"Command syntax:\n"
" create [-e] [-6] [-b base_image] [-f fmt] filename [size]\n"
" commit [-f fmt] filename\n"
- " convert [-c] [-e] [-6] [-f fmt] [-O output_fmt] filename [filename2 [...]] output_filename\n"
+ " convert [-c] [-e] [-6] [-f fmt] [-O output_fmt] [-B output_base_image] filename [filename2 [...]] output_filename\n"
" info [-f fmt] filename\n"
"\n"
"Command parameters:\n"
" 'filename' is a disk image filename\n"
" 'base_image' is the read-only disk image which is used as base for a copy on\n"
" write image; the copy on write image only stores the modified data\n"
+ " 'output_base_image' forces the output image to be created as a copy on write\n"
+ " image of the specified base image; 'output_base_image' should have the same\n"
+ " content as the input's base image, however the path, image format, etc may\n"
+ " differ\n"
" 'fmt' is the disk image format. It is guessed automatically in most cases\n"
" 'size' is the disk image size in kilobytes. Optional suffixes 'M' (megabyte)\n"
" and 'G' (gigabyte) are supported\n"
return 0;
}
+/*
+ * Returns true iff the first sector pointed to by 'buf' contains at least
+ * a non-NUL byte.
+ *
+ * 'pnum' is set to the number of sectors (including and immediately following
+ * the first one) that are known to be in the same allocated/unallocated state.
+ */
static int is_allocated_sectors(const uint8_t *buf, int n, int *pnum)
{
int v, i;
static int img_convert(int argc, char **argv)
{
int c, ret, n, n1, bs_n, bs_i, flags, cluster_size, cluster_sectors;
- const char *fmt, *out_fmt, *out_filename;
+ const char *fmt, *out_fmt, *out_baseimg, *out_filename;
BlockDriver *drv;
BlockDriverState **bs, *out_bs;
int64_t total_sectors, nb_sectors, sector_num, bs_offset;
fmt = NULL;
out_fmt = "raw";
+ out_baseimg = NULL;
flags = 0;
for(;;) {
- c = getopt(argc, argv, "f:O:hce6");
+ c = getopt(argc, argv, "f:O:B:hce6");
if (c == -1)
break;
switch(c) {
case 'O':
out_fmt = optarg;
break;
+ case 'B':
+ out_baseimg = optarg;
+ break;
case 'c':
flags |= BLOCK_FLAG_COMPRESS;
break;
if (bs_n < 1) help();
out_filename = argv[argc - 1];
+
+ if (bs_n > 1 && out_baseimg)
+ error("-B makes no sense when concatenating multiple input images");
bs = calloc(bs_n, sizeof(BlockDriverState *));
if (!bs)
if (flags & BLOCK_FLAG_ENCRYPT && flags & BLOCK_FLAG_COMPRESS)
error("Compression and encryption not supported at the same time");
- ret = bdrv_create(drv, out_filename, total_sectors, NULL, flags);
+ ret = bdrv_create(drv, out_filename, total_sectors, out_baseimg, flags);
if (ret < 0) {
if (ret == -ENOTSUP) {
error("Formatting not supported for file format '%s'", fmt);
/* signal EOF to align */
bdrv_write_compressed(out_bs, 0, NULL, 0);
} else {
- sector_num = 0;
+ sector_num = 0; // total number of sectors converted so far
for(;;) {
nb_sectors = total_sectors - sector_num;
if (nb_sectors <= 0)
if (n > bs_offset + bs_sectors - sector_num)
n = bs_offset + bs_sectors - sector_num;
+ /* If the output image is being created as a copy on write image,
+ assume that sectors which are unallocated in the input image
+ are present in both the output's and input's base images (no
+ need to copy them). */
+ if (out_baseimg) {
+ if (!bdrv_is_allocated(bs[bs_i], sector_num - bs_offset, n, &n1)) {
+ sector_num += n1;
+ continue;
+ }
+ /* The next 'n1' sectors are allocated in the input image. Copy
+ only those as they may be followed by unallocated sectors. */
+ n = n1;
+ }
+
if (bdrv_read(bs[bs_i], sector_num - bs_offset, buf, n) < 0)
error("error while reading");
/* NOTE: at the same time we convert, we do not write zero
should add a specific call to have the info to go faster */
buf1 = buf;
while (n > 0) {
- if (is_allocated_sectors(buf1, n, &n1)) {
+ /* If the output image is being created as a copy on write image,
+ copy all sectors even the ones containing only NUL bytes,
+ because they may differ from the sectors in the base image. */
+ if (out_baseimg || is_allocated_sectors(buf1, n, &n1)) {
if (bdrv_write(out_bs, sector_num, buf1, n1) < 0)
error("error while writing");
}
projects / qemu / blobdiff