diff -rup qemu-0.9.1.orig/block.c qemu-0.9.1.new/block.c

--- qemu-0.9.1.orig/block.c	2008-02-26 18:03:00.000000000 -0500

+++ qemu-0.9.1.new/block.c	2008-02-26 18:05:26.000000000 -0500

@@ -123,6 +123,60 @@ void path_combine(char *dest, int dest_s

     }

 }

+static int bdrv_rd_badreq_sectors(BlockDriverState *bs,

+                                  int64_t sector_num, int nb_sectors)

+{

+    return

+        nb_sectors < 0 ||

+        sector_num < 0 ||

+        nb_sectors > bs->total_sectors ||

+        sector_num > bs->total_sectors - nb_sectors;

+}

+

+static int bdrv_rd_badreq_bytes(BlockDriverState *bs,

+                                int64_t offset, int count)

+{

+    int64_t size = bs->total_sectors << SECTOR_BITS;

+    return

+        count < 0 ||

+        size < 0 ||

+        count > size ||

+        offset > size - count;

+}

+

+static int bdrv_wr_badreq_sectors(BlockDriverState *bs,

+                                  int64_t sector_num, int nb_sectors)

+{

+    if (sector_num < 0 ||

+        nb_sectors < 0)

+        return 1;

+

+    if (sector_num > bs->total_sectors - nb_sectors) {

+        if (bs->autogrow)

+            bs->total_sectors = sector_num + nb_sectors;

+        else

+            return 1;

+    }

+    return 0;

+}

+

+static int bdrv_wr_badreq_bytes(BlockDriverState *bs,

+                                int64_t offset, int count)

+{

+    int64_t size = bs->total_sectors << SECTOR_BITS;

+    if (count < 0 ||

+        offset < 0)

+        return 1;

+

+    if (offset > size - count) {

+        if (bs->autogrow)

+            bs->total_sectors = (offset + count + SECTOR_SIZE - 1) >> SECTOR_BITS;

+        else

+            return 1;

+    }

+    return 0;

+}

+

 static void bdrv_register(BlockDriver *bdrv)

 {

@@ -331,6 +385,10 @@ int bdrv_open2(BlockDriverState *bs, con

     bs->read_only = 0;

     bs->is_temporary = 0;

     bs->encrypted = 0;

+    bs->autogrow = 0;

+

+    if (flags & BDRV_O_AUTOGROW)

+        bs->autogrow = 1;

     if (flags & BDRV_O_SNAPSHOT) {

         BlockDriverState *bs1;

@@ -375,6 +433,7 @@ int bdrv_open2(BlockDriverState *bs, con

     }

     bs->drv = drv;

     bs->opaque = qemu_mallocz(drv->instance_size);

+    bs->total_sectors = 0; /* driver will set if it does not do getlength */

     if (bs->opaque == NULL && drv->instance_size > 0)

         return -1;

     /* Note: for compatibility, we open disk image files as RDWR, and

@@ -440,6 +499,7 @@ void bdrv_close(BlockDriverState *bs)

         bs->drv = NULL;

         /* call the change callback */

+        bs->total_sectors = 0;

         bs->media_changed = 1;

         if (bs->change_cb)

             bs->change_cb(bs->change_opaque);

@@ -505,6 +565,8 @@ int bdrv_read(BlockDriverState *bs, int6

     if (!drv)

         return -ENOMEDIUM;

+    if (bdrv_rd_badreq_sectors(bs, sector_num, nb_sectors))

+        return -EDOM;

     if (sector_num == 0 && bs->boot_sector_enabled && nb_sectors > 0) {

             memcpy(buf, bs->boot_sector_data, 512);

         sector_num++;

@@ -545,6 +607,8 @@ int bdrv_write(BlockDriverState *bs, int

         return -ENOMEDIUM;

     if (bs->read_only)

         return -EACCES;

+    if (bdrv_wr_badreq_sectors(bs, sector_num, nb_sectors))

+        return -EDOM;

     if (sector_num == 0 && bs->boot_sector_enabled && nb_sectors > 0) {

         memcpy(bs->boot_sector_data, buf, 512);

     }

@@ -670,6 +734,8 @@ int bdrv_pread(BlockDriverState *bs, int

         return -ENOMEDIUM;

     if (!drv->bdrv_pread)

         return bdrv_pread_em(bs, offset, buf1, count1);

+    if (bdrv_rd_badreq_bytes(bs, offset, count1))

+        return -EDOM;

     return drv->bdrv_pread(bs, offset, buf1, count1);

 }

@@ -685,6 +751,8 @@ int bdrv_pwrite(BlockDriverState *bs, in

         return -ENOMEDIUM;

     if (!drv->bdrv_pwrite)

         return bdrv_pwrite_em(bs, offset, buf1, count1);

+    if (bdrv_wr_badreq_bytes(bs, offset, count1))

+        return -EDOM;

     return drv->bdrv_pwrite(bs, offset, buf1, count1);

 }

@@ -951,6 +1019,8 @@ int bdrv_write_compressed(BlockDriverSta

         return -ENOMEDIUM;

     if (!drv->bdrv_write_compressed)

         return -ENOTSUP;

