[jira] [Commented] (THRIFT-4781) C++ clients crash when exceptions are typedefed in the IDL

["Zezeng Wang (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/THRIFT-4781?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17083366#comment-17083366 ] 

Zezeng Wang commented on THRIFT-4781:
-------------------------------------

Hi [~andrejn] , can you post the key code to show how to reproduce this bug? I know what you mean but I can't reproduce this bug.

> C++ clients crash when exceptions are typedefed in the IDL
> ----------------------------------------------------------
>
>                 Key: THRIFT-4781
>                 URL: https://issues.apache.org/jira/browse/THRIFT-4781
>             Project: Thrift
>          Issue Type: Bug
>          Components: C++ - Compiler
>    Affects Versions: 0.11.0, 0.12.0
>            Reporter: Andrej Nazarov
>            Priority: Major
>
> If exceptions are typedefed in the IDL, they're generated as pointers in Cpp. This causes a runtime crash (memory access violation) on the C++ client-side when a server sends that exception and the client tries to read it. Example follows:
> {code:java|title=service.thrift}
> namespace * thrifttest.service
> include "errors.thrift"
> typedef errors.FooError FooError
> service FooBarService
> {
> 	string getFooString(1: i32 stringLength) throws (1: FooError e);
> 	string getBarString(1: i32 stringLength) throws (1: errors.BarError e);
> }
> {code}
> {code:java|title=errors.thrift}
> namespace * thrifttest.errors
> exception FooError {
>   1: string message
> }
> exception BarError {
>   1: string message
> }
> {code}
> {code:java|title=FooBarService.h}
> class FooBarService_getFooString_presult {
>  public:
>   virtual ~FooBarService_getFooString_presult() throw();
>   std::string* success;
>   FooError* e; //note pointer declaration of the exception field
> // snip...
> class FooBarService_getBarString_presult {
>  public:
>   virtual ~FooBarService_getBarString_presult() throw();
>   std::string* success;
>    ::thrifttest::errors::BarError e; //note different declaration of the exception field
> //snip
> {code}
> {code:java|title=FooBarService.cpp}
> uint32_t FooBarService_getFooString_presult::read(::apache::thrift::protocol::TProtocol* iprot) {
> // snip...
>   while (true)
>   {
> // snip...
>     switch (fid)
>     {
> // snip...
>       case 1:
>         if (ftype == ::apache::thrift::protocol::T_STRUCT) {
>           xfer += (*(this->e)).read(iprot); // <-- this line causes access violation crash because the pointer is not initialized
>           this->__isset.e = true;
>        // snip...
> uint32_t FooBarService_getBarString_presult::read(::apache::thrift::protocol::TProtocol* iprot) {
> // snip...
>   while (true)
>   {
> // snip...
>     switch (fid)
>     {
> // snip...
>       case 1:
>         if (ftype == ::apache::thrift::protocol::T_STRUCT) {
>           xfer += this->e.read(iprot); //<-- this gets read OK.
>           this->__isset.e = true;
> //snip
> {code}
> This happens regardless of server language (reproducible if server throwing the exceptions is Java, Python or C++)
>  I guess this logic in [t_cpp_generator.cc:1104|https://github.com/apache/thrift/blob/0.11.0/compiler/cpp/src/thrift/generate/t_cpp_generator.cc#L1104] gets deceived in case of typedefed exceptions:
> {code:java|title=t_cpp_generator.cc}
> (pointers && !(*m_iter)->get_type()->is_xception()),
> {code}
> I'm no Thrift compiler expert, but I assume there is a reason why you don't want exceptions to be declared as pointers. Yet in this case they clearly are.



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