From: Arvind Sankar <nivedita@alum.mit.edu>
Date: Mon, 18 May 2020 15:07:00 -0400
Subject: efi/printf: Factor out flags parsing and handle '%' earlier
Patch-mainline: v5.8-rc1
Git-commit: 3b8350959cba0df4070741618e50c367319793bb
References: jsc#SLE-16407

Move flags parsing code out into a helper function.

The '%%' case can be handled up front: it is not allowed to have flags,
width etc.

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20200518190716.751506-9-nivedita@alum.mit.edu
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Lee, Chun-Yi <jlee@suse.com>
---
 drivers/firmware/efi/libstub/vsprintf.c |   56 +++++++++++++++++---------------
 1 file changed, 31 insertions(+), 25 deletions(-)

--- a/drivers/firmware/efi/libstub/vsprintf.c
+++ b/drivers/firmware/efi/libstub/vsprintf.c
@@ -202,6 +202,35 @@ static char *number(char *str, long long
 	return str;
 }
 
+static
+int get_flags(const char **fmt)
+{
+	int flags = 0;
+
+	do {
+		switch (**fmt) {
+		case '-':
+			flags |= LEFT;
+			break;
+		case '+':
+			flags |= PLUS;
+			break;
+		case ' ':
+			flags |= SPACE;
+			break;
+		case '#':
+			flags |= SPECIAL;
+			break;
+		case '0':
+			flags |= ZEROPAD;
+			break;
+		default:
+			return flags;
+		}
+		++(*fmt);
+	} while (1);
+}
+
 int vsprintf(char *buf, const char *fmt, va_list args)
 {
 	int len;
@@ -218,32 +247,13 @@ int vsprintf(char *buf, const char *fmt,
 	int qualifier;		/* 'h', 'hh', 'l' or 'll' for integer fields */
 
 	for (str = buf; *fmt; ++fmt) {
-		if (*fmt != '%') {
+		if (*fmt != '%' || *++fmt == '%') {
 			*str++ = *fmt;
 			continue;
 		}
 
 		/* process flags */
-		flags = 0;
-	      repeat:
-		++fmt;		/* this also skips first '%' */
-		switch (*fmt) {
-		case '-':
-			flags |= LEFT;
-			goto repeat;
-		case '+':
-			flags |= PLUS;
-			goto repeat;
-		case ' ':
-			flags |= SPACE;
-			goto repeat;
-		case '#':
-			flags |= SPECIAL;
-			goto repeat;
-		case '0':
-			flags |= ZEROPAD;
-			goto repeat;
-		}
+		flags = get_flags(&fmt);
 
 		/* get field width */
 		field_width = -1;
@@ -321,10 +331,6 @@ int vsprintf(char *buf, const char *fmt,
 				     field_width, precision, flags);
 			continue;
 
-		case '%':
-			*str++ = '%';
-			continue;
-
 			/* integer number formats - set up the flags and "break" */
 		case 'o':
 			base = 8;