e2image: Support for conversion QCOW2 image into raw

This commit adds support for converting QCOW2 image created previously
with e2image into raw image. The QCOW2 image is detected automatically,
so there is not new option. Just use following command:

  e2image -r image.qcow image.raw

No that this tool is aimed to quickly convert qcow2 image created with
e2image into raw image. In order to improve speed we are doing some
assumption I believe might not be true for regular qcow2 images. So it
was not tested with regular QCOW2 images and it might not work with
them. The intention of this tool is only convert images previously
created by e2image.

Note that there is nothing special with QCOW2 images created by e2images
and it can be used with tools like qemu-img, or qemu-nbd without any
problems.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

2 files changed, 54 insertions, 1 deletions

diff --git a/misc/e2image.8.in b/misc/e2image.8.in
index 90be0d92..74d2a0bb 100644
--- a/misc/e2image.8.in
+++ b/misc/e2image.8.in
@@ -131,6 +131,10 @@ the
 option will prevent analysis of problems related to hash-tree indexed
 directories.
 .PP
+Note that this will work even if you substitute "/dev/hda1" for another raw
+disk image, or QCOW2 image previously created by
+.BR e2image .
+.PP
 .SH QCOW2 IMAGE FILES
 The
 .B \-Q
diff --git a/misc/e2image.c b/misc/e2image.c
index 40ed713b..3f91f64f 100644
--- a/misc/e2image.c
+++ b/misc/e2image.c
@@ -1216,16 +1216,33 @@ static void install_image(char *device, char *image_fn, int type)
 	exit (0);
 }
 
+static struct ext2_qcow2_hdr *check_qcow2_image(int *fd, char *name)
+{
+
+#ifdef HAVE_OPEN64
+	*fd = open64(name, O_RDONLY, 0600);
+#else
+	*fd = open(name, O_RDONLY, 0600);
+#endif
+	if (*fd < 0)
+		return NULL;
+
+	return qcow2_read_header(*fd);
+}
+
 int main (int argc, char ** argv)
 {
 	int c;
 	errcode_t retval;
 	ext2_filsys fs;
 	char *image_fn;
+	struct ext2_qcow2_hdr *header = NULL;
 	int open_flag = EXT2_FLAG_64BITS;
 	int img_type = 0;
 	int flags = 0;
+	int qcow2_fd = 0;
 	int fd = 0;
+	int ret = 0;
 
 #ifdef ENABLE_NLS
 	setlocale(LC_MESSAGES, "");
@@ -1269,6 +1286,14 @@ int main (int argc, char ** argv)
 		exit (0);
 	}
 
+	if (img_type & E2IMAGE_RAW) {
+		header = check_qcow2_image(&qcow2_fd, device_name);
+		if (header) {
+			flags |= E2IMAGE_IS_QCOW2_FLAG;
+			goto skip_device;
+		}
+	}
+
 	retval = ext2fs_open (device_name, open_flag, 0, 0,
 			      unix_io_manager, &fs);
         if (retval) {
@@ -1278,6 +1303,7 @@ int main (int argc, char ** argv)
 		exit(1);
 	}
 
+skip_device:
 	if (strcmp(image_fn, "-") == 0)
 		fd = 1;
 	else {
@@ -1299,12 +1325,35 @@ int main (int argc, char ** argv)
 		exit(1);
 	}
 
+	if (flags & E2IMAGE_IS_QCOW2_FLAG) {
+		ret = qcow2_write_raw_image(qcow2_fd, fd, header);
+		if (ret) {
+			if (ret == -QCOW_COMPRESSED)
+				fprintf(stderr, "Image (%s) is compressed\n",
+					image_fn);
+			if (ret == -QCOW_ENCRYPTED)
+				fprintf(stderr, "Image (%s) is encrypted\n",
+					image_fn);
+			com_err(program_name, ret,
+				_("while trying to convert qcow2 image"
+				" (%s) into raw image (%s)"),
+				device_name, image_fn);
+		}
+		goto out;
+	}
+
+
 	if (img_type)
 		write_raw_image_file(fs, fd, img_type, flags);
 	else
 		write_image_file(fs, fd);
 
 	ext2fs_close (fs);
+out:
+	if (header)
+		free(header);
+	if (qcow2_fd)
+		close(qcow2_fd);
 	remove_error_table(&et_ext2_error_table);
-	exit (0);
+	return ret;
 }