[v2] iotests: Dump QCOW2 dirty bitmaps metadata

Add dirty bitmap information to QCOW2 metadata dump in qcow2.py script.
The sample output:

Header extension:         Bitmaps
magic                     0x23852875
length                    24
nb_bitmaps                2
reserved32                0
bitmap_directory_size     0x40
bitmap_directory_offset   0x100000

Bitmap name               bitmap-1
flag                      "auto"
bitmap_table_offset       0x90000
bitmap_table_size         8
flags                     2
type                      1
granularity_bits          15
name_size                 8
extra_data_size           0

Bitmap table
   0     serialized, offset 0xa0000
   1     all-zeroes, offset 0x0
   2     all-zeroes, offset 0x0
   3     all-zeroes, offset 0x0
   4     all-zeroes, offset 0x0
   5     all-zeroes, offset 0x0
   6     all-zeroes, offset 0x0
   7     all-zeroes, offset 0x0

Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
---
v2:
  01: Refactoring of the Python code in the script qcow2.py.
      New methods were added. The bitmap dictionary was instantiated.
      The all of bitmaps information is read completely before
      printing the dictionary.
  02: The outputs of the tests 031, 036 and 061 were modified.

 tests/qemu-iotests/031.out  |  22 +++---
 tests/qemu-iotests/036.out  |   4 +-
 tests/qemu-iotests/061.out  |  14 ++--
 tests/qemu-iotests/qcow2.py | 167 +++++++++++++++++++++++++++++++++++++++++---
 4 files changed, 179 insertions(+), 28 deletions(-)

