Re: [PATCH v5 15/16] remote-svn: add marks-file regeneration

> fast-import mark files are stored outside the object database and are
> therefore not fetched and can be lost somehow else.  marks provide a
> svn revision --> git sha1 mapping, while the notes that are attached
> to each commit when it is imported provide a git sha1 --> svn revision
> mapping.
>
> If the marks file is not available or not plausible, regenerate it by
> walking through the notes tree.  , i.e.  The plausibility check tests
> if the highest revision in the marks file matches the revision of the
> top ref. It doesn't ensure that the mark file is completely correct.
> This could only be done with an effort equal to unconditional
> regeneration.
>
> Signed-off-by: Florian Achleitner <florian.achleitner.2.6.31@gmail.com>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
>  remote-testsvn.c |   63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 63 insertions(+)
>
> diff --git a/remote-testsvn.c b/remote-testsvn.c
> index e90d221..2c0dc99 100644
> --- a/remote-testsvn.c
> +++ b/remote-testsvn.c
> @@ -86,6 +86,68 @@ static int parse_rev_note(const char *msg, struct rev_note *res) {
>  	return 0;
>  }
>  
> +static int note2mark_cb(const unsigned char *object_sha1,
> +		const unsigned char *note_sha1, char *note_path,
> +		void *cb_data) {
> +	FILE *file = (FILE *)cb_data;
> +	char *msg;
> +	unsigned long msglen;
> +	enum object_type type;
> +	struct rev_note note;
> +	if (!(msg = read_sha1_file(note_sha1, &type, &msglen)) ||
> +			!msglen || type != OBJ_BLOB) {
> +		free(msg);
> +		return 1;
> +	}
> +	if (parse_rev_note(msg, &note))
> +		return 2;
> +	if (fprintf(file, ":%d %s\n", note.rev_nr, sha1_to_hex(object_sha1)) < 1)
> +		return 3;
> +	return 0;
> +}
> +
> +static void regenerate_marks() {
> +	int ret;
> +	FILE *marksfile;
> +	marksfile = fopen(marksfilename, "w+");

> +	if (!marksfile)
> +		die_errno("Couldn't create mark file %s.", marksfilename);
> +	ret = for_each_note(NULL, 0, note2mark_cb, marksfile);
> +	if (ret)
> +		die("Regeneration of marks failed, returned %d.", ret);
> +	fclose(marksfile);
> +}
> +
> +static void check_or_regenerate_marks(int latestrev) {
> +	FILE *marksfile;
> +	char *line = NULL;
> +	size_t linelen = 0;
> +	struct strbuf sb = STRBUF_INIT;
> +	int found = 0;
> +
> +	if (latestrev < 1)
> +		return;
> +
> +	init_notes(NULL, notes_ref, NULL, 0);
> +	marksfile = fopen(marksfilename, "r");
> +	if (!marksfile)
> +		regenerate_marks(marksfile);