Faster test for overflow in str2txid, from Marko.

tglsfdc · tglsfdc · commit 9f3bd2994c30 · 2007-10-08T22:07:16.000Z
diff --git a/contrib/txid/txid.c b/contrib/txid/txid.c
@@ -234,24 +234,27 @@ static txid
 str2txid(const char *s, const char **endp)
 {
 	txid val = 0;
+	txid cutoff = MAX_TXID / 10;
+	txid cutlim = MAX_TXID % 10;
 
 	for (; *s; s++)
 	{
-		txid last = val;
+		unsigned d;
 
 		if (*s < '0' || *s > '9')
 			break;
-
-		val = val * 10 + (*s - '0');
+		d = *s - '0';
 
 		/*
 		 * check for overflow
 		 */
-		if (val > MAX_TXID || (val / 10) != last)
+		if (val > cutoff || (val == cutoff && d > cutlim))
 		{
 			val = 0;
 			break;
 		}
+
+		val = val * 10 + d;
 	}
 	if (endp)
 		*endp = s;

Original file line number	Diff line number	Diff line change
`@@ -234,24 +234,27 @@ static txid`
`234`	`234`	`str2txid(const char s, const char *endp)`
`235`	`235`	`{`
`236`	`236`	`txid val = 0;`
	`237`	`+ txid cutoff = MAX_TXID / 10;`
	`238`	`+ txid cutlim = MAX_TXID % 10;`
`237`	`239`
`238`	`240`	`for (; *s; s++)`
`239`	`241`	`{`
`240`		`- txid last = val;`
	`242`	`+ unsigned d;`
`241`	`243`
`242`	`244`	`if (s < '0' \|\| s > '9')`
`243`	`245`	`break;`
`244`		`-`
`245`		`- val = val * 10 + (*s - '0');`
	`246`	`+ d = *s - '0';`
`246`	`247`
`247`	`248`	`/*`
`248`	`249`	`* check for overflow`
`249`	`250`	`*/`
`250`		`- if (val > MAX_TXID \|\| (val / 10) != last)`
	`251`	`+ if (val > cutoff \|\| (val == cutoff && d > cutlim))`
`251`	`252`	`{`
`252`	`253`	`val = 0;`
`253`	`254`	`break;`
`254`	`255`	`}`
	`256`	`+`
	`257`	`+ val = val * 10 + d;`
`255`	`258`	`}`
`256`	`259`	`if (endp)`
`257`	`260`	`*endp = s;`