From: Omar Polo <op@omarpolo.com>
Subject: Re: gotwebd: openat(2) and less params for scraping repo info
To: Stefan Sperling <stsp@stsp.name>
Cc: gameoftrees@openbsd.org
Date: Tue, 22 Nov 2022 20:10:15 +0100

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...


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