[hackers] [sbase][PATCH] expr: tonum: handle case where result was previously calculated

From: Randy Palamar <randy_AT_rnpnr.xyz>
Date: Mon, 22 Jan 2024 14:18:10 -0700

As pointed out in a mail to dev expr was segfaulting when multiple
math operations were specified on the command line: eg. 'expr 3 \*
2 + 1'. This happens because the tonum(), introduced in e50d533,
assumed that v->str was always non null. parse() guarantees this
for user input but this is not the case when doop() is called with
the result of a previous calculation. However in that case we know
that v->num is already valid so we can simply return.

---
 expr.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/expr.c b/expr.c
index 3afb94b..044c6c1 100644
--- a/expr.c
+++ b/expr.c
_AT_@ -21,7 +21,13 @@ static void
 tonum(struct val *v)
 {
 	const char *errstr;
-	long long d = strtonum(v->str, LLONG_MIN, LLONG_MAX, &errstr);
+	long long d;
+
+	/* check if val is the result of an earlier calculation */
+	if (!v->str)
+		return;
+
+	d = strtonum(v->str, LLONG_MIN, LLONG_MAX, &errstr);
 	if (errstr)
 		enprintf(2, "error: expected integer, got %s\n", v->str);
 	v->num = d;
-- 
2.43.0

Received on Mon Jan 22 2024 - 22:18:10 CET