+    if (bdrv_wr_badreq_sectors(bs, sector_num, nb_sectors))

+        return -EDOM;

     return drv->bdrv_write_compressed(bs, sector_num, buf, nb_sectors);

 }

@@ -1097,6 +1167,8 @@ BlockDriverAIOCB *bdrv_aio_read(BlockDri

     if (!drv)

         return NULL;

+    if (bdrv_rd_badreq_sectors(bs, sector_num, nb_sectors))

+        return NULL;

     /* XXX: we assume that nb_sectors == 0 is suppored by the async read */

     if (sector_num == 0 && bs->boot_sector_enabled && nb_sectors > 0) {

@@ -1128,6 +1200,8 @@ BlockDriverAIOCB *bdrv_aio_write(BlockDr

         return NULL;

     if (bs->read_only)

         return NULL;

+    if (bdrv_wr_badreq_sectors(bs, sector_num, nb_sectors))

+        return NULL;

     if (sector_num == 0 && bs->boot_sector_enabled && nb_sectors > 0) {

         memcpy(bs->boot_sector_data, buf, 512);

     }

diff -rup qemu-0.9.1.orig/block.h qemu-0.9.1.new/block.h

--- qemu-0.9.1.orig/block.h	2008-01-06 14:38:42.000000000 -0500

+++ qemu-0.9.1.new/block.h	2008-02-26 17:41:47.000000000 -0500

@@ -45,6 +45,7 @@ typedef struct QEMUSnapshotInfo {

                                      it (default for

                                      bdrv_file_open()) */

 #define BDRV_O_DIRECT      0x0020

+#define BDRV_O_AUTOGROW    0x0040 /* Allow backing file to extend when writing past end of file */

 #ifndef QEMU_IMG

 void bdrv_info(void);

diff -rup qemu-0.9.1.orig/block_int.h qemu-0.9.1.new/block_int.h

--- qemu-0.9.1.orig/block_int.h	2008-01-06 14:38:42.000000000 -0500

+++ qemu-0.9.1.new/block_int.h	2008-02-26 17:41:47.000000000 -0500

@@ -97,6 +97,7 @@ struct BlockDriverState {

     int locked;    /* if true, the media cannot temporarily be ejected */

     int encrypted; /* if true, the media is encrypted */

     int sg;        /* if true, the device is a /dev/sg* */

+    int autogrow;  /* if true, the backing store can auto-extend to allocate new extents */

     /* event callback when inserting/removing */

     void (*change_cb)(void *opaque);

     void *change_opaque;

diff -rup qemu-0.9.1.orig/block-qcow2.c qemu-0.9.1.new/block-qcow2.c

--- qemu-0.9.1.orig/block-qcow2.c	2008-01-06 14:38:42.000000000 -0500

+++ qemu-0.9.1.new/block-qcow2.c	2008-02-26 18:01:06.000000000 -0500

@@ -191,7 +191,7 @@ static int qcow_open(BlockDriverState *b

     int len, i, shift, ret;

     QCowHeader header;

-    ret = bdrv_file_open(&s->hd, filename, flags);

+    ret = bdrv_file_open(&s->hd, filename, flags | BDRV_O_AUTOGROW);

     if (ret < 0)

         return ret;

     if (bdrv_pread(s->hd, 0, &header, sizeof(header)) != sizeof(header))

diff -rup qemu-0.9.1.orig/block-qcow.c qemu-0.9.1.new/block-qcow.c

--- qemu-0.9.1.orig/block-qcow.c	2008-01-06 14:38:41.000000000 -0500

+++ qemu-0.9.1.new/block-qcow.c	2008-02-26 18:00:53.000000000 -0500

@@ -95,7 +95,7 @@ static int qcow_open(BlockDriverState *b

     int len, i, shift, ret;

     QCowHeader header;

-    ret = bdrv_file_open(&s->hd, filename, flags);

+    ret = bdrv_file_open(&s->hd, filename, flags | BDRV_O_AUTOGROW);

     if (ret < 0)

         return ret;

     if (bdrv_pread(s->hd, 0, &header, sizeof(header)) != sizeof(header))

diff -rup qemu-0.9.1.orig/block-vmdk.c qemu-0.9.1.new/block-vmdk.c

--- qemu-0.9.1.orig/block-vmdk.c	2008-01-06 14:38:42.000000000 -0500

+++ qemu-0.9.1.new/block-vmdk.c	2008-02-26 18:02:17.000000000 -0500

@@ -376,7 +376,7 @@ static int vmdk_open(BlockDriverState *b

         flags = BDRV_O_RDONLY;

     fprintf(stderr, "(VMDK) image open: flags=0x%x filename=%s\n", flags, bs->filename);

-    ret = bdrv_file_open(&s->hd, filename, flags);

+    ret = bdrv_file_open(&s->hd, filename, flags | BDRV_O_AUTOGROW);

     if (ret < 0)

         return ret;

     if (bdrv_pread(s->hd, 0, &magic, sizeof(magic)) != sizeof(magic))