ERROR_SEQUENCE;
+
+	if (tar->state != 0 || tar->current.link_target == NULL)
+		return tar->state < 0 ? tar->state : SQFS_ERROR_NO_ENTRY;
+
+	*out = strdup(tar->current.link_target);
+	return (*out == NULL) ? SQFS_ERROR_ALLOC : 0;
+}
+
+static int it_open_subdir(dir_iterator_t *it, dir_iterator_t **out)
+{
+	(void)it;
+	*out = NULL;
+	return SQFS_ERROR_UNSUPPORTED;
+}
+
+static void it_ignore_subdir(dir_iterator_t *it)
+{
+	(void)it;
+	/* TODO: skip list */
+}
+
+static int it_open_file_ro(dir_iterator_t *it, istream_t **out)
+{
+	tar_iterator_t *tar = (tar_iterator_t *)it;
+	tar_istream_t *strm;
+
+	*out = NULL;
+	if (tar->locked)
+		return SQFS_ERROR_SEQUENCE;
+
+	if (tar->state != 0)
+		return tar->state < 0 ? tar->state : SQFS_ERROR_NO_ENTRY;
+
+	if (!S_ISREG(tar->current.mode))
+		return SQFS_ERROR_NOT_FILE;
+
+	strm = calloc(1, sizeof(*strm));
+	if (strm == NULL)
+		return SQFS_ERROR_ALLOC;
+
+	sqfs_object_init(strm, strm_destroy, NULL);
+	strm->parent = sqfs_grab(tar);
+
+	((istream_t *)strm)->precache = strm_precache;
+	((istream_t *)strm)->get_filename = strm_get_filename;
+	((istream_t *)strm)->buffer = strm->buffer;
+
+	tar->locked = true;
+	*out = (istream_t *)strm;
+	return 0;
+}
+
+static int it_read_xattr(dir_iterator_t *it, dir_entry_xattr_t **out)
+{
+	tar_iterator_t *tar = (tar_iterator_t *)it;
+
+	*out = NULL;
+	if (tar->locked)
+		return SQFS_ERROR_SEQUENCE;
+
+	if (tar->state != 0)
+		return tar->state < 0 ? tar->state : SQFS_ERROR_NO_ENTRY;
+
+	if (tar->current.xattr != NULL) {
+		*out = dir_entry_xattr_list_copy(tar->current.xattr);
+		if (*out == NULL)
+			return SQFS_ERROR_ALLOC;
+	}
+
+	return 0;
+}
+
+static void it_destroy(sqfs_object_t *obj)
+{
+	tar_iterator_t *tar = (tar_iterator_t *)obj;
+
+	clear_header(&(tar->current));
+	sqfs_drop(tar->stream);
+	free(tar);
+}
+
+dir_iterator_t *tar_open_stream(istream_t *stream)
+{
+	tar_iterator_t *tar = calloc(1, sizeof(*tar));
+	dir_iterator_t *it = (dir_iterator_t *)tar;
+
+	if (tar == NULL)
+		return NULL;
+
+	sqfs_object_init(it, it_destroy, NULL);
+	tar->stream = sqfs_grab(stream);
+	it->next = it_next;
+	it->read_link = it_read_link;
+	it->open_subdir = it_open_subdir;
+	it->ignore_subdir = it_ignore_subdir;
+	it->open_file_ro = it_open_file_ro;
+	it->read_xattr = it_read_xattr;
+
+	return it;
+}