From: Stefan Sperling <stsp@stsp.name>
Subject: Re: gotwebd: openat(2) and less params for scraping repo info
To: Omar Polo <op@omarpolo.com>
Cc: gameoftrees@openbsd.org
Date: Tue, 29 Nov 2022 11:04:36 +0100

On Tue, Nov 22, 2022 at 08:10:15PM +0100, Omar Polo wrote:
> On 2022/11/22 19:49:34 +0100, Stefan Sperling <stsp@stsp.name> wrote:
> > On Tue, Nov 22, 2022 at 07:43:17PM +0100, Omar Polo wrote:
> > > P.S.: the check len < SIZE_MAX - 1 is there just to avoid the implicit
> > > cast.  It's silly to try to calloc a number like that, but here i'd
> > > like to focus on just switchi to openat and reducing the seeks, a
> > > sensible upper limit can be discussed and applied later.
> > 
> > Yeah. We should probably be asking getrlimit() for RLIMIT_DATA more often.
> 
> hum, not so sure in this case.  I'd just settle on a sensible maximum
> value, like 1024.  we can't malloc RLIMIT_DATA either because we've
> already allocated memory for other things, or am I mixing things?
> 
> These are files that are displayed in the gotwebd UI, it doesn't make
> sense to have a lot of content.  They should be just a few lines.
> Furthermore, description and cloneurl are just informative and can be
> safely truncated.
> 
> just to provide a datapoint, this is what I currently have:
> 
> 	antartica$ find /var/www/got/public/ \
> 		-name description -o -name cloneurl \
> 		-exec stat -f %z {} + | sort -rh | head
> 	140
> 	137
> 	134
> 	128
> 	125
> 	116
> 	113
> 	113
> 	113
> 	113
> 
> these are bytes...

Yes, a fixed liimt makes sense here. ok

> diff /home/op/w/got
> commit - 3b81530f7d0ffe60024f054f6d87ff8dd558e3fe
> path + /home/op/w/got
> blob - 6991dbcb9481482215de315ffb2caf894bad5350
> file + gotwebd/gotweb.c
> --- gotwebd/gotweb.c
> +++ gotwebd/gotweb.c
> @@ -2510,8 +2510,8 @@ gotweb_get_repo_description(char **description, struct
>  	}
>  
>  	len = sb.st_size;
> -	if (len > SIZE_MAX - 1)
> -		len = SIZE_MAX - 1;
> +	if (len > GOTWEBD_MAXDESCRSZ - 1)
> +		len = GOTWEBD_MAXDESCRSZ - 1;
>  
>  	*description = calloc(len + 1, sizeof(**description));
>  	if (*description == NULL) {
> @@ -2556,8 +2556,8 @@ gotweb_get_clone_url(char **url, struct server *srv, c
>  	}
>  
>  	len = sb.st_size;
> -	if (len > SIZE_MAX - 1)
> -		len = SIZE_MAX - 1;
> +	if (len > GOTWEBD_MAXCLONEURLSZ - 1)
> +		len = GOTWEBD_MAXCLONEURLSZ - 1;
>  
>  	*url = calloc(len + 1, sizeof(**url));
>  	if (*url == NULL) {
> blob - 0a9217f7fb5cc2256686d1d01c59b69e5f96d4ad
> file + gotwebd/gotwebd.h
> --- gotwebd/gotwebd.h
> +++ gotwebd/gotwebd.h
> @@ -39,6 +39,8 @@
>  
>  #define GOTWEBD_USER		 "www"
>  
> +#define GOTWEBD_MAXDESCRSZ	 1024
> +#define GOTWEBD_MAXCLONEURLSZ	 1024
>  #define GOTWEBD_CACHESIZE	 1024
>  #define GOTWEBD_MAXCLIENTS	 1024
>  #define GOTWEBD_MAXTEXT		 511
>