Re: [RFC PATCH] sequencer: fix quoting in write_author_script

> From: Phillip Wood <phillip.wood@dunelm.org.uk>
>
> Single quotes should be escaped as \' not \\'. Note that this only
> affects authors that contain a single quote and then only external
> scripts that read the author script and users whose git is upgraded from
> the shell version of rebase -i while rebase was stopped. This is because
> the parsing in read_env_script() expected the broken version and for
> some reason sq_dequote() called by read_author_ident() seems to handle
> the broken quoting correctly.
>
> Ideally write_author_script() would be rewritten to use
> split_ident_line() and sq_quote_buf() but this commit just fixes the
> immediate bug.
>
> Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
> ---
>
> This is untested, unfortuantely I don't have really have time to write a test or
> follow this up at the moment, if someone else want to run with it then please
> do.

>
> sequencer.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/sequencer.c b/sequencer.c
> index 5354d4d51e..0b78d1f100 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -638,21 +638,21 @@ static int write_author_script(const char *message)
>  		else if (*message != '\'')
>  			strbuf_addch(&buf, *(message++));
>  		else
> -			strbuf_addf(&buf, "'\\\\%c'", *(message++));
> +			strbuf_addf(&buf, "'\\%c'", *(message++));
>  	strbuf_addstr(&buf, "'\nGIT_AUTHOR_EMAIL='");
>  	while (*message && *message != '\n' && *message != '\r')
>  		if (skip_prefix(message, "> ", &message))
>  			break;
>  		else if (*message != '\'')
>  			strbuf_addch(&buf, *(message++));
>  		else
> -			strbuf_addf(&buf, "'\\\\%c'", *(message++));
> +			strbuf_addf(&buf, "'\\%c'", *(message++));
>  	strbuf_addstr(&buf, "'\nGIT_AUTHOR_DATE='@");
>  	while (*message && *message != '\n' && *message != '\r')
>  		if (*message != '\'')
>  			strbuf_addch(&buf, *(message++));
>  		else
> -			strbuf_addf(&buf, "'\\\\%c'", *(message++));
> +			strbuf_addf(&buf, "'\\%c'", *(message++));
>  	res = write_message(buf.buf, buf.len, rebase_path_author_script(), 1);
>  	strbuf_release(&buf);
>  	return res;
> @@ -666,13 +666,21 @@ static int read_env_script(struct argv_array *env)
>  {
>  	struct strbuf script = STRBUF_INIT;
>  	int i, count = 0;
> -	char *p, *p2;
> +	const char *p2;
> +	char *p;
>  
>  	if (strbuf_read_file(&script, rebase_path_author_script(), 256) <= 0)
>  		return -1;
>  
>  	for (p = script.buf; *p; p++)
> -		if (skip_prefix(p, "'\\\\''", (const char **)&p2))
> +		/*
> +		 * write_author_script() used to escape "'" incorrectly as
> +		 * "'\\\\''" rather than "'\\''" so we check for the correct
> +		 * version the incorrect version in case git was upgraded while
> +		 * rebase was stopped.
> +		 */
> +		if (skip_prefix(p, "'\\''", &p2) ||
> +		    skip_prefix(p, "'\\\\''", &p2))
>  			strbuf_splice(&script, p - script.buf, p2 - p, "'", 1);
>  		else if (*p == '\'')
>  			strbuf_splice(&script, p-- - script.buf, 1, "", 0);