From 1b3fc33f810b605e0e6dfcba96dddae432ccaab3 Mon Sep 17 00:00:00 2001 From: Bruno Haible Date: Thu, 7 Jan 2021 02:06:17 +0100 Subject: argp: Don't rely on undefined behaviour of _tolower(). Patch by Eric Blake . * argp/argp-help.c (hol_entry_cmp): Don't use _tolower on values that are not upper-case. Pass correct range to tolower. Reviewed-by: Adhemerval Zanella --- argp/argp-help.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) (limited to 'argp') diff --git a/argp/argp-help.c b/argp/argp-help.c index f417e1294c..5844d5ba1c 100644 --- a/argp/argp-help.c +++ b/argp/argp-help.c @@ -780,13 +780,11 @@ hol_entry_cmp (const struct hol_entry *entry1, first, but as they're not displayed, it doesn't matter where they are. */ { - char first1 = short1 ? short1 : long1 ? *long1 : 0; - char first2 = short2 ? short2 : long2 ? *long2 : 0; -#ifdef _tolower - int lower_cmp = _tolower (first1) - _tolower (first2); -#else + unsigned char first1 = short1 ? short1 : long1 ? *long1 : 0; + unsigned char first2 = short2 ? short2 : long2 ? *long2 : 0; + /* Use tolower, not _tolower, since the latter has undefined + behaviour for characters that are not uppercase letters. */ int lower_cmp = tolower (first1) - tolower (first2); -#endif /* Compare ignoring case, except when the options are both the same letter, in which case lower-case always comes first. */ return lower_cmp ? lower_cmp : first2 - first1; -- cgit 1.4.1