Improve pack download error handling

Make sure tar extraction errors count towards pack errors, and use the
generic ENOSWUPDSERVER if download retries do not resolve the issue.

Signed-off-by: Patrick McCarty <patrick.mccarty@intel.com>

src/packs.c

@@ -85,7 +85,12 @@ static int download_pack(int oldversion, int newversion, char *module)
 		fclose(tarfile);
 	}
 
-	return err;
+	// Only negative return values should indicate errors
+	if (err > 0) {
+		return -err;
+	} else {
+		return err;
+	}
 }
 
 /* pull in packs for base and any subscription */

src/update.c

@@ -368,6 +368,7 @@ download_packs:
 			goto download_packs;
 		}
 		printf("No network, or server unavailable for pack downloads\n");
+		ret = ENOSWUPDSERVER;
 		goto clean_exit;
 	}
 

src/verify.c

@@ -231,7 +231,7 @@ static int get_all_files(struct manifest *official_manifest, struct list *subs)
 		 * 	logging needed */
 		printf("zero pack downloads failed. \n");
 		printf("Failed - Server-side error, cannot download necessary files\n");
-		return ret;
+		return -ENOSWUPDSERVER;
 	}
 	iter = list_head(official_manifest->files);
 	while (iter) {