[Libguestfs] [PATCH 2/3] mllib: Add function for comparing LVM2 UUIDs, ignoring '-' characters.

--- mllib/common_utils.ml | 21 +++++++++++++++++++++ mllib/common_utils.mli | 3 +++ 2 files changed, 24 insertions(+) diff --git a/mllib/common_utils.ml b/mllib/common_utils.ml index d4994cf..898be17 100644 --- a/mllib/common_utils.ml +++ b/mllib/common_utils.ml @@ -506,6 +506,27 @@ let compare_version v1 v2 = in compare (split_version v1) (split_version v2) +(* Annoying LVM2 returns a differing UUID strings for different + * function calls (sometimes containing or not containing '-' + * characters), so we have to normalize each string before + * comparison. c.f. 'compare_pvuuids' in virt-filesystem. + *) +let compare_lvm2_uuids uuid1 uuid2 = + let n1 = String.length uuid1 and n2 = String.length uuid2 in + let rec loop i1 i2 = + if i1 = n1 && i2 = n2 then 0 (* matching *) + else if i1 >= n1 then 1 (* different lengths *) + else if i2 >= n2 then -1 + else if uuid1.[i1] = '-' then loop (i1+1) i2 (* ignore '-' characters *) + else if uuid2.[i2] = '-' then loop i1 (i2+1) + else ( + let c = compare uuid1.[i1] uuid2.[i2] in + if c <> 0 then c (* not matching *) + else loop (i1+1) (i2+1) + ) + in + loop 0 0 + (* Run an external command, slurp up the output as a list of lines. *) let external_command ~prog cmd = let chan = Unix.open_process_in cmd in diff --git a/mllib/common_utils.mli b/mllib/common_utils.mli index ccb2e5f..5d3149a 100644 --- a/mllib/common_utils.mli +++ b/mllib/common_utils.mli @@ -106,6 +106,9 @@ val display_long_options : unit -> 'a val compare_version : string -> string -> int (** Compare two version strings. *) +val compare_lvm2_uuids : string -> string -> int +(** Compare two LVM2 UUIDs, ignoring '-' characters. *) + val external_command : prog:string -> string -> string list (** Run an external command, slurp up the output as a list of lines. *) -- 2.1.0