Rather than passing the next-to-use file descriptor set Id
and the hash table for remembering the mappings of aliases to
file descriptor sets around, encapsulate the two in a class.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>

---
 v6->v7:
  - followed Eric's & Corey's comments on v6

 v5->v6:
  - following to changeset 2e5d7798df

 v4->v5:
  - followed Daniel Berrange's comments
  - converted to virObject
  - provide virFdSetNew

---
 src/Makefile.am          |    1 
 src/libvirt_private.syms |    8 ++
 src/util/virfdset.c      |  179 +++++++++++++++++++++++++++++++++++++++++++++++
 src/util/virfdset.h      |   94 ++++++++++++++++++++++++
 4 files changed, 282 insertions(+)

Index: libvirt/src/util/virfdset.c
===================================================================
--- /dev/null
+++ libvirt/src/util/virfdset.c
@@ -0,0 +1,179 @@
+/*
+ * virfdset.c: File descriptor set support
+ *
+ * Copyright (C) 2013 IBM Corporation
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * Author: Stefan Berger <stefanb@linux.vnet.ibm.com>
+ */
+
+#include <config.h>
+
+#include "virfdset.h"
+#include "virobject.h"
+#include "viralloc.h"
+#include "virutil.h"
+#include "virerror.h"
+#include "virbuffer.h"
+
+#define VIR_FROM_THIS VIR_FROM_NONE
+
+
+struct _virFdSet {
+    virObject object;
+    virHashTablePtr aliasToFdSet;
+    unsigned int nextfdset;
+};
+
+static virClassPtr virFdSetClass;
+static void virFdSetDispose(void *obj);
+
+static int virFdSetOnceInit(void)
+{
+    if (!(virFdSetClass = virClassNew(virClassForObject(),
+                                      "virFdSet",
+                                      sizeof(virFdSet),
+                                      virFdSetDispose)))
+        return -1;
+
+    return 0;
+}
+
+VIR_ONCE_GLOBAL_INIT(virFdSet)
+
+static void virFdSetDispose(void *obj)
+{
+    virFdSetPtr fdset = obj;
+
+    virHashFree(fdset->aliasToFdSet);
+}
+
+virFdSetPtr virFdSetNew(void)
+{
+    virFdSetPtr fdset;
+
+    if (virFdSetInitialize() < 0)
+        return NULL;
+
+    if (!(fdset = virObjectNew(virFdSetClass)))
+        return NULL;
+
+    if (!(fdset->aliasToFdSet = virHashCreate(10, NULL))) {
+        virObjectUnref(fdset);
+        return NULL;
+    }
+    fdset->nextfdset = 1;
+
+    return fdset;
+}
+
+static void virFdSetReset(virFdSetPtr fdset)
+{
+    virHashRemoveAll(fdset->aliasToFdSet);
+    fdset->nextfdset = 1;
+}
+
+void virFdSetRemoveAlias(virFdSetPtr fdset, const char *alias)
+{
+   virHashRemoveEntry(fdset->aliasToFdSet, alias);
+}
+
+int virFdSetNextSet(virFdSetPtr fdset, const char *alias,
+                    unsigned int *fdsetnum)
+{
+    if (virHashAddEntry(fdset->aliasToFdSet, alias,
+                        (void *)(intptr_t)fdset->nextfdset) < 0)
+        return -1;
+
+    *fdsetnum = fdset->nextfdset++;
+
+    return 0;
+}
+
+static void virFdSetPrintAliasToFdSet(void *payload,
+                                      const void *name,
+                                      void *data)
+{
+    virBufferPtr buf = data;
+
+    virBufferAsprintf(buf, "  <entry alias='%s' fdset='%u'/>\n",
+                      (char *)name,
+                      (unsigned int)(intptr_t)payload);
+}
+
+void virFdSetFormatXML(virFdSetPtr fdset, virBufferPtr buf)
+{
+    virBufferAsprintf(buf, "<fdsets>\n");
+    virHashForEach(fdset->aliasToFdSet, virFdSetPrintAliasToFdSet, buf);
+    virBufferAsprintf(buf, "</fdsets>\n");
+}
+
+int virFdSetParseXML(virFdSetPtr fdset, const char *xPath,
+                     xmlXPathContextPtr ctxt)
+{
+    xmlNodePtr *nodes = NULL;
+    int n, i;
+    char *key = NULL;
+    char *val = NULL;
+    unsigned int fdsetnum;
+    int ret = -1;
+
+    virFdSetReset(fdset);
+
+    if ((n = virXPathNodeSet(xPath, ctxt, &nodes)) < 0) {
+        /* nothing to parse is not an error */
+        ret = 0;
+        goto cleanup;
+    }
+
+    if (n > 0) {
+        for (i = 0 ; i < n ; i++) {
+            key = virXMLPropString(nodes[i], "alias");
+            val = virXMLPropString(nodes[i], "fdset");
+            if (key && val) {