26.05.2020 23:26, Andrey Shinkevich wrote:
> Add dirty bitmap information to QCOW2 metadata dump in qcow2.py script.
> The sample output:
> 
> Header extension:         Bitmaps
> magic                     0x23852875
> length                    24
> nb_bitmaps                2
> reserved32                0
> bitmap_directory_size     0x40
> bitmap_directory_offset   0x100000
> 
> Bitmap name               bitmap-1
> flag                      "auto"
> bitmap_table_offset       0x90000
> bitmap_table_size         8
> flags                     2
> type                      1
> granularity_bits          15
> name_size                 8
> extra_data_size           0
> 
> Bitmap table
>     0     serialized, offset 0xa0000
>     1     all-zeroes, offset 0x0
>     2     all-zeroes, offset 0x0
>     3     all-zeroes, offset 0x0
>     4     all-zeroes, offset 0x0
>     5     all-zeroes, offset 0x0
>     6     all-zeroes, offset 0x0
>     7     all-zeroes, offset 0x0
> 
> Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
> ---
> v2:
>    01: Refactoring of the Python code in the script qcow2.py.
>        New methods were added. The bitmap dictionary was instantiated.
>        The all of bitmaps information is read completely before
>        printing the dictionary.
>    02: The outputs of the tests 031, 036 and 061 were modified.
> 
>   tests/qemu-iotests/031.out  |  22 +++---
>   tests/qemu-iotests/036.out  |   4 +-
>   tests/qemu-iotests/061.out  |  14 ++--
>   tests/qemu-iotests/qcow2.py | 167 +++++++++++++++++++++++++++++++++++++++++---
>   4 files changed, 179 insertions(+), 28 deletions(-)
> 
> diff --git a/tests/qemu-iotests/031.out b/tests/qemu-iotests/031.out
> index 46f97c5..0383ebb 100644
> --- a/tests/qemu-iotests/031.out
> +++ b/tests/qemu-iotests/031.out
> @@ -24,7 +24,7 @@ autoclear_features        []
>   refcount_order            4
>   header_length             72
>   
> -Header extension:
> +Header extension:         Unknown
>   magic                     0x12345678
>   length                    31
>   data                      'This is a test header extension'
> @@ -52,7 +52,7 @@ autoclear_features        []
>   refcount_order            4
>   header_length             72
>   
> -Header extension:
> +Header extension:         Unknown
>   magic                     0x12345678
>   length                    31
>   data                      'This is a test header extension'
> @@ -80,12 +80,12 @@ autoclear_features        []
>   refcount_order            4
>   header_length             72
>   
> -Header extension:
> +Header extension:         Backing format
>   magic                     0xe2792aca
>   length                    11
>   data                      'host_device'
>   
> -Header extension:
> +Header extension:         Unknown
>   magic                     0x12345678
>   length                    31
>   data                      'This is a test header extension'
> @@ -115,12 +115,12 @@ autoclear_features        []
>   refcount_order            4
>   header_length             104
>   
> -Header extension:
> +Header extension:         Feature table
>   magic                     0x6803f857
>   length                    288
>   data                      <binary>
>   
> -Header extension:
> +Header extension:         Unknown
>   magic                     0x12345678
>   length                    31
>   data                      'This is a test header extension'
> @@ -148,12 +148,12 @@ autoclear_features        []
>   refcount_order            4
>   header_length             104
>   
> -Header extension:
> +Header extension:         Feature table
>   magic                     0x6803f857
>   length                    288
>   data                      <binary>
>   
> -Header extension:
> +Header extension:         Unknown
>   magic                     0x12345678
>   length                    31
>   data                      'This is a test header extension'
> @@ -181,17 +181,17 @@ autoclear_features        []
>   refcount_order            4
>   header_length             104
>   
> -Header extension:
> +Header extension:         Backing format
>   magic                     0xe2792aca
>   length                    11
>   data                      'host_device'
>   
> -Header extension:
> +Header extension:         Feature table
>   magic                     0x6803f857
>   length                    288
>   data                      <binary>
>   
> -Header extension:
> +Header extension:         Unknown
>   magic                     0x12345678
>   length                    31
>   data                      'This is a test header extension'
> diff --git a/tests/qemu-iotests/036.out b/tests/qemu-iotests/036.out
> index 23b699c..d305f1a 100644
> --- a/tests/qemu-iotests/036.out
> +++ b/tests/qemu-iotests/036.out
> @@ -24,7 +24,7 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
>   incompatible_features     []
>   compatible_features       []
>   autoclear_features        [63]
> -Header extension:
> +Header extension:         Feature table
>   magic                     0x6803f857
>   length                    288
>   data                      <binary>
> @@ -36,7 +36,7 @@ No errors were found on the image.
>   incompatible_features     []
>   compatible_features       []
>   autoclear_features        []
> -Header extension:
> +Header extension:         Feature table
>   magic                     0x6803f857
>   length                    288
>   data                      <binary>
> diff --git a/tests/qemu-iotests/061.out b/tests/qemu-iotests/061.out
> index 5a8d36d..bb4b236 100644
> --- a/tests/qemu-iotests/061.out
> +++ b/tests/qemu-iotests/061.out
> @@ -24,7 +24,7 @@ autoclear_features        []
>   refcount_order            4
>   header_length             104
>   
> -Header extension:
> +Header extension:         Feature table
>   magic                     0x6803f857
>   length                    288
>   data                      <binary>
> @@ -82,7 +82,7 @@ autoclear_features        []
>   refcount_order            4
>   header_length             104
>   
> -Header extension:
> +Header extension:         Feature table
>   magic                     0x6803f857
>   length                    288
>   data                      <binary>
> @@ -138,7 +138,7 @@ autoclear_features        []
>   refcount_order            4
>   header_length             104
>   
> -Header extension:
> +Header extension:         Feature table
>   magic                     0x6803f857
>   length                    288
>   data                      <binary>
> @@ -193,7 +193,7 @@ autoclear_features        [42]
>   refcount_order            4
>   header_length             104
>   
> -Header extension:
> +Header extension:         Feature table
>   magic                     0x6803f857
>   length                    288
>   data                      <binary>
> @@ -262,7 +262,7 @@ autoclear_features        []
>   refcount_order            4
>   header_length             104
>   
> -Header extension:
> +Header extension:         Feature table
>   magic                     0x6803f857
>   length                    288
>   data                      <binary>
> @@ -324,7 +324,7 @@ autoclear_features        []
>   refcount_order            4
>   header_length             104
>   
> -Header extension:
> +Header extension:         Feature table
>   magic                     0x6803f857
>   length                    288
>   data                      <binary>
> @@ -353,7 +353,7 @@ autoclear_features        []
>   refcount_order            4
>   header_length             104
>   
> -Header extension:
> +Header extension:         Feature table
>   magic                     0x6803f857
>   length                    288
>   data                      <binary>
> diff --git a/tests/qemu-iotests/qcow2.py b/tests/qemu-iotests/qcow2.py
> index 94a07b2..483decb 100755
> --- a/tests/qemu-iotests/qcow2.py
> +++ b/tests/qemu-iotests/qcow2.py
> @@ -4,6 +4,132 @@ import sys
>   import struct
>   import string
>   
> +
> +class Qcow2BitmapDirEntry:
> +
> +    name = ''
> +    BME_FLAG_IN_USE = 1
> +    BME_FLAG_AUTO = 1 << 1
> +
> +    uint8_t = 'B'
> +    uint16_t = 'H'
> +    uint32_t = 'I'
> +    uint64_t = 'Q'
> +
> +    fields = [
> +        [uint64_t, '%#x', 'bitmap_table_offset'],
> +        [uint32_t, '%d',  'bitmap_table_size'],
> +        [uint32_t, '%d',  'flags'],
> +        [uint8_t,  '%d',  'type'],
> +        [uint8_t,  '%d',  'granularity_bits'],
> +        [uint16_t, '%d',  'name_size'],
> +        [uint32_t, '%d',  'extra_data_size']
> +    ]
> +
> +    fmt = '>' + ''.join(field[0] for field in fields)
> +
> +    def __init__(self, data):
> +

