[Xen-devel] [PATCH v2] tools/python: Python 3 compatibility

[Andrew Cooper <andrew.cooper3@citrix.com>]

convert-legacy-stream is only used for incomming migration from pre Xen 4.7,
and verify-stream-v2 appears to only be used by me during migration
development - it is little surprise that they missed the main converstion
effort in Xen 4.13.

Fix it all up.

Move open_file_or_fd() into a new util.py to avoid duplication, making it a
more generic wrapper around open() or fdopen().

In libxc.py, drop all long() conversion.  Python 2 will DTRT with int => long
promotion, even on 32bit builds.

In convert-legacy-stream, don't pass empty strings to write_record().  Join on
the empty argl will do the right thing.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Ian Jackson <Ian.Jackson@citrix.com>
CC: Wei Liu <wl@xen.org>
CC: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>

v2:
 * Drop int/long in libxc.py.  Python 2 will DTRT with int turning into long.
 * More b prefixes in convert-legacy-stream.  Drop empty string passing

This needs backporting to 4.13 ASAP
---
 tools/python/scripts/convert-legacy-stream | 67 +++++++++---------------------
 tools/python/scripts/verify-stream-v2      | 42 ++++---------------
 tools/python/xen/__init__.py               |  1 -
 tools/python/xen/lowlevel/__init__.py      |  1 -
 tools/python/xen/migration/libxc.py        | 34 +++++++--------
 tools/python/xen/migration/libxl.py        |  2 +-
 tools/python/xen/migration/verify.py       |  4 +-
 tools/python/xen/util.py                   | 23 ++++++++++
 8 files changed, 69 insertions(+), 105 deletions(-)
 create mode 100644 tools/python/xen/util.py

diff --git a/tools/python/scripts/convert-legacy-stream b/tools/python/scripts/convert-legacy-stream
index 5f80f13654..d316ae16f0 100755
--- a/tools/python/scripts/convert-legacy-stream
+++ b/tools/python/scripts/convert-legacy-stream
@@ -5,6 +5,8 @@
 Convert a legacy migration stream to a v2 stream.
 """
 
+from __future__ import print_function
+
 import sys
 import os, os.path
 import syslog
@@ -12,6 +14,7 @@ import traceback
 
 from struct import calcsize, unpack, pack
 
+from xen.util import open_file_or_fd as open_file_or_fd
 from xen.migration import legacy, public, libxc, libxl, xl
 
 __version__ = 1
@@ -39,16 +42,16 @@ def info(msg):
             for line in msg.split("\n"):
                 syslog.syslog(syslog.LOG_INFO, line)
         else:
-            print msg
+            print(msg)
 
 def err(msg):
     """Error message, routed to appropriate destination"""
     if log_to_syslog:
         for line in msg.split("\n"):
             syslog.syslog(syslog.LOG_ERR, line)
-    print >> sys.stderr, msg
+    print(msg, file = sys.stderr)
 
-class StreamError(StandardError):
+class StreamError(Exception):
     """Error with the incoming migration stream"""
     pass
 
@@ -70,7 +73,7 @@ class VM(object):
 
         # libxl
         self.libxl = fmt == "libxl"
-        self.emu_xenstore = "" # NUL terminated key&val pairs from "toolstack" records
+        self.emu_xenstore = b"" # NUL terminated key&val pairs from "toolstack" records
 
 def write_libxc_ihdr():
     stream_write(pack(libxc.IHDR_FORMAT,
@@ -102,12 +105,12 @@ def write_libxl_hdr():
                       ))
 
 def write_record(rt, *argl):
-    alldata = ''.join(argl)
+    alldata = b''.join(argl)
     length = len(alldata)
 
     record = pack(libxc.RH_FORMAT, rt, length) + alldata
     plen = (8 - (length & 7)) & 7
-    record += '\x00' * plen
+    record += b'\x00' * plen
 
     stream_write(record)
 
@@ -164,10 +167,10 @@ def write_libxc_hvm_params(params):
                  pack("Q" * len(params), *params))
 
 def write_libxl_end():
-    write_record(libxl.REC_TYPE_end, "")
+    write_record(libxl.REC_TYPE_end)
 
 def write_libxl_libxc_context():
-    write_record(libxl.REC_TYPE_libxc_context, "")
+    write_record(libxl.REC_TYPE_libxc_context)
 
 def write_libxl_emulator_xenstore_data(data):
     write_record(libxl.REC_TYPE_emulator_xenstore_data,
@@ -225,7 +228,7 @@ def read_pv_extended_info(vm):
         so_far += datasz
 
