Subject: Re: [PATCH 6/8] refs: fix identity for migrated reflogs

From: Toon Claes <[email-masked]>
Date: Thu, 24 Jul 2025 14:56:11 +0200

Patrick Steinhardt <[email-masked]> writes:

> When migrating reflog entries between different storage formats we must
> reconstruct the identity of reflog entries. This is done by passing the
> committer passed to the `migrate_one_reflog_entry()` callback function
> to `fmt_ident()`.
>
> This results in an invalid identity though: `fmt_ident()` expects the
> caller to provide both name and mail of the author, but we pass the full
> identity as mail. This leads to an identity like:
>
>     pks <Patrick Steinhardt [email-masked]>
>
> Fix the bug by splitting the identity line first. This allows us to
> extract both the name and mail so that we can pass them to `fmt_ident()`
> separately.
>
> This commit does not yet add any tests as there is another bug in the
> reflog migration that will be fixed in a subsequent commit. Once that
> bug is fixed we'll make the reflog verification in t1450 stricter, and
> that will catch both this bug here and the other bug.
>
> Signed-off-by: Patrick Steinhardt <[email-masked]>
> ---
>  refs.c | 21 ++++++++++++++++++---
>  1 file changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/refs.c b/refs.c
> index 188989e4113..64544300dc3 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -2945,7 +2945,7 @@ struct migration_data {
>  	struct ref_store *old_refs;
>  	struct ref_transaction *transaction;
>  	struct strbuf *errbuf;
> -	struct strbuf sb;
> +	struct strbuf sb, name, mail;
>  };
>  
>  static int migrate_one_ref(const char *refname, const char *referent UNUSED, const struct object_id *oid,
> @@ -2984,7 +2984,7 @@ struct reflog_migration_data {
>  	struct ref_store *old_refs;
>  	struct ref_transaction *transaction;
>  	struct strbuf *errbuf;
> -	struct strbuf *sb;
> +	struct strbuf *sb, *name, *mail;
>  };
>  
>  static int migrate_one_reflog_entry(struct object_id *old_oid,
> @@ -2994,13 +2994,22 @@ static int migrate_one_reflog_entry(struct object_id *old_oid,
>  				    const char *msg, void *cb_data)
>  {
>  	struct reflog_migration_data *data = cb_data;
> +	struct ident_split ident;
>  	const char *date;
>  	int ret;
>  
> +	if (split_ident_line(&ident, committer, strlen(committer)) < 0)
> +		return -1;
> +
> +	strbuf_reset(data->name);
> +	strbuf_add(data->name, ident.name_begin, ident.name_end - ident.name_begin);
> +	strbuf_reset(data->mail);
> +	strbuf_add(data->mail, ident.mail_begin, ident.mail_end - ident.mail_begin);
> +
>  	date = show_date(timestamp, tz, DATE_MODE(NORMAL));
>  	strbuf_reset(data->sb);
>  	/* committer contains name and email */

This comment doesn't make sense here no more. Better leave it out.

> -	strbuf_addstr(data->sb, fmt_ident("", committer, WANT_BLANK_IDENT, date, 0));
> +	strbuf_addstr(data->sb, fmt_ident(data->name->buf, data->mail->buf, WANT_BLANK_IDENT, date, 0));

I was checking whether we could use IDENT_NO_NAME instead of parsing the
ident. But fmt_ident() calls strbuf_addstr_without_crud() which strips
out the angle brackets from the email address, which builds an invalid
identity like: "C O Mitter [email-masked] 1112911993 -0700"

We could opt to add a flag IDENT_LEAVE_CRUD which calls strbuf_addstr()
instead, but I'm not sure we want to go there.

-- 
Cheers,
Toon