Re: [PATCH v2 1/3] read-cache: plug a few leaks

["René Scharfe" <rene.scharfe@lsrfire.ath.cx>]

Am 30.05.2013 15:34, schrieb Felipe Contreras:
> We don't free 'istate->cache' properly.
> 
> Apparently 'initialized' doesn't really mean initialized, but loaded, or
> rather 'not-empty', and the cache can be used even if it's not
> 'initialized', so we can't rely on this variable to keep track of the
> 'istate->cache'.
> 
> So assume it always has data, and free it before overwriting it.
> 
> Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
> ---
>   read-cache.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/read-cache.c b/read-cache.c
> index 04ed561..e5dc96f 100644
> --- a/read-cache.c
> +++ b/read-cache.c
> @@ -1449,6 +1449,7 @@ int read_index_from(struct index_state *istate, const char *path)
>   	istate->version = ntohl(hdr->hdr_version);
>   	istate->cache_nr = ntohl(hdr->hdr_entries);
>   	istate->cache_alloc = alloc_nr(istate->cache_nr);
> +	free(istate->cache);

With that change, callers of read_index_from need to set ->cache to
NULL for uninitialized (on-stack) index_state variables.  They only had
to set ->initialized to 0 before in that situation.  It this chunk safe
for all existing callers?  Shouldn't the same free in discard_index
(added below) be enough?

>   	istate->cache = xcalloc(istate->cache_alloc, sizeof(struct cache_entry *));
>   	istate->initialized = 1;
>   
> @@ -1510,6 +1511,9 @@ int discard_index(struct index_state *istate)
>   
>   	for (i = 0; i < istate->cache_nr; i++)
>   		free(istate->cache[i]);
> +	free(istate->cache);
> +	istate->cache = NULL;
> +	istate->cache_alloc = 0;
>   	resolve_undo_clear_index(istate);
>   	istate->cache_nr = 0;
>   	istate->cache_changed = 0;

I was preparing a similar change, looks good.  There is a comment at
the end of discard_index() that becomes wrong due to that patch,
though -- better remove it as well.  It was already outdated as it
mentioned active_cache, while the function can be used with any
index_state.

diff --git a/read-cache.c b/read-cache.c
index e5dc96f..0f868af 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1522,8 +1522,6 @@ int discard_index(struct index_state *istate)
 	free_name_hash(istate);
 	cache_tree_free(&(istate->cache_tree));
 	istate->initialized = 0;
-
-	/* no need to throw away allocated active_cache */
 	return 0;
 }