extra empty line

> +        entry = struct.unpack(Qcow2BitmapDirEntry.fmt, data)
> +        self.__dict__ = dict((field[2], entry[i])
> +                             for i, field in enumerate(
> +                                 Qcow2BitmapDirEntry.fields))
> +
> +        self.bitmap_table_size = self.bitmap_table_size \
> +            * struct.calcsize(self.uint64_t)

hmm, you multiply it here [...]

> +
> +    def bitmap_dir_entry_raw_size(self):
> +        return struct.calcsize(self.fmt) + self.name_size + \
> +            self.extra_data_size
> +
> +    def dump_bitmap_dir_entry(self):
> +        print("%-25s" % 'Bitmap name', self.name)

I recommend to use .format() or f-strings instead of old % notation.

> +        if (self.flags & self.BME_FLAG_IN_USE) != 0:
> +            print("%-25s" % 'flag', '"in-use"')
> +        if (self.flags & self.BME_FLAG_AUTO) != 0:
> +            print("%-25s" % 'flag', '"auto"')

Some empty lines around if and for blocks will be nice, IMHO.

> +        for f in Qcow2BitmapDirEntry.fields:
> +            value = self.__dict__[f[2]]
> +            value_str = f[1] % value
> +
> +            print("%-25s" % f[2], value_str)
> +        print("")
> +
> +    def read_bitmap_table(self, fd):
> +        fd.seek(self.bitmap_table_offset)
> +        table_size = self.bitmap_table_size * struct.calcsize(self.uint64_t)

[...] and here. this seems wrong. I'd keep multiplication only here.

> +        table = [e[0] for e in struct.iter_unpack('>Q', fd.read(table_size))]
> +        self.bitmap_table = enumerate(table)

enumerate returns an iterator, I think you need list(enumerate(table))

> +
> +    def print_bitmap_table(self):
> +        BME_TABLE_ENTRY_OFFSET_MASK = 0x00fffffffffffe00
> +        BME_TABLE_ENTRY_FLAG_ALL_ONES = 1
> +        bmt_type = ['all-zeroes', 'all-ones', 'serialized']
> +
> +        print("Bitmap table")
> +        for i, entry in self.bitmap_table:
> +            offset = entry & BME_TABLE_ENTRY_OFFSET_MASK
> +            if offset != 0:
> +                index = 2
> +            else:
> +                index = entry & BME_TABLE_ENTRY_FLAG_ALL_ONES
> +            print("   %-4d  %s, offset %#x" % (i, bmt_type[index], offset))
> +        print("")
> +
> +
> +class Qcow2BitmapExt:
> +
> +    uint32_t = 'I'
> +    uint64_t = 'Q'
> +
> +    fields = [
> +        [uint32_t, '%d',  'nb_bitmaps'],
> +        [uint32_t, '%d',  'reserved32'],
> +        [uint64_t, '%#x', 'bitmap_directory_size'],
> +        [uint64_t, '%#x', 'bitmap_directory_offset']
> +    ]
> +
> +    fmt = '>' + ''.join(field[0] for field in fields)

Would be good to keep common functionality in a parent class somehow.

