[hackers] [st] fix buffer overflow when handling long composed input || Hiltjo Posthuma

[git]

commit e5e959835b195c023d1f685ef4dbbcfc3b5120b2
Author:     Hiltjo Posthuma <hil...@codemadness.org>
AuthorDate: Tue Oct 25 17:11:11 2022 +0200
Commit:     Hiltjo Posthuma <hil...@codemadness.org>
CommitDate: Tue Oct 25 17:11:11 2022 +0200

    fix buffer overflow when handling long composed input
    
    To reproduce the issue:
    
    "
    If you already have the multi-key enabled on your system, then add this line
    to your ~/.XCompose file:
    
    [...]
    <question> <T> <E> <S> <T> <question> :
    "1234567890123456789012345678901234567890123456789012345678901234567890"
    "
    
    Reported by and an initial patch by Andy Gozas <a...@gozas.me>, thanks!
    
    Adapted the patch, for now st (like dmenu) handles a fixed amount of 
composed
    characters, or otherwise ignores it. This is done for simplicity sake.

diff --git a/x.c b/x.c
index 2a3bd38..aa09997 100644
--- a/x.c
+++ b/x.c
@@ -1833,7 +1833,7 @@ void
 kpress(XEvent *ev)
 {
        XKeyEvent *e = &ev->xkey;
-       KeySym ksym;
+       KeySym ksym = NoSymbol;
        char buf[64], *customkey;
        int len;
        Rune c;
@@ -1843,10 +1843,13 @@ kpress(XEvent *ev)
        if (IS_SET(MODE_KBDLOCK))
                return;
 
-       if (xw.ime.xic)
+       if (xw.ime.xic) {
                len = XmbLookupString(xw.ime.xic, e, buf, sizeof buf, &ksym, 
&status);
-       else
+               if (status == XBufferOverflow)
+                       return;
+       } else {
                len = XLookupString(e, buf, sizeof buf, &ksym, NULL);
+       }
        /* 1. shortcuts */
        for (bp = shortcuts; bp < shortcuts + LEN(shortcuts); bp++) {
                if (ksym == bp->keysym && match(bp->mod, e->state)) {