trouble with files bigger than 4GB

Daniel Solaz <>
Fri Apr 18 16:18:07 CEST 2003


On Thursday 17 April 2003 10:14 Raimo Niskanen wrote:
> There is some way to compile a program for solaris so that fopen()
> means fopen64(), off_t becomes 64 bit, and so on. If this is done,
> the code should work. It is perhaps even so that for an Erlang/OTP
> system built for Solaris8 it works, while not for a system built for
> Solaris2.5.1.
Yes, this is described in the lfcompile(5) man page.
I'll try to hack the appropriate Makefile(s) and recompile so I can 
check whether this is enough to get the code working, where working 
means "like in FreeBSD".

> Since the size of off_t is configured when building open source
> Erlang, on a system with 64 bits off_t - large file operations should
> work. Have a look in $ERL_TOP/erts/$PLATFORM/config.h for
> SIZEOF_OFF_T and see if it is 4 (bytes). $PLATFORM is the system name
> $ERL_TOP/erts/autoconf/config.guess reports when executed. $ERL_TOP
> is your open source build root.
You're right, off_t is reported to be 4 bytes long.

> Please try some more file operations on your large file. Try
> file:open, file:position, file:read, and see if it seems to work on
> FreeBSD. I am really curious.
> I have browsed the source and think I see a bug in reading the size
> field for file:read_file_info - the high word of the size field is
> ignored, so if other file operations work, it is a small bug fix and
> can be done for R9C. If no other file operations work, it is a bigger
> problem and will have to wait. Please let me know.
Reading the large file buffer by buffer all the way from the beginning 
works fine; file:position(F, {bof, 4294967296}) returns {ok, 0} BUT the 
file pointer is actually set to byte 4294967296, as does 
file:position(F, {eof, 0}) on a 4 GB file.
So it seems the problem lies in the code that reports sizes and offsets 
ignoring the high word of the file size or position.

-Daniel



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