[Libguestfs] [PATCH 1/2] Add simple handling of /etc/os-release

[Pino Toscano]

Introduce a simple module to read and cache fields of /etc/os-release
that might be needed, and there is only ID for now.
---
 src/Makefile.am    |  3 +++
 src/os_release.ml  | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/os_release.mli | 26 ++++++++++++++++++
 3 files changed, 107 insertions(+)
 create mode 100644 src/os_release.ml
 create mode 100644 src/os_release.mli

diff --git a/src/Makefile.am b/src/Makefile.am
index 11adf31..767117f 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -47,6 +47,8 @@ SOURCES = \
 	utils.ml \
 	utils.mli \
 	types.ml \
+	os_release.ml \
+	os_release.mli \
 	package_handler.ml \
 	package_handler.mli \
 	rpm.ml \
@@ -71,6 +73,7 @@ SOURCES_ML = \
 	config.ml \
 	utils.ml \
 	types.ml \
+	os_release.ml \
 	package_handler.ml \
 	rpm.ml \
 	dpkg.ml \
diff --git a/src/os_release.ml b/src/os_release.ml
new file mode 100644
index 0000000..b2de259
--- /dev/null
+++ b/src/os_release.ml
@@ -0,0 +1,78 @@
+(* supermin 5
+ * Copyright (C) 2016 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *)
+
+open Utils
+
+let split sep str =
+  let len = String.length sep in
+  let seplen = String.length str in
+  let i = find str sep in
+  if i = -1 then str, ""
+  else (
+    String.sub str 0 i, String.sub str (i + len) (seplen - i - len)
+  )
+
+type os_release = {
+  id : string;
+}
+
+let data = ref None
+let parsed = ref false
+
+let rec get_data () =
+  if !parsed = false then (
+    data := parse ();
+    parsed := true;
+  );
+
+  !data
+
+and parse () =
+  let file = "/etc/os-release" in
+  if Sys.file_exists file then (
+    let chan = open_in file in
+    let lines = input_all_lines chan in
+    close_in chan;
+    let lines = List.filter ((<>) "") lines in
+    let lines = List.filter (fun s -> s.[0] <> '#') lines in
+
+    let id = ref "" in
+
+    List.iter (
+      fun line ->
+        let field, value = split "=" line in
+        let value =
+          let len = String.length value in
+          if len > 1 &&
+             ((value.[0] = '"' && value.[len-1] = '"') ||
+              (value.[0] = '\'' && value.[len-1] = '\'')) then
+            String.sub value 1 (len - 2)
+          else value in
+        match field with
+        | "ID" -> id := value
+        | _ -> ()
+    ) lines;
+
+    Some { id = !id; }
+  ) else
+    None
+
+let get_id () =
+  match get_data () with
+  | None -> ""
+  | Some d -> d.id
diff --git a/src/os_release.mli b/src/os_release.mli
new file mode 100644
index 0000000..2ae349b
--- /dev/null
+++ b/src/os_release.mli
@@ -0,0 +1,26 @@
+(* supermin 5
+ * Copyright (C) 2016 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *)
+
+(** Handling of /etc/os-release. *)
+
+val get_id : unit -> string
+(** Get the value of the "ID" field from the /etc/os-release file
+    on the current system.
+
+    An empty string is returned if the file does not exist or cannot
+    be read. *)
-- 
2.7.4