split stack overflow while in exception handler #1779
Description
This program:
package main
func main() {
var pad [28*100]byte
a := 0
b := 10 / a
println(b)
println(len(pad))
}
outputs this:
runtime: split stack overflow: 0x1084a5a8 < 0x1084a800
throw: runtime: split stack overflow
runtime.throw+0x42 /root/hg/go/src/pkg/runtime/runtime.c:102
runtime.throw(0x41f365, 0x1084a5a8)
runtime.newstack+0x9b /root/hg/go/src/pkg/runtime/proc.c:741
runtime.newstack()
runtime.morestack+0x4c /root/hg/go/src/pkg/runtime/386/asm.s:220
runtime.morestack()
----- morestack called from goroutine 1 -----
runtime.sigtramp1+0x19 /root/hg/go/src/pkg/runtime/windows/386/sys.s:68
runtime.sigtramp1(0x1084a5c4, 0x1084a5d0, 0x77fbb272, 0x1084a670, 0x6ffbc, ...)
runtime.sigtramp+0xd /root/hg/go/src/pkg/runtime/windows/386/sys.s:63
runtime.sigtramp()
----- goroutine created by -----
_rt0_386+0xbf /root/hg/go/src/pkg/runtime/386/asm.s:80
goroutine 1 [2]:
runtime.mainstart /root/hg/go/src/pkg/runtime/386/asm.s:91
runtime.mainstart()
runtime.goexit /root/hg/go/src/pkg/runtime/proc.c:178
runtime.goexit()
----- goroutine created by -----
_rt0_386+0xbf /root/hg/go/src/pkg/runtime/386/asm.s:80
I expect output to be different. And similar program:
package main
func main() {
var pad [20*100]byte
a := 0
b := 10 / a
println(b)
println(len(pad))
}
outputs correct text:
panic: runtime error: integer divide by zero
[signal 0xc0000094 code=0x1003f addr=0x0 pc=0x40103a]
runtime.panic+0x9e /root/hg/go/src/pkg/runtime/proc.c:1060
runtime.panic(0x40e66c, 0x10840000)
runtime.panicstring+0x94 /root/hg/go/src/pkg/runtime/runtime.c:116
runtime.panicstring(0x41e822, 0xb)
runtime.sigpanic+0xc5 /root/hg/go/src/pkg/runtime/windows/thread.c:279
runtime.sigpanic()
main.main+0x3a /home/sambauser/pub/t2/a.go:6
main.main()
runtime.mainstart+0xf /root/hg/go/src/pkg/runtime/386/asm.s:93
runtime.mainstart()
runtime.goexit /root/hg/go/src/pkg/runtime/proc.c:178
runtime.goexit()
----- goroutine created by -----
_rt0_386+0xbf /root/hg/go/src/pkg/runtime/386/asm.s:80
I think this is what happens:
1) division by zero occurs and exception is raised;
2) Windows exception handler runs, it puts some data on the stack;
3) Windows exception handler calls our exception handler runtime.settramp;
4) runtime.settramp calls runtime.settramp1;
5) as runtime.settramp1 is not '#pragma textflag 7', it will try to check stack only to
discover that it is overflown;
6) CRASH!
My:
hd id is 29f6e2e230a3,
GOARCH is 386
GOOS is windows
Alex