From 50ababbd552abfa8ef3b16ccdaea54b58f5c031c Mon Sep 17 00:00:00 2001 From: Russ Cox Date: Tue, 3 Jun 2014 00:16:48 -0400 Subject: acme: fix bufread crash due to typing-point scrolling Acme tracks the most recent typing insertion point and the home and end keys stop there on their way up to the top or down to the bottom of the file. That point should be iq1, and it should be adjusted properly so that it's always between 0 and t->file->b.nc inclusive. (This is all code from an external contributor, years old at this point but new since Plan 9.) Somehow, sometimes iq1 ends up a little beyond b.nc, and when passed to textbacknl it crashes acme in bufread. I can't see how that can happen but if it does, avoid the crash. It's tempting to pull the insertion point code out entirely but this is a little less invasive and should fix things for now. TBR=rsc https://codereview.appspot.com/107730043 --- src/cmd/acme/text.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/src/cmd/acme/text.c b/src/cmd/acme/text.c index 463db9ff..c537d277 100644 --- a/src/cmd/acme/text.c +++ b/src/cmd/acme/text.c @@ -725,6 +725,10 @@ texttype(Text *t, Rune r) case Kend: typecommit(t); if(t->iq1 > t->org+t->fr.nchars) { + if(t->iq1 > t->file->b.nc) { + // should not happen, but does. and it will crash textbacknl. + t->iq1 = t->file->b.nc; + } q0 = textbacknl(t, t->iq1, 1); textsetorigin(t, q0, TRUE); } else -- cgit v1.2.3