         # Eww, but this is how it is done :(
-        if blkid == "vcpu":
+        if blkid == b"vcpu":
 
             vm.basic_len = datasz
 
@@ -242,10 +245,10 @@ def read_pv_extended_info(vm):
 
             write_libxc_pv_info(vm)
 
-        elif blkid == "extv":
+        elif blkid == b"extv":
             vm.extd = True
 
-        elif blkid == "xcnt":
+        elif blkid == b"xcnt":
             vm.xsave_len, = unpack("I", data[:4])
             info("xcnt sz 0x%x" % (vm.xsave_len, ))
 
@@ -296,7 +299,7 @@ def read_pv_tail(vm):
     info("Got shinfo")
 
     write_record(libxc.REC_TYPE_shared_info, shinfo)
-    write_record(libxc.REC_TYPE_end, "")
+    write_record(libxc.REC_TYPE_end)
 
 
 def read_libxl_toolstack(vm, data):
@@ -336,7 +339,7 @@ def read_libxl_toolstack(vm, data):
         if twidth == 64:
             name = name[:-4]
 
-        if name[-1] != '\x00':
+        if name[-1] != b'\x00':
             raise StreamError("physmap name not NUL terminated")
 
         root = "physmap/%x" % (phys,)
@@ -347,7 +350,7 @@ def read_libxl_toolstack(vm, data):
         for key, val in zip(kv[0::2], kv[1::2]):
             info("    '%s' = '%s'" % (key, val))
 
-        vm.emu_xenstore += '\x00'.join(kv) + '\x00'
+        vm.emu_xenstore += b'\x00'.join(kv) + b'\x00'
 
 
 def read_chunks(vm):
@@ -524,7 +527,7 @@ def read_hvm_tail(vm):
     blob = rdexact(blobsz)
 
     write_record(libxc.REC_TYPE_hvm_context, blob)
-    write_record(libxc.REC_TYPE_end, "")
+    write_record(libxc.REC_TYPE_end)
 
 
 
@@ -534,7 +537,7 @@ def read_qemu(vm):
     sig, = unpack("21s", rawsig)
     info("Qemu signature: %s" % (sig, ))
 
-    if sig == "DeviceModelRecord0002":
+    if sig == b"DeviceModelRecord0002":
         rawsz = rdexact(4)
         sz, = unpack("I", rawsz)
         qdata = rdexact(sz)
@@ -617,36 +620,6 @@ def read_legacy_stream(vm):
         return 2
     return 0
 
-def open_file_or_fd(val, mode):
-    """
-    If 'val' looks like a decimal integer, open it as an fd.  If not, try to
-    open it as a regular file.
-    """
-
-    fd = -1
-    try:
-        # Does it look like an integer?
-        try:
-            fd = int(val, 10)
-        except ValueError:
-            pass
-
-        # Try to open it...
-        if fd != -1:
-            return os.fdopen(fd, mode, 0)
-        else:
-            return open(val, mode, 0)
-
-    except StandardError, e:
-        if fd != -1:
-            err("Unable to open fd %d: %s: %s" %
-                (fd, e.__class__.__name__, e))
-        else:
-            err("Unable to open file '%s': %s: %s" %
-                (val, e.__class__.__name__, e))
-
-    raise SystemExit(1)
-
 
 def main():
     from optparse import OptionParser
@@ -723,7 +696,7 @@ def main():
 if __name__ == "__main__":
     try:
         sys.exit(main())
-    except SystemExit, e:
+    except SystemExit as e:
         sys.exit(e.code)
     except KeyboardInterrupt:
         sys.exit(1)
diff --git a/tools/python/scripts/verify-stream-v2 b/tools/python/scripts/verify-stream-v2
index 3daf25791e..8bac04d566 100755
--- a/tools/python/scripts/verify-stream-v2
+++ b/tools/python/scripts/verify-stream-v2
@@ -3,12 +3,15 @@
 
 """ Verify a v2 format migration stream """
 
+from __future__ import print_function
+
 import sys
 import struct
 import os, os.path
 import syslog
 import traceback
 
+from xen.util import open_file_or_fd as open_file_or_fd
 from xen.migration.verify import StreamError, RecordError
 from xen.migration.libxc import VerifyLibxc
 from xen.migration.libxl import VerifyLibxl
@@ -25,7 +28,7 @@ def info(msg):
             for line in msg.split("\n"):
                 syslog.syslog(syslog.LOG_INFO, line)
         else:
-            print msg
+            print(msg)
 
 def err(msg):
     """Error message, routed to appropriate destination"""
@@ -33,7 +36,7 @@ def err(msg):
         if log_to_syslog:
             for line in msg.split("\n"):
                 syslog.syslog(syslog.LOG_ERR, line)
-        print >> sys.stderr, msg
+        print(msg, file = sys.stderr)
 
 def stream_read(_ = None):
     """Read from input"""
@@ -56,7 +59,7 @@ def skip_xl_header():
     """Skip over an xl header in the stream"""
 
     hdr = rdexact(32)
-    if hdr != "Xen saved domain, xl format\n \0 \r":
+    if hdr != b"Xen saved domain, xl format\n \0 \r":
         raise StreamError("No xl header")
 
