threads / discuss / 13438

GIT max file size.

Subject: GIT max file size.

## tl;dr

3 messages between May 8, 2008 and May 8, 2008.

replies: 2people: 3as markdown or json

epankala@cc.hut.fi· May 8, 2008, 16:33 UTC · lore

Hello.

I received "fatal: Out of memory, malloc failed" error when I tried to check in file of ~2.5G

It can be argued that binary file of that size (or binary file altogether) has no place in version control anyways, but still I pursued it a bit more.

In #git@freenode channel I received some hints and in the end I started running "git-hash-object -w images/filesystem_ext2.img.bz2"

It would seem that sha1_file.c:write_sha1_file() has defined size variable as integer.

This wraps around in "size = 8 + deflateBound(&stream, len+hdrlen);" and gives big number for mmap() mmap(NULL, 18446744071976239104, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = -1 ENOMEM (Cannot allocate memory)

size is used in "stream.avail_out = size;" and zstream.avail_out seems to be unsigned int "uInt avail_out; /* remaining free space at next_out */"

If size would be changed to unsigned would the max filesize be increased to ~4G or would it blow up elsewhere?

Is git going to support >2G files or is having "everything that is needed to complete build process from beginning to bitter end" in version control something that git is not meant for?

If latter is true then this would be pretty much pointless change. If former then changing 'size' to integer won't be enough anyways...

Best Regards Janne Pänkälä

-- 
Janne Pänkälä

Alex Riesen· May 8, 2008, 18:46 UTC · re: epankala@cc.hut.fi · lore

Re: GIT max file size.

2008/5/8 epankala@cc.hut.fi <epankala@cc.hut.fi>:

>  Is git going to support >2G files

Maybe sometime. For now, the error could be handled better.

> ... or is having "everything that is
>  needed to complete build process from beginning to bitter end" in
>  version control something that git is not meant for?

That was the plan :)

Linus Torvalds· May 8, 2008, 20:46 UTC · re: epankala@cc.hut.fi · lore

Re: GIT max file size.

On Thu, 8 May 2008, epankala@cc.hut.fi wrote:

> 
> I received "fatal: Out of memory, malloc failed" error when I tried to
> check in file of ~2.5G

There's two issues there.

One is that a lot of what git does is simply "whole file at a time". The diff machinery, and a lot of the core stuff, simply just expects to be able to mmap() or read the whole file in one go. So on a 32-bit architecture, you'll generally be limited to the size of the address space, not to anything else.

The other thing is then that (partly because of the above) there probably are places where we haven't been as careful about size-type things as we could have been. A lot of the code uses size_t, but I bet not everything does.

		Linus