Libguestfs - Nov 2009 - [PATCH] daemon/RHEL: Choose correct udev settle script.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
New in Fedora 11: Fedora Windows cross-compiler. Compile Windows
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>From 018e8b562b3980a002bd2f9c42cf7dab541ac005 Mon Sep 17 00:00:00 2001
From: Richard Jones <rjones at centos5x32.home.annexia.org>
Date: Wed, 18 Nov 2009 16:02:53 +0000
Subject: [PATCH] daemon/RHEL: Choose correct udev settle script.

On RHEL/CentOS 5.4, udevadm settle command does not work.  This didn't
affect us before, but now that we're using parted for partitioning, we
*do* need to wait for udev to settle (because parted isn't waiting for
this, unlike sfdisk).

This commit chooses the correct program to run.
---
 daemon/guestfsd.c |   22 +++++++++++++++++++++-
 1 files changed, 21 insertions(+), 1 deletions(-)

diff --git a/daemon/guestfsd.c b/daemon/guestfsd.c
index db0bff9..9375ede 100644
--- a/daemon/guestfsd.c
+++ b/daemon/guestfsd.c
@@ -976,5 +976,25 @@ device_name_translation (char *device, const char *func)
 void
 udev_settle (void)
 {
-  command (NULL, NULL, "/sbin/udevadm", "settle", NULL);
+  static int which_prog = 0;
+
+  if (which_prog == 0) {
+    if (access ("/sbin/udevsettle", X_OK) == 0)
+      which_prog = 2;
+    else if (access ("/sbin/udevadm", X_OK) == 0)
+      which_prog = 1;
+    else
+      which_prog = 3;
+  }
+
+  switch (which_prog) {
+  case 1:
+    command (NULL, NULL, "/sbin/udevadm", "settle", NULL);
+    break;
+  case 2:
+    command (NULL, NULL, "/sbin/udevsettle", NULL);
+    break;
+  default:
+    ;
+  }
 }
-- 
1.5.5.6

Richard W.M. Jones wrote:
> Subject: [PATCH] daemon/RHEL: Choose correct udev settle script.
>
> On RHEL/CentOS 5.4, udevadm settle command does not work.  This didn't
> affect us before, but now that we're using parted for partitioning, we
> *do* need to wait for udev to settle (because parted isn't waiting for
> this, unlike sfdisk).
>
> This commit chooses the correct program to run.
> ---
>  daemon/guestfsd.c |   22 +++++++++++++++++++++-
>  1 files changed, 21 insertions(+), 1 deletions(-)
>
> diff --git a/daemon/guestfsd.c b/daemon/guestfsd.c
> index db0bff9..9375ede 100644
> --- a/daemon/guestfsd.c
> +++ b/daemon/guestfsd.c
> @@ -976,5 +976,25 @@ device_name_translation (char *device, const char
*func)
>  void
>  udev_settle (void)
>  {
> -  command (NULL, NULL, "/sbin/udevadm", "settle",
NULL);
> +  static int which_prog = 0;
> +
> +  if (which_prog == 0) {
> +    if (access ("/sbin/udevsettle", X_OK) == 0)
> +      which_prog = 2;
> +    else if (access ("/sbin/udevadm", X_OK) == 0)
> +      which_prog = 1;
> +    else
> +      which_prog = 3;
> +  }
> +  switch (which_prog) {
> +  case 1:
> +    command (NULL, NULL, "/sbin/udevadm", "settle",
NULL);
> +    break;
> +  case 2:
> +    command (NULL, NULL, "/sbin/udevsettle", NULL);
> +    break;
> +  default:
> +    ;
> +  }
Looks fine.
Only thought was "why bother with the static var and separate switch"
just to save a call or two to access.  If you're about to invoke
one of those programs, the expense of a syscall is nil.