     _, mflags, _, optlen = unpack_exact("=IIII")
@@ -86,7 +89,7 @@ def read_stream(fmt):
         err(traceback.format_exc())
         return 1
 
-    except StandardError:
+    except Exception:
         err("Script Error:")
         err(traceback.format_exc())
         err("Please fix me")
@@ -94,35 +97,6 @@ def read_stream(fmt):
 
     return 0
 
-def open_file_or_fd(val, mode, buffering):
-    """
-    If 'val' looks like a decimal integer, open it as an fd.  If not, try to
-    open it as a regular file.
-    """
-
-    fd = -1
-    try:
-        # Does it look like an integer?
-        try:
-            fd = int(val, 10)
-        except ValueError:
-            pass
-
-        # Try to open it...
-        if fd != -1:
-            return os.fdopen(fd, mode, buffering)
-        else:
-            return open(val, mode, buffering)
-
-    except StandardError, e:
-        if fd != -1:
-            err("Unable to open fd %d: %s: %s" %
-                (fd, e.__class__.__name__, e))
-        else:
-            err("Unable to open file '%s': %s: %s" %
-                (val, e.__class__.__name__, e))
-
-    raise SystemExit(2)
 
 def main():
     """ main """
@@ -168,7 +142,7 @@ def main():
 if __name__ == "__main__":
     try:
         sys.exit(main())
-    except SystemExit, e:
+    except SystemExit as e:
         sys.exit(e.code)
     except KeyboardInterrupt:
         sys.exit(2)
diff --git a/tools/python/xen/__init__.py b/tools/python/xen/__init__.py
index 8d1c8b69c3..e69de29bb2 100644
--- a/tools/python/xen/__init__.py
+++ b/tools/python/xen/__init__.py
@@ -1 +0,0 @@
- 
diff --git a/tools/python/xen/lowlevel/__init__.py b/tools/python/xen/lowlevel/__init__.py
index 8d1c8b69c3..e69de29bb2 100644
--- a/tools/python/xen/lowlevel/__init__.py
+++ b/tools/python/xen/lowlevel/__init__.py
@@ -1 +0,0 @@
- 
diff --git a/tools/python/xen/migration/libxc.py b/tools/python/xen/migration/libxc.py
index f24448a9ef..0a329c2090 100644
--- a/tools/python/xen/migration/libxc.py
+++ b/tools/python/xen/migration/libxc.py
@@ -14,10 +14,6 @@
 
 from xen.migration.verify import StreamError, RecordError, VerifyBase
 
-# In Python3 long type have been merged into int, 1L syntax is no longer valid
-if sys.version_info > (3,):
-    long = int
-
 # Image Header
 IHDR_FORMAT = "!QIIHHI"
 
@@ -87,23 +83,23 @@
 
 # page_data
 PAGE_DATA_FORMAT             = "II"
-PAGE_DATA_PFN_MASK           = (long(1) << 52) - 1
-PAGE_DATA_PFN_RESZ_MASK      = ((long(1) << 60) - 1) & ~((long(1) << 52) - 1)
+PAGE_DATA_PFN_MASK           = (1 << 52) - 1
+PAGE_DATA_PFN_RESZ_MASK      = ((1 << 60) - 1) & ~((1 << 52) - 1)
 
