[libvirt] [PATCH 1/2] util: extend virGetUserID and virGetGroupID to support names and IDs

[Peter Krempa]

On 10/06/12 04:52, Marcelo Cerri wrote:
> This patch updates virGetUserID and virGetGroupID to be able to parse a
> user or group name in a similar way to coreutils' chown. This means that
> a numeric value with a leading plus sign is always parsed as an ID,
> otherwise the functions try to parse the input first as a user or group
> name and if this fails they try to parse it as an ID.
> ---
>   src/util/util.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++++---------
>   1 file changed, 74 insertions(+), 13 deletions(-)
>
> diff --git a/src/util/util.c b/src/util/util.c
> index 43fdaf1..694ed3d 100644
> --- a/src/util/util.c
> +++ b/src/util/util.c
> @@ -2495,9 +2495,11 @@ char *virGetGroupName(gid_t gid)
>       return virGetGroupEnt(gid);
>   }
>
> -
> -int virGetUserID(const char *name,
> -                 uid_t *uid)
> +/* Search in the password database for a user id that matches the user name
> + * `name`. Returns 0 on success, -1 on a critical failure or 1 if name cannot
> + * be parsed.
> + */
> +static int virGetUserIDByName(const char *name, uid_t *uid)
>   {
>       char *strbuf;
>       struct passwd pwbuf;
> @@ -2530,11 +2532,10 @@ int virGetUserID(const char *name,
>           }
>       }
>       if (rc != 0 || pw == NULL) {
> -        virReportSystemError(rc,
> -                             _("Failed to find user record for name '%s'"),
> -                             name);
> +        VIR_DEBUG("Failed to find user record for user '%s' (error = %d)",
> +                  name, rc);

Although this will work most of the times when an error occurs it will 
be masked as if the user wasn't found. Unfortunately getpwuid_r and 
friends have very bad error reporting. The only effective way to 
distinguish errors from non-existent user entries (according to the 
manpage) is to check set errno before the call and check it afterwards.

>           VIR_FREE(strbuf);
> -        return -1;
> +        return 1;
>       }
>
>       *uid = pw->pw_uid;
> @@ -2544,9 +2545,41 @@ int virGetUserID(const char *name,
>       return 0;
>   }
>
> +/* Try to match a user id based on `user`. The default behavior is to parse
> + * `user` first as a user name and then as a user id. However if `user`
> + * contains a leading '+', the rest of the string is always parsed as a uid.
> + *
> + * Returns 0 on success and -1 otherwise.
> + */
> +int virGetUserID(const char *user, uid_t *uid)
> +{
> +    unsigned int uint_uid;
>
> -int virGetGroupID(const char *name,
> -                  gid_t *gid)
> +    if (*user == '+') {
> +        user++;
> +    } else {
> +        int rc = virGetUserIDByName(user, uid);
> +        if (rc <= 0)
> +            return rc;
> +    }
> +
> +    if (virStrToLong_ui(user, NULL, 10, &uint_uid) < 0 ||
> +        ((uid_t) uint_uid) != uint_uid) {
> +        virReportError(VIR_ERR_INVALID_ARG, _("Failed to parse user '%s'"),
> +                       user);
> +        return -1;
> +    }
> +
> +    *uid = uint_uid;
> +
> +    return 0;
> +}
> +

Otherwise looks ok, so ACK. I'll push this after I get a review on the 
followup patch that fixes the issue with errors being masked while 
getting the user entry.

Peter