Large file support and stat vs stat64 in extension modules

[Skip Montanaro]

If I simply use the stat() system call, I get an EOVERFLOW error
(OSError: [Errno 75] Value too large for defined data type).  It seems
that I should be using the newer stat64() call, but:

Did you #include <sys/stat.h>?

    Ben> 1.  posixmodule.c appears just to use plain old stat().  I cannot
    Ben>     figure out why I get errors and it works fine.  Quite a
    Ben>     mystery.

In /usr/include/sys/stat.h on my Mandrake 8.1 system (very similar to your
RH 7.2 I believe), stat is #defined as stat64 if __USE_FILE_OFFSET64 is
defined, which it probably is if your system supports POSIX large files.

    Ben> 2.  I don't know what #if defined's to put in to choose between
    Ben>     stat and stat64 correctly.

Shouldn't need anything.

    Ben> Does anyone know how to correctly stat a file within an extension
    Ben> module?  Why does:

    Ben>     struct stat st;
    Ben>     res = stat("bigfile", &st)

    Ben> not work for me, but in posixmodule.c the same thing (apparently)
    Ben> is done and works fine?

Note that in posixmodule.c references are made to a HAVE_LARGEFILE_SUPPORT
macro.  When #defined, it causes the output struct to be interpreted
differently (the sizes of some fields change).

You might scan through your configure.in file.  If "long long" support is
present and sizeof(off_t) is greater than sizeof(long) and sizeof(long long)
is greater than or equal to sizeof(off_t), large file support is assumed.

-- 
Skip Montanaro
skip at pobox.com
consulting: http://manatee.mojam.com/~skip/resume.html