Add warning message to XML definition files stored on disk

Users often edit XML file stored in configuration directory
thinking of modifying a domain/network/pool/etc. Thus it is wise
to let them know they are using the wrong way and give them hint.

AUTHORS

@@ -27,6 +27,7 @@ The primary maintainers and people with commit access rights:
   Justin Clift         <jclift@redhat.com>
   Osier Yang           <jyang@redhat.com>
   Wen Congyang         <wency@cn.fujitsu.com>
+  Michal Prívozník     <mprivozn@redhat.com>
 
 Previous maintainers:
   Karel Zak            <kzak@redhat.com>
@@ -146,7 +147,6 @@ Patches have also been contributed by:
   Paweł Krześniak      <pawel.krzesniak@gmail.com>
   Kay Schubert         <kayegypt@web.de>
   Marc-André Lureau    <marcandre.lureau@redhat.com>
-  Michal Prívozník     <mprivozn@redhat.com>
   Juerg Haefliger      <juerg.haefliger@hp.com>
   Matthias Dahl        <mdvirt@designassembly.de>
   Niels de Vos         <ndevos@redhat.com>

src/conf/domain_conf.c

@@ -8561,6 +8561,8 @@ int virDomainSaveXML(const char *configDir,
         goto cleanup;
     }
 
+    virEmitXMLWarning(fd, def->name, "edit");
+
     towrite = strlen(xml);
     if (safewrite(fd, xml, towrite) < 0) {
         virReportSystemError(errno,

src/conf/network_conf.c

@@ -925,6 +925,8 @@ int virNetworkSaveXML(const char *configDir,
         goto cleanup;
     }
 
+    virEmitXMLWarning(fd, def->name, "net-edit");
+
     towrite = strlen(xml);
     if (safewrite(fd, xml, towrite) < 0) {
         virReportSystemError(errno,

src/conf/nwfilter_conf.c

@@ -2249,6 +2249,8 @@ int virNWFilterSaveXML(const char *configDir,
         goto cleanup;
     }
 
+    virEmitXMLWarning(fd, def->name, "nwfilter-edit");
+
     towrite = strlen(xml);
     if (safewrite(fd, xml, towrite) < 0) {
         virReportSystemError(errno,
@@ -2645,6 +2647,8 @@ virNWFilterObjSaveDef(virNWFilterDriverStatePtr driver,
         goto cleanup;
     }
 
+    virEmitXMLWarning(fd, def->name, "nwfilter-edit");
+
     towrite = strlen(xml);
     if (safewrite(fd, xml, towrite) != towrite) {
         virReportSystemError(errno,

src/conf/storage_conf.c

@@ -1551,6 +1551,8 @@ virStoragePoolObjSaveDef(virStorageDriverStatePtr driver,
         goto cleanup;
     }
 
+    virEmitXMLWarning(fd, def->name, "pool-edit");
+
     towrite = strlen(xml);
     if (safewrite(fd, xml, towrite) != towrite) {
         virReportSystemError(errno,

src/libvirt_private.syms

@@ -901,6 +901,7 @@ virArgvToString;
 virAsprintf;
 virBuildPathInternal;
 virDirCreate;
+virEmitXMLWarning;
 virEnumFromString;
 virEnumToString;
 virEventAddHandle;

src/util/util.c

@@ -3207,3 +3207,40 @@ bool virIsDevMapperDevice(const char *devname ATTRIBUTE_UNUSED)
     return false;
 }
 #endif
+
+int virEmitXMLWarning(int fd,
+                      const char *name,
+                      const char *cmd) {
+    size_t len;
+    const char *prologue = "<!--\n\
+WARNING: THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BE \n\
+OVERWRITTEN AND LOST. Changes to this xml configuration should be made using:\n\
+  virsh ";
+    const char *epilogue = "\n\
+or other application using the libvirt API.\n\
+-->\n\n";
+
+    if (fd < 0 || !name || !cmd)
+        return -1;
+
+    len = strlen(prologue);
+    if (safewrite(fd, prologue, len) != len)
+        return -1;
+
+    len = strlen(cmd);
+    if (safewrite(fd, cmd, len) != len)
+        return -1;
+
+    if (safewrite(fd, " ", 1) != 1)
+        return -1;
+
+    len = strlen(name);
+    if (safewrite(fd, name, len) != len)
+        return -1;
+
+    len = strlen(epilogue);
+    if (safewrite(fd, epilogue, len) != len)
+        return -1;
+
+    return 0;
+}

src/util/util.h

@@ -299,4 +299,8 @@ int virBuildPathInternal(char **path, ...) ATTRIBUTE_SENTINEL;
 char *virTimestamp(void);
 
 bool virIsDevMapperDevice(const char *devname) ATTRIBUTE_NONNULL(1);
+
+int virEmitXMLWarning(int fd,
+                      const char *name,
+                      const char *cmd) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3);
 #endif /* __VIR_UTIL_H__ */