[pacman-dev] [PATCH v2] Do not continuously try to open an invalid database

[Dave Reisner]

On Tue, Jan 09, 2018 at 10:07:13PM +1000, Allan McRae wrote:
> If you manage to download a bad database (e.g. an html file when
> behind a proxy or with a badly configured webserver), pacman makes
> sure you know about it.  Here is some example output:
> 
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> error: could not open file /var/lib/pacman/sync/extra.db: Unrecognized archive format
> 
> I don't know how many times that gets printed because it goes beyond my scrollback
> buffer.
> 
> Flag a database that we can "open" and "fstat" but not read from as invalid to avoid
> this.
> 
> Signed-off-by: Allan McRae <allan at archlinux.org>
> ---
> 
> Review of v1:
> https://lists.archlinux.org/pipermail/pacman-dev/2017-May/022027.html
> 
> v2 - do much less stuff to achive the same result...
> 
> 
>  lib/libalpm/be_sync.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/lib/libalpm/be_sync.c b/lib/libalpm/be_sync.c
> index 1b7c8b6f..389e964c 100644
> --- a/lib/libalpm/be_sync.c
> +++ b/lib/libalpm/be_sync.c
> @@ -486,6 +486,7 @@ static int sync_db_populate(alpm_db_t *db)
>  	fd = _alpm_open_archive(db->handle, dbpath, &buf,
>  			&archive, ALPM_ERR_DB_OPEN);
>  	if(fd < 0) {
> +		db->status &= DB_STATUS_INVALID;

Given that DB_STATUS_INVALID is a single bit, shouldn't this be a simple
assignment? A bitwise 'and' here will result in the status remaining
invalid if it's already invalid, or zero'ing it out (DB_STATUS_VALID) if
it's some other set of bits. That doesn't seem like what we want.

Semi-related thought: it's a bit odd that we semantically chose "0" as
valid, and "1" as invalid.

>  		return -1;
>  	}
>  	est_count = estimate_package_count(&buf, archive);
> -- 
> 2.15.1