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nimRawSetjmp: support Windows (#19197)

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* nimRawSetjmp: support Windows

Using `_setjmp()` directly is required to avoid some rare (but very
annoying) exception-related stack corruption leading to segfaults on
Windows, with Mingw-w64 and SEH.
More details: https://github.com/status-im/nimbus-eth2/issues/3121

Also add "nimBuiltinSetjmp" - mostly for benchmarking.

* fix for Apple's Clang++
This commit is contained in:
Ștefan Talpalaru
2021-12-10 06:31:29 +01:00
committed by GitHub
parent 32d4bf3525
commit 69aabdab80
5 changed files with 199 additions and 10 deletions
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46
lib/system/ansi_c.nim
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@@ -31,7 +31,10 @@ proc c_abort*() {.
importc: "abort", header: "<stdlib.h>", noSideEffect, noreturn.}
when defined(linux) and defined(amd64):
when defined(nimBuiltinSetjmp):
type
C_JmpBuf* = array[5, pointer]
elif defined(linux) and defined(amd64):
type
C_JmpBuf* {.importc: "jmp_buf", header: "<setjmp.h>", bycopy.} = object
abi: array[200 div sizeof(clong), clong]
@@ -92,18 +95,47 @@ when defined(macosx):
elif defined(haiku):
const SIGBUS* = cint(30)
when defined(nimSigSetjmp) and not defined(nimStdSetjmp):
# "nimRawSetjmp" is defined by default for certain platforms, so we need the
# "nimStdSetjmp" escape hatch with it.
when defined(nimSigSetjmp):
proc c_longjmp*(jmpb: C_JmpBuf, retval: cint) {.
header: "<setjmp.h>", importc: "siglongjmp".}
template c_setjmp*(jmpb: C_JmpBuf): cint =
proc c_setjmp*(jmpb: C_JmpBuf): cint =
proc c_sigsetjmp(jmpb: C_JmpBuf, savemask: cint): cint {.
header: "<setjmp.h>", importc: "sigsetjmp".}
c_sigsetjmp(jmpb, 0)
elif defined(nimBuiltinSetjmp):
proc c_longjmp*(jmpb: C_JmpBuf, retval: cint) =
# Apple's Clang++ has trouble converting array names to pointers, so we need
# to be very explicit here.
proc c_builtin_longjmp(jmpb: ptr pointer, retval: cint) {.
importc: "__builtin_longjmp", nodecl.}
# The second parameter needs to be 1 and sometimes the C/C++ compiler checks it.
c_builtin_longjmp(unsafeAddr jmpb[0], 1)
proc c_setjmp*(jmpb: C_JmpBuf): cint =
proc c_builtin_setjmp(jmpb: ptr pointer): cint {.
importc: "__builtin_setjmp", nodecl.}
c_builtin_setjmp(unsafeAddr jmpb[0])
elif defined(nimRawSetjmp) and not defined(nimStdSetjmp):
proc c_longjmp*(jmpb: C_JmpBuf, retval: cint) {.
header: "<setjmp.h>", importc: "_longjmp".}
proc c_setjmp*(jmpb: C_JmpBuf): cint {.
header: "<setjmp.h>", importc: "_setjmp".}
when defined(windows):
# No `_longjmp()` on Windows.
proc c_longjmp*(jmpb: C_JmpBuf, retval: cint) {.
header: "<setjmp.h>", importc: "longjmp".}
# The Windows `_setjmp()` takes two arguments, with the second being an
# undocumented buffer used by the SEH mechanism for stack unwinding.
# Mingw-w64 has been trying to get it right for years, but it's still
# prone to stack corruption during unwinding, so we disable that by setting
# it to NULL.
# More details: https://github.com/status-im/nimbus-eth2/issues/3121
proc c_setjmp*(jmpb: C_JmpBuf): cint =
proc c_setjmp_win(jmpb: C_JmpBuf, ctx: pointer): cint {.
header: "<setjmp.h>", importc: "_setjmp".}
c_setjmp_win(jmpb, nil)
else:
proc c_longjmp*(jmpb: C_JmpBuf, retval: cint) {.
header: "<setjmp.h>", importc: "_longjmp".}
proc c_setjmp*(jmpb: C_JmpBuf): cint {.
header: "<setjmp.h>", importc: "_setjmp".}
else:
proc c_longjmp*(jmpb: C_JmpBuf, retval: cint) {.
header: "<setjmp.h>", importc: "longjmp".}