From ed5e255c023c9b78120d9ff2246d6516f652d4b7 Mon Sep 17 00:00:00 2001
From: Javier Martinez Canillas <javierm@redhat.com>
Date: Mon, 10 Feb 2020 19:32:39 +0100
Subject: [PATCH] Fix stringop-overflow warning

GCC gives the following compile warning:

grubby.c: In function 'main':
grubby.c:4508:27: error: writing 1 byte into a region of size 0 [-Werror=stringop-overflow=]
 4508 |     saved_command_line[0] = '\0';
      |     ~~~~~~~~~~~~~~~~~~~~~~^~~~~~
grubby.c:4503:26: note: at offset 0 to an object with size 0 allocated by 'malloc' here
 4503 |     saved_command_line = malloc(i);
          |                          ^~~~~~~~~
cc1: all warnings being treated as errors
make: *** [Makefile:38: grubby.o] Error 1

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
---
 grubby.c | 35 +++++++++++++++++++----------------
 1 file changed, 19 insertions(+), 16 deletions(-)

diff --git a/grubby.c b/grubby.c
index 5ca689539cf..0c0f67a0ae5 100644
--- a/grubby.c
+++ b/grubby.c
@@ -4500,23 +4500,26 @@ int main(int argc, const char ** argv) {
     int i = 0;
     for (int j = 1; j < argc; j++)
 	i += strlen(argv[j]) + 1;
-    saved_command_line = malloc(i);
-    if (!saved_command_line) {
-	fprintf(stderr, "grubby: %m\n");
-	exit(1);
-    }
-    saved_command_line[0] = '\0';
-    int cmdline_len = 0, arg_len;
-    for (int j = 1; j < argc; j++) {
-	arg_len = strlen(argv[j]);
-	memcpy(saved_command_line + cmdline_len, argv[j], arg_len);
-	cmdline_len += arg_len;
-	if (j != argc - 1) {
-	    memcpy(saved_command_line + cmdline_len, " ", 1);
-	    cmdline_len++;
-	}
+
+    if (i > 0) {
+	    saved_command_line = malloc(i);
+	    if (!saved_command_line) {
+		    fprintf(stderr, "grubby: %m\n");
+		    exit(1);
+	    }
+	    saved_command_line[0] = '\0';
+	    int cmdline_len = 0, arg_len;
+	    for (int j = 1; j < argc; j++) {
+		    arg_len = strlen(argv[j]);
+		    memcpy(saved_command_line + cmdline_len, argv[j], arg_len);
+		    cmdline_len += arg_len;
+		    if (j != argc - 1) {
+			    memcpy(saved_command_line + cmdline_len, " ", 1);
+			    cmdline_len++;
+		    }
+	    }
+	    saved_command_line[cmdline_len] = '\0';
     }
-    saved_command_line[cmdline_len] = '\0';
 
     optCon = poptGetContext("grubby", argc, argv, options, 0);
     poptReadDefaultConfig(optCon, 1);
-- 
2.24.1