From a38efb3c072811eb4e3bce265f1b8903a10ffad4 Mon Sep 17 00:00:00 2001
From: Javier Martinez Canillas <javierm@redhat.com>
Date: Sun, 27 Sep 2020 22:40:28 +0800
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 | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/grubby.c b/grubby.c
index 947b458..7923a7d 100644
--- a/grubby.c
+++ b/grubby.c
@@ -5217,24 +5217,26 @@ 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);
-- 
2.19.1.6.gb485710b