Now that each of the 3 callers to "query-block" has relatively the same
flow, combine the remaining flow into qemuMonitorJSONQueryBlock and of
course rework the function comments to describe the expectations.

The qemuMonitorJSONQueryBlock will now take multiple parameters, "blindly"
building up the qemuMonitorJSONQueryBlockArgs, and then calling the
specific callback for each of the three consumers.

Each of the callers is essentially reduced to a shim calling the common
function with its specific qemuMonitorJSONQueryBlockFill* helper to
handle the needs for the specific caller.

NB: Also adjust the first "error message in the devices parsing loop
    to make it easier to distinguish which failure occurred.

Signed-off-by: John Ferlan <jfer...@redhat.com>
---
 src/qemu/qemu_monitor_json.c | 222 +++++++++++++++++--------------------------
 1 file changed, 89 insertions(+), 133 deletions(-)

diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
index 24fb397..357660a 100644
--- a/src/qemu/qemu_monitor_json.c
+++ b/src/qemu/qemu_monitor_json.c
@@ -142,6 +142,8 @@ struct _qemuMonitorJSONQueryBlockArgs {
     char *foundDevice;
 };
 
+typedef int 
(*qemuMonitorJSONQueryBlockFillCallback)(qemuMonitorJSONQueryBlockArgsPtr args);
+
 static int
 qemuMonitorEventCompare(const void *key, const void *elt)
 {
@@ -1787,29 +1789,97 @@ qemuMonitorJSONSetMemoryStatsPeriod(qemuMonitorPtr mon,
 
 /* qemuMonitorJSONQueryBlock:
  * @mon: Monitor pointer
+ * @table: The hash table pointer to insert a device into
+ * @backingChain: Boolean whether to follow backing chaing
+ * @searchDevice: Specific device name to search on
+ * @top: Top of a chain to start looking
+ * @target: The backing element target
+ * @foundDevice: Pointer to address of returned found device string
+ * @cb: The callback function to fill in the specific data needs
+ *
+ * This helper will attempt to make a "query-block" call, check for
+ * errors, and scan the reply list of devices calling out the @cb program
+ * in order to perform the action on the element.
+ *
+ * The function can be used in one of two ways - either passing a hash
+ * @table and whether to search the backing chain in order to fill in the
+ * hash table with all the found devices or to pass a @searchDevice, @top,
+ * and @target in order to search the returned data for a specific device
+ * and return the @foundDevice string.
  *
- * This helper will attempt to make a "query-block" call and check for
- * errors before returning with the reply.
+ * The @cb program is expected to return -1 for error and quit, 0 for
+ * good status and continue, and 1 for good status and return. The caller
+ * for usage of @foundDevice is expected to pass a non-NULL argument.
  *
- * Returns: NULL on error, reply on success
+ * Returns: -1 on error, 0 on success
  */
-static virJSONValuePtr
-qemuMonitorJSONQueryBlock(qemuMonitorPtr mon)
+static int
+qemuMonitorJSONQueryBlock(qemuMonitorPtr mon,
+                          virHashTablePtr table,
+                          bool backingChain,
+                          const char *searchDevice,
+                          virStorageSourcePtr top,
+                          virStorageSourcePtr target,
+                          char **foundDevice,
+                          qemuMonitorJSONQueryBlockFillCallback cb)
 {
+    int ret = -1;
+    size_t i;
     virJSONValuePtr cmd;
     virJSONValuePtr reply = NULL;
+    virJSONValuePtr devices;
 
     if (!(cmd = qemuMonitorJSONMakeCommand("query-block", NULL)))
-        return NULL;
+        return -1;
 
     if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0 ||
-        qemuMonitorJSONCheckError(cmd, reply) < 0) {
-        virJSONValueFree(reply);
-        reply = NULL;
+        qemuMonitorJSONCheckError(cmd, reply) < 0)
+        goto cleanup;
+
+    if (!(devices = virJSONValueObjectGetArray(reply, "return"))) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("block info reply was missing device list"));
+        goto cleanup;
+    }
+
+    for (i = 0; i < virJSONValueArraySize(devices); i++) {
+        int rc;
+        qemuMonitorJSONQueryBlockArgs args = {0};
+
+        args.dev = virJSONValueArrayGet(devices, i);
+        if (!args.dev || args.dev->type != VIR_JSON_TYPE_OBJECT) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("block info device or type was not in "
+                             "expected format"));
+            goto cleanup;
+        }
+
+        if (!(args.thisdev = virJSONValueObjectGetString(args.dev, "device"))) 
{
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("block info device entry was not in "
+                             "expected format"));
+            goto cleanup;
+        }
+
+        args.table = table;
+        args.backingChain = backingChain;
+        args.searchDevice = searchDevice;
+        args.top = top;
+        args.target = target;
+        if ((rc = cb(&args)) < 0)
+            goto cleanup;
+
+        if (rc == 1) {
+            *foundDevice = args.foundDevice;
+            break;
+        }
     }
+    ret = 0;
 
+ cleanup:
+    virJSONValueFree(reply);
     virJSONValueFree(cmd);
-    return reply;
+    return ret;
 }
 
