Operator=(const String &c)

[David Sugar]

I found there is no = operator defined for String to String, and the default 
operator I verified does copy the String content data structure literally, 
since after an equal, both strings have pointers to the same memory buffer.  
In addition to defining that operator, I also rewrote the copy constructor a 
bit in general.  This removed one error, but there is still at least one more 
case where the values of content seem duplicatable between String objects, 
which I am still tracking down.

On Saturday 10 April 2004 05:58 am, David Sugar wrote:
> My first thought is that most of these operations depend on getLength
> returning the correct string length (in effect strlen() + 1 null byte).
> However, the String class actually stores a length field, which is what
> getLength() actually returns, and maybe that length field is not being kept
> in sync with the actual string length in some circumstances!  It would be
> interesting to compare the length returned by getLength with the length
> returned by strlen() in front of each of these memmove's...
>
> On Friday 09 April 2004 05:00 pm, you wrote:
> > In addition, none of these problems occur with commoncpp2 1.0.13 only in
> > 1.1.2.
> >
> > Joshua Moore-Oliva.
> >
> > On April 8, 2004 9:19 pm, David Sugar wrote:
> > > So what you did is basically replace every memcpy with a memmove?
> > > Hmm...in at least some cases, memcpy may be inline'd with assembler
> > > code. Perhaps there is something odd in the inline code substitution? 
> > > Also, your patch got a little chopped up in the debugging text...
> > >
> > > David
> > >
> > > On Friday 09 April 2004 04:02 am, Joshua Moore-Oliva wrote:
> > > > I created a program with quite a few options, and I got a
> > > > segmentation fault that appears to be a mis-use of memcpy.
> > > >
> > > > Included is a test program to reproduce the problem and some
> > > > debugging output.
> > > >
> > > > I was able to remove the problems with memcpy with the changes in the
> > > > included patch, however I am not familiar enough with the code to
> > > > determine why the getSpace function in the String library is going
> > > > out of bounds...
> > > >
> > > > debugging output before patch
> > > >
> > > > ==17692== Source and destination overlap in memcpy(0x41E1A83C,
> > > > 0x41E1A87C, 86) ==17692==    at 0x40022224: memcpy (in
> > > > /usr/lib/valgrind/vgskin_memcheck.so) ==17692==    by 0x40277A94:
> > > > ost::String::set(char const*, unsigned) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==17692==    by 0x40277B07:
> > > > ost::String::set(ost::String const&) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==17692==    by 0x402B16C1:
> > > > ost::String::operator=(ost::String const&) (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==17692==    by 0x402B7B10:
> > > > ost::CommandOptionParse_impl::makePrintErrors() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==17692==    by 0x402B6CAC:
> > > > ost::CommandOptionParse_impl::printErrors() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==17692==    by 0x8048BD8: main (in
> > > > /home/chatgris/a.out)
> > > > ==17692==
> > > > ==17692== Source and destination overlap in memcpy(0x41E1A87C,
> > > > 0x41E1A83C, 87) ==17692==    at 0x40022224: memcpy (in
> > > > /usr/lib/valgrind/vgskin_memcheck.so) ==17692==    by 0x40277C75:
> > > > ost::String::copy(ost::String const&) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==17692==    by 0x4027647B:
> > > > ost::String::String(ost::String const&) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==17692==    by 0x4027887C:
> > > > ost::operator+(ost::String const&, char const*) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==17692==    by 0x402B7B83:
> > > > ost::CommandOptionParse_impl::makePrintErrors() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==17692==    by 0x402B6CAC:
> > > > ost::CommandOptionParse_impl::printErrors() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==17692==    by 0x8048BD8: main (in
> > > > /home/chatgris/a.out)
> > > > ==17692==
> > > > ==17692== Source and destination overlap in memcpy(0x41E1AC68,
