config: avoid calling labs() on too-large data type

dscho · gitster · commit 9dae4fe79f85 · 2019-06-13T09:34:17.000-07:00
The `labs()` function operates, as the initial `l` suggests, on `long`
parameters. However, in `config.c` we tried to use it on values of type
`intmax_t`.

This problem was found by GCC v9.x.

To fix it, let's just "unroll" the function (i.e. negate the value if it
is negative).

Signed-off-by: Johannes Schindelin &lt;johannes.schindelin@gmx.de&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
diff --git a/config.c b/config.c
@@ -869,9 +869,9 @@ static int git_parse_signed(const char *value, intmax_t *ret, intmax_t max)
 			errno = EINVAL;
 			return 0;
 		}
-		uval = labs(val);
+		uval = val < 0 ? -val : val;
 		uval *= factor;
-		if (uval > max || labs(val) > uval) {
+		if (uval > max || (val < 0 ? -val : val) > uval) {
 			errno = ERANGE;
 			return 0;
 		}

Original file line number	Diff line number	Diff line change
`@@ -869,9 +869,9 @@ static int git_parse_signed(const char value, intmax_t ret, intmax_t max)`
`869`	`869`	`errno = EINVAL;`
`870`	`870`	`return 0;`
`871`	`871`	`}`
`872`		`- uval = labs(val);`
	`872`	`+ uval = val < 0 ? -val : val;`
`873`	`873`	`uval *= factor;`
`874`		`- if (uval > max \|\| labs(val) > uval) {`
	`874`	`+ if (uval > max \|\| (val < 0 ? -val : val) > uval) {`
`875`	`875`	`errno = ERANGE;`
`876`	`876`	`return 0;`
`877`	`877`	`}`