On Fri, Mar 29 2019, Jeff Hostetler via GitGitGadget wrote:
> From: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
>
> Update SID component construction to use the current UTC datetime
> and a portion of the SHA1 of the hostname.
>
> Use an simplified date/time format to make it easier to use the
> SID component as a logfile filename.
> [...]
> +static void tr2_sid_append_my_sid_component(void)
> +{
> + const struct git_hash_algo *algo = &hash_algos[GIT_HASH_SHA1];
> + struct tr2_tbuf tb_now;
> + git_hash_ctx ctx;
> + unsigned char hash[GIT_MAX_RAWSZ + 1];
> + char hex[GIT_MAX_HEXSZ + 1];
> + char hostname[HOST_NAME_MAX + 1];
> +
> + tr2_tbuf_utc_datetime_for_filename(&tb_now);
> + strbuf_addstr(&tr2sid_buf, tb_now.buf);
> + strbuf_addch(&tr2sid_buf, '-');
> +
> + if (xgethostname(hostname, sizeof(hostname)))
> + xsnprintf(hostname, sizeof(hostname), "localhost");
> +
> + algo->init_fn(&ctx);
> + algo->update_fn(&ctx, hostname, strlen(hostname));
> + algo->final_fn(hash, &ctx);
> + hash_to_hex_algop_r(hex, hash, algo);
> + strbuf_add(&tr2sid_buf, hex, 8);
> +
> + strbuf_addch(&tr2sid_buf, '-');
> + strbuf_addf(&tr2sid_buf, "%06"PRIuMAX, (uintmax_t)getpid());
> +}
> +
Thanks for turning my shitty half-formed idea into a patch :)
I wrote this on top to bikeshed this a bit further, wonder what you
think:
https://github.com/gitgitgadget/git/compare/pr-169/jeffhostetler/core-tr2-startup-and-sysenv-v2...avar:pr-169/jeffhostetler/core-tr2-startup-and-sysenv-v2
So e.g.:
Before: 20190329-220413-446441-c2f5b994-018702
After: 20190329T220431.244562Z-Hc2f5b994-P19812F
I.e:
* Using <date>T<time> as is ISO 8601 convention/easier to read
* <dateime>.<microseconds>Z, so seperating with "." to indicate it's
the same value + add "Z" for "it's UTC". I'm least sure about the
".". Is that going to cause issues on Windows these days (the rest
being the "extension"...).
* I changed the hostname discovery so if gethostbyname() fails we'll
print "-H00000000-" for that part, instead of "-H<first 8 chars of
the sha1 for 'localhost'>-". Also prefix with "H" for "Host".
* Wrap pids to 0xffff, prefix with "P" (Pid)" and trail with either "F"
= Full or "W" = Wrapped (not the real PID).
* I didn't add "T<datetime>" like "H" and "P" for the rest, since it's
obvious what sort of value it is.
Maybe this is going a bit overboard, but I think it's easier to read at
a glance for humans, and since it's meant to be opaque to machines
anyway and the length is simliar enough not to matter I figure it's
worth it.
