[pacman-dev] [PATCH] Fix segfault during install when a package update adds a new file to 'backup'

[Allan McRae]

On 02/04/16 00:52, Will Miles wrote:
> When a new package release adds a new entry to the backup list, no hash exists
> for that file in the previously installed package version.  Fix two places
> where that nonexistent hash may be dereferenced.
> 
> Signed-off-by: Will Miles <wmiles at sgl.com>
> ---

Just as a query, where are you seeing these non-existent backup hashes?
 Corrupt local databases?

>  lib/libalpm/add.c      | 2 +-
>  lib/libalpm/be_local.c | 4 +++-
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/libalpm/add.c b/lib/libalpm/add.c
> index f5c9a95..ff0b81d 100644
> --- a/lib/libalpm/add.c
> +++ b/lib/libalpm/add.c
> @@ -341,7 +341,7 @@ static int extract_single_file(alpm_handle_t *handle, struct archive *archive,
>  		_alpm_log(handle, ALPM_LOG_DEBUG, "checking hashes for %s\n", origfile);
>  		_alpm_log(handle, ALPM_LOG_DEBUG, "current:  %s\n", hash_local);
>  		_alpm_log(handle, ALPM_LOG_DEBUG, "new:      %s\n", hash_pkg);
> -		_alpm_log(handle, ALPM_LOG_DEBUG, "original: %s\n", hash_orig);
> +		_alpm_log(handle, ALPM_LOG_DEBUG, "original: %s\n", (hash_orig ? hash_orig : "NULL") );
>  

Fine - I guess this is needed for non-glibc systems.

>  		if(hash_local && hash_pkg && strcmp(hash_local, hash_pkg) == 0) {
>  			/* local and new files are the same, updating anyway to get
> diff --git a/lib/libalpm/be_local.c b/lib/libalpm/be_local.c
> index f817822..5e39199 100644
> --- a/lib/libalpm/be_local.c
> +++ b/lib/libalpm/be_local.c
> @@ -1037,7 +1037,9 @@ int _alpm_local_db_write(alpm_db_t *db, alpm_pkg_t *info, alpm_dbinfrq_t inforeq
>  			fputs("%BACKUP%\n", fp);
>  			for(lp = info->backup; lp; lp = lp->next) {
>  				const alpm_backup_t *backup = lp->data;
> -				fprintf(fp, "%s\t%s\n", backup->name, backup->hash);
> +				if (backup->hash) {
> +					fprintf(fp, "%s\t%s\n", backup->name, backup->hash);
> +				}

How can this ever happen?

>  			}
>  			fputc('\n', fp);
>  		}
>