I don't think this is really the direction we want to go with libzfs_core; it increases the complexity of the operation and the possible error cases. That said, I understand why you want to do it since otherwise there's no way to set the name based on the BEGIN record, using libzfs_core. Maybe the existing lzc_receive is just the wrong interface, and it should take the BEGIN record as an argument, forcing the caller to read and decode it (and decide on the name based on it, if desired). We could then provide a convenience routine that works like the current lzc_receive().
What do you think? --matt On Fri, Jul 3, 2015 at 10:46 AM, Andriy Gapon <[email protected]> wrote: > > Currently lzc_receive() requires that its 'snapname' argument is a > snapshot name > (contains '@'). zfs receive allows to specify just a dataset name and > would try > to deduce the snapshot name from the stream. I propose to allow > lzc_receive() > to do the same. That is quite easy to achieve, it requires only a small > amount > of logic, it does not require any additional system calls or any > additional data > from the stream. > Below is a proof of concept patch that seems to work. > > --- lib/libzfs_core/common/libzfs_core.c > +++ lib/libzfs_core/common/libzfs_core.c > @@ -721,9 +721,8 @@ lzc_receive > /* zc_name is name of containing filesystem */ > (void) strlcpy(zc.zc_name, snapname, sizeof (zc.zc_name)); > atp = strchr(zc.zc_name, '@'); > - if (atp == NULL) > - return (EINVAL); > - *atp = '\0'; > + if (atp != NULL) > + *atp = '\0'; > > /* if the fs does not exist, try its parent. */ > if (!lzc_exists(zc.zc_name)) { > @@ -734,9 +733,6 @@ lzc_receive > > } > > - /* zc_value is full name of the snapshot to create */ > - (void) strlcpy(zc.zc_value, snapname, sizeof (zc.zc_value)); > - > if (props != NULL) { > /* zc_nvlist_src is props to set */ > packed = fnvlist_pack(props, &size); > @@ -754,6 +750,20 @@ lzc_receive > goto out; > zc.zc_begin_record = drr.drr_u.drr_begin; > > + /* zc_value is full name of the snapshot to create */ > + (void) strlcpy(zc.zc_value, snapname, sizeof (zc.zc_value)); > + > + /* if snapshot name is not provided try to take it from the stream > */ > + atp = strchr(zc.zc_value, '@'); > + if (atp == NULL) { > + atp = strchr(zc.zc_begin_record.drr_toname, '@'); > + if (atp == NULL) > + return (EINVAL); > + if (strlen(zc.zc_value) + strlen(atp) >= > sizeof(zc.zc_value)) > + return (ENAMETOOLONG); > + strcat(zc.zc_value, atp); > + } > + > /* zc_cookie is fd to read from */ > zc.zc_cookie = fd; > > > -- > Andriy Gapon > _______________________________________________ > developer mailing list > [email protected] > http://lists.open-zfs.org/mailman/listinfo/developer >
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