util/nvmutil: make cmd an integer

point directly to the command table.

run through an intermediary function to check
bounds, for safety.

this will allow me to then set things like
the invert config directly in that struct.

Signed-off-by: Leah Rowe <leah@libreboot.org>

util/nvmutil/nvmutil.c

@@ -30,6 +30,7 @@
 static void set_cmd(int argc, char *argv[]);
 static void check_cmd_args(int argc, char *argv[]);
 static size_t conv_argv_part_num(const char *part_str);
+static void run_cmd(ssize_t c);
 static void set_io_flags(int argc, char *argv[]);
 static void open_gbe_file(void);
 #ifndef HAVE_ARC4RANDOM_BUF
@@ -149,7 +150,7 @@ static const char *argv0;
 
 struct commands {
 	const char *str;
-	void (*cmd)(void);
+	void (*run)(void);
 	int args;
 };
 static const struct commands command[] = {
@@ -160,8 +161,15 @@ static const struct commands command[] = {
 	{ "brick", cmd_brick, 4 },
 	{ "setchecksum", cmd_setchecksum, 4 },
 };
+#define CMD_NULL -1
+#define CMD_DUMP 0
+#define CMD_SETMAC 1
+#define CMD_SWAP 2
+#define CMD_COPY 3
+#define CMD_BRICK 4
+#define CMD_SETCHECKSUM 5
 
-static void (*cmd)(void) = NULL;
+static ssize_t cmd = CMD_NULL;
 
 int
 main(int argc, char *argv[])
@@ -226,7 +234,7 @@ main(int argc, char *argv[])
 #endif
 
 	read_gbe_file();
-	(*cmd)();
+	run_cmd(cmd);
 	write_gbe_file();
 
 	if (close(gbe_fd) == -1)
@@ -249,7 +257,7 @@ main(int argc, char *argv[])
 	 * However, if we're not using cmd_dump, then
 	 * we have a bug somewhere in the code.
 	 */
-	if (cmd != cmd_dump) {
+	if (cmd != CMD_DUMP) {
 		if (errno)
 			err(ECANCELED, "Unhandled error on exit");
 	}
@@ -263,14 +271,12 @@ main(int argc, char *argv[])
 static void
 set_cmd(int argc, char *argv[])
 {
-	size_t i;
-
 	/*
 	 * No extra args: ./nvmutil gbe.bin
 	 * Equivalent: ./nvmutil gbe.bin setmac xx:xx:xx:xx:xx:xx
 	 */
 	if (argc == 2) {
-		cmd = cmd_setmac;
+		cmd = CMD_SETMAC;
 		return;
 	}
 
@@ -278,43 +284,44 @@ set_cmd(int argc, char *argv[])
 	 * Three or more args.
 	 * Example: ./nvmutil gbe.bin copy 0
 	 */
-	for (i = 0; i < items(command); i++) {
+	for (cmd = 0; cmd < (ssize_t)items(command); cmd++) {
-		if (strcmp(argv[2], command[i].str) != 0)
+		if (strcmp(argv[2], command[cmd].str) != 0)
 			continue;
-		if (argc >= command[i].args) {
+		if (argc >= command[cmd].args) {
-			cmd = command[i].cmd;
+			return;
-			break;
 		}
 
-		err(EINVAL, "Too few args: command '%s'", command[i].str);
+		err(EINVAL, "Too few args: command '%s'", command[cmd].str);
 	}
+
+	cmd = CMD_NULL;
 }
 
 static void
 check_cmd_args(int argc, char *argv[])
 {
-	if (cmd == NULL && argc > 2) {
+	if (cmd == CMD_NULL && argc > 2) {
 		/*
 		 * Example: ./nvmutil gbe.bin xx:1f:16:xx:xx:xx
 		 * Equivalent ./nvmutil gbe.bin setmac xx:1f:16:xx:xx:xx
 		 */
 		mac_str = argv[2];
-		cmd = cmd_setmac;
+		cmd = CMD_SETMAC;
-	} else if (cmd == cmd_setmac) {
+	} else if (cmd == CMD_SETMAC) { /* 1 is setmac */
 		/*
 		 * Example: ./nvmutil gbe.bin setmac xx:1f:16:xx:xx:xx
 		 */
 		mac_str = rmac; /* random MAC */
 		if (argc > 3)
 			mac_str = argv[3];
-	} else if (cmd != NULL && argc > 3) { /* user-supplied partnum */
+	} else if (cmd != CMD_NULL && argc > 3) { /* user-supplied partnum */
 		/*
 		 * Example: ./nvmutil gbe.bin copy 0
 		 */
 		part = conv_argv_part_num(argv[3]);
 	}
 
-	if (cmd == NULL)
+	if (cmd == CMD_NULL)
 		err(EINVAL, "Bad command");
 }
 
@@ -339,6 +346,17 @@ conv_argv_part_num(const char *part_str)
 	return (size_t)(ch - '0');
 }
 
+static void
+run_cmd(ssize_t c)
+{
+	size_t d = (size_t)c;
+
+	if (d >= items(command))
+		err(ECANCELED, "Invalid run_cmd arg: %zd", c);
+
+	command[d].run();
+}
+
 static void
 set_io_flags(int argc, char *argv[])
 {
@@ -418,9 +436,9 @@ read_gbe_file(void)
 	 *
 	 * We can skip reading the other part, thus:
 	 */
-	if (cmd == cmd_copy ||
+	if (cmd == CMD_COPY ||
-	    cmd == cmd_brick ||
+	    cmd == CMD_BRICK ||
-	    cmd == cmd_setchecksum)
+	    cmd == CMD_SETCHECKSUM)
 		do_read[part ^ 1] = 0;
 
 	/*
@@ -435,7 +453,7 @@ read_gbe_file(void)
 	 * will directly manipulate part_modified[], telling write_gbe_file()
 	 * to also write in reverse, as in read_gbe_file().
 	 */
-	if (cmd == cmd_copy || cmd == cmd_swap)
+	if (cmd == CMD_COPY || cmd == CMD_SWAP)
 		invert = 1;
 
 	for (p = 0; p < 2; p++) {