lib: add strtod_or_err()

Signed-off-by: Sami Kerola <kerolasa@iki.fi>

lib/strutils.c

@@ -29,6 +29,30 @@ long strtol_or_err(const char *str, const char *errmesg)
 	else
 		errx(EXIT_FAILURE, "%s: '%s'", errmesg, str);
 }
+/*
+ * same as strtod(3) but exit on failure instead of returning crap
+ */
+double strtod_or_err(const char *str, const char *errmesg)
+{
+	double num;
+	char *end = NULL;
+
+	if (str == NULL || *str == '\0')
+		goto err;
+	errno = 0;
+	num = strtod(str, &end);
+
+	if (errno || str == end || (end && *end))
+		goto err;
+
+	return num;
+ err:
+	if (errno)
+		err(EXIT_FAILURE, "%s: '%s'", errmesg, str);
+	else
+		errx(EXIT_FAILURE, "%s: '%s'", errmesg, str);
+	return 0;
+}
 
 #ifdef TEST_PROGRAM
 int main(int argc, char *argv[])