Libguestfs - Sep 2017 - [supermin][PATCH v2] os-release: use ID_LIKE as a fallback for SUSE detection

SUSE distros all have in common suse in ID_LIKE field. The ID field
could be varying and is even set to 'Dummy' when building the packages.
If the usual values for openSUSE/SLE can't be found in ID, try with
ID_LIKE.
---
 Diff with v1:
   * Use Utils.string_split rather than too recent String.split_on_char

 src/os_release.ml  | 10 +++++++++-
 src/os_release.mli |  7 +++++++
 src/ph_rpm.ml      |  1 +
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/os_release.ml b/src/os_release.ml
index b2de259..abf2bea 100644
--- a/src/os_release.ml
+++ b/src/os_release.ml
@@ -29,6 +29,7 @@ let split sep str  
 type os_release = {
   id : string;
+  id_like : string list;
 }
 
 let data = ref None
@@ -52,6 +53,7 @@ and parse ()      let lines = List.filter (fun s -> s.[0]
<> '#') lines in
 
     let id = ref "" in
+    let id_like = ref [] in
 
     List.iter (
       fun line ->
@@ -65,10 +67,11 @@ and parse ()            else value in
         match field with
         | "ID" -> id := value
+        | "ID_LIKE" -> id_like := string_split " " value
         | _ -> ()
     ) lines;
 
-    Some { id = !id; }
+    Some { id = !id; id_like = !id_like }
   ) else
     None
 
@@ -76,3 +79,8 @@ let get_id ()    match get_data () with
   | None -> ""
   | Some d -> d.id
+
+let get_id_like () +  match get_data () with
+  | None -> []
+  | Some d -> d.id_like
diff --git a/src/os_release.mli b/src/os_release.mli
index 2ae349b..e9f2993 100644
--- a/src/os_release.mli
+++ b/src/os_release.mli
@@ -24,3 +24,10 @@ val get_id : unit -> string
 
     An empty string is returned if the file does not exist or cannot
     be read. *)
+
+val get_id_like : unit -> string list
+(** Get the value of the "ID_LIKE" field from the /etc/os-release
file
+    on the current system.
+
+    An empty list is returned if the file does not exist, cannot
+    be read or the ID_LIKE field is not defined. *)
diff --git a/src/ph_rpm.ml b/src/ph_rpm.ml
index b0a5eb2..fd87822 100644
--- a/src/ph_rpm.ml
+++ b/src/ph_rpm.ml
@@ -41,6 +41,7 @@ let opensuse_detect ()    Config.rpm <> "no"
&& Config.rpm2cpio <> "no" && rpm_is_available
() &&
     Config.zypper <> "no" &&
     (List.mem (Os_release.get_id ()) [ "opensuse"; "sled";
"sles" ] ||
+     List.mem "suse" (Os_release.get_id_like ()) ||
      try (stat "/etc/SuSE-release").st_kind = S_REG with Unix_error _
-> false)
 
 let mageia_detect () -- 
2.13.2