+                if (virStrToLong_ui(val, NULL, 10, &fdsetnum) < 0) {
+                    virReportError(VIR_ERR_INTERNAL_ERROR,
+                                   _("incorrect fdset '%s', expected positive"
+                                   "integer"), val);
+                    goto cleanup;
+                }
+
+                if (fdset->nextfdset <= fdsetnum)
+                    fdset->nextfdset = fdsetnum + 1;
+
+                if (virHashAddEntry(fdset->aliasToFdSet, key,
+                                    (void *)(intptr_t)&fdsetnum) < 0) {
+                    virReportOOMError();
+                    goto cleanup;
+                }
+            }
+            VIR_FREE(key);
+            VIR_FREE(val);
+        }
+    }
+
+    ret = 0;
+
+cleanup:
+    if (ret < 0)
+        virFdSetReset(fdset);
+
+    VIR_FREE(nodes);
+    VIR_FREE(key);
+    VIR_FREE(val);
+
+    return ret;
+}
Index: libvirt/src/util/virfdset.h
===================================================================
--- /dev/null
+++ libvirt/src/util/virfdset.h
@@ -0,0 +1,94 @@
+/*
+ * virfdset.h: File descriptor set support
+ *
+ * Copyright (C) 2013 IBM Corporation
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * Author: Stefan Berger <stefanb@linux.vnet.ibm.com>
+ */
+#ifndef __FDSET_H__
+# define __FDSET_H__
+
+# include "internal.h"
+# include "virbuffer.h"
+# include "virxml.h"
+# include "virhash.h"
+
+typedef struct _virFdSet virFdSet;
+typedef virFdSet *virFdSetPtr;
+
+
+/**
+ * virFdSetNew
+ *
+ * Create a new FdSet,
+ * Returns pointer to new FdSet on success, NULL if no memory was available.
+ */
+virFdSetPtr virFdSetNew(void) ATTRIBUTE_RETURN_CHECK;
+
+/**
+ * virFdSetRemoveAlias
+ * @fdset: the fdset
+ * @alias: the alias to remove
+ *
+ * Remove the given alias' mapping from @fdset
+ */
+void virFdSetRemoveAlias(virFdSetPtr fdset, const char *alias)
+     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
+
+
+/**
+ * virFdSetNextSet
+ * @fdset: fdset
+ * @alias: device alias
+ * @fdsetnum: pointer to unsigned int for storing the file descriptor set id
+ *
+ * Get the next file descriptor set number and store it with the given
+ * @alias. If successful, return the file descriptor set id in @fdsetnum.
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+int virFdSetNextSet(virFdSetPtr fdset, const char *alias,
+                    unsigned int *fdsetnum)
+     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3)
+     ATTRIBUTE_RETURN_CHECK;
+
+/**
+ * virFdSetFormatXML
+ * @fdset: fdset
+ * @buf: virBufferPtr for writing into
+ *
+ * Write XML representation of the @fdset into the buffer @buf.
+ */
+void virFdSetFormatXML(virFdSetPtr fdset, virBufferPtr buf)
+     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
+
+/**
+ * virFdSetParseXML
+ * @fdset: fdset
+ * @xPath: xpath expression to find the @fdset's XML nodes
+ * @ctxt: xpath context
+ *
+ * Parse the fdset XML representation and collect the data into @fdset.
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+int virFdSetParseXML(virFdSetPtr fdset, const char *xPath,
+                     xmlXPathContextPtr ctxt)
+     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3)
+     ATTRIBUTE_RETURN_CHECK;
+
+#endif
Index: libvirt/src/Makefile.am
===================================================================
--- libvirt.orig/src/Makefile.am
+++ libvirt/src/Makefile.am
@@ -79,6 +79,7 @@ UTIL_SOURCES =							\
 		util/virerror.c util/virerror.h			\
 		util/virevent.c util/virevent.h			\
 		util/vireventpoll.c util/vireventpoll.h		\
+		util/virfdset.c util/virfdset.h			\
 		util/virfile.c util/virfile.h			\
 		util/virhash.c util/virhash.h			\
 		util/virhashcode.c util/virhashcode.h		\
Index: libvirt/src/libvirt_private.syms
===================================================================
--- libvirt.orig/src/libvirt_private.syms
+++ libvirt/src/libvirt_private.syms
@@ -650,6 +650,14 @@ virFDStreamOpen;
 virFDStreamOpenFile;
 
 
+# virfdset.h
+virFdSetFormatXML;
+virFdSetNew;
+virFdSetNextSet;
+virFdSetParseXML;
+virFdSetRemoveAlias;
+
+
 # hash.h
 virHashAddEntry;
 virHashCreate;