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* [newlib-cygwin] Cygwin: main exception handler (64-bit): continue GCC exceptions
@ 2020-08-18 11:05 Ken Brown
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From: Ken Brown @ 2020-08-18 11:05 UTC (permalink / raw)
To: cygwin-cvs
https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=74cf7dabcb69ea0608163ba84ecc3d798d5b0421
commit 74cf7dabcb69ea0608163ba84ecc3d798d5b0421
Author: Ken Brown <kbrown@cornell.edu>
Date: Mon Aug 17 16:24:59 2020 -0400
Cygwin: main exception handler (64-bit): continue GCC exceptions
This is necessary in order to be consistent with the following comment
in the definition of _Unwind_RaiseException() in the GCC source file
libgcc/unwind-seh.c:
The exception handler installed in crt0 will continue any GCC
exception that reaches there (and isn't marked non-continuable).
Previously we failed to do this and, as a consequence, the C++ runtime
didn't call std::terminate after an unhandled exception.
This fixes the problem reported here:
https://cygwin.com/pipermail/cygwin/2019-October/242795.html
https://sourceware.org/pipermail/cygwin/2020-August/245897.html
Diff:
---
winsup/cygwin/exceptions.cc | 19 +++++++++++++++++++
winsup/cygwin/release/3.1.7 | 4 ++++
2 files changed, 23 insertions(+)
diff --git a/winsup/cygwin/exceptions.cc b/winsup/cygwin/exceptions.cc
index 0d9e8f70e..61406e5d1 100644
--- a/winsup/cygwin/exceptions.cc
+++ b/winsup/cygwin/exceptions.cc
@@ -762,6 +762,25 @@ exception::handle (EXCEPTION_RECORD *e, exception_list *frame, CONTEXT *in,
handling. */
return ExceptionContinueExecution;
+#ifdef __x86_64__
+/* From the GCC source file libgcc/unwind-seh.c. */
+#define STATUS_USER_DEFINED (1U << 29)
+#define GCC_MAGIC (('G' << 16) | ('C' << 8) | 'C')
+#define GCC_EXCEPTION(TYPE) \
+ (STATUS_USER_DEFINED | ((TYPE) << 24) | GCC_MAGIC)
+#define STATUS_GCC_THROW GCC_EXCEPTION (0)
+#define STATUS_GCC_UNWIND GCC_EXCEPTION (1)
+#define STATUS_GCC_FORCED GCC_EXCEPTION (2)
+
+ case STATUS_GCC_THROW:
+ case STATUS_GCC_UNWIND:
+ case STATUS_GCC_FORCED:
+ /* According to a comment in the GCC function
+ _Unwind_RaiseException(), GCC expects us to continue all the
+ (continuable) GCC exceptions that reach us. */
+ return ExceptionContinueExecution;
+#endif
+
default:
/* If we don't recognize the exception, we have to assume that
we are doing structured exception handling, and we let
diff --git a/winsup/cygwin/release/3.1.7 b/winsup/cygwin/release/3.1.7
index 2f4856495..83cff2b46 100644
--- a/winsup/cygwin/release/3.1.7
+++ b/winsup/cygwin/release/3.1.7
@@ -11,3 +11,7 @@ Bug Fixes:
- Fix an mmap issue that could cause failure with errno EFBIG
Partially addresses: https://sourceware.org/pipermail/cygwin/2020-July/245557.html
+
+- Fix the behavior of C++ apps after an unhandled exception (64-bit only)
+ Addresses: https://cygwin.com/pipermail/cygwin/2019-October/242795.html
+ https://cygwin.com/pipermail/cygwin/2020-August/245897.html
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2020-08-18 11:05 [newlib-cygwin] Cygwin: main exception handler (64-bit): continue GCC exceptions Ken Brown
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