threads / bug / 38969

[bug (maybe)] Applying patch with '---'

Subject: [bug (maybe)] Applying patch with '---'

## tl;dr

3 messages between Apr 1, 2015 and Apr 1, 2015.

replies: 2people: 2as markdown or json

Chris Packham· Apr 1, 2015, 02:37 UTC · lore

Hi List,

So I was just sent a patch generated with 'git format-patch' that 'git am' fails to apply correctly. It applies but part of the commit message is lost.

The problem is that the commit message has lines like

--- Foo happened
    did some things to handle Foo
--- Bar happened
    Still processing update from Foo which led to a crash

git mailinfo seems to discard everything after the first '--- Blah'. I know ^---$ is special but I thought ^---.+$ would be OK. I know git mailinfo shouldn't handle garbage input but I guess the problem I have is that the patch was generated by git format-patch so surely git mailinfo (and therefore git am) _should_ handle something generated by generated by git format-patch.

Do people agree with my thinking? I'm not sure if it would be appropriate for git format-patch to produce a warning or for git mailinfo to tighten the matching of '---'.

Regards, Chris

Junio C Hamano· Apr 1, 2015, 06:20 UTC · re: Chris Packham · lore

Re: [bug (maybe)] Applying patch with '---'

Chris Packham <judge.packham@gmail.com> writes:

Show 12 quoted lines

> So I was just sent a patch generated with 'git format-patch' that 'git
> am' fails to apply correctly. It applies but part of the commit
> message is lost.
>
> The problem is that the commit message has lines like
>
> --- Foo happened
>     did some things to handle Foo
> --- Bar happened
>     Still processing update from Foo which led to a crash
>
> git mailinfo seems to discard everything after the first '--- Blah'.

Yes, this is well known. So is a line that begins with "diff --git" makes mailinfo to guess that it is the end of the log message.

> ... I know git
> mailinfo shouldn't handle garbage input but I guess the problem I have
> is that the patch was generated by git format-patch ...

Whatever message you write format-patch emits without escaping, so "patch was generated by format-patch" does not guarantee anything, unfortunately. A related similar issue is that a line that begins with "From " may be corrupted into a line that begins with ">From " by the time the message hits your mailbox. These are unfortunately something you have to know and long-time users learned to avoid doing so unconsciously ;-).

Chris Packham· Apr 1, 2015, 08:06 UTC · re: Junio C Hamano · lore

Re: [bug (maybe)] Applying patch with '---'

On Wed, Apr 1, 2015 at 7:20 PM, Junio C Hamano <gitster@pobox.com> wrote:

Show 18 quoted lines

> Chris Packham <judge.packham@gmail.com> writes:
>
>> So I was just sent a patch generated with 'git format-patch' that 'git
>> am' fails to apply correctly. It applies but part of the commit
>> message is lost.
>>
>> The problem is that the commit message has lines like
>>
>> --- Foo happened
>>     did some things to handle Foo
>> --- Bar happened
>>     Still processing update from Foo which led to a crash
>>
>> git mailinfo seems to discard everything after the first '--- Blah'.
>
> Yes, this is well known.  So is a line that begins with "diff --git"
> makes mailinfo to guess that it is the end of the log message.
>

So it looks like code in mailinfo.c to handle

  --- a/file
  +++ b/file

Also interprets

  --- Blah
  more text

as the start of the patch portion. Perhaps mailinfo could search for both the --- and +++ lines before deciding it's the patch portion has started. Or search for "diff -" first and work backwards towards to drop text up to the "---".

Show 11 quoted lines

>> ... I know git
>> mailinfo shouldn't handle garbage input but I guess the problem I have
>> is that the patch was generated by git format-patch ...
>
> Whatever message you write format-patch emits without escaping, so
> "patch was generated by format-patch" does not guarantee anything,
> unfortunately.  A related similar issue is that a line that begins
> with "From " may be corrupted into a line that begins with ">From "
> by the time the message hits your mailbox.  These are unfortunately
> something you have to know and long-time users learned to avoid
> doing so unconsciously ;-).

So perhaps the newer users need some training wheels built into format-patch :). It'd actually annoy me if it was too intrusive as I actually use --- as a light weight alternative to git-notes for commentary I want to include with a patch submission. But a message saying "if you send this verbatim commit message text will be lost" would at least let the user know that something needs attention .