[Libguestfs] [PATCH v6 28/41] daemon: Reimplement ‘list_md_devices’ API in OCaml.

Richard W.M. Jones
Thu, 15 Jun 2017 17:06:18 -0000

---
 daemon/Makefile.am        |   2 +
 daemon/md.c               | 125 ++++++++++++----------------------------------
 daemon/md.ml              |  48 ++++++++++++++++++
 daemon/md.mli             |  19 +++++++
 generator/actions_core.ml |   1 +
 5 files changed, 101 insertions(+), 94 deletions(-)

diff --git a/daemon/Makefile.am b/daemon/Makefile.am
index 0525b4d72..0c5389557 100644
--- a/daemon/Makefile.am
+++ b/daemon/Makefile.am
@@ -268,6 +268,7 @@ SOURCES_MLI = \
 	ldm.mli \
 	link.mli \
 	lvm.mli \
+	md.mli \
 	mount.mli \
 	mountable.mli \
 	parted.mli \
@@ -288,6 +289,7 @@ SOURCES_ML = \
 	ldm.ml \
 	link.ml \
 	lvm.ml \
+	md.ml \
 	mount.ml \
 	parted.ml \
 	realpath.ml \
diff --git a/daemon/md.c b/daemon/md.c
index 64d98fae5..5c9ecd136 100644
--- a/daemon/md.c
+++ b/daemon/md.c
@@ -24,7 +24,6 @@
 #include <inttypes.h>
 #include <unistd.h>
 #include <fcntl.h>
-#include <glob.h>

 #ifdef HAVE_LINUX_RAID_MD_U_H
 #include <sys/ioctl.h>
@@ -32,6 +31,8 @@
 #include <linux/raid/md_u.h>
 #endif /* HAVE_LINUX_RAID_MD_U_H */

+#include <caml/mlvalues.h>
+
 #include "daemon.h"
 #include "actions.h"
 #include "optgroups.h"
@@ -45,6 +46,35 @@ optgroup_mdadm_available (void)
   return prog_exists (str_mdadm);
 }

+/* Check if 'dev' is a real RAID device, because in the case where md
+ * is linked directly into the kernel (not a module), /dev/md0 is
+ * sometimes created.  This is called from OCaml function
+ * Md.list_md_devices.
+ */
+extern value guestfs_int_daemon_is_raid_device (value devicev);
+
+/* NB: This is a "noalloc" call. */
+value
+guestfs_int_daemon_is_raid_device (value devv)
+{
+  const char *dev = String_val (devv);
+  int ret = 1;
+
+#if defined(HAVE_LINUX_RAID_MD_U_H) && defined(GET_ARRAY_INFO)
+  int fd;
+  mdu_array_info_t array;
+
+  fd = open (dev, O_RDONLY);
+  if (fd >= 0) {
+    if (ioctl (fd, GET_ARRAY_INFO, &array) == -1 && errno ==
ENODEV)
+      ret = 0;
+    close (fd);
+  }
+#endif
+
+  return Val_bool (ret);
+}
+
 static size_t
 count_bits (uint64_t bitmap)
 {
@@ -188,99 +218,6 @@ do_md_create (const char *name, char *const *devices,
 #pragma GCC diagnostic pop
 #endif

