[Qemu-devel] [PATCH] dump-guest-memory.py: fix python 2 support

[Qemu-devel] [PATCH] dump-guest-memory.py: fix python 2 support

[Marc-André Lureau]

Python GDB support may use Python 2 or 3.

Inferior.read_memory() may return a buffer with Python 2 or a
memoryview with Python 3 (see also
https://sourceware.org/gdb/onlinedocs/gdb/Inferiors-In-Python.html)

The elf.add_vmcoreinfo_note() method expect a byte string, but Python 2
buffer doesn't provide the tobyes() method. Wrap the read_memory()
result to a memoryview, available in Python 2.7. (if the return object
is already a memoryview, this adds a useless identity view on top)

Fixes a regression introduced with commit
d23bfa91b7789534d16ede6cb7d925bfac3f3c4c ("add vmcoreinfo").

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 scripts/dump-guest-memory.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/scripts/dump-guest-memory.py b/scripts/dump-guest-memory.py
index 09bec92b50..6f7e1a83b3 100644
--- a/scripts/dump-guest-memory.py
+++ b/scripts/dump-guest-memory.py
@@ -564,7 +564,9 @@ shape and this command should mostly work."""
 
         vmcoreinfo = self.phys_memory_read(addr, size)
         if vmcoreinfo:
-            self.elf.add_vmcoreinfo_note(vmcoreinfo.tobytes())
+            # Python 2.7 returns a buffer
+            vmciview = memoryview(vmcoreinfo)
+            self.elf.add_vmcoreinfo_note(vmciview.tobytes())
 
     def invoke(self, args, from_tty):
         """Handles command invocation from gdb."""
-- 
2.16.0.rc1.1.gef27df75a1

Re: [Qemu-devel] [PATCH] dump-guest-memory.py: fix python 2 support

[Laszlo Ersek]

On 01/17/18 12:44, Marc-André Lureau wrote:
> Python GDB support may use Python 2 or 3.
> 
> Inferior.read_memory() may return a buffer with Python 2 or a
> memoryview with Python 3 (see also
> https://sourceware.org/gdb/onlinedocs/gdb/Inferiors-In-Python.html)
> 
> The elf.add_vmcoreinfo_note() method expect a byte string, but Python 2
> buffer doesn't provide the tobyes() method. Wrap the read_memory()
> result to a memoryview, available in Python 2.7. (if the return object
> is already a memoryview, this adds a useless identity view on top)

OOP is awesome.

> 
> Fixes a regression introduced with commit
> d23bfa91b7789534d16ede6cb7d925bfac3f3c4c ("add vmcoreinfo").

Do you want to CC stable? Commit d23bfa91b778 is part of v2.11.0.

> 
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  scripts/dump-guest-memory.py | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/dump-guest-memory.py b/scripts/dump-guest-memory.py
> index 09bec92b50..6f7e1a83b3 100644
> --- a/scripts/dump-guest-memory.py
> +++ b/scripts/dump-guest-memory.py
> @@ -564,7 +564,9 @@ shape and this command should mostly work."""
>  
>          vmcoreinfo = self.phys_memory_read(addr, size)
>          if vmcoreinfo:
> -            self.elf.add_vmcoreinfo_note(vmcoreinfo.tobytes())
> +            # Python 2.7 returns a buffer
> +            vmciview = memoryview(vmcoreinfo)
> +            self.elf.add_vmcoreinfo_note(vmciview.tobytes())
>  
>      def invoke(self, args, from_tty):
>          """Handles command invocation from gdb."""
> 

Reviewed-by: Laszlo Ersek <lersek@redhat.com>

Laszlo

Re: [Qemu-devel] [PATCH] dump-guest-memory.py: fix python 2 support

[Marc-André Lureau]

On Wed, Jan 17, 2018 at 12:44 PM, Marc-André Lureau
<marcandre.lureau@redhat.com> wrote:
> Python GDB support may use Python 2 or 3.
>
> Inferior.read_memory() may return a buffer with Python 2 or a
> memoryview with Python 3 (see also
> https://sourceware.org/gdb/onlinedocs/gdb/Inferiors-In-Python.html)
>
> The elf.add_vmcoreinfo_note() method expect a byte string, but Python 2
> buffer doesn't provide the tobyes() method. Wrap the read_memory()
> result to a memoryview, available in Python 2.7. (if the return object
> is already a memoryview, this adds a useless identity view on top)
>
> Fixes a regression introduced with commit
> d23bfa91b7789534d16ede6cb7d925bfac3f3c4c ("add vmcoreinfo").

