From 3814aed56039dcb7d6d2f72eb5fd692669e09dcd Mon Sep 17 00:00:00 2001
From: David van Moolenbroek <david@minix3.org>
Date: Tue, 23 Dec 2014 14:58:03 +0000
Subject: [PATCH] libsa: add string precision support to vprintf

We already had a hack to ignore the precision, but the ACPI driver
requires an actual implementation--it prints garbage at the end of
some strings otherwise.  This patch adds support for precision for
strings only, limiting printing to the given number of characters.
For all other specifiers, precision is still unsupported.

Change-Id: I1d41fc70a0d0494db695c22ba609262a50b86e08
---
 sys/lib/libsa/subr_prf.c | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/sys/lib/libsa/subr_prf.c b/sys/lib/libsa/subr_prf.c
index 93f101728..d6fc0defc 100644
--- a/sys/lib/libsa/subr_prf.c
+++ b/sys/lib/libsa/subr_prf.c
@@ -191,6 +191,9 @@ kdoprnt(void (*put)(int), const char *fmt, va_list ap)
 #ifdef LIBSA_PRINTF_WIDTH_SUPPORT
 	int width;
 	char *q;
+#if defined(__minix)
+	int max;
+#endif /* defined(__minix) */
 #endif
 
 	for (;;) {
@@ -202,18 +205,20 @@ kdoprnt(void (*put)(int), const char *fmt, va_list ap)
 		lflag = 0;
 #ifdef LIBSA_PRINTF_WIDTH_SUPPORT
 		width = 0;
+#if defined(__minix)
+		max = -1;
+#endif /* defined(__minix) */
 #endif
 reswitch:
 		switch (ch = *fmt++) {
 #ifdef LIBSA_PRINTF_WIDTH_SUPPORT
 #if defined(__minix)
-		/* LSC: FIXME: this is a simple hack which ignores the thing for now. */
 		case '.':
-			/* eat up digits */
-			while( ((('1' >= *fmt) && ( *fmt <= '9'))
-				 || (*fmt == '*')) )
-				 fmt++;
-			fmt++;
+			if (*fmt == '*') {
+				max = va_arg(ap, int);
+				fmt++;
+			} else for (max = 0; *fmt >= '0' && *fmt <= '9'; fmt++)
+				max = max * 10 + *fmt - '0';
 			goto reswitch;
 #endif /* defined(__minix) */
 		case '#':
@@ -274,10 +279,19 @@ reswitch:
 #ifdef LIBSA_PRINTF_WIDTH_SUPPORT
 			for (q = p; *q != '\0'; ++q)
 				continue;
+#if defined(__minix)
+			if (max >= 0 && q - p > max)
+				q = &p[max];
+#endif /* defined(__minix) */
 			width -= q - p;
 #endif
 			RPAD();
+#if defined(LIBSA_PRINTF_WIDTH_SUPPORT) && defined(__minix)
+			while ((max < 0 || max-- > 0) &&
+			    (ch = (unsigned char)*p++))
+#else /* !defined(LIBSA_PRINTF_WIDTH_SUPPORT) || !defined(__minix) */
 			while ((ch = (unsigned char)*p++))
+#endif /* !defined(LIBSA_PRINTF_WIDTH_SUPPORT) || !defined(__minix) */
 				put(ch);
 			LPAD();
 			break;