eh

Author: arnetheduck

lib/system/excpt.nim

@@ -17,7 +17,7 @@ const noStacktraceAvailable = "No stack traceback available\n"
 
 var
   errorMessageWriter*: (proc(msg: string) {.tags: [WriteIOEffect], benign,
-                                            nimcall.})
+                                            nimcall, raises: [].})
     ## Function that will be called
     ## instead of `stdmsg.write` when printing stacktrace.
     ## Unstable API.
@@ -632,7 +632,7 @@ when not defined(noSignalHandler) and not defined(useNimRtl):
   #      for libbacktrace.
   var sigHandlerBuf = newStringOfCap(32*1024)
 
-  proc signalHandler(sign: cint) {.exportc: "signalHandler", noconv.} =
+  proc signalHandler(sign: cint) {.exportc: "signalHandler", noconv, raises: [].} =
     template processSignal(s, action: untyped) {.dirty.} =
       if s == SIGINT: action("SIGINT: Interrupted by Ctrl-C.\n")
       elif s == SIGSEGV:
@@ -654,7 +654,12 @@ when not defined(noSignalHandler) and not defined(useNimRtl):
     # print stack trace and quit
     when defined(memtracker):
       logPendingOps()
-    when hasSomeStackTrace:
+    # On windows, it is common that the signal handler is called from a non-Nim
+    # thread - until `rawWriteStackTrace` and friends learns to not allocate
+    # memory, we'll skip the memory allocation and avoid crashes this way
+    # On other platforms, the memory allocation may still cause crashes, but
+    # not as frequently. YOLO.
+    when hasSomeStackTrace and not defined(windows):
       when not usesDestructors: GC_disable()
       rawWriteStackTrace(sigHandlerBuf)
       processSignal(sign, sigHandlerBuf.add) # nice hu? currying a la Nim :-)
@@ -665,9 +670,11 @@ when not defined(noSignalHandler) and not defined(useNimRtl):
       template asgn(y) =
         msg = y
       processSignal(sign, asgn)
-      # xxx use string for msg instead of cstring, and here use showErrorMessage2(msg)
-      # unless there's a good reason to use cstring in signal handler to avoid
-      # using gc?
+      # showErrorMessage may allocate, which may cause a crash, and calls C
+      # library functions which is undefined behavior, ie it may also crash.
+      # Nevertheless, we sometimes manage to emit the message regardless which
+      # pragmatically makes this attempt "useful enough".
+      # See also https://en.cppreference.com/w/c/program/signal
       showErrorMessage(msg, msg.len)
 
     when defined(posix):

lib/system/memtracker.nim

@@ -35,7 +35,7 @@ type
     count*: int
     disabled: bool
     data*: array[400, LogEntry]
-  TrackLogger* = proc (log: TrackLog) {.nimcall, tags: [], gcsafe.}
+  TrackLogger* = proc (log: TrackLog) {.nimcall, tags: [], gcsafe, raises: [].}
 
 var
   gLog*: TrackLog