 
@@ -1876,46 +1946,9 @@ 
qemuMonitorJSONQueryBlockFillBlockInfoTable(qemuMonitorJSONQueryBlockArgsPtr arg
 int qemuMonitorJSONGetBlockInfo(qemuMonitorPtr mon,
                                 virHashTablePtr table)
 {
-    int ret = -1;
-    size_t i;
-
-    virJSONValuePtr reply;
-    virJSONValuePtr devices;
-
-    if (!(reply = qemuMonitorJSONQueryBlock(mon)))
-        return -1;
-
-    if (!(devices = virJSONValueObjectGetArray(reply, "return"))) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                       _("block info reply was missing device list"));
-        goto cleanup;
-    }
-
-    for (i = 0; i < virJSONValueArraySize(devices); i++) {
-        qemuMonitorJSONQueryBlockArgs args = {0};
-
-        args.dev = virJSONValueArrayGet(devices, i);
-        if (!args.dev || args.dev->type != VIR_JSON_TYPE_OBJECT) {
-            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                           _("block info device entry was not in expected 
format"));
-            goto cleanup;
-        }
-
-        if (!(args.thisdev = virJSONValueObjectGetString(args.dev, "device"))) 
{
-            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                           _("block info device entry was not in expected 
format"));
-            goto cleanup;
-        }
-
-        args.table = table;
-        if (qemuMonitorJSONQueryBlockFillBlockInfoTable(&args) < 0)
-            goto cleanup;
-    }
-
-    ret = 0;
- cleanup:
-    virJSONValueFree(reply);
-    return ret;
+    return qemuMonitorJSONQueryBlock(mon, table, false,
+                                     NULL, NULL, NULL, NULL,
+                                     
qemuMonitorJSONQueryBlockFillBlockInfoTable);
 }
 
 
@@ -2135,49 +2168,9 @@ qemuMonitorJSONBlockStatsUpdateCapacity(qemuMonitorPtr 
mon,
                                         virHashTablePtr stats,
                                         bool backingChain)
 {
-    int ret = -1;
-    size_t i;
-    virJSONValuePtr reply;
-    virJSONValuePtr devices;
-
-    if (!(reply = qemuMonitorJSONQueryBlock(mon)))
-        return -1;
-
-    if (!(devices = virJSONValueObjectGetArray(reply, "return"))) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                       _("query-block reply was missing device list"));
-        goto cleanup;
-    }
-
-    for (i = 0; i < virJSONValueArraySize(devices); i++) {
-        qemuMonitorJSONQueryBlockArgs args = {0};
-
-        args.dev = virJSONValueArrayGet(devices, i);
-        if (!args.dev || args.dev->type != VIR_JSON_TYPE_OBJECT) {
-            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                           _("query-block device entry was not "
-                             "in expected format"));
-            goto cleanup;
-        }
-
-        if (!(args.thisdev = virJSONValueObjectGetString(args.dev, "device"))) 
{
-            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                           _("query-block device entry was not "
-                             "in expected format"));
-            goto cleanup;
-        }
-
-        args.table = stats;
-        args.backingChain = backingChain;
-        if (qemuMonitorJSONQueryBlockFillBlockStatsTable(&args) < 0)
-            goto cleanup;
-    }
-
-    ret = 0;
-
- cleanup:
-    virJSONValueFree(reply);
-    return ret;
+    return qemuMonitorJSONQueryBlock(mon, stats, backingChain,
+                                     NULL, NULL, NULL, NULL,
+                                     
qemuMonitorJSONQueryBlockFillBlockStatsTable);
 }
 
 
@@ -4076,46 +4069,12 @@ qemuMonitorJSONDiskNameLookup(qemuMonitorPtr mon,
                               virStorageSourcePtr target)
 {
     char *ret = NULL;
-    virJSONValuePtr reply;
-    virJSONValuePtr devices;
-    size_t i;
 
-    if (!(reply = qemuMonitorJSONQueryBlock(mon)))
+    if (qemuMonitorJSONQueryBlock(mon, NULL, false,
+                                  device, top, target, &ret,
+                                  qemuMonitorJSONQueryBlockDiskNameLookup) < 0)
         return NULL;
 
-    if (!(devices = virJSONValueObjectGetArray(reply, "return"))) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                       _("block info reply was missing device list"));
-        goto cleanup;
-    }
-
-    for (i = 0; i < virJSONValueArraySize(devices); i++) {
-        qemuMonitorJSONQueryBlockArgs args = {0};
-        int rc;
-
-        args.dev = virJSONValueArrayGet(devices, i);
-        if (!args.dev || args.dev->type != VIR_JSON_TYPE_OBJECT) {
-            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                           _("block info device entry was not in expected 
format"));
-            goto cleanup;
-        }
-
-        if (!(args.thisdev = virJSONValueObjectGetString(args.dev, "device"))) 
{
-            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                           _("block info device entry was not in expected 
format"));
-            goto cleanup;
-        }
-
-        args.searchDevice = device;
-        args.top = top;
-        args.target = target;
-        if ((rc = qemuMonitorJSONQueryBlockDiskNameLookup(&args)) < 0)
-            goto cleanup;
-        if (rc == 1) {
-            ret = args.foundDevice;
-            break;
-        }
-    }
     /* Guarantee an error when returning NULL, but don't override a
      * more specific error if one was already generated.  */
     if (!ret && !virGetLastError())
@@ -4123,9 +4082,6 @@ qemuMonitorJSONDiskNameLookup(qemuMonitorPtr mon,
                        _("unable to find backing name for device %s"),
                        device);
 
- cleanup:
-    virJSONValueFree(reply);
-
     return ret;
 }
 
-- 
2.7.4

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