[pacman-dev] [PATCH] Handle null pkgcache for local/sync db_populate()

[Dan McGee]

On Mon, Feb 7, 2011 at 4:59 PM, Pang Yan Han <pangyanhan at gmail.com> wrote:
> In sync_db_populate() and local_db_populate(), a NULL
> db->pkgcache is not caught, allowing the functions to continue
> instead of exiting.
>
> A later alpm_list_msort() call which uses alpm_list_nth()
> will thus traverse invalid pointers in a non-existent
> db->pkgcache->list.
>
> pmerrno is set to PM_ERR_MEMORY as _alpm_pkghash_create() will
> only return NULL when we run out of memory / exceed max hash
> table size. The local/sync db_populate() functions are also
> exited.
>
> db->pkgcache_loaded is initialized to 0 in _alpm_db_new() as
> this value is used to ascertain the whether db->pkgcache is
> loaded.
Note that this an unnecessary addition; the use of CALLOC guarantees
all fields are zeroed out when we get the chunk of memory. I'll patch
this out when I apply this, the rest looks fine.

> Signed-off-by: Pang Yan Han <pangyanhan at gmail.com>
> ---
>  lib/libalpm/be_local.c |    4 ++++
>  lib/libalpm/be_sync.c  |    8 +++++++-
>  lib/libalpm/db.c       |    1 +
>  3 files changed, 12 insertions(+), 1 deletions(-)
>
> diff --git a/lib/libalpm/be_local.c b/lib/libalpm/be_local.c
> index c5b2498..5858270 100644
> --- a/lib/libalpm/be_local.c
> +++ b/lib/libalpm/be_local.c
> @@ -393,6 +393,10 @@ static int local_db_populate(pmdb_t *db)
>
>        /* initialize hash at 50% full */
>        db->pkgcache = _alpm_pkghash_create(est_count * 2);
> +       if(db->pkgcache == NULL){
> +               closedir(dbdir);
> +               RET_ERR(PM_ERR_MEMORY, -1);
> +       }
>
>        while((ent = readdir(dbdir)) != NULL) {
>                const char *name = ent->d_name;
> diff --git a/lib/libalpm/be_sync.c b/lib/libalpm/be_sync.c
> index 4ad045c..4e9b4d3 100644
> --- a/lib/libalpm/be_sync.c
> +++ b/lib/libalpm/be_sync.c
> @@ -234,6 +234,9 @@ static int sync_db_populate(pmdb_t *db)
>
>        /* initialize hash at 66% full */
>        db->pkgcache = _alpm_pkghash_create(est_count * 3 / 2);
> +       if(db->pkgcache == NULL) {
> +               RET_ERR(PM_ERR_MEMORY, -1);
> +       }
>
>        while(archive_read_next_header(archive, &entry) == ARCHIVE_OK) {
>                const struct stat *st;
> @@ -348,6 +351,9 @@ static int sync_db_read(pmdb_t *db, struct archive *archive,
>        if(likely_pkg && strcmp(likely_pkg->name, pkgname) == 0) {
>                pkg = likely_pkg;
>        } else {
> +               if(db->pkgcache == NULL) {
> +                       RET_ERR(PM_ERR_MEMORY, -1);
> +               }
>                pkg = _alpm_pkghash_find(db->pkgcache, pkgname);
>        }
>        if(pkg == NULL) {
> @@ -459,10 +465,10 @@ pmdb_t *_alpm_db_register_sync(const char *treename)
>        _alpm_log(PM_LOG_DEBUG, "registering sync database '%s'\n", treename);
>
>        db = _alpm_db_new(treename, 0);
> -       db->ops = &sync_db_ops;
>        if(db == NULL) {
>                RET_ERR(PM_ERR_DB_CREATE, NULL);
>        }
> +       db->ops = &sync_db_ops;
>
>        handle->dbs_sync = alpm_list_add(handle->dbs_sync, db);
>        return(db);
> diff --git a/lib/libalpm/db.c b/lib/libalpm/db.c
> index 02f8282..d43a16b 100644
> --- a/lib/libalpm/db.c
> +++ b/lib/libalpm/db.c
> @@ -370,6 +370,7 @@ pmdb_t *_alpm_db_new(const char *treename, int is_local)
>        CALLOC(db, 1, sizeof(pmdb_t), RET_ERR(PM_ERR_MEMORY, NULL));
>        STRDUP(db->treename, treename, RET_ERR(PM_ERR_MEMORY, NULL));
>        db->is_local = is_local;
> +       db->pkgcache_loaded = 0;
>
>        return(db);
>  }
> --
> 1.7.4
>
>
>