Re: [boost] [filesystem] On POSIX, any reliable way to find file size?

From: Beman Dawes (bdawes_at_[hidden])
Date: 2004-02-01 16:50:24

At 11:25 AM 2/1/2004, Momchil Velikov wrote:

 >    Beman> Hum... Perhaps mistakenly, I assumed stat() was a macro that
 >           expanded
 >    Beman> to call stat64() if _FILE_OFFSET_BITS=64 was defined.
 >
 >  Indeed, probably is is "redirected" in some way to the appropriate
 >syscall/function name.  E.g. glibc on GNU/Linux can do something like:
 >
 >  a) #define stat stat64, or
 >
 >  b) extern int stat (struct stat *) asm ("stat64"), or
 >
 >  c) extern int stat (struct stat *) __attribute__ ((weak,
 >alias("stat64")));

And of course there is always (d) "compiler magic" :-)

 >
 >    Beman> Put another way,
 >    Beman> is a program linking these two files OK?
 >
 >    Beman> file_a.cpp
 >    Beman>    #define _FILE_OFFSET_BITS=64
 >    Beman>    #include <sty/stat.h>
 >    Beman>    long long func_a()
 >    Beman>    {
 >    Beman>      struct stat s;
 >    Beman>      if ( stat( "foo", &s ) != 0 ) { throw ... }
 >    Beman>      return s.st_size;
 >    Beman>    }
 >
 >    Beman> file_b.cpp
 >    Beman>    #include <sty/stat.h>
 >    Beman>    long func_b()
 >    Beman>    {
 >    Beman>      struct stat s;
 >    Beman>      if ( stat( "bar", &s ) != 0 ) { throw ... }
 >    Beman>      return s.st_size;
 >    Beman>    }
 >
 >  Yes, this is probably ok.  The problem is if parts of the program
 >attempt to communicate ``struct stat'' values.

OK, thanks for the clarification. I'll be careful not to do that. A trial 
implementation should be in CVS in few days - that will allow months of 
testing before the next release.

--Beman