> > > > 0x41E1ABA8, 215) ==17692==    at 0x40022224: memcpy (in
> > > > /usr/lib/valgrind/vgskin_memcheck.so) ==17692==    by 0x40278310:
> > > > ost::String::resize(unsigned) (in /usr/lib/libccgnu2-1.1.so.0.0.2)
> > > > ==17692==    by 0x40277A71: ost::String::set(char const*, unsigned)
> > > > (in /usr/lib/libccgnu2-1.1.so.0.0.2) ==17692==    by 0x40277B07:
> > > > ost::String::set(ost::String const&) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==17692==    by 0x402B16C1:
> > > > ost::String::operator=(ost::String const&) (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==17692==    by 0x402B7DD5:
> > > > ost::CommandOptionParse_impl::makePrintErrors() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==17692==    by 0x402B6CAC:
> > > > ost::CommandOptionParse_impl::printErrors() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==17692==    by 0x8048BD8: main (in
> > > > /home/chatgris/a.out)
> > > > Value required for option '--connection_string' is missing
> > > > Value==17692==
> > > > ==17692== Source and destination overlap in memcpy(0x41E1A7BC,
> > > > 0x41E1A7DC, 41) ==17692==    at 0x40022224: memcpy (in
> > > > /usr/lib/valgrind/vgskin_memcheck.so) ==17692==    by 0x40277C75:
> > > > ost::String::copy(ost::String const&) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==17692==    by 0x4027647B:
> > > > ost::String::String(ost::String const&) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==17692==    by 0x402787B2:
> > > > ost::operator+(ost::String const&, char) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==17692==    by 0x402B8015:
> > > > ost::CommandOptionParse_impl::makePrintUsage() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==17692==    by 0x402B6C7A:
> > > > ost::CommandOptionParse_impl::printUsage() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==17692==    by 0x8048BFA: main (in
> > > > /home/chatgris/a.out)
> > > > ==17692==
> > > > ==17692== Invalid read of size 4
> > > > ==17692==    at 0x40278576: ost::String::getSpace(unsigned) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==17692==    by 0x402781F6:
> > > > ost::String::resize(unsigned) (in /usr/lib/libccgnu2-1.1.so.0.0.2)
> > > > ==17692==    by 0x40277A71: ost::String::set(char const*, unsigned)
> > > > (in /usr/lib/libccgnu2-1.1.so.0.0.2) ==17692==    by 0x40277B07:
> > > > ost::String::set(ost::String const&) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==17692==    by 0x402B16C1:
> > > > oValue==26722== Invalid read of size 4 ==26722==    at 0x40278576:
> > > > ost::String::getSpace(unsigned) (in /usr/lib/libccgnu2-1.1.so.0.0.2)
> > > > ==26722==    by 0x402781F6:
> > > > ost::String::resize(unsigned) (in /usr/lib/libccgnu2-1.1.so.0.0.2)
> > > > ==26722==    by 0x40277A71: ost::String::set(char const*, unsigned)
> > > > (in /usr/lib/libccgnu2-1.1.so.0.0.2) ==26722==    by 0x40277B07:
> > > > ost::String::set(ost::String const&) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==26722==    by 0x402B16C1:
> > > > ost::String::operator=(ost::String const&) (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==26722==    by 0x402B802A:
> > > > ost::CommandOptionParse_impl::makePrintUsage() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==26722==    by 0x402B6C7A:
> > > > ost::CommandOptionParse_impl::printUsage() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==26722==    by 0x8048BFA: main
> > > > (main.cpp:69)
> > > > ==26722==  Address 0x20202020 is not stack'd, malloc'd or free'd
> > > > ==26722==
> > > > ==26722== Process terminating with default action of signal 11
> > > > (SIGSEGV): dumping core ==26722==  Address not mapped to object at
> > > > address 0x20202020 ==26722==    at 0x40278576:
> > > > ost::String::getSpace(unsigned) (in /usr/lib/libccgnu2-1.1.so.0.0.2)
> > > > ==26722==    by 0x402781F6:
> > > > ost::String::resize(unsigned) (in /usr/lib/libccgnu2-1.1.so.0.0.2)
> > > > ==26722==    by 0x40277A71: ost::String::set(char const*, unsigned)
> > > > (in /usr/lib/libccgnu2-1.1.so.0.0.2) ==26722==    by 0x40277B07:
> > > > ost::String::set(ost::String const&) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==26722==    by 0x402B16C1:
> > > > ost::String::operator=(ost::String const&) (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==26722==    by 0x402B802A:
> > > > ost::CommandOptionParse_impl::makePrintUsage() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==26722==    by 0x402B6C7A:
> > > > ost::CommandOptionParse_impl::printUsage() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==26722==    by 0x8048BFA: main
> > > > (main.cpp:69)st::String::operator=(ost::String const&) (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==17692==    by 0x402B802A:
> > > > ost::CommandOptionParse_impl::makePrintUsage() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==17692==    by 0x402B6C7A:
> > > > ost::CommandOptionParse_impl::printUsage() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==17692==    by 0x8048BFA: main (in
> > > > /home/chatgris/a.out)
> > > > ==17692==  Address 0x20202020 is not stack'd, malloc'd or free'd
> > > > ==17692==
> > > > ==17692== Process terminating with default action of signal 11
> > > > (SIGSEGV): dumping core ==17692==  Address not mapped to object at
> > > > address 0x20202020 ==17692==    at 0x40278576:
> > > > ost::String::getSpace(unsigned) (in /usr/lib/libccgnu2-1.1.so.0.0.2)
> > > > ==17692==    by 0x402781F6:
> > > > ost::String::resize(unsigned) (in /usr/lib/libccgnu2-1.1.so.0.0.2)
> > > > ==17692==    by 0x40277A71: ost::String::set(char const*, unsigned)
> > > > (in /usr/lib/libccgnu2-1.1.so.0.0.2) ==17692==    by 0x40277B07:
> > > > ost::String::set(ost::String const&) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==17692==    by 0x402B16C1:
> > > > ost::String::operator=(ost::String const&) (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==17692==    by 0x402B802A:
> > > > ost::CommandOptionParse_impl::makePrintUsage() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==17692==    by 0x402B6C7A:
> > > > ost::CommandOptionParse_impl::printUsage() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==17692==    by 0x8048BFA: main (in
> > > > /home/chatgris/a.out)
> > > >
> > > >
> > > > test case
> > > >
> > > > #include <iostream>
> > > > #include <cc++/common.h>
> > > >
> > > > ost::CommandOptionArg optConnInfo (
> > > >   "connection_string", "c", "Connection String.", true
> > > > );
> > > >
> > > > ost::CommandOptionArg optMergeDelimiterField (
> > > >   "field_delimiter", "f", "Field delimiter for merge information",
> > > > true );
> > > >
> > > > ost::CommandOptionArg optMergeDelimiterRecord (
> > > >   "record_delimiter", "r", "Record delimiter for merge information",
> > > > true );
> > > >
> > > > ost::CommandOptionArg optMergeNames (
> > > >   "merge_names", "n", "Merge Field Names (tab delimited)", true
> > > > );
> > > >
> > > > ost::CommandOptionArg optMessageSource (
> > > >   "message_source", "s", "Message Source", true
> > > > );
> > > >
> > > > ost::CommandOptionArg optQuery (
> > > >   "query", "q", "Query to retrieve send data", true
> > > > );
> > > >
> > > > ost::CommandOptionArg optSortDir (
> > > >   "sort_dir", "sd", "Directory where the sort binary resides", true
> > > > );
> > > >
> > > > ost::CommandOptionArg optSortName (
> > > >   "sort_name", "sn", "Name of the sort binary", true
> > > > );
> > > >
> > > > ost::CommandOptionArg optSortTmpDir (
> > > >   "sort_tmp_dir", "st", "Temp dir for sort to use", true
> > > > );
> > > >
> > > > ost::CommandOptionArg optMaxBatchSize (
> > > >   "max_batch_size", "b", "Maximum Batch Size", true
> > > > );
> > > >
> > > > ost::CommandOptionArg optPriority (
> > > >   "priority", "p", "Priority for mailing", true
> > > > );
> > > >
> > > > ost::CommandOptionNoArg optHelpArg (
> > > >   "help", "?", "Print help usage"
> > > > );
> > > >
> > > > int main ( int argc, char ** argv ) {
> > > >   ost::CommandOptionParse * optArgs =
> > > >     ost::makeCommandOptionParse ( argc
> > > >                                 , argv
> > > >                                 , "Configurable Procmail receiver.\n"
> > > >   );
> > > >
> > > >   // If the user requested help then suppress all the usage error
> > > >   // messages.
