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authorRich Felker <dalias@aerifal.cx>2014-04-07 13:50:05 -0400
committerRich Felker <dalias@aerifal.cx>2014-04-07 13:50:05 -0400
commite94d0692864ecf9522fd6a97610a47a2f718d3de (patch)
tree9270fe106eae71c137ab703d3209ce9c1b466ed8 /src/stdio/vfprintf.c
parentefe07b0f8914eccf5eabce0dbd6ea5da7d7db38c (diff)
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fix printf rounding with %g for some corner case midpoints
the subsequent rounding code assumes the end pointer (z) accurately
reflects the end of significance in the decimal expansion, but for
certain large integers, spurious trailing zero slots were left behind
when applying the binary exponent.

issue reported by Morten Welinder; the analysis of the cause was
performed by nsz, who also proposed this change.
Diffstat (limited to 'src/stdio/vfprintf.c')
-rw-r--r--src/stdio/vfprintf.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/src/stdio/vfprintf.c b/src/stdio/vfprintf.c
index 0be75498..f6e7f38d 100644
--- a/src/stdio/vfprintf.c
+++ b/src/stdio/vfprintf.c
@@ -308,8 +308,8 @@ static int fmt_fp(FILE *f, long double y, int w, int p, int fl, int t)
 			*d = x % 1000000000;
 			carry = x / 1000000000;
 		}
-		if (!z[-1] && z>a) z--;
 		if (carry) *--a = carry;
+		while (z>a && !z[-1]) z--;
 		e2-=sh;
 	}
 	while (e2<0) {