Bug 50733
| Summary: | ostrstream is broken in function calls | ||
|---|---|---|---|
| Product: | [Retired] Red Hat Linux | Reporter: | Dan Mergens <dan> |
| Component: | gcc | Assignee: | Jakub Jelinek <jakub> |
| Status: | CLOSED NOTABUG | QA Contact: | David Lawrence <dkl> |
| Severity: | high | Docs Contact: | |
| Priority: | medium | ||
| Version: | 7.0 | ||
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | i686 | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2001-08-08 09:47:55 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
I had another problem that wasn't so easily isolated, but is similar. When I print out "" it is sometimes replaced with "(null)". This is a consistent bug in my code, but I can't seem to get a simple test case to show it. From: http://www.cygnus.com/pubs/gnupro-97r1/4_GNUPro_Libraries/c_The_GNU_C++_Iostream_Library/libioReading_and_writing_in_memory.html The char* the str() function returns isn't null terminated!! You need to do ostrstream o; o << "Hi there" << endl << '\0'; Yeah, either that or os << "hello" << endl << ends; Yes, that is the obvious workaround. However, str() is supposed to add the string terminator. The programmer is NOT supposed to do it manually. Notice that this only happens in the above test case which suggests a subtle problem with the try/catch mechanism. Since I can't PROVE that str() is supposed to add the null terminator (although after years of programming C++ I've never had a problem with it), I'll concede that it is not an official bug. The above URL clearly states that you HAVE TO do it manually and str() is not supposed to do it for you. Checking libstdc++-v3 from GCC 3.0.1, it has exactly the same behaviour. Reading [depr.strstreambuf] section in ISO C++ does not say anything that str() should do it, it should just freeze() and then return the beginning. |
From Bugzilla Helper: User-Agent: Mozilla/4.76 [en] (X11; U; Linux 2.2.16-22 i686) Description of problem: An error occurs where garbage is added to the end of ostrstream strings. This occurs when a function is called from a catch block when the function allocates the ostrstream locally. How reproducible: Always Steps to Reproduce: Compile and run the following code: ------------------------------------------------- #include <strstream.h> #include <stdio.h> #include <stdlib.h> void func() { ostrstream os; os << "hello" << endl; cout << os.str() << endl; } int main( int argc, char* const* argv ) { try { throw( "error" ); } catch( const char* err ) { func(); } } Actual Results: hello @*@,*@T*@t*@*@<*@\*@|*@+@@+@`+@+@,+@T+@t+@?,@8,@X,@?,@ ,@@,@h,-@a Expected Results: hello Additional info: This problem does not occur when the ostrstream is local to the main routine or if called from outside the catch block. I would classify this with loss of data as printing of information is trashed. (loss of data)