1 files changed, 272 insertions, 0 deletions
diff --git a/lib/ext2fs/qcow2.c b/lib/ext2fs/qcow2.c
new file mode 100644
index 0000000..2082417
--- /dev/null
+++ b/lib/ext2fs/qcow2.c
@@ -0,0 +1,272 @@
+/*
+ * qcow2.c --- Functions to generate qcow2 formatted disk images.  This
+ * format is used originally by QEMU for virtual machines, and stores the
+ * filesystem data on disk in a packed format to avoid creating sparse
+ * image files that need lots of seeking to read and write.
+ *
+ * The qcow2 format supports zlib compression, but that is not yet
+ * implemented.
+ *
+ * It is possible to directly mount a qcow2 image using qemu-nbd:
+ *
+ * [root]# modprobe nbd max_part=63
+ * [root]# qemu-nbd -c /dev/nbd0 image.img
+ * [root]# mount /dev/nbd0p1 /mnt/qemu
+ *
+ * Format details at http://people.gnome.org/~markmc/qcow-image-format.html
+ *
+ * Copyright (C) 2010 Red Hat, Inc., Lukas Czerner <lczerner@redhat.com>
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU Public
+ * License.
+ * %End-Header%
+ */
+
+#ifndef _LARGEFILE_SOURCE
+#define _LARGEFILE_SOURCE
+#endif
+#ifndef _LARGEFILE64_SOURCE
+#define _LARGEFILE64_SOURCE
+#endif
+
+#include "config.h"
+#include <fcntl.h>
+#include <grp.h>
+#include <pwd.h>
+#include <stdio.h>
+#ifdef HAVE_STDLIB_H
+#include <stdlib.h>
+#endif
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <assert.h>
+
+#include "ext2fs/ext2fs.h"
+#include "qcow2.h"
+
+/* Functions for converting qcow2 image into raw image */
+
+struct ext2_qcow2_hdr *qcow2_read_header(int fd)
+{
+	void *buffer = NULL;
+	struct ext2_qcow2_hdr *hdr = NULL;
+	size_t size;
+	errcode_t ret;
+
+	ret = ext2fs_get_mem(sizeof(struct ext2_qcow2_hdr), &buffer);
+	if (ret)
+		return NULL;
+	memset(buffer, 0, sizeof(struct ext2_qcow2_hdr));
+
+	if (ext2fs_llseek(fd, 0, SEEK_SET < 0)) {
+		ext2fs_free_mem(&buffer);
+		return NULL;
+	}
+
+	size = read(fd, buffer, sizeof(struct ext2_qcow2_hdr));
+	if (size != sizeof(struct ext2_qcow2_hdr)) {
+		ext2fs_free_mem(&buffer);
+		return NULL;
+	}
+
+	hdr = (struct ext2_qcow2_hdr *)(buffer);
+
+	if ((ext2fs_be32_to_cpu(hdr->magic) != QCOW_MAGIC) ||
+	    (ext2fs_be32_to_cpu(hdr->version) != 2)) {
+		ext2fs_free_mem(&hdr);
+		return NULL;
+	}
+
+	return hdr;
+}
+
+static int qcow2_read_l1_table(struct ext2_qcow2_image *img)
+{
+	int fd = img->fd;
+	size_t size, l1_size = img->l1_size * sizeof(blk64_t);
+	blk64_t *table;
+	errcode_t ret;
+
+	ret = ext2fs_get_memzero(l1_size, &table);
+	if (ret)
+		return ret;
+
+	if (ext2fs_llseek(fd, img->l1_offset, SEEK_SET) < 0) {
+		ext2fs_free_mem(&table);
+		return errno;
+	}
+
+	size = read(fd, table, l1_size);
+	if (size != l1_size) {
+		ext2fs_free_mem(&table);
+		return errno;
+	}
+
+	img->l1_table = table;
+
+	return 0;
+}
+
+static int qcow2_read_l2_table(struct ext2_qcow2_image *img,
+			       __u64 offset, blk64_t **l2_table)
+{
+	int fd = img->fd;
+	size_t size;
+
+	assert(*l2_table);
+
+	if (ext2fs_llseek(fd, offset, SEEK_SET) < 0)
+		return errno;
+
+	size = read(fd, *l2_table, img->cluster_size);
+	if (size != img->cluster_size)
+		return errno;
+
+	return 0;
+}
+
+static int qcow2_copy_data(int fdin, int fdout, __u64 off_in,