-static int
-glob_errfunc (const char *epath, int eerrno)
-{
-  fprintf (stderr, "glob: failure reading %s: %s\n", epath, strerror
(eerrno));
-  return 1;
-}
-
-/* Check if 'dev' is a real RAID device, because in the case where md
- * is linked directly into the kernel (not a module), /dev/md0 is
- * sometimes created.
- */
-static int
-is_raid_device (const char *dev)
-{
-  int ret = 1;
-
-#if defined(HAVE_LINUX_RAID_MD_U_H) && defined(GET_ARRAY_INFO)
-  int fd;
-  mdu_array_info_t array;
-
-  fd = open (dev, O_RDONLY);
-  if (fd >= 0) {
-    if (ioctl (fd, GET_ARRAY_INFO, &array) == -1 && errno ==
ENODEV)
-      ret = 0;
-    close (fd);
-  }
-#endif
-
-  return ret;
-}
-
-char **
-do_list_md_devices (void)
-{
-  CLEANUP_FREE_STRINGSBUF DECLARE_STRINGSBUF (ret);
-  glob_t mds;
-
-  memset (&mds, 0, sizeof mds);
-
-#define PREFIX "/sys/block/md"
-#define SUFFIX "/md"
-
-  /* Look for directories under /sys/block matching md[0-9]*
-   * As an additional check, we also make sure they have a md subdirectory.
-   */
-  const int err = glob (PREFIX "[0-9]*" SUFFIX, GLOB_ERR,
glob_errfunc, &mds);
-  if (err == GLOB_NOSPACE) {
-    reply_with_error ("glob: returned GLOB_NOSPACE: "
-                      "rerun with LIBGUESTFS_DEBUG=1");
-    goto error;
-  } else if (err == GLOB_ABORTED) {
-    reply_with_error ("glob: returned GLOB_ABORTED: "
-                      "rerun with LIBGUESTFS_DEBUG=1");
-    goto error;
-  }
-
-  for (size_t i = 0; i < mds.gl_pathc; i++) {
-    size_t len;
-    char *dev, *n;
-
-    len = strlen (mds.gl_pathv[i]) - strlen (PREFIX) - strlen (SUFFIX);
-
-#define DEV "/dev/md"
-    dev = malloc (strlen (DEV) + len + 1);
-    if (NULL == dev) {
-      reply_with_perror ("malloc");
-      goto error;
-    }
-
-    n = dev;
-    n = mempcpy (n, DEV, strlen (DEV));
-    n = mempcpy (n, &mds.gl_pathv[i][strlen (PREFIX)], len);
-    *n = '\0';
-
-    if (!is_raid_device (dev)) {
-      free (dev);
-      continue;
-    }
-
-    if (add_string_nodup (&ret, dev) == -1) goto error;
-  }
-
-  if (end_stringsbuf (&ret) == -1) goto error;
-  globfree (&mds);
-
-  return take_stringsbuf (&ret);
-
- error:
-  globfree (&mds);
-
-  return NULL;
-}
-
 char **
 do_md_detail (const char *md)
 {
diff --git a/daemon/md.ml b/daemon/md.ml
new file mode 100644
index 000000000..caf87cf8f
--- /dev/null
+++ b/daemon/md.ml
@@ -0,0 +1,48 @@
+(* guestfs-inspection
+ * Copyright (C) 2009-2017 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 Printf
+
+open Std_utils
+
+open Utils
+
+external is_raid_device : string -> bool +
"guestfs_int_daemon_is_raid_device" "noalloc"
+
+let re_md = Str.regexp "^md[0-9]+$"
+
+let list_md_devices () +  (* Look for directories under /sys/block matching
md[0-9]+
+   * As an additional check, we also make sure they have a md subdirectory.
+   *)
+  let devs = Sys.readdir "/sys/block" in
+  let devs = Array.to_list devs in
+  let devs = List.filter (fun d -> Str.string_match re_md d 0) devs in
+  let devs = List.filter (
+    fun d -> is_directory (sprintf "/sys/block/%s/md" d)
+  ) devs in
+
+  (* Construct the equivalent /dev/md[0-9]+ device names. *)
+  let devs = List.map ((^) "/dev/") devs in
+
+  (* Check they are really RAID devices. *)
+  let devs = List.filter is_raid_device devs in
+
+  (* Return the list sorted. *)
+  sort_device_names devs
diff --git a/daemon/md.mli b/daemon/md.mli
new file mode 100644
index 000000000..56b6ea65e
--- /dev/null
+++ b/daemon/md.mli
@@ -0,0 +1,19 @@
+(* guestfs-inspection
+ * Copyright (C) 2009-2017 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.
+ *)
+
+val list_md_devices : unit -> string list
diff --git a/generator/actions_core.ml b/generator/actions_core.ml
index f6f006eee..140ba6c1b 100644
--- a/generator/actions_core.ml
+++ b/generator/actions_core.ml
@@ -6632,6 +6632,7 @@ If not set, this defaults to C<raid1>.
   { defaults with
     name = "list_md_devices"; added = (1, 15, 4);
     style = RStringList (RDevice, "devices"), [], [];
+    impl = OCaml "Md.list_md_devices";
     shortdesc = "list Linux md (RAID) devices";
     longdesc = "\
 List all Linux md devices." };
--
2.13.0