In order to add caching of the nbdkit capabilities, we will need to
compare against file modification times, etc. So look up this
information when creating the nbdkit caps.

Add a nbdkit_moddir build option to allow the builder to specify the
location to look for nbdkit plugins and filters.

Signed-off-by: Jonathon Jongsma <jjongsma@redhat.com>
---
 meson.build            |  6 ++++++
 meson_options.txt      |  1 +
 src/qemu/qemu_nbdkit.c | 39 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 46 insertions(+)

diff --git a/meson.build b/meson.build
index 0b3187ad88..2b0425f1f6 100644
--- a/meson.build
+++ b/meson.build
@@ -1744,6 +1744,12 @@ if not get_option('driver_qemu').disabled()
       qemu_dbus_daemon_path = '/usr/bin/dbus-daemon'
     endif
     conf.set_quoted('QEMU_DBUS_DAEMON', qemu_dbus_daemon_path)
+
+    nbdkit_moddir = get_option('nbdkit_moddir')
+    if nbdkit_moddir == ''
+      nbdkit_moddir = libdir / 'nbdkit'
+    endif
+    conf.set_quoted('NBDKIT_MODDIR', nbdkit_moddir)
   endif
 endif
 
diff --git a/meson_options.txt b/meson_options.txt
index 5b43cdbd6b..382174bc03 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -71,6 +71,7 @@ option('driver_vbox', type: 'feature', value: 'auto', description: 'VirtualBox X
 option('vbox_xpcomc_dir', type: 'string', value: '', description: 'Location of directory containing VirtualBox XPCOMC library')
 option('driver_vmware', type: 'feature', value: 'auto', description: 'VMware driver')
 option('driver_vz', type: 'feature', value: 'auto', description: 'Virtuozzo driver')
+option('nbdkit_moddir', type: 'string', value: '', description: 'set the directory where nbdkit modules are located')
 
 option('secdriver_apparmor', type: 'feature', value: 'auto', description: 'use AppArmor security driver')
 option('apparmor_profiles', type: 'feature', value: 'auto', description: 'install apparmor profiles')
diff --git a/src/qemu/qemu_nbdkit.c b/src/qemu/qemu_nbdkit.c
index f55f68299f..0ea1b754cd 100644
--- a/src/qemu/qemu_nbdkit.c
+++ b/src/qemu/qemu_nbdkit.c
@@ -42,6 +42,9 @@
 
 VIR_LOG_INIT("qemu.nbdkit");
 
+#define NBDKIT_PLUGINDIR NBDKIT_MODDIR "/plugins"
+#define NBDKIT_FILTERDIR NBDKIT_MODDIR "/filters"
+
 VIR_ENUM_IMPL(qemuNbdkitCaps,
     QEMU_NBDKIT_CAPS_LAST,
     /* 0 */
@@ -55,6 +58,11 @@ struct _qemuNbdkitCaps {
 
     char *path;
     char *version;
+    time_t ctime;
+    time_t libvirtCtime;
+    time_t pluginDirMtime;
+    time_t filterDirMtime;
+    unsigned int libvirtVersion;
 
     virBitmap *flags;
 };
@@ -177,9 +185,40 @@ qemuNbdkitCapsNew(const char *path)
 }
 
 
+static time_t
+getDirMtime(const char *moddir)
+{
+    struct stat st;
+
+    if (stat(moddir, &st) < 0) {
+        VIR_DEBUG("Failed to stat nbdkit module directory '%s': %s",
+                  moddir,
+                  g_strerror(errno));
+        return 0;
+    }
+
+    return st.st_mtime;
+}
+
+
 static void
 qemuNbdkitCapsQuery(qemuNbdkitCaps *caps)
 {
+    struct stat st;
+
+    if (stat(caps->path, &st) < 0) {
+        VIR_DEBUG("Failed to stat nbdkit binary '%s': %s",
+                  caps->path,
+                  g_strerror(errno));
+        caps->ctime  = 0;
+    } else  {
+        caps->ctime = st.st_ctime;
+    }
+    caps->filterDirMtime = getDirMtime(NBDKIT_FILTERDIR);
+    caps->pluginDirMtime = getDirMtime(NBDKIT_PLUGINDIR);
+    caps->libvirtCtime = virGetSelfLastChanged();
+    caps->libvirtVersion = LIBVIR_VERSION_NUMBER;
+
     qemuNbdkitCapsQueryPlugins(caps);
     qemuNbdkitCapsQueryFilters(caps);
     qemuNbdkitCapsQueryVersion(caps);
-- 
2.37.1

On Wed, Aug 31, 2022 at 13:40:48 -0500, Jonathon Jongsma wrote:
> In order to add caching of the nbdkit capabilities, we will need to
> compare against file modification times, etc. So look up this
> information when creating the nbdkit caps.
> 
> Add a nbdkit_moddir build option to allow the builder to specify the
> location to look for nbdkit plugins and filters.
> 
> Signed-off-by: Jonathon Jongsma <jjongsma@redhat.com>
> ---
>  meson.build            |  6 ++++++
>  meson_options.txt      |  1 +
>  src/qemu/qemu_nbdkit.c | 39 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 46 insertions(+)


> @@ -177,9 +185,40 @@ qemuNbdkitCapsNew(const char *path)
>  }
>  
>  
> +static time_t
> +getDirMtime(const char *moddir)

Missing file prefix in function name.

> +{
> +    struct stat st;
> +
> +    if (stat(moddir, &st) < 0) {
> +        VIR_DEBUG("Failed to stat nbdkit module directory '%s': %s",
> +                  moddir,
> +                  g_strerror(errno));
> +        return 0;
> +    }
> +
> +    return st.st_mtime;
> +}
> +
> +
>  static void
>  qemuNbdkitCapsQuery(qemuNbdkitCaps *caps)
>  {
> +    struct stat st;
> +
> +    if (stat(caps->path, &st) < 0) {
> +        VIR_DEBUG("Failed to stat nbdkit binary '%s': %s",
> +                  caps->path,
> +                  g_strerror(errno));
> +        caps->ctime  = 0;

So does attempting to query the capabilities make sense after this
point?

> +    } else  {
> +        caps->ctime = st.st_ctime;
> +    }
> +    caps->filterDirMtime = getDirMtime(NBDKIT_FILTERDIR);
> +    caps->pluginDirMtime = getDirMtime(NBDKIT_PLUGINDIR);
> +    caps->libvirtCtime = virGetSelfLastChanged();
> +    caps->libvirtVersion = LIBVIR_VERSION_NUMBER;
> +
>      qemuNbdkitCapsQueryPlugins(caps);
>      qemuNbdkitCapsQueryFilters(caps);
>      qemuNbdkitCapsQueryVersion(caps);
> -- 
> 2.37.1
>