+			   __u64 off_out, void *buf, size_t count)
+{
+	size_t size;
+
+	assert(buf);
+
+	if (ext2fs_llseek(fdout, off_out, SEEK_SET) < 0)
+		return errno;
+
+	if (ext2fs_llseek(fdin, off_in, SEEK_SET) < 0)
+		return errno;
+
+	size = read(fdin, buf, count);
+	if (size != count)
+		return errno;
+
+	size = write(fdout, buf, count);
+	if (size != count)
+		return errno;
+
+	return 0;
+}
+
+
+int qcow2_write_raw_image(int qcow2_fd, int raw_fd,
+			      struct ext2_qcow2_hdr *hdr)
+{
+	struct ext2_qcow2_image img;
+	errcode_t ret = 0;
+	unsigned int l1_index, l2_index;
+	__u64 offset;
+	blk64_t *l1_table, *l2_table = NULL;
+	void *copy_buf = NULL;
+	size_t size;
+	unsigned int max_l1_size;
+
+	if (hdr->crypt_method)
+		return -QCOW_ENCRYPTED;
+
+	img.fd = qcow2_fd;
+	img.hdr = hdr;
+	img.l2_cache = NULL;
+	img.l1_table = NULL;
+	img.cluster_bits = ext2fs_be32_to_cpu(hdr->cluster_bits);
+	if (img.cluster_bits < 9 || img.cluster_bits > 31)
+		return -QCOW_CORRUPTED;
+	img.cluster_size = 1 << img.cluster_bits;
+	img.l1_size = ext2fs_be32_to_cpu(hdr->l1_size);
+	img.l1_offset = ext2fs_be64_to_cpu(hdr->l1_table_offset);
+	img.l2_size = 1 << (img.cluster_bits - 3);
+	img.image_size = ext2fs_be64_to_cpu(hdr->size);
+
+	if (img.l1_offset & (img.cluster_size - 1))
+		return -QCOW_CORRUPTED;
+
+	max_l1_size = (img.image_size >> ((2 * img.cluster_bits) - 3)) +
+		img.cluster_size;
+	if (img.l1_size > max_l1_size)
+		return -QCOW_CORRUPTED;
+
+	ret = ext2fs_get_memzero(img.cluster_size, &l2_table);
+	if (ret)
+		goto out;
+
+	ret = ext2fs_get_memzero(1 << img.cluster_bits, &copy_buf);
+	if (ret)
+		goto out;
+
+	if (ext2fs_llseek(raw_fd, 0, SEEK_SET) < 0) {
+		ret = errno;
+		goto out;
+	}
+
+	ret = qcow2_read_l1_table(&img);
+	if (ret)
+		goto out;
+
+	l1_table = img.l1_table;
+	/* Walk through l1 table */
+	for (l1_index = 0; l1_index < img.l1_size; l1_index++) {
+		__u64 off_out;
+
+		offset = ext2fs_be64_to_cpu(l1_table[l1_index]) &
+			 ~QCOW_OFLAG_COPIED;
+
+		if ((offset > img.image_size) ||
+		    (offset <= 0))
+			continue;
+
+		if (offset & QCOW_OFLAG_COMPRESSED) {
+			ret = -QCOW_COMPRESSED;
+			goto out;
+		}
+
+		ret = qcow2_read_l2_table(&img, offset, &l2_table);
+		if (ret)
+			break;
+
+		/* Walk through l2 table and copy data blocks into raw image */
+		for (l2_index = 0; l2_index < img.l2_size; l2_index++) {
+			offset = ext2fs_be64_to_cpu(l2_table[l2_index]) &
+				 ~QCOW_OFLAG_COPIED;
+
+			if (offset == 0)
+				continue;
+
+			off_out = ((__u64)l1_index * img.l2_size) +
+				  l2_index;
+			off_out <<= img.cluster_bits;
+			ret = qcow2_copy_data(qcow2_fd, raw_fd, offset,
+					off_out, copy_buf, img.cluster_size);
+			if (ret)
+				goto out;
+		}
+	}
+
+	/* Resize the output image to the filesystem size */
+	if (ext2fs_llseek(raw_fd, img.image_size - 1, SEEK_SET) < 0) {
+		ret = errno;
+		goto out;
+	}
+
+	((char *)copy_buf)[0] = 0;
+	size = write(raw_fd, copy_buf, 1);
+	if (size != 1) {
+		ret = errno;
+		goto out;
+	}
+
+out:
+	if (copy_buf)
+		ext2fs_free_mem(&copy_buf);
+	if (img.l1_table)
+		ext2fs_free_mem(&img.l1_table);
+	if (l2_table)
+		ext2fs_free_mem(&l2_table);
+	return ret;
+}