[Libguestfs] [PATCH] New API: resize2fs_P

[Richard W.M. Jones]

On Tue, Oct 13, 2015 at 06:26:25PM +0300, Maxim Perevedentsev wrote:
> Added support for getting ext2/3/4 filesystem minimum size.
> This is needed primarily for shrinking images.
> 
> ---
>  daemon/ext2.c        | 35 +++++++++++++++++++++++++++++++++++
>  generator/actions.ml | 10 ++++++++++
>  src/MAX_PROC_NR      |  2 +-
>  3 files changed, 46 insertions(+), 1 deletion(-)
> 
> diff --git a/daemon/ext2.c b/daemon/ext2.c
> index ebaf0f0..3dae40f 100644
> --- a/daemon/ext2.c
> +++ b/daemon/ext2.c
> @@ -279,6 +279,41 @@ do_resize2fs_M (const char *device)
>    return 0;
>  }
> 
> +int64_t
> +do_resize2fs_P (const char *device)
> +{
> +  CLEANUP_FREE char *err = NULL, *out = NULL;
> +  CLEANUP_FREE_STRING_LIST char **lines = NULL;
> +  int r;
> +  size_t i;
> +  char *p;
> +  int64_t ret;
> +  char pattern[] = "Estimated minimum size of the filesystem: ";
> +
> +  r = command (&out, &err, str_resize2fs, "-P", device, NULL);
> +  if (r == -1) {
> +    reply_with_error ("%s", err);
> +    return -1;
> +  }
> +
> +  lines = split_lines (out);
> +  if (lines == NULL)
> +    return -1;
> +
> +  for (i = 0; lines[i] != NULL; ++i) {
> +    if (verbose)
> +      fprintf (stderr, "resize2fs-P: lines[%zu] = \"%s\"\n", i, lines[i]);
> +
> +    if ((p = strstr (lines[i], pattern))) {
> +      if (sscanf (p + strlen(pattern), "%" SCNu64, &ret) != 1)
> +        return -1;
> +      return ret;
> +    }
> +  }
> +
> +  return -1;
> +}
> +
>  /* Takes optional arguments, consult optargs_bitmask. */
>  int
>  do_e2fsck (const char *device,
> diff --git a/generator/actions.ml b/generator/actions.ml
> index a76b466..7e2bfac 100644
> --- a/generator/actions.ml
> +++ b/generator/actions.ml
> @@ -12751,6 +12751,16 @@ Only some filesystem types support setting UUIDs.
> 
>  To read the UUID on a filesystem, call C<guestfs_vfs_uuid>." };
> 
> +  { defaults with
> +    name = "resize2fs_P"; added = (1, 31, 17);
> +    style = RInt64 "sizeinblocks", [Device "device"], [];
> +    proc_nr = Some 457;
> +    shortdesc = "get minimum filesystem size in blocks";
> +    longdesc = "\
> +Get the minimum filesystem size in blocks.
> +
> +See also L<resize2fs(8)>." };
> +
>  ]
> 
>  (* Non-API meta-commands available only in guestfish.
> diff --git a/src/MAX_PROC_NR b/src/MAX_PROC_NR
> index 8d38505..de2a00c 100644
> --- a/src/MAX_PROC_NR
> +++ b/src/MAX_PROC_NR
> @@ -1 +1 @@
> -456
> +457

Looks fine to me.  Pino: any comment?

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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