Re: git fast-export not preserving executable permissions?

[Taylor Blau <me@ttaylorr.com>]

On Fri, May 01, 2020 at 09:35:28AM -0400, Doug Glidden wrote:
> Taylor,

(My full response is below, but please in general do not top-quote mail
here.)

>
> Thanks for your response! It looks like git does not actually
> recognize the file as executable:
>
>     $ git ls-tree HEAD
>     100644 blob 7d2f57b2381766924e1e4ffcc62615c637bbd784    executable_script.sh
>     100644 blob d1d7cf309e091f54f268503b31653d8eba42fe88
> non_executable_file.txt
>
> Now you have me wondering if the real problem here is that I'm working
> in git-bash on a Windows machine, which means the file permissions
> aren't completely native.

I was wondering if that was the case ;-). If you are using NTFS or
FAT32, neither of these filesystems support execute permission bits. (I
am certainly not an expert here, but I know that Dscho (cc'd) would be
able to answer authoritatively here.)

That said, *Git* understands executable permissions, even if your
filesystem doesn't. You can tell Git to mark a file as executable by
the following:

  $ git update-index --chmod=+x /path/to/file

and then committing the result. Round-tripping this through 'git
fast-{im,ex}port' should preserve the permissions from Git's
perspective, and ditto for checking out the contents of a repository on
a filesystem that does support the executable permission bit.

> I'm going to run a similar experiment in a native Linux environment
> and see if I get the same results. I'll let you know what I find.

Sounds good. I'll be very surprised if it doesn't work as you expect.

> Thanks,
> Doug
>
>
>
> On Wed, Apr 29, 2020 at 2:49 PM Taylor Blau <me@ttaylorr.com> wrote:
> >
> > Hi Doug,
> >
> > On Wed, Apr 29, 2020 at 09:36:31AM -0400, Doug Glidden wrote:
> > > Hello Git world!
> > >
> > > I have run into an issue that I cannot seem to resolve with git
> > > fast-export. When running a fast-export on a repo that contains
> > > scripts with executable permissions (e.g. a gradlew script), the
> > > resulting export does not properly reflect the executable permissions
> > > on the script files.
> >
> > Interesting. fast-import and fast-export both understand executable
> > modes (although Git only understands the modes 644 and 755 for blobs),
> > so this should be working.
> >
> > I can not reproduce the issue as-is. Round-tripping a fast-import and
> > fast-export preserves executable bits for me:
> >
> >   #!/bin/bash
> >
> >   set -e
> >
> >   rm -rf repo client
> >
> >   git init -q repo
> >   git init -q client
> >
> >   (
> >     cd repo
> >     printf "x" >x
> >     printf "y" >y
> >     chmod +x x
> >     git add x y
> >     git commit -q -m "initial commit"
> >   )
> >
> >   git -C repo fast-export HEAD | git -C client fast-import
> >
> >   diff -u <(git -C repo ls-tree HEAD) <(git -C client ls-tree HEAD)
> >
> > > To illustrate this issue, I created a small sample repo, with one
> > > executable file and one non-executable file. From the output below,
> > > you can see that the mode in the output from fast-export is the same
> > > for both files; according to the documentation for fast-import, the
> > > mode for the executable file should be 100755 instead of 100644.
> > >
> > >     $ ls -gG
> > >     total 2
> > >     -rwxr-xr-x 1 106 Apr 29 09:13 executable_script.sh*
> > >     -rw-r--r-- 1  63 Apr 29 09:12 non_executable_file.txt
> > >
> > >     $ git fast-export --all
> > >     blob
> > >     mark :1
> > >     data 106
> > >     #!/bin/bash
> > >
> > >     # This is a shell script that should be executable.
> > >     echo 'The script executed successfully!'
> > >
> > >     blob
> > >     mark :2
> > >     data 63
> > >     This file is a simple text file that should not be executable.
> > >
> > >     reset refs/heads/dev
> > >     commit refs/heads/dev
> > >     mark :3
> > >     author Doug <41mortimer@gmail.com> 1588167102 -0400
> > >     committer Doug <41mortimer@gmail.com> 1588167102 -0400
> > >     data 25
> > >     Adding some sample files
> > >     M 100644 :1 executable_script.sh
> > >     M 100644 :2 non_executable_file.txt
> > >
> > > Please let me know if there is any further information I can provide
> > > about this issue.
> >
> > Does Git think that the file is executable? Please run 'git ls-tree
> > HEAD' to find out.
> >
> > > Thank you,
> > > Doug
> >
> > Thanks,
> > Taylor
Thanks,
Taylor