Roy's Blog

A Hacker's musings on Code | Tech | Life

I've been using Fossil for quite a while now as my SCM. I like Fossil. But Fossil is not Git, and most people seem to like Git. It could be better to say that most people like GitