virsh: domain: Use global constant for XML file size limit

Few places still used hardcoded limit for maximum XML size for commands
that accept XML files. The hardcoded limits ranged from 8k to 1M. Use
VSH_MAX_XML_FILE to express this limit in a unified way. This will bump
the limit for the commands that used hardcoded string lengths to 10M.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1152427

tools/virsh-domain.c

@@ -1984,7 +1984,7 @@ cmdBlockCopy(vshControl *ctl, const vshCmd *cmd)
     }
 
     if (xml) {
-        if (virFileReadAll(xml, 8192, &xmlstr) < 0) {
+        if (virFileReadAll(xml, VSH_MAX_XML_FILE, &xmlstr) < 0) {
             vshReportError(ctl);
             goto cleanup;
         }
@@ -3889,7 +3889,7 @@ doSave(void *opaque)
         goto out;
 
     if (xmlfile &&
-        virFileReadAll(xmlfile, 8192, &xml) < 0) {
+        virFileReadAll(xmlfile, VSH_MAX_XML_FILE, &xml) < 0) {
         vshReportError(ctl);
         goto out;
     }
@@ -4182,7 +4182,7 @@ cmdSaveImageDefine(vshControl *ctl, const vshCmd *cmd)
     if (vshCommandOptStringReq(ctl, cmd, "xml", &xmlfile) < 0)
         return false;
 
-    if (virFileReadAll(xmlfile, 8192, &xml) < 0)
+    if (virFileReadAll(xmlfile, VSH_MAX_XML_FILE, &xml) < 0)
         goto cleanup;
 
     if (virDomainSaveImageDefineXML(ctl->conn, file, xml, flags) < 0) {
@@ -4765,7 +4765,7 @@ cmdRestore(vshControl *ctl, const vshCmd *cmd)
         return false;
 
     if (xmlfile &&
-        virFileReadAll(xmlfile, 8192, &xml) < 0)
+        virFileReadAll(xmlfile, VSH_MAX_XML_FILE, &xml) < 0)
         goto cleanup;
 
     if (((flags || xml)
@@ -8945,7 +8945,7 @@ cmdDomXMLFromNative(vshControl *ctl, const vshCmd *cmd)
         vshCommandOptStringReq(ctl, cmd, "config", &configFile) < 0)
         return false;
 
-    if (virFileReadAll(configFile, 1024*1024, &configData) < 0)
+    if (virFileReadAll(configFile, VSH_MAX_XML_FILE, &configData) < 0)
         return false;
 
     xmlData = virConnectDomainXMLFromNative(ctl->conn, format, configData, flags);
@@ -9001,7 +9001,7 @@ cmdDomXMLToNative(vshControl *ctl, const vshCmd *cmd)
         vshCommandOptStringReq(ctl, cmd, "xml", &xmlFile) < 0)
         return false;
 
-    if (virFileReadAll(xmlFile, 1024*1024, &xmlData) < 0)
+    if (virFileReadAll(xmlFile, VSH_MAX_XML_FILE, &xmlData) < 0)
         return false;
 
     configData = virConnectDomainXMLToNative(ctl->conn, format, xmlData, flags);
@@ -9318,7 +9318,7 @@ doMigrate(void *opaque)
     if (opt) {
         char *xml;
 
-        if (virFileReadAll(opt, 1024 * 1024, &xml) < 0) {
+        if (virFileReadAll(opt, VSH_MAX_XML_FILE, &xml) < 0) {
             vshError(ctl, _("cannot read file '%s'"), opt);
             goto save_error;
         }