On Tue, 04/23 10:24, Jeff Cody wrote: > +/* opens the specified header block from the VHDX file header section */ > +static int vhdx_parse_header(BlockDriverState *bs, BDRVVHDXState *s) > +{ > + int ret = 0; > + vhdx_header *header1; > + vhdx_header *header2; > + uint64_t h1_seq = 0; > + uint64_t h2_seq = 0; > + uint8_t *buffer; > + > + header1 = qemu_blockalign(bs, sizeof(vhdx_header)); > + header2 = qemu_blockalign(bs, sizeof(vhdx_header)); > + > + buffer = qemu_blockalign(bs, VHDX_HEADER_SIZE); > + > + s->headers[0] = header1; > + s->headers[1] = header2; > + Logic for header1 and header2 are completely the same, IMO it might be better to avoid code with a loop. > + /* We have to read the whole VHDX_HEADER_SIZE instead of > + * sizeof(vhdx_header), because the checksum is over the whole > + * region */ > + ret = bdrv_pread(bs->file, VHDX_HEADER1_OFFSET, buffer, > VHDX_HEADER_SIZE); > + if (ret < 0) { > + goto fail; > + } > + /* copy over just the relevant portion that we need */ > + memcpy(header1, buffer, sizeof(vhdx_header)); > + vhdx_header_le_import(header1); > + > + if (vhdx_checksum_is_valid(buffer, VHDX_HEADER_SIZE, 4) && > + header1->signature == VHDX_HDR_MAGIC) { > + h1_seq = header1->sequence_number; > + } Do we need to check the version here? As the specification page 15 says:
The Version field specifies the version of the VHDX format used within the VHDX file. This field must be set to 1. If it is not, a parser must not attempt to parse the file using the details from this format specification. > + > + ret = bdrv_pread(bs->file, VHDX_HEADER2_OFFSET, buffer, > VHDX_HEADER_SIZE); > + if (ret < 0) { > + goto fail; > + } > + /* copy over just the relevant portion that we need */ > + memcpy(header2, buffer, sizeof(vhdx_header)); > + vhdx_header_le_import(header2); > + > + if (vhdx_checksum_is_valid(buffer, VHDX_HEADER_SIZE, 4) && > + header2->signature == VHDX_HDR_MAGIC) { > + h2_seq = header2->sequence_number; > + } Same as above. > + > + if (h1_seq > h2_seq) { > + s->curr_header = 0; > + } else if (h2_seq > h1_seq) { > + s->curr_header = 1; > + } else { > + printf("NO VALID HEADER\n"); > + ret = -EINVAL; > + goto fail; > + } > + > + ret = 0; > + > + goto exit; > + > +fail: > + qemu_vfree(header1); > + qemu_vfree(header2); > + s->headers[0] = NULL; > + s->headers[1] = NULL; > +exit: > + qemu_vfree(buffer); > + return ret; > +} -- Fam