8944 vsnprintf is still confused about padding numbers

Reviewed by: Andy Stormont <astormont@racktopsystems.com>
Reviewed by: Toomas Soome <tsoome@me.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

1 files changed, 41 insertions, 19 deletions

diff --git a/usr/src/common/util/string.c b/usr/src/common/util/string.c
index 26e5744485..5fe5ddab13 100644
--- a/usr/src/common/util/string.c
+++ b/usr/src/common/util/string.c
@@ -26,6 +26,7 @@
 
 /*
  * Copyright (c) 2016 by Delphix. All rights reserved.
+ * Copyright 2018 Nexenta Systems, Inc.
  */
 
 /*
@@ -70,11 +71,13 @@ vsnprintf(char *buf, size_t buflen, const char *fmt, va_list aargs)
 {
 	uint64_t ul, tmp;
 	char *bufp = buf;	/* current buffer pointer */
-	int pad, width, base, sign, c, num;
+	char c, pad;
+	int width, base, sign, num;
 	int prec, h_count, l_count, dot_count;
 	int pad_count, transfer_count, left_align;
 	char *digits, *sp, *bs;
 	char numbuf[65];	/* sufficient for a 64-bit binary value */
+	int numwidth;
 	va_list args;
 
 	/*
@@ -91,7 +94,7 @@ vsnprintf(char *buf, size_t buflen, const char *fmt, va_list aargs)
 			continue;
 		}
 
-		width = prec = 0;
+		width = prec = numwidth = 0;
 		left_align = base = sign = 0;
 		h_count = l_count = dot_count = 0;
 		pad = ' ';
@@ -256,34 +259,53 @@ next_fmt:
 			base = *bs++;
 		}
 
-		/* avoid repeated division if width is 0 */
-		if (width > 0) {
-			tmp = ul;
-			do {
-				width--;
-			} while ((tmp /= base) != 0);
-		}
+		/*
+		 * Fill in the number string buffer and calculate the
+		 * number string length.
+		 */
+		tmp = ul;
+		sp = numbuf;
+		do {
+			*sp++ = digits[tmp % base];
+			numwidth++;
+		} while ((tmp /= base) != 0);
+
+		/*
+		 * Reduce the total field width by precision or the number
+		 * string length depending on which one is bigger, and sign.
+		 */
+		if (prec >= numwidth)
+			width -= prec;
+		else
+			width -= numwidth;
+		width -= sign;
 
+		/* Add the sign if width is '0'-padded */
 		if (sign && pad == '0')
 			ADDCHAR('-');
-		while ((!left_align) && (width-- > sign))
-			ADDCHAR(pad);
-		if (sign && pad == ' ')
+
+		/* If not left-aligned, add the width padding */
+		if (!left_align) {
+			while (width-- > 0)
+				ADDCHAR(pad);
+		}
+
+		/* Add the sign if width is NOT '0'-padded */
+		if (sign && pad != '0')
 			ADDCHAR('-');
 
-		sp = numbuf;
-		tmp = ul;
-		do {
-			*sp++ = digits[tmp % base];
-		} while ((tmp /= base) != 0);
+		/* Add the precision '0'-padding */
+		while (prec-- > numwidth)
+			ADDCHAR('0');
 
+		/* Print out the number */
 		while (sp > numbuf) {
 			sp--;
 			ADDCHAR(*sp);
 		}
 
-		/* add left-alignment padding */
-		while (width-- > sign)
+		/* Add left-alignment padding */
+		while (width-- > 0)
 			ADDCHAR(' ');
 
 		if (c == 'b' && ul != 0) {