Re: [Quickfix-developers] Usage of non-threadsafe C functions in QF

[Joerg T. <Joe...@ma...>]

OM...@th... wrote:
> It appears under windows they are not thread safe. 
 > [....]
> This looks like an important fix so it should probably go out with 1.4.1,
> initially using locking for windows.

May I provide some sample code from our software:

For gethostbyname_r(() there are difference between Linux and Solaris:

     102     /* Get the IP address of the localhost.
     103      * Note: This thread-safe version needs some extra data structures.
     104      */
     105     {
     106         struct hostent host;
     107         struct hostent *host_ptr = NULL;
     108         char   gethostname_buffer[ 1024 ];
     109         int    error;
     110
     111 #ifdef SYSTEM_linux
     112         gethostbyname_r( "localhost", &host, gethostname_buffer, sizeof( gethostname_buffer ), &host_ptr, &error );
     113 #endif
     114 #ifdef SYSTEM_sunos
     115         host_ptr = gethostbyname_r( "localhost", &host, gethostname_buffer, sizeof( gethostname_buffer ), &error );
     116 #endif
     117
     118         if ( NULL == host_ptr ) {
     119             logError( "openSocketQueue: Could not resolve 'localhost'" );
     120             return -1;
     121         }
     122
     123         memcpy( &sin.sin_addr, host_ptr->h_addr_list[0], sizeof( sin.sin_addr ) );
     124     }

localtime() and gmtime() are simple, since you only have to provide an extra buffer instead
of using the returned value. Note that there man pages may be missing on Linux. But you could use
http://docs.sun.com to look up the Solaris man pages, which are equivalent here:

SYNOPSIS
      #include <time.h>

      [...deleted...]	
      struct tm *localtime_r(const time_t *clock, struct tm *res);

      struct tm *gmtime_r(const time_t *clock, struct tm *res);

DESCRIPTION
      [...]
      The localtime_r() and gmtime_r()  functions  have  the  same
      functionality  as  localtime()  and  gmtime()  respectively,
      except that the caller must supply a buffer res to store the
      result.
      [...]

ERRORS
      The ctime_r() and asctime_r() functions will fail if:

      ERANGE
            The length of the buffer supplied by the caller is not
            large enough to store the result.

Cheers, Jörg

-- 
Joerg Thoennes
                                http://macd.com
Tel.: +49 (0)241 44597-24      Macdonald Associates GmbH
Fax : +49 (0)241 44597-10      Lothringer Str. 52, D-52070 Aachen