 # flags from xen/public/domctl.h: XEN_DOMCTL_PFINFO_* shifted by 32 bits
 PAGE_DATA_TYPE_SHIFT         = 60
-PAGE_DATA_TYPE_LTABTYPE_MASK = (long(0x7) << PAGE_DATA_TYPE_SHIFT)
-PAGE_DATA_TYPE_LTAB_MASK     = (long(0xf) << PAGE_DATA_TYPE_SHIFT)
-PAGE_DATA_TYPE_LPINTAB       = (long(0x8) << PAGE_DATA_TYPE_SHIFT) # Pinned pagetable
-
-PAGE_DATA_TYPE_NOTAB         = (long(0x0) << PAGE_DATA_TYPE_SHIFT) # Regular page
-PAGE_DATA_TYPE_L1TAB         = (long(0x1) << PAGE_DATA_TYPE_SHIFT) # L1 pagetable
-PAGE_DATA_TYPE_L2TAB         = (long(0x2) << PAGE_DATA_TYPE_SHIFT) # L2 pagetable
-PAGE_DATA_TYPE_L3TAB         = (long(0x3) << PAGE_DATA_TYPE_SHIFT) # L3 pagetable
-PAGE_DATA_TYPE_L4TAB         = (long(0x4) << PAGE_DATA_TYPE_SHIFT) # L4 pagetable
-PAGE_DATA_TYPE_BROKEN        = (long(0xd) << PAGE_DATA_TYPE_SHIFT) # Broken
-PAGE_DATA_TYPE_XALLOC        = (long(0xe) << PAGE_DATA_TYPE_SHIFT) # Allocate-only
-PAGE_DATA_TYPE_XTAB          = (long(0xf) << PAGE_DATA_TYPE_SHIFT) # Invalid
+PAGE_DATA_TYPE_LTABTYPE_MASK = (0x7 << PAGE_DATA_TYPE_SHIFT)
+PAGE_DATA_TYPE_LTAB_MASK     = (0xf << PAGE_DATA_TYPE_SHIFT)
+PAGE_DATA_TYPE_LPINTAB       = (0x8 << PAGE_DATA_TYPE_SHIFT) # Pinned pagetable
+
+PAGE_DATA_TYPE_NOTAB         = (0x0 << PAGE_DATA_TYPE_SHIFT) # Regular page
+PAGE_DATA_TYPE_L1TAB         = (0x1 << PAGE_DATA_TYPE_SHIFT) # L1 pagetable
+PAGE_DATA_TYPE_L2TAB         = (0x2 << PAGE_DATA_TYPE_SHIFT) # L2 pagetable
+PAGE_DATA_TYPE_L3TAB         = (0x3 << PAGE_DATA_TYPE_SHIFT) # L3 pagetable
+PAGE_DATA_TYPE_L4TAB         = (0x4 << PAGE_DATA_TYPE_SHIFT) # L4 pagetable
+PAGE_DATA_TYPE_BROKEN        = (0xd << PAGE_DATA_TYPE_SHIFT) # Broken
+PAGE_DATA_TYPE_XALLOC        = (0xe << PAGE_DATA_TYPE_SHIFT) # Allocate-only
+PAGE_DATA_TYPE_XTAB          = (0xf << PAGE_DATA_TYPE_SHIFT) # Invalid
 
 # x86_pv_info
 X86_PV_INFO_FORMAT        = "BBHI"
@@ -223,7 +219,7 @@ def verify_record(self):
             self.squashed_pagedata_records += 1
 
         padding = content[length:]
-        if padding != "\x00" * len(padding):
+        if padding != b"\x00" * len(padding):
             raise StreamError("Padding containing non0 bytes found")
 
         if rtype not in record_verifiers:
diff --git a/tools/python/xen/migration/libxl.py b/tools/python/xen/migration/libxl.py
index d5f54dc489..79f4024e72 100644
--- a/tools/python/xen/migration/libxl.py
+++ b/tools/python/xen/migration/libxl.py
@@ -128,7 +128,7 @@ def verify_record(self):
         content = self.rdexact(contentsz)
 
         padding = content[length:]
-        if padding != "\x00" * len(padding):
+        if padding != b"\x00" * len(padding):
             raise StreamError("Padding containing non0 bytes found")
 
         if rtype not in record_verifiers:
diff --git a/tools/python/xen/migration/verify.py b/tools/python/xen/migration/verify.py
index 7a42dbfc58..1e38f4a3c0 100644
--- a/tools/python/xen/migration/verify.py
+++ b/tools/python/xen/migration/verify.py
@@ -7,11 +7,11 @@
 
 from struct import calcsize, unpack
 
-class StreamError(StandardError):
+class StreamError(Exception):
     """Error with the stream"""
     pass
 
-class RecordError(StandardError):
+class RecordError(Exception):
     """Error with a record in the stream"""
     pass
 
diff --git a/tools/python/xen/util.py b/tools/python/xen/util.py
new file mode 100644
index 0000000000..a11358eefa
--- /dev/null
+++ b/tools/python/xen/util.py
@@ -0,0 +1,23 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+import os
+
+def open_file_or_fd(val, *argl, **kwargs):
+    """
+    If 'val' looks like a decimal integer, open it as an fd.  If not, try to
+    open it as a regular file.
+    """
+
+    fd = -1
+    try:
+        # Does it look like an integer?
+        fd = int(val, 10)
+    except ValueError:
+        pass
+
+    # Try to open it...
+    if fd != -1:
+        return os.fdopen(fd, *argl, **kwargs)
+    else:
+        return open(val, *argl, **kwargs)
-- 
2.11.0


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