Libguestfs - Jun 2015 - [PATCH v2 0/3] daemon: parted: Always use -s option even with -m.

version 2:

 - Turn the "unrecognised disk label" error into errno == EINVAL

 - Fix virt-alignment-scan

 - Rework the fix for virt-v2v bug 1232192 (see description of patch 3/3)

See: https://bugzilla.redhat.com/show_bug.cgi?id=1232241#c3

However adding the -s parameter changes the error code returned by
parted when it processes a blank disk (or other unrecognized partition
table).  Without -s it prints an error but returns a non-error exit
code (0).  With -s it prints an error and return an error exit code.

Because it's useful to be able to catch this case in user code, turn
"unrecognised disk label" into EINVAL.

Change virt-alignment-scan to catch this error and ignore it.
---
 align/scan.c    | 14 ++++++++++----
 daemon/parted.c | 14 ++++++++++----
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/align/scan.c b/align/scan.c
index 202b148..188450c 100644
--- a/align/scan.c
+++ b/align/scan.c
@@ -282,11 +282,17 @@ scan (guestfs_h *g, const char *prefix, FILE *fp)
 
   for (i = 0; devices[i] != NULL; ++i) {
     CLEANUP_FREE char *name = NULL;
+    CLEANUP_FREE_PARTITION_LIST struct guestfs_partition_list *parts = NULL;
 
-    CLEANUP_FREE_PARTITION_LIST struct guestfs_partition_list *parts -     
guestfs_part_list (g, devices[i]);
-    if (parts == NULL)
-      return -1;
+    guestfs_push_error_handler (g, NULL, NULL);
+    parts = guestfs_part_list (g, devices[i]);
+    guestfs_pop_error_handler (g);
+    if (parts == NULL) {
+      if (guestfs_last_errno (g) == EINVAL) /* unrecognised disk label */
+        continue;
+      else
+        return -1;
+    }
 
     /* Canonicalize the name of the device for printing. */
     name = guestfs_canonical_device_name (g, devices[i]);
diff --git a/daemon/parted.c b/daemon/parted.c
index a36e4e7..b516067 100644
--- a/daemon/parted.c
+++ b/daemon/parted.c
@@ -356,7 +356,7 @@ print_partition_table (const char *device,
   int r;
 
   if (PARTED_OPT_HAS_M == parted_has_m_opt)
-    r = command (&out, &err, str_parted, "-m",
"--", device,
+    r = command (&out, &err, str_parted, "-m",
"-s", "--", device,
                  "unit", "b",
                  "print", NULL);
   else
@@ -364,9 +364,15 @@ print_partition_table (const char *device,
                  "unit", "b",
                  "print", NULL);
   if (r == -1) {
-    reply_with_error ("parted print: %s: %s", device,
-                      /* Hack for parted 1.x which sends errors to stdout. */
-                      *err ? err : out);
+    /* Hack for parted 1.x which sends errors to stdout. */
+    const char *msg = *err ? err : out;
+    int errcode = 0;
+
+    /* Translate "unrecognised disk label" into an errno code. */
+    if (msg && strstr (msg, "unrecognised disk label") !=
NULL)
+      errcode = EINVAL;
+
+    reply_with_error_errno (errcode, "parted print: %s: %s", device,
msg);
     free (out);
     return NULL;
   }
-- 
2.3.1

---
 generator/ocaml.ml | 3 +++
 ocaml/guestfs-c.c  | 8 ++++++++
 2 files changed, 11 insertions(+)

diff --git a/generator/ocaml.ml b/generator/ocaml.ml
index d2a4690..05c7456 100644
--- a/generator/ocaml.ml
+++ b/generator/ocaml.ml
@@ -132,6 +132,7 @@ val last_errno : t -> int
     which you can use to test the return value of {!Guestfs.last_errno}. *)
 
 module Errno : sig
+  val errno_EINVAL : int
   val errno_ENOTSUP : int
   val errno_EPERM : int
   val errno_ESRCH : int
@@ -286,6 +287,8 @@ external event_to_string : event list -> string
 external last_errno : t -> int = \"ocaml_guestfs_last_errno\"
 
 module Errno = struct
+  external einval : unit -> int = \"ocaml_guestfs_get_EINVAL\"
\"noalloc\"
+  let errno_EINVAL = einval ()
   external enotsup : unit -> int = \"ocaml_guestfs_get_ENOTSUP\"
\"noalloc\"
   let errno_ENOTSUP = enotsup ()
   external eperm : unit -> int = \"ocaml_guestfs_get_EPERM\"
\"noalloc\"
diff --git a/ocaml/guestfs-c.c b/ocaml/guestfs-c.c
index f1a941c..9603f04 100644
--- a/ocaml/guestfs-c.c
+++ b/ocaml/guestfs-c.c
@@ -63,6 +63,7 @@ value ocaml_guestfs_set_event_callback (value gv, value
closure, value events);
 value ocaml_guestfs_delete_event_callback (value gv, value eh);
 value ocaml_guestfs_event_to_string (value events);
 value ocaml_guestfs_last_errno (value gv);
+value ocaml_guestfs_get_EINVAL (value unitv);
 value ocaml_guestfs_get_ENOTSUP (value unitv);
 value ocaml_guestfs_get_EPERM (value unitv);
 value ocaml_guestfs_get_ESRCH (value unitv);
@@ -444,6 +445,13 @@ ocaml_guestfs_last_errno (value gv)
 
 /* NB: "noalloc" function. */
 value
+ocaml_guestfs_get_EINVAL (value unitv)
+{
+  return Val_int (EINVAL);
+}
+
+/* NB: "noalloc" function. */
+value
 ocaml_guestfs_get_ENOTSUP (value unitv)
 {
   return Val_int (ENOTSUP);
-- 
2.3.1

In commit 4c73d1d4f142c6f6211c963beea68773e11fd3ef, I changed the
behaviour of virt-v2v so it ignores all errors from the
g#part_get_parttype method.  However that would ignore I/O errors and
similar.

Only ignore the "unrecognised disk label" error from parted, by
testing if the return code is EINVAL.

This fixes commit 4c73d1d4f142c6f6211c963beea68773e11fd3ef.
---
 v2v/v2v.ml | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/v2v/v2v.ml b/v2v/v2v.ml
index 3f49f68..418c836 100644
--- a/v2v/v2v.ml
+++ b/v2v/v2v.ml
@@ -555,7 +555,9 @@ and inspect_source g root_choice        g#part_get_gpt_type
dev (Int32.to_int partnum) = uefi_ESP_guid
     and parttype_is_gpt dev        try g#part_get_parttype dev =
"gpt"
-      with G.Error msg ->
+      with G.Error msg as exn ->
+        (* If it's _not_ "unrecognised disk label" then re-raise
it. *)
+        if g#last_errno () <> G.Errno.errno_EINVAL then raise exn;
         if verbose () then printf "%s (ignored)\n" msg;
         false
     and is_uefi_bootable_device dev -- 
2.3.1