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[Qemu-devel] [PATCH 35/46] qemu-iotests: qcow2.py
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH 35/46] qemu-iotests: qcow2.py |
Date: |
Thu, 5 Apr 2012 17:52:13 +0200 |
This adds a tool that is meant to inspect and edit qcow2 files in a
low-level way, that wouldn't be possible with qemu-img/io, for example
by adding yet unknown extensions or flags. This way we can test whether
qemu deals properly with future backwards compatible extensions.
For now, let's start with the image header and header extensions.
Signed-off-by: Kevin Wolf <address@hidden>
---
tests/qemu-iotests/qcow2.py | 207 +++++++++++++++++++++++++++++++++++++++++++
1 files changed, 207 insertions(+), 0 deletions(-)
create mode 100755 tests/qemu-iotests/qcow2.py
diff --git a/tests/qemu-iotests/qcow2.py b/tests/qemu-iotests/qcow2.py
new file mode 100755
index 0000000..bfb47e8
--- /dev/null
+++ b/tests/qemu-iotests/qcow2.py
@@ -0,0 +1,207 @@
+#!/usr/bin/env python
+
+import sys
+import struct
+import string
+
+class QcowHeaderExtension:
+
+ def __init__(self, magic, length, data):
+ self.magic = magic
+ self.length = length
+ self.data = data
+
+ @classmethod
+ def create(cls, magic, data):
+ return QcowHeaderExtension(magic, len(data), data)
+
+class QcowHeader:
+
+ uint32_t = 'I'
+ uint64_t = 'Q'
+
+ fields = [
+ # Version 2 header fields
+ [ uint32_t, '%#x', 'magic' ],
+ [ uint32_t, '%d', 'version' ],
+ [ uint64_t, '%#x', 'backing_file_offset' ],
+ [ uint32_t, '%#x', 'backing_file_size' ],
+ [ uint32_t, '%d', 'cluster_bits' ],
+ [ uint64_t, '%d', 'size' ],
+ [ uint32_t, '%d', 'crypt_method' ],
+ [ uint32_t, '%d', 'l1_size' ],
+ [ uint64_t, '%#x', 'l1_table_offset' ],
+ [ uint64_t, '%#x', 'refcount_table_offset' ],
+ [ uint32_t, '%d', 'refcount_table_clusters' ],
+ [ uint32_t, '%d', 'nb_snapshots' ],
+ [ uint64_t, '%#x', 'snapshot_offset' ],
+ ];
+
+ fmt = '>' + ''.join(field[0] for field in fields)
+
+ def __init__(self, fd):
+
+ buf_size = struct.calcsize(QcowHeader.fmt)
+
+ fd.seek(0)
+ buf = fd.read(buf_size)
+
+ header = struct.unpack(QcowHeader.fmt, buf)
+ self.__dict__ = dict((field[2], header[i])
+ for i, field in enumerate(QcowHeader.fields))
+
+ self.cluster_size = 1 << self.cluster_bits
+
+ fd.seek(self.get_header_length())
+ self.load_extensions(fd)
+
+ if self.backing_file_offset:
+ fd.seek(self.backing_file_offset)
+ self.backing_file = fd.read(self.backing_file_size)
+ else:
+ self.backing_file = None
+
+ def get_header_length(self):
+ if self.version == 2:
+ return 72
+ else:
+ raise Exception("version != 2 not supported")
+
+ def load_extensions(self, fd):
+ self.extensions = []
+
+ if self.backing_file_offset != 0:
+ end = min(self.cluster_size, self.backing_file_offset)
+ else:
+ end = self.cluster_size
+
+ while fd.tell() < end:
+ (magic, length) = struct.unpack('>II', fd.read(8))
+ if magic == 0:
+ break
+ else:
+ padded = (length + 7) & ~7
+ data = fd.read(padded)
+ self.extensions.append(QcowHeaderExtension(magic, length,
data))
+
+ def update_extensions(self, fd):
+
+ fd.seek(self.get_header_length())
+ extensions = self.extensions
+ extensions.append(QcowHeaderExtension(0, 0, ""))
+ for ex in extensions:
+ buf = struct.pack('>II', ex.magic, ex.length)
+ fd.write(buf)
+ fd.write(ex.data)
+
+ if self.backing_file != None:
+ self.backing_file_offset = fd.tell()
+ fd.write(self.backing_file)
+
+ if fd.tell() > self.cluster_size:
+ raise Exception("I think I just broke the image...")