CC stable (commit d23bfa91b778 is part of v2.11.0., suggested by Laszlo)

>
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  scripts/dump-guest-memory.py | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/dump-guest-memory.py b/scripts/dump-guest-memory.py
> index 09bec92b50..6f7e1a83b3 100644
> --- a/scripts/dump-guest-memory.py
> +++ b/scripts/dump-guest-memory.py
> @@ -564,7 +564,9 @@ shape and this command should mostly work."""
>
>          vmcoreinfo = self.phys_memory_read(addr, size)
>          if vmcoreinfo:
> -            self.elf.add_vmcoreinfo_note(vmcoreinfo.tobytes())
> +            # Python 2.7 returns a buffer
> +            vmciview = memoryview(vmcoreinfo)
> +            self.elf.add_vmcoreinfo_note(vmciview.tobytes())
>
>      def invoke(self, args, from_tty):
>          """Handles command invocation from gdb."""
> --
> 2.16.0.rc1.1.gef27df75a1
>
>



-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH] dump-guest-memory.py: fix python 2 support

[Eric Blake]

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On 01/17/2018 08:18 AM, Laszlo Ersek wrote:
> On 01/17/18 12:44, Marc-André Lureau wrote:
>> Python GDB support may use Python 2 or 3.
>>
>> Inferior.read_memory() may return a buffer with Python 2 or a
>> memoryview with Python 3 (see also
>> https://sourceware.org/gdb/onlinedocs/gdb/Inferiors-In-Python.html)
>>
>> The elf.add_vmcoreinfo_note() method expect a byte string, but Python 2
>> buffer doesn't provide the tobyes() method. Wrap the read_memory()
>> result to a memoryview, available in Python 2.7. (if the return object
>> is already a memoryview, this adds a useless identity view on top)
> 
> OOP is awesome.
> 
>>
>> Fixes a regression introduced with commit
>> d23bfa91b7789534d16ede6cb7d925bfac3f3c4c ("add vmcoreinfo").
> 
> Do you want to CC stable? Commit d23bfa91b778 is part of v2.11.0.

Configure says we still support python 2.6; does this still work there?

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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Re: [Qemu-devel] [PATCH] dump-guest-memory.py: fix python 2 support

[Marc-André Lureau]

Hi

On Wed, Jan 17, 2018 at 3:59 PM, Eric Blake <eblake@redhat.com> wrote:
> On 01/17/2018 08:18 AM, Laszlo Ersek wrote:
>> On 01/17/18 12:44, Marc-André Lureau wrote:
>>> Python GDB support may use Python 2 or 3.
>>>
>>> Inferior.read_memory() may return a buffer with Python 2 or a
>>> memoryview with Python 3 (see also
>>> https://sourceware.org/gdb/onlinedocs/gdb/Inferiors-In-Python.html)
>>>
>>> The elf.add_vmcoreinfo_note() method expect a byte string, but Python 2
>>> buffer doesn't provide the tobyes() method. Wrap the read_memory()
>>> result to a memoryview, available in Python 2.7. (if the return object
>>> is already a memoryview, this adds a useless identity view on top)
>>
>> OOP is awesome.
>>
>>>
>>> Fixes a regression introduced with commit
>>> d23bfa91b7789534d16ede6cb7d925bfac3f3c4c ("add vmcoreinfo").
>>
>> Do you want to CC stable? Commit d23bfa91b778 is part of v2.11.0.
>
> Configure says we still support python 2.6; does this still work there?

 memoryview is not available with python 2.6.

Is the configure version check a configure-time check, or are we
suppose to support that version for gdb scripts as well?

>
> --
> Eric Blake, Principal Software Engineer
> Red Hat, Inc.           +1-919-301-3266
> Virtualization:  qemu.org | libvirt.org
>



-- 
Marc-André Lureau