On 1/24/24 15:17, Matteo Italia wrote:
Ping! That's a one-line fix, and you can find all the details in the
bugzilla entry. Also, I can provide executables built with the affected
toolchains, demonstrating the problem and the fix.
Thanks,
Matteo
I was away last week. LH, care to comment? Changes look fine to me.
Il 17/01/24 12:51, Matteo Italia ha scritto:
SEH _Unwind_Resume_or_Rethrow invokes abort directly if
_Unwind_RaiseException doesn't manage to find a handler for the rethrown
exception; this is incorrect, as in this case std::terminate should be
invoked, allowing an application-provided terminate handler to handle
the situation instead of straight crashing the application through
abort.
The bug can be demonstrated with this simple test case:
===
static void custom_terminate_handler() {
fprintf(stderr, "custom_terminate_handler invoked\n");
std::exit(1);
}
int main(int argc, char *argv[]) {
std::set_terminate(&custom_terminate_handler);
if (argc < 2) return 1;
const char *mode = argv[1];
fprintf(stderr, "%s\n", mode);
if (strcmp(mode, "throw") == 0) {
throw std::exception();
} else if (strcmp(mode, "rethrow") == 0) {
try {
throw std::exception();
} catch (...) {
throw;
}
} else {
return 1;
}
return 0;
}
===
On all gcc builds with non-SEH exceptions, this will print
"custom_terminate_handler invoked" both if launched as ./a.out throw or
as ./a.out rethrow, on SEH builds instead if will work as expected only
with ./a.exe throw, but will crash with the "built-in" abort message
with ./a.exe rethrow.
This patch fixes the problem, forwarding back the error code to the
caller (__cxa_rethrow), that calls std::terminate if
_Unwind_Resume_or_Rethrow returns.
The change makes the code path coherent with SEH _Unwind_RaiseException,
and with the generic _Unwind_Resume_or_Rethrow from libgcc/unwind.inc
(used for SjLj and Dw2 exception backend).
libgcc/ChangeLog:
* unwind-seh.c (_Unwind_Resume_or_Rethrow): forward
_Unwind_RaiseException return code back to caller instead of
calling abort, allowing __cxa_rethrow to invoke std::terminate
in case of uncaught rethrown exception
---
libgcc/unwind-seh.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/libgcc/unwind-seh.c b/libgcc/unwind-seh.c
index 8ef0257b616..f1b8f5a8519 100644
--- a/libgcc/unwind-seh.c
+++ b/libgcc/unwind-seh.c
@@ -395,9 +395,9 @@ _Unwind_Reason_Code
_Unwind_Resume_or_Rethrow (struct _Unwind_Exception *exc)
{
if (exc->private_[0] == 0)
- _Unwind_RaiseException (exc);
- else
- _Unwind_ForcedUnwind_Phase2 (exc);
+ return _Unwind_RaiseException (exc);
+
+ _Unwind_ForcedUnwind_Phase2 (exc);
abort ();
}
