net: Prefer command line arguments

We can call commands like dhcp and bootp without arguments or with
explicit command line arguments that really should tell the code where
to look for files instead.

Unfortunately, the current code simply overwrites command line arguments
in the dhcp case with dhcp values.

This patch allows the code to preserve the command line values if they
were set on the command line. That way the semantics are slightly more
intuitive.

The reason this patch does that by introducing a new variable is that we
can not rely on net_boot_file_name[0] being unset, as today it's
completely legal to call "dhcp" and afterwards run "tftp" and expect the
latter to repeat the same query as before. I would prefer not to break
that behavior in case anyone relies on it.

Signed-off-by: Alexander Graf <agraf@suse.de>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

cmd/net.c

@@ -183,6 +183,8 @@ static int netboot_common(enum proto_t proto, cmd_tbl_t *cmdtp, int argc,
 	int   size;
 	ulong addr;
 
+	net_boot_file_name_explicit = false;
+
 	/* pre-set load_addr */
 	s = env_get("loadaddr");
 	if (s != NULL)
@@ -199,15 +201,18 @@ static int netboot_common(enum proto_t proto, cmd_tbl_t *cmdtp, int argc,
 		 * mis-interpreted as a valid number.
 		 */
 		addr = simple_strtoul(argv[1], &end, 16);
-		if (end == (argv[1] + strlen(argv[1])))
+		if (end == (argv[1] + strlen(argv[1]))) {
 			load_addr = addr;
-		else
+		} else {
+			net_boot_file_name_explicit = true;
 			copy_filename(net_boot_file_name, argv[1],
 				      sizeof(net_boot_file_name));
+		}
 		break;
 
 	case 3:
 		load_addr = simple_strtoul(argv[1], NULL, 16);
+		net_boot_file_name_explicit = true;
 		copy_filename(net_boot_file_name, argv[2],
 			      sizeof(net_boot_file_name));
 
@@ -220,6 +225,7 @@ static int netboot_common(enum proto_t proto, cmd_tbl_t *cmdtp, int argc,
 			printf("Invalid address/size\n");
 			return CMD_RET_USAGE;
 		}
+		net_boot_file_name_explicit = true;
 		copy_filename(net_boot_file_name, argv[3],
 			      sizeof(net_boot_file_name));
 		break;

include/net.h

@@ -540,6 +540,8 @@ enum proto_t {
 };
 
 extern char	net_boot_file_name[1024];/* Boot File name */
+/* Indicates whether the file name was specified on the command line */
+extern bool	net_boot_file_name_explicit;
 /* The actual transferred size of the bootfile (in bytes) */
 extern u32	net_boot_file_size;
 /* Boot file size in blocks as reported by the DHCP server */

net/bootp.c

@@ -157,7 +157,8 @@ static void store_net_params(struct bootp_hdr *bp)
 #if defined(CONFIG_CMD_DHCP)
 	    !(dhcp_option_overload & OVERLOAD_FILE) &&
 #endif
-	    (strlen(bp->bp_file) > 0)) {
+	    (strlen(bp->bp_file) > 0) &&
+	    !net_boot_file_name_explicit) {
 		copy_filename(net_boot_file_name, bp->bp_file,
 			      sizeof(net_boot_file_name));
 	}
@@ -889,10 +890,13 @@ static void dhcp_process_options(uchar *popt, uchar *end)
 		case 66:	/* Ignore TFTP server name */
 			break;
 		case 67:	/* Bootfile option */
-			size = truncate_sz("Bootfile",
-					   sizeof(net_boot_file_name), oplen);
-			memcpy(&net_boot_file_name, popt + 2, size);
-			net_boot_file_name[size] = 0;
+			if (!net_boot_file_name_explicit) {
+				size = truncate_sz("Bootfile",
+						   sizeof(net_boot_file_name),
+						   oplen);
+				memcpy(&net_boot_file_name, popt + 2, size);
+				net_boot_file_name[size] = 0;
+			}
 			break;
 		default:
 #if defined(CONFIG_BOOTP_VENDOREX)

net/net.c

@@ -174,6 +174,8 @@ ushort		net_native_vlan = 0xFFFF;
 
 /* Boot File name */
 char net_boot_file_name[1024];
+/* Indicates whether the file name was specified on the command line */
+bool net_boot_file_name_explicit;
 /* The actual transferred size of the bootfile (in bytes) */
 u32 net_boot_file_size;
 /* Boot file size in blocks as reported by the DHCP server */