Re: [PATCH 2/2] sequencer: fix "rebase -i --root" corrupting author header timezone

[Phillip Wood <phillip.wood@talktalk.net>]

Hi Eric
On 30/07/18 10:29, Eric Sunshine wrote:
> When "git rebase -i --root" creates a new root commit, it corrupts the
> "author" header's timezone by repeating the last digit:
> 
>     author A U Thor <author@example.com> @1112912773 -07000
> 
> This is due to two bugs.
> 
> First, write_author_script() neglects to add the closing quote to the
> value of GIT_AUTHOR_DATE when generating "rebase-merge/author-script".
> 
> Second, although sq_dequote() correctly diagnoses the missing closing
> quote, read_author_ident() ignores sq_dequote()'s return value and
> blindly uses the result of the aborted dequote.
> 
> sq_dequote() performs dequoting in-place by removing quoting and
> shifting content downward. When it detects misquoting (lack of closing
> quote, in this case), it gives up and returns an error without inserting
> a NUL-terminator at the end of the shifted content, which explains the
> duplicated last digit in the timezone.
> 
> Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
> ---
>  sequencer.c                   | 7 ++++++-
>  t/t3404-rebase-interactive.sh | 2 +-
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/sequencer.c b/sequencer.c
> index 78864d9072..1008f6d71a 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -654,6 +654,7 @@ static int write_author_script(const char *message)
>  			strbuf_addch(&buf, *(message++));
>  		else
>  			strbuf_addf(&buf, "'\\\\%c'", *(message++));
> +	strbuf_addch(&buf, '\'');
>  	res = write_message(buf.buf, buf.len, rebase_path_author_script(), 1);
>  	strbuf_release(&buf);
>  	return res;
> @@ -724,7 +725,11 @@ static const char *read_author_ident(struct strbuf *buf)
>  
>  		eol = strchrnul(in, '\n');
>  		*eol = '\0';
> -		sq_dequote(in);
> +		if (!sq_dequote(in)) {
> +			warning(_("bad quoting on %s value in '%s'"),
> +				keys[i], rebase_path_author_script());
> +			return NULL;

I think we want to handle the broken author script properly rather than
returning NULL. If we had a single function
int read_author_script(const char **name, const char **author, const
char **date)
to read the author script that tried sq_dequote() and then fell back to
code based on read_env_script() that handled the missing "'" at the end
and also the bad quoting of "'" if sq_dequote() failed it would make it
easier to fix the existing bugs, rather than having to fix
read_author_ident() and read_env_script() separately. What do you think?

Best Wishes

Phillip

> +		}
>  		len = strlen(in);
>  
>  		if (i > 0) /* separate values by spaces */
> diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
> index 8509c89a26..37796bb4c1 100755
> --- a/t/t3404-rebase-interactive.sh
> +++ b/t/t3404-rebase-interactive.sh
> @@ -1420,7 +1420,7 @@ test_expect_success 'valid author header after --root swap' '
>  	set_fake_editor &&
>  	FAKE_LINES="2 1" git rebase -i --root &&
>  	git cat-file commit HEAD^ >out &&
> -	grep "^author ..* @[0-9][0-9]* [-+][0-9][0-9]*$" out
> +	grep "^author ..* @[0-9][0-9]* [-+][0-9][0-9][0-9][0-9]$" out
>  '
>  
>  test_done
>