> > > >   if ( optHelpArg.numSet ) {
> > > >     std::cerr << optArgs->printUsage();
> > > >     return 0;
> > > >   }
> > > >
> > > >   // Print usage your way.
> > > >   if ( optArgs->argsHaveError() ) {
> > > >     std::cerr << optArgs->printErrors();
> > > >     std::cerr << optArgs->printUsage();
> > > >     return 1;
> > > >   }
> > > >
> > > >   std::cout << "Success" << std::endl;
> > > >
> > > >   delete optArgs;
> > > >
> > > >   return 0;
> > > > }
> > > >
> > > > Patch to get rid of memcpy
> > > >
> > > > 170c170
> > > > <               memmove(ptr + start, str, count);
> > > > ---
> > > >
> > > > >               memcpy(ptr + start, str, count);
> > > >
> > > > 218c218
> > > > <       memmove(ptr + start, ptr + start + count, len - start -
> > > > count); ---
> > > >
> > > > >       memcpy(ptr + start, ptr + start + count, len - start -
> > > > > count);
> > > >
> > > > 253c253
> > > > <       memmove(getText() + getLength(), str, len);
> > > > ---
> > > >
> > > > >       memcpy(getText() + getLength(), str, len);
> > > >
> > > > 391c391
> > > > <       memmove(getText(), str, Value==26722== Invalid read of size 4
> > > > ==26722==    at 0x40278576: ost::String::getSpace(unsigned) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==26722==    by 0x402781F6:
> > > > ost::String::resize(unsigned) (in /usr/lib/libccgnu2-1.1.so.0.0.2)
> > > > ==26722==    by 0x40277A71: ost::String::set(char const*, unsigned)
> > > > (in /usr/lib/libccgnu2-1.1.so.0.0.2) ==26722==    by 0x40277B07:
> > > > ost::String::set(ost::String const&) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==26722==    by 0x402B16C1:
> > > > ost::String::operator=(ost::String const&) (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==26722==    by 0x402B802A:
> > > > ost::CommandOptionParse_impl::makePrintUsage() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==26722==    by 0x402B6C7A:
> > > > ost::CommandOptionParse_impl::printUsage() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==26722==    by 0x8048BFA: main
> > > > (main.cpp:69)
> > > > ==26722==  Address 0x20202020 is not stack'd, malloc'd or free'd
> > > > ==26722==
> > > > ==26722== Process terminating with default action of signal 11
> > > > (SIGSEGV): dumping core ==26722==  Address not mapped to object at
> > > > address 0x20202020 ==26722==    at 0x40278576:
> > > > ost::String::getSpace(unsigned) (in /usr/lib/libccgnu2-1.1.so.0.0.2)
> > > > ==26722==    by 0x402781F6:
> > > > ost::String::resize(unsigned) (in /usr/lib/libccgnu2-1.1.so.0.0.2)
> > > > ==26722==    by 0x40277A71: ost::String::set(char const*, unsigned)
> > > > (in /usr/lib/libccgnu2-1.1.so.0.0.2) ==26722==    by 0x40277B07:
> > > > ost::String::set(ost::String const&) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==26722==    by 0x402B16C1:
> > > > ost::String::operator=(ost::String const&) (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==26722==    by 0x402B802A:
> > > > ost::CommandOptionParse_impl::makePrintUsage() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==26722==    by 0x402B6C7A:
> > > > ost::CommandOptionParse_impl::printUsage() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==26722==    by 0x8048BFA: main
> > > > (main.cpp:69)len);
> > > > ---
> > > >