> +
> +    def __init__(self, data):
> +
> +        extension = struct.unpack(Qcow2BitmapExt.fmt, data)
> +        self.__dict__ = dict((field[2], extension[i])
> +                             for i, field in enumerate(Qcow2BitmapExt.fields))
> +
> +    def dump_bitmap_ext(self):
> +        for f in Qcow2BitmapExt.fields:
> +            value = self.__dict__[f[2]]
> +            value_str = f[1] % value
> +
> +            print("%-25s" % f[2], value_str)
> +        print("")
> +
> +    def read_bitmap_directory(self, fd):
> +        self.bitmaps = []
> +        fd.seek(self.bitmap_directory_offset)
> +        buf_size = struct.calcsize(Qcow2BitmapDirEntry.fmt)
> +
> +        for n in range(self.nb_bitmaps):
> +            buf = fd.read(buf_size)
> +            dir_entry = Qcow2BitmapDirEntry(buf)
> +            fd.seek(dir_entry.extra_data_size, 1)
> +            bitmap_name = fd.read(dir_entry.name_size)
> +            dir_entry.name = bitmap_name.decode('ascii')
> +            self.bitmaps.append(dir_entry)
> +            entry_raw_size = dir_entry.bitmap_dir_entry_raw_size()
> +            shift = ((entry_raw_size + 7) & ~7) - entry_raw_size
> +            fd.seek(shift, 1)
> +
> +        for bm in self.bitmaps:
> +            bm.read_bitmap_table(fd)
> +
> +    def print_bitmaps(self):
> +        for bm in self.bitmaps:
> +            bm.dump_bitmap_dir_entry()
> +            bm.print_bitmap_table()
> +
> +
>   class QcowHeaderExtension:
>   
>       def __init__(self, magic, length, data):
> @@ -21,6 +147,11 @@ class QcowHeaderExtension:
>   
>   class QcowHeader:
>   
> +    QCOW2_EXT_MAGIC_BACKING_FORMAT = 0xE2792ACA
> +    QCOW2_EXT_MAGIC_FEATURE_TABLE = 0x6803f857
> +    QCOW2_EXT_MAGIC_CRYPTO_HEADER = 0x0537be77
> +    QCOW2_EXT_MAGIC_BITMAPS = 0x23852875
> +    QCOW2_EXT_MAGIC_DATA_FILE = 0x44415441
>       uint32_t = 'I'
>       uint64_t = 'Q'
>   
> @@ -127,6 +258,15 @@ class QcowHeader:
>           buf = buf[0:header_bytes-1]
>           fd.write(buf)
>   
> +    def extension_name(self, magic):
> +        return {
> +            self.QCOW2_EXT_MAGIC_BACKING_FORMAT: 'Backing format',
> +            self.QCOW2_EXT_MAGIC_FEATURE_TABLE: 'Feature table',
> +            self.QCOW2_EXT_MAGIC_CRYPTO_HEADER: 'Crypto header',
> +            self.QCOW2_EXT_MAGIC_BITMAPS: 'Bitmaps',
> +            self.QCOW2_EXT_MAGIC_DATA_FILE: 'Data file',
> +        }.get(magic, 'Unknown')
> +
>       def dump(self):
>           for f in QcowHeader.fields:
>               value = self.__dict__[f[2]]
> @@ -142,30 +282,41 @@ class QcowHeader:
>               print("%-25s" % f[2], value_str)
>           print("")
>   
> -    def dump_extensions(self):
> +    def dump_extensions(self, fd):
>           for ex in self.extensions:
>   
> +            print("%-25s %s" % ("Header extension:", self.extension_name(
> +                ex.magic)))

Could you do this improvement together with iotests change in a separate preparation patch?

> +            print("%-25s %#x" % ("magic", ex.magic))
> +            print("%-25s %d" % ("length", ex.length))
> +
>               data = ex.data[:ex.length]
>               if all(c in string.printable.encode('ascii') for c in data):
>                   data = "'%s'" % data.decode('ascii')
> +                print("%-25s %s" % ("data", data))
>               else:
> -                data = "<binary>"
> +                self.dump_extension_data(fd, ex)
>   
> -            print("Header extension:")
> -            print("%-25s %#x" % ("magic", ex.magic))
> -            print("%-25s %d" % ("length", ex.length))
> -            print("%-25s %s" % ("data", data))
>               print("")
>   
> +    def dump_extension_data(self, fd, ext):
> +        if ext.magic == self.QCOW2_EXT_MAGIC_BITMAPS:
> +            b_ext = Qcow2BitmapExt(ext.data)
> +            b_ext.dump_bitmap_ext()
> +            b_ext.read_bitmap_directory(fd)
> +            b_ext.print_bitmaps()
> +        else:
> +            print("%-25s %s" % ("data", "<binary>"))
> +
>   
>   def cmd_dump_header(fd):
>       h = QcowHeader(fd)
>       h.dump()
> -    h.dump_extensions()
> +    h.dump_extensions(fd)
>   
>   def cmd_dump_header_exts(fd):
>       h = QcowHeader(fd)
> -    h.dump_extensions()
> +    h.dump_extensions(fd)
>   
>   def cmd_set_header(fd, name, value):
>       try:
>