storage: gluster: Remove build-time dependency on the 'gluster' cli tool

The tool is used for pool discovery. Since we call an external binary we
don't really need to compile out the code that uses it. We can check
whether it exists at runtime.

configure.ac

@@ -605,7 +605,7 @@ LIBVIRT_STORAGE_CHECK_ZFS
 
 if test "$with_storage_fs" = "yes" ||
    test "$with_storage_gluster" = "yes"; then
-  AC_PATH_PROG([GLUSTER_CLI], [gluster], [], [$LIBVIRT_SBIN_PATH])
+  AC_PATH_PROG([GLUSTER_CLI], [gluster], [gluster], [$LIBVIRT_SBIN_PATH])
   if test "x$GLUSTER_CLI" != "x"; then
       AC_DEFINE_UNQUOTED([GLUSTER_CLI], ["$GLUSTER_CLI"],
         [Location or name of the gluster command line tool])

src/storage/storage_backend.c

@@ -2548,12 +2548,12 @@ virStorageBackendVolWipeLocal(virConnectPtr conn ATTRIBUTE_UNUSED,
 }
 
 
-#ifdef GLUSTER_CLI
 /**
  * virStorageBackendFindGlusterPoolSources:
  * @host: host to detect volumes on
  * @pooltype: src->format is set to this value
  * @list: list of storage pool sources to be filled
+ * @report: report error if the 'gluster' cli tool is missing
  *
  * Looks up gluster volumes on @host and fills them to @list.
  *
@@ -2562,8 +2562,10 @@ virStorageBackendVolWipeLocal(virConnectPtr conn ATTRIBUTE_UNUSED,
 int
 virStorageBackendFindGlusterPoolSources(const char *host,
                                         int pooltype,
-                                        virStoragePoolSourceListPtr list)
+                                        virStoragePoolSourceListPtr list,
+                                        bool report)
 {
+    char *glusterpath = NULL;
     char *outbuf = NULL;
     virCommandPtr cmd = NULL;
     xmlDocPtr doc = NULL;
@@ -2576,7 +2578,17 @@ virStorageBackendFindGlusterPoolSources(const char *host,
 
     int ret = -1;
 
-    cmd = virCommandNewArgList(GLUSTER_CLI,
+    if (!(glusterpath = virFindFileInPath(GLUSTER_CLI))) {
+        if (report) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("'gluster' command line tool not found"));
+            return -1;
+        } else {
+            return 0;
+        }
+    }
+
+    cmd = virCommandNewArgList(glusterpath,
                                "--xml",
                                "--log-file=/dev/null",
                                "volume", "info", "all", NULL);
@@ -2629,18 +2641,9 @@ virStorageBackendFindGlusterPoolSources(const char *host,
     xmlFreeDoc(doc);
     VIR_FREE(outbuf);
     virCommandFree(cmd);
+    VIR_FREE(glusterpath);
     return ret;
 }
-#else /* #ifdef GLUSTER_CLI */
-int
-virStorageBackendFindGlusterPoolSources(const char *host ATTRIBUTE_UNUSED,
-                                        int pooltype ATTRIBUTE_UNUSED,
-                                        virStoragePoolSourceListPtr list ATTRIBUTE_UNUSED)
-{
-    VIR_INFO("gluster cli tool not installed");
-    return 0;
-}
-#endif /* #ifdef GLUSTER_CLI */
 
 
 #if WITH_BLKID

src/storage/storage_backend.h

@@ -135,7 +135,8 @@ virStorageBackendGetBuildVolFromFunction(virStorageVolDefPtr vol,
 
 int virStorageBackendFindGlusterPoolSources(const char *host,
                                             int pooltype,
-                                            virStoragePoolSourceListPtr list);
+                                            virStoragePoolSourceListPtr list,
+                                            bool report);
 
 int virStorageBackendVolUploadLocal(virConnectPtr conn,
                                     virStoragePoolObjPtr pool,

src/storage/storage_backend_fs.c

@@ -306,15 +306,13 @@ virStorageBackendFileSystemNetFindPoolSources(virConnectPtr conn ATTRIBUTE_UNUSE
 
     retNFS = virStorageBackendFileSystemNetFindNFSPoolSources(&state);
 
-# ifdef GLUSTER_CLI
     retGluster = virStorageBackendFindGlusterPoolSources(state.host,
                                                          VIR_STORAGE_POOL_NETFS_GLUSTERFS,
-                                                         &state.list);
+                                                         &state.list, false);
 
     if (retGluster < 0)
         goto cleanup;
 
-# endif
     /* If both fail, then we won't return an empty list - return an error */
     if (retNFS < 0 && retGluster == 0) {
         virReportError(VIR_ERR_OPERATION_FAILED,

src/storage/storage_backend_gluster.c

@@ -513,7 +513,7 @@ virStorageBackendGlusterFindPoolSources(virConnectPtr conn ATTRIBUTE_UNUSED,
 
     if ((rc = virStorageBackendFindGlusterPoolSources(source->hosts[0].name,
                                                       0, /* currently ignored */
-                                                      &list)) < 0)
+                                                      &list, true)) < 0)
         goto cleanup;
 
     if (rc == 0) {