From: John Snow <jsnow@redhat.com>
To: "Philippe Mathieu-Daudé" <philmd@redhat.com>, qemu-devel@nongnu.org
Cc: Fam Zheng <fam@euphon.net>, Paolo Bonzini <pbonzini@redhat.com>,
Jason Wang <jasowang@redhat.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
qemu-block@nongnu.org
Subject: Re: [Qemu-devel] [Qemu-block] [PATCH 2/2] trace: Forbid event format ending with newline character
Date: Fri, 13 Sep 2019 17:08:00 -0400 [thread overview]
Message-ID: <95ace4c1-e718-256c-e53e-34b24a2fbcde@redhat.com> (raw)
In-Reply-To: <a5664c3e-2c83-b9fc-e3f9-5797356d6b6e@redhat.com>
On 9/13/19 5:00 PM, Philippe Mathieu-Daudé wrote:
> On 9/13/19 10:01 PM, John Snow wrote:
>> On 9/13/19 6:52 AM, Philippe Mathieu-Daudé wrote:
>>> Event format ending with newlines confuse the trace reports.
>>> Forbid them.
>>>
>>> Add a check to refuse new format added with trailing newline:
>>>
>>> $ make
>>> [...]
>>> GEN hw/misc/trace.h
>>> Traceback (most recent call last):
>>> File "scripts/tracetool.py", line 152, in <module>
>>> main(sys.argv)
>>> File "scripts/tracetool.py", line 143, in main
>>> events.extend(tracetool.read_events(fh, arg))
>>> File "scripts/tracetool/__init__.py", line 367, in read_events
>>> event = Event.build(line)
>>> File "scripts/tracetool/__init__.py", line 281, in build
>>> raise ValueError("Event format can not end with a newline character")
>>> ValueError: Error at hw/misc/trace-events:121: Event format can not end with a newline character
>>>
>>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>>> ---
>>> docs/devel/tracing.txt | 2 ++
>>> scripts/tracetool/__init__.py | 3 +++
>>> 2 files changed, 5 insertions(+)
>>>
>>> diff --git a/docs/devel/tracing.txt b/docs/devel/tracing.txt
>>> index 76e492a489..8231bbf5d1 100644
>>> --- a/docs/devel/tracing.txt
>>> +++ b/docs/devel/tracing.txt
>>> @@ -112,6 +112,8 @@ Trace events should use types as follows:
>>> Format strings should reflect the types defined in the trace event. Take
>>> special care to use PRId64 and PRIu64 for int64_t and uint64_t types,
>>> respectively. This ensures portability between 32- and 64-bit platforms.
>>> +Format strings must not end with a newline character. It is the responsibility
>>> +of backends to adapt line ending for proper logging.
>>>
>>> Each event declaration will start with the event name, then its arguments,
>>> finally a format string for pretty-printing. For example:
>>> diff --git a/scripts/tracetool/__init__.py b/scripts/tracetool/__init__.py
>>> index 6fca674936..57df74e67c 100644
>>> --- a/scripts/tracetool/__init__.py
>>> +++ b/scripts/tracetool/__init__.py
>>> @@ -277,6 +277,9 @@ class Event(object):
>>> if fmt.find("%m") != -1 or fmt_trans.find("%m") != -1:
>>> raise ValueError("Event format '%m' is forbidden, pass the error "
>>> "as an explicit trace argument")
>>> + if fmt.endswith("\\n\""):
>>> + raise ValueError("Event format must not end with a newline "
>>
>> It's barely worth mentioning, but you can use r"\n" for cases like this,
>> if it makes it easier to read.
>
> TIL Python r"" :)
>
> This would be r"\n\"", right? We need to match the trailing '"'.
> Same length, not sure which string is easier to review =)
>
Ah, wow, I did misread this. It's confusing!
In this case, you can use r'\n"' to get the job done.
(My r-b stands, anyway.)
--js
next prev parent reply other threads:[~2019-09-13 21:08 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-13 10:52 [Qemu-devel] [PATCH 0/2] trace: Forbid trailing newline in event format Philippe Mathieu-Daudé
2019-09-13 10:52 ` [Qemu-devel] [PATCH 1/2] trace: Remove trailing newline in events Philippe Mathieu-Daudé
2019-09-13 10:52 ` [Qemu-devel] [PATCH 2/2] trace: Forbid event format ending with newline character Philippe Mathieu-Daudé
2019-09-13 20:01 ` [Qemu-devel] [Qemu-block] " John Snow
2019-09-13 21:00 ` Philippe Mathieu-Daudé
2019-09-13 21:08 ` John Snow [this message]
2019-09-13 20:10 ` [Qemu-devel] [Qemu-block] [PATCH 0/2] trace: Forbid trailing newline in event format John Snow
2019-09-16 8:07 ` Kevin Wolf
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