Re: Errors in handling of boost::asio errors ('boost' was compiled with wrong std::string representation?)

["John Hein" <3fbmqnhaz4@snkmail.com>]

Роман wrote at 11:33 +0600 on Nov 21, 2015:
 > Following program:
 > 
 > --------------- begin of code
 > #include <stdio.h>
 > #include <boost/system/error_code.hpp>
 > 
 > int main()
 > {
 >      std::string s = 
 > boost::system::generic_category().message(22);
 > 
 >      printf("size=%lu, c_str=\"%s\".\n",
 >              s.size(),
 >              s.c_str());
 > 
 >      return 0;
 > }
 > --------------- end of code
 > 
 > Give out following output:
 > 
 > --------------- begin of output
 > size=1628781863, c_str="Invalid argument".
 > --------------- end of output

Use 'size=%zu'.  And get into the habit of compiling with -Wall at
least.  That part has nothing to do with cygwin or boost (or windows
or ...).

That said, I can't reproduce your issue on win xp or win 7 / 32 bit
and boost 1.58.0-1, even when using %lu.  On those platforms size_t &
unsigned long are both 4 bytes.  I set LANG=ru_RU.UTF-8 before
compiling and running.  I didn't set up the windows environment
with any non-default language options.

Using '%z' would only matter (other than warnings) if the size of
size_t is not the same as the size of unsigned long.  In that case,
printf would interpret the wrong sizes for varargs parsing and would
print out garbage (and possibly crash depending on how lots of
variables played out).  In that case, I'd expect the string output to
be wrong as well.

 > If I try to use such string, for example:
 >    std::string a("");
 >    a += s;
 > program crashes.

Also works fine for me when I add those lines to the test program.


 > The program was compiled from cygwin command line by 
 > following commands:
 > 
 > --------------- begin of commands
 > g++ -c test.cpp
 > gcc -s test.o -lstdc++ -lboost_system
 > --------------- end of commands
 > 
 > I used fresh installed cygwin with following additional 
 > packages:
 >    Devel / gcc-core 5.2.0-1
 >    Devel / gcc-g++ 5.2.0-1
 >    Libs / libgcc1 5.2.0-1
 >    Libs / libstdc++6 5.2.0-1
 >    Devel / make 4.1-1
 >    Libs / libboost-devel 1.58.0-1
 > 
 > Operating system: Windows XP, 32 bits, russian language
 > Processor: Intel Pentium 4 (3 GHz)
 > Version of installator: setup-x86.exe, 2.873
 > 
 > With libboost-devel 1.57.0-1 effect is the same.
 > 
 > With Windows 7, 64 bit, russian language, effect is the 
 > same (with 32-bit and with 64-bit cygwin), with the 
 > exception that another wrong values are exposed for 
 > 'size'.
 > 
 > When I compile boost from sources ('boost_1_59_0.7z' from 
 > boost org), the same program is running as proper:
 > 
 > --------------- begin of correct output
 > size=16, c_str="Invalid argument".
 > --------------- end of correct output
 > 
 > Constant '22' corresponds to 
 > 'boost::asio::error::invalid_argument'. Some other ASIO 
 > error codes also brings to the same effect. Aforementioned 
 > code is used in handling of exceptions from ASIO functions 
 > and brings to crashes in various unpredictable situations.
 > 
 > There is more real-life piece of code that produce same 
 > error:
 > 
 > --------------- begin of example #2
 > #include <stdio.h>
 > #include <boost/asio.hpp>
 > 
 > int main()
 > {
 >      boost::asio::ip::address_v4 a;
 >      boost::system::error_code ec;
 >      a.from_string("127.0.0.1111", ec);
 > 
 >      std::string s = ec.message();
 > 
 >      printf("size=%lu, c_str=\"%s\".\n",
 >              s.size(),
 >              s.c_str());
 > 
 >      return 0;
 > }
 > --------------- end of example #2

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