> > > > >       memcpy(getText(), str, len);
> > > >
> > > > 418c418
> > > > <               memmove(content.ministring.text, getText(),
> > > > getLength() + 1); ---
> > > >
> > > > >               memcpy(content.ministring.text, getText(),
> > > > > getLength() + 1);
> > > >
> > > > 426c426
> > > > <       memmove(content.bigstring.text, ptr, getLength() + 1);
> > > > ---
> > > >
> > > > >       memcpy(content.bigstring.text, ptr, getLength() + 1);
> > > >
> > > > 576c576
> > > > <               memmove(ptr, content.ministring.text, length);
> > > > ---
> > > >
> > > > >               memcpy(ptr, content.ministring.text, length);
> > > >
> > > > 588c588
> > > > <               memmove(content.ministring.text, ptr, length);
> > > > ---
> > > >
> > > > >               memcpy(content.ministring.text, ptr, length);
> > > >
> > > > 597c597
> > > > <       memmove(ptr, getText(), length);
> > > > ---
> > > >
> > > > >       memcpy(ptr, getText(), length);
> > > >
> > > > Debugging results of above program after patch applied
> > > >
> > > > Value==26722== Invalid read of size 4
> > > > ==26722==    at 0x40278576: ost::String::getSpace(unsigned) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==26722==    by 0x402781F6:
> > > > ost::String::resize(unsigned) (in /usr/lib/libccgnu2-1.1.so.0.0.2)
> > > > ==26722==    by 0x40277A71: ost::String::set(char const*, unsigned)
> > > > (in /usr/lib/libccgnu2-1.1.so.0.0.2) ==26722==    by 0x40277B07:
> > > > ost::String::set(ost::String const&) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==26722==    by 0x402B16C1:
> > > > ost::String::operator=(ost::String const&) (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==26722==    by 0x402B802A:
> > > > ost::CommandOptionParse_impl::makePrintUsage() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==26722==    by 0x402B6C7A:
> > > > ost::CommandOptionParse_impl::printUsage() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==26722==    by 0x8048BFA: main
> > > > (main.cpp:69)
> > > > ==26722==  Address 0x20202020 is not stack'd, malloc'd or free'd
> > > > ==26722==
> > > > ==26722== Process terminating with default action of signal 11
> > > > (SIGSEGV): dumping core ==26722==  Address not mapped to object at
> > > > address 0x20202020 ==26722==    at 0x40278576:
> > > > ost::String::getSpace(unsigned) (in /usr/lib/libccgnu2-1.1.so.0.0.2)
> > > > ==26722==    by 0x402781F6:
> > > > ost::String::resize(unsigned) (in /usr/lib/libccgnu2-1.1.so.0.0.2)
> > > > ==26722==    by 0x40277A71: ost::String::set(char const*, unsigned)
> > > > (in /usr/lib/libccgnu2-1.1.so.0.0.2) ==26722==    by 0x40277B07:
> > > > ost::String::set(ost::String const&) (in
> > > > /usr/lib/libccgnu2-1.1.so.0.0.2) ==26722==    by 0x402B16C1:
> > > > ost::String::operator=(ost::String const&) (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==26722==    by 0x402B802A:
> > > > ost::CommandOptionParse_impl::makePrintUsage() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==26722==    by 0x402B6C7A:
> > > > ost::CommandOptionParse_impl::printUsage() (in
> > > > /usr/lib/libccext2-1.1.so.0.0.2) ==26722==    by 0x8048BFA: main
> > > > (main.cpp:69)
> > > >
> > > >
> > > > _______________________________________________
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