block: vpc - use QEMU_PACKED for on-disk structures

The VHD footer and header structs (vhd_footer and vhd_dyndisk_header)
are on-disk structures for the image format, and as such should be
packed.

Go ahead and make these typedefs as well, with the preferred QEMU
naming convention, so that the packed attribute is used consistently
with the struct.

Signed-off-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/vpc.c

@@ -46,7 +46,7 @@ enum vhd_type {
 #define VHD_TIMESTAMP_BASE 946684800
 
 // always big-endian
-struct vhd_footer {
+typedef struct vhd_footer {
     char        creator[8]; // "conectix"
     uint32_t    features;
     uint32_t    version;
@@ -79,9 +79,9 @@ struct vhd_footer {
     uint8_t     uuid[16];
 
     uint8_t     in_saved_state;
-};
+} QEMU_PACKED VHDFooter;
 
-struct vhd_dyndisk_header {
+typedef struct vhd_dyndisk_header {
     char        magic[8]; // "cxsparse"
 
     // Offset of next header structure, 0xFFFFFFFF if none
@@ -111,7 +111,7 @@ struct vhd_dyndisk_header {
         uint32_t    reserved;
         uint64_t    data_offset;
     } parent_locator[8];
-};
+} QEMU_PACKED VHDDynDiskHeader;
 
 typedef struct BDRVVPCState {
     CoMutex lock;
@@ -160,8 +160,8 @@ static int vpc_open(BlockDriverState *bs, QDict *options, int flags,
 {
     BDRVVPCState *s = bs->opaque;
     int i;
-    struct vhd_footer* footer;
-    struct vhd_dyndisk_header* dyndisk_header;
+    VHDFooter *footer;
+    VHDDynDiskHeader *dyndisk_header;
     uint8_t buf[HEADER_SIZE];
     uint32_t checksum;
     int disk_type = VHD_DYNAMIC;
@@ -172,7 +172,7 @@ static int vpc_open(BlockDriverState *bs, QDict *options, int flags,
         goto fail;
     }
 
-    footer = (struct vhd_footer*) s->footer_buf;
+    footer = (VHDFooter *) s->footer_buf;
     if (strncmp(footer->creator, "conectix", 8)) {
         int64_t offset = bdrv_getlength(bs->file);
         if (offset < 0) {
@@ -224,7 +224,7 @@ static int vpc_open(BlockDriverState *bs, QDict *options, int flags,
             goto fail;
         }
 
-        dyndisk_header = (struct vhd_dyndisk_header *) buf;
+        dyndisk_header = (VHDDynDiskHeader *) buf;
 
         if (strncmp(dyndisk_header->magic, "cxsparse", 8)) {
             ret = -EINVAL;
@@ -446,7 +446,7 @@ static int vpc_read(BlockDriverState *bs, int64_t sector_num,
     int ret;
     int64_t offset;
     int64_t sectors, sectors_per_block;
-    struct vhd_footer *footer = (struct vhd_footer *) s->footer_buf;
+    VHDFooter *footer = (VHDFooter *) s->footer_buf;
 
     if (cpu_to_be32(footer->type) == VHD_FIXED) {
         return bdrv_read(bs->file, sector_num, buf, nb_sectors);
@@ -495,7 +495,7 @@ static int vpc_write(BlockDriverState *bs, int64_t sector_num,
     int64_t offset;
     int64_t sectors, sectors_per_block;
     int ret;
-    struct vhd_footer *footer =  (struct vhd_footer *) s->footer_buf;
+    VHDFooter *footer =  (VHDFooter *) s->footer_buf;
 
     if (cpu_to_be32(footer->type) == VHD_FIXED) {
         return bdrv_write(bs->file, sector_num, buf, nb_sectors);
@@ -597,8 +597,8 @@ static int calculate_geometry(int64_t total_sectors, uint16_t* cyls,
 
 static int create_dynamic_disk(int fd, uint8_t *buf, int64_t total_sectors)
 {
-    struct vhd_dyndisk_header* dyndisk_header =
-        (struct vhd_dyndisk_header*) buf;
+    VHDDynDiskHeader *dyndisk_header =
+        (VHDDynDiskHeader *) buf;
     size_t block_size, num_bat_entries;
     int i;
     int ret = -EIO;
@@ -688,7 +688,7 @@ static int vpc_create(const char *filename, QEMUOptionParameter *options,
                       Error **errp)
 {
     uint8_t buf[1024];
-    struct vhd_footer *footer = (struct vhd_footer *) buf;
+    VHDFooter *footer = (VHDFooter *) buf;
     QEMUOptionParameter *disk_type_param;
     int fd, i;
     uint16_t cyls = 0;
@@ -791,7 +791,7 @@ static int vpc_create(const char *filename, QEMUOptionParameter *options,
 static int vpc_has_zero_init(BlockDriverState *bs)
 {
     BDRVVPCState *s = bs->opaque;
-    struct vhd_footer *footer =  (struct vhd_footer *) s->footer_buf;
+    VHDFooter *footer =  (VHDFooter *) s->footer_buf;
 
     if (cpu_to_be32(footer->type) == VHD_FIXED) {
         return bdrv_has_zero_init(bs->file);