[Libguestfs] [RFC PATCH v1 2/3] daemon: devsparts: add is_partitioned_device function

[Mykola Ivanets]

The function takes one argument - device path (e.g. /dev/sda) and returns true if device contains partition(s) or false otherwise. The function look in /sys/block/<device>/ for entries starting with <device>, eg. /sys/block/sda/sda1.
---
 daemon/devsparts.ml  | 14 ++++++++++++++
 daemon/devsparts.mli |  1 +
 2 files changed, 15 insertions(+)

diff --git a/daemon/devsparts.ml b/daemon/devsparts.ml
index 54108bb..60ac11a 100644
--- a/daemon/devsparts.ml
+++ b/daemon/devsparts.ml
@@ -71,6 +71,20 @@ let list_devices () =
     map_block_devices ~return_md:false ((^) "/dev/") in
   sort_device_names devices
 
+let is_partitioned_device device =
+  assert (String.is_prefix device "/dev/");
+  assert (not (String.is_prefix device "/dev/mapper/"));
+  let device = String.sub device 5 (String.length device - 5) in
+
+  (* Open the device's directory under /sys/block *)
+  let parts = Sys.readdir ("/sys/block/" ^ device) in
+  let parts = Array.to_list parts in
+
+  (* Look in /sys/block/<device>/ for entries starting with
+   * <device>, eg. /sys/block/sda/sda1.
+   *)
+  List.exists (fun part -> String.is_prefix part device) parts
+
 let rec list_partitions () =
   let partitions = map_block_devices ~return_md:true add_partitions in
   let partitions = List.flatten partitions in
diff --git a/daemon/devsparts.mli b/daemon/devsparts.mli
index 7b669c2..d3224a1 100644
--- a/daemon/devsparts.mli
+++ b/daemon/devsparts.mli
@@ -21,5 +21,6 @@ val list_partitions : unit -> string list
 val part_to_dev : string -> string
 val part_to_partnum : string -> int
 val is_whole_device : string -> bool
+val is_partitioned_device : string -> bool
 val nr_devices : unit -> int
 val device_index : string -> int
-- 
2.9.5