acme was in an infinite loop because frame called a string varient with a negative string length since len is signed, the proposed fix is len > 0. this fix is similar to something gerold has done. the snapped process is here: /n/sources/contrib/quanstro/acme.snap.bz2 acid; stk() cachechars(f=0x9de28,ss=0xef0a4,rr=0x0,subfontname=0xeef98,max=0xfffffffa,cp=0xeefa8,wp=0xef074)+0x44 /sys/src/libdraw/font.c:27 _string(len=0xfffffffa,f=0x9de28,.ret=0x680ec,s=0x40e60b,r=0x685ec,dst=0xa6708,op=0xb,bg=0xa67c8,src=0x9ae58,pt=0x1bf,clipr=0x4c,sp=0x0,bgp=0x0)+0x118 /sys/src/libdraw/string.c:85 stringnbg(src=0x9ae58,f=0x9de28,s=0x40e60b,len=0xfffffffa,bg=0xa67c8,dst=0xa6708,.ret=0x680ec,pt=0x1bf,sp=0x0,bgp=0x0)+0xd4 /sys/src/libdraw/stringbg.c:20 frdrawsel0(p0=0x3b,f=0x321398,.ret=0x680ec,p1=0x35,pt=0x1bf,back=0xa67c8,text=0x9ae58)+0x5a8 /sys/src/libframe/frdraw.c:105 frdrawsel(p0=0x3b,p1=0x35,issel=0x1,f=0xef178,pt=0x1bf)+0x110 /sys/src/libframe/frdraw.c:57 textsetselect(q0=0x3b,q1=0x35,t=0x321394)+0x198 /sys/src/cmd/acme/text.c:1093 texttype(r=0x1b,t=0x321394)+0x930 /sys/src/cmd/acme/text.c:744 wintype(t=0x321394,r=0x1b,w=0x321380)+0x20 /sys/src/cmd/acme/wind.c:308 rowtype(row=0x77c50,p=0x1bf,r=0x1b)+0x118 /sys/src/cmd/acme/rows.c:408 keyboardthread()+0x168 /sys/src/cmd/acme/acme.c:398 launchermips(arg=0x0,f=0x5344)+0x14 /sys/src/libthread/mips.c:10 launchermips(arg=0x0,f=0x5344)+0xfffffffffffffff8 /sys/src/libthread/xincmips.s:44 _string+0x118 /sys/src/libdraw/string.c:85 acid; stk() cachechars(f=0x9de28,ss=0xef0a4,rr=0x0,subfontname=0xeef98,max=0xfffffffa,cp=0xeefa8,wp=0xef074)+0x4 /sys/src/libdraw/font.c:11 _string(len=0xfffffffa,f=0x9de28,.ret=0x680ec,s=0x40e60b,r=0x685ec,dst=0xa6708,op=0xb,bg=0xa67c8,src=0x9ae58,pt=0x1bf,clipr=0x4c,sp=0x0,bgp=0x0)+0x118 /sys/src/libdraw/string.c:85 stringnbg(src=0x9ae58,f=0x9de28,s=0x40e60b,len=0xfffffffa,bg=0xa67c8,dst=0xa6708,.ret=0x680ec,pt=0x1bf,sp=0x0,bgp=0x0)+0xd4 /sys/src/libdraw/stringbg.c:20 frdrawsel0(p0=0x3b,f=0x321398,.ret=0x680ec,p1=0x35,pt=0x1bf,back=0xa67c8,text=0x9ae58)+0x5a8 /sys/src/libframe/frdraw.c:105 frdrawsel(p0=0x3b,p1=0x35,issel=0x1,f=0xef178,pt=0x1bf)+0x110 /sys/src/libframe/frdraw.c:57 textsetselect(q0=0x3b,q1=0x35,t=0x321394)+0x198 /sys/src/cmd/acme/text.c:1093 texttype(r=0x1b,t=0x321394)+0x930 /sys/src/cmd/acme/text.c:744 wintype(t=0x321394,r=0x1b,w=0x321380)+0x20 /sys/src/cmd/acme/wind.c:308 rowtype(row=0x77c50,p=0x1bf,r=0x1b)+0x118 /sys/src/cmd/acme/rows.c:408 keyboardthread()+0x168 /sys/src/cmd/acme/acme.c:398 launchermips(arg=0x0,f=0x5344)+0x14 /sys/src/libthread/mips.c:10 launchermips(arg=0x0,f=0x5344)+0xfffffffffffffff8 /sys/src/libthread/xincmips.s:44 _string+0x118 /sys/src/libdraw/string.c:85 acid; lstk() cachechars(f=0x9de28,ss=0xef0a4,rr=0x0,subfontname=0xeef98,max=0xfffffffa,cp=0xeefa8,wp=0xef074)+0x1c0 /sys/src/libdraw/font.c:98 rp=0x68548 wid=0x0 i=0x0 sp=0x4e9a0 w=0x826cc vr=0xef028 rw=0x0 h=0x3a7a0 _string(len=0xfffffffa,f=0x9de28,.ret=0x680ec,s=0x40e60b,r=0x685ec,dst=0xa6708,op=0xb,bg=0xa67c8,src=0x9ae58,pt=0x1bf,clipr=0x4c,sp=0x0,bgp=0x0)+0x118 /sys/src/libdraw/string.c:85 sptr=0xef0a4 rptr=0x0 sf=0x0 cbuf=0x0 wid=0x0 subfontname=0x0 n=0x0 stringnbg(src=0x9ae58,f=0x9de28,s=0x40e60b,len=0xfffffffa,bg=0xa67c8,dst=0xa6708,.ret=0x680ec,pt=0x1bf,sp=0x0,bgp=0x0)+0xd4 /sys/src/libdraw/stringbg.c:20 frdrawsel0(p0=0x3b,f=0x321398,.ret=0x680ec,p1=0x35,pt=0x1bf,back=0xa67c8,text=0x9ae58)+0x5a8 /sys/src/libframe/frdraw.c:105 trim=0x1 nb=0x0 nr=0xfffffffa p=0x3b qt=0x40e60b b=0x391380 ptr=0x40e60b w=0x0 frdrawsel(p0=0x3b,p1=0x35,issel=0x1,f=0xef178,pt=0x1bf)+0x110 /sys/src/libframe/frdraw.c:57 textsetselect(q0=0x3b,q1=0x35,t=0x321394)+0x198 /sys/src/cmd/acme/text.c:1093 p1=0x35 p0=0x3b texttype(r=0x1b,t=0x321394)+0x930 /sys/src/cmd/acme/text.c:744 nr=0x1 rp=0xef1d4 nnb=0x2ef14 q0=0x23778 q1=0x321380 i=0x321380 nb=0x237e4 u=0x241 n=0x2ee8c wintype(t=0x321394,r=0x1b,w=0x321380)+0x20 /sys/src/cmd/acme/wind.c:308 i=0x0 rowtype(row=0x77c50,p=0x1bf,r=0x1b)+0x118 /sys/src/cmd/acme/rows.c:408 t=0x321394 w=0x321380 keyboardthread()+0x168 /sys/src/cmd/acme/acme.c:398 r=0x1b timer=0xe45a0 t=0x321394 launchermips(arg=0x0,f=0x5344)+0x14 /sys/src/libthread/mips.c:10 launchermips(arg=0x0,f=0x5344)+0xfffffffffffffff8 /sys/src/libthread/xincmips.s:44 _string+0x118 /sys/src/libdraw/string.c:85 acid; *(0x391380\X+4) :7: (error) indir: can't translate address 0x22f acid; *0x391380 0x0000022b acid; *(0x391380\X+4) 0x0000005c