+
+
+ def update(self, fd):
+ header_bytes = self.get_header_length()
+
+ self.update_extensions(fd)
+
+ fd.seek(0)
+ header = tuple(self.__dict__[f] for t, p, f in QcowHeader.fields)
+ buf = struct.pack(QcowHeader.fmt, *header)
+ buf = buf[0:header_bytes-1]
+ fd.write(buf)
+
+ def dump(self):
+ for f in QcowHeader.fields:
+ print "%-25s" % f[2], f[1] % self.__dict__[f[2]]
+ print ""
+
+ def dump_extensions(self):
+ for ex in self.extensions:
+
+ data = ex.data[:ex.length]
+ if all(c in string.printable for c in data):
+ data = "'%s'" % data
+ else:
+ data = "<binary>"
+
+ print "Header extension:"
+ print "%-25s %#x" % ("magic", ex.magic)
+ print "%-25s %d" % ("length", ex.length)
+ print "%-25s %s" % ("data", data)
+ print ""
+
+
+def cmd_dump_header(fd):
+ h = QcowHeader(fd)
+ h.dump()
+ h.dump_extensions()
+
+def cmd_add_header_ext(fd, magic, data):
+ try:
+ magic = int(magic, 0)
+ except:
+ print "'%s' is not a valid magic number" % magic
+ sys.exit(1)
+
+ h = QcowHeader(fd)
+ h.extensions.append(QcowHeaderExtension.create(magic, data))
+ h.update(fd)
+
+def cmd_del_header_ext(fd, magic):
+ try:
+ magic = int(magic, 0)
+ except:
+ print "'%s' is not a valid magic number" % magic
+ sys.exit(1)
+
+ h = QcowHeader(fd)
+ found = False
+
+ for ex in h.extensions:
+ if ex.magic == magic:
+ found = True
+ h.extensions.remove(ex)
+
+ if not found:
+ print "No such header extension"
+ return
+
+ h.update(fd)
+
+cmds = [
+ [ 'dump-header', cmd_dump_header, 0, 'Dump image header and header
extensions' ],
+ [ 'add-header-ext', cmd_add_header_ext, 2, 'Add a header extension' ],
+ [ 'del-header-ext', cmd_del_header_ext, 1, 'Delete a header extension' ],
+]
+
+def main(filename, cmd, args):
+ fd = open(filename, "r+b")
+ try:
+ for name, handler, num_args, desc in cmds:
+ if name != cmd:
+ continue
+ elif len(args) != num_args:
+ usage()
+ return
+ else:
+ handler(fd, *args)
+ return
+ print "Unknown command '%s'" % cmd
+ finally:
+ fd.close()
+
+def usage():
+ print "Usage: %s <file> <cmd> [<arg>, ...]" % sys.argv[0]
+ print ""
+ print "Supported commands:"
+ for name, handler, num_args, desc in cmds:
+ print " %-20s - %s" % (name, desc)
+
+if len(sys.argv) < 3:
+ usage()
+ sys.exit(1)
+
+main(sys.argv[1], sys.argv[2], sys.argv[3:])
--
1.7.6.5
- [Qemu-devel] [PATCH 44/46] migration: clear BDRV_O_INCOMING flags on end of incoming live migration, (continued)
- [Qemu-devel] [PATCH 44/46] migration: clear BDRV_O_INCOMING flags on end of incoming live migration, Kevin Wolf, 2012/04/05
- [Qemu-devel] [PATCH 34/46] sheepdog: fix send req helpers, Kevin Wolf, 2012/04/05
- [Qemu-devel] [PATCH 31/46] qed: track dirty flag status, Kevin Wolf, 2012/04/06
- [Qemu-devel] [PATCH 40/46] block: Add new BDRV_O_INCOMING flag to notice incoming live migration, Kevin Wolf, 2012/04/06
- [Qemu-devel] [PATCH 46/46] qed: remove incoming live migration blocker, Kevin Wolf, 2012/04/06
- [Qemu-devel] [PATCH 16/46] vdi: move end-of-I/O handling at the end, Kevin Wolf, 2012/04/06
- [Qemu-devel] [PATCH 30/46] qemu-img: add dirty flag status, Kevin Wolf, 2012/04/06
- [Qemu-devel] [PATCH 41/46] block: add a function to clear incoming live migration flags, Kevin Wolf, 2012/04/06
- [Qemu-devel] [PATCH 39/46] block stream: close unused files and update ->backing_hd, Kevin Wolf, 2012/04/06
- [Qemu-devel] [PATCH 26/46] block: set job->speed in block_set_speed, Kevin Wolf, 2012/04/06
- [Qemu-devel] [PATCH 35/46] qemu-iotests: qcow2.py,
Kevin Wolf <=
- Re: [Qemu-devel] [PULL 00/46] Block patches, Anthony Liguori, 2012/04/10