Support for multiple (3) console= on kernel cmdline

Some targets, like Raspberry Pi, have both serial and HDMI console
enabled.  Depending on the order of arguments on the kernel cmdline
either one were selected the default 'stderr', which finit used.

This patch adds support for parsing the console= string(s) and
opening multiple outputs for system startup/progress.  In the
end, however, a getty still needs to be started on each of the
consoles to use.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/conf.c

@@ -89,6 +89,9 @@ static void parse_arg(char *arg, int *dbg)
 
 	if (string_compare(arg, "splash"))
 		splash = 1;
+
+	if (string_match(arg, "console="))
+		add_console(arg);
 }
 
 void conf_parse_cmdline(int argc, char *argv[])

src/helpers.c

@@ -67,6 +67,62 @@ static const char *status2[] = STATUS_CLASS;
 #define CHOOSE(x,y,z) z
 static const char *color[] = STATUS_CLASS;
 
+/*
+ * System consoles, can be given multiple times on the kernel cmdline.
+ * We support only three currently.
+ */
+#define MAX_CONS 3
+
+static int fds[MAX_CONS];
+static int num_cons = 0;
+
+
+void add_console(char *str)
+{
+	char *cons, *ptr;
+	char path[80];
+
+	if (num_cons == NELEMS(fds)) {
+		_e("too many consoles, max %d supported", NELEMS(fds));
+		return;
+	}
+
+	cons = strchr(str, '=');
+	if (!cons)
+		return;
+	cons++;
+
+	/* drop any options */
+	ptr = strchr(cons, ',');
+	if (ptr)
+		*ptr = 0;
+
+	snprintf(path, sizeof(path), "/dev/%s", cons);
+	fds[num_cons] = open(path, O_WRONLY);
+	if (fds[num_cons] < 0) {
+		_pe("Failed opening console %s", path);
+		return;
+	}
+	num_cons++;
+}
+
+ssize_t cprintf(const char *fmt, ...)
+{
+	const size_t len = strlen(fmt) * 2;
+	char buf[len < 256 ? 256 : len];
+	size_t size;
+	va_list ap;
+	int i;
+
+	va_start(ap, fmt);
+	size = vsnprintf(buf, sizeof(buf), fmt, ap);
+	va_end(ap);
+
+	for (i = 0; i < num_cons; i++)
+		(void)write(fds[i], buf, size);
+
+	return size;
+}
 
 char *strip_line(char *line)
 {
@@ -162,8 +218,7 @@ void print_banner(const char *heading)
 		pad(buf, sizeof(buf), "═", wmax);
 	}
 	strlcat(buf, "\e[0m\n", sizeof(buf));
-
-	(void)write(STDERR_FILENO, buf, strlen(buf));
+	cprintf("%s", buf);
 }
 
 static size_t print_timestamp(char *buf, size_t len)
@@ -221,9 +276,9 @@ void printv(const char *fmt, va_list ap)
 	vsnprintf(&buf[len], sizeof(buf) - len, fmt, ap);
 
 	if (progress_style == 1)
-		fprintf(stderr, "\r%s ", pad(buf, sizeof(buf), ".", sizeof(buf)));
+		cprintf("\r%s ", pad(buf, sizeof(buf), ".", sizeof(buf)));
 	else
-		fprintf(stderr, "\r\e[2K%s%s", status(3), buf);
+		cprintf("\r\e[2K%s%s", status(3), buf);
 }
 
 void print(int rc, const char *fmt, ...)
@@ -243,9 +298,9 @@ void print(int rc, const char *fmt, ...)
 		return;
 
 	if (progress_style == 1)
-		fprintf(stderr, "%s\n", status(rc));
+		cprintf("%s\n", status(rc));
 	else
-		fprintf(stderr, "\r%s\n", status(rc));
+		cprintf("\r%s\n", status(rc));
 }
 
 void print_desc(char *action, char *desc)

src/helpers.h

@@ -50,6 +50,9 @@ void          endfsent  (void);
 struct fstab *getfsent  (void);
 #endif	/* HAVE_GETFSENT */
 
+void    add_console     (char *str);
+ssize_t cprintf         (const char *fmt, ...);
+
 char   *strip_line      (char *line);
 
 int     getty           (char *tty, speed_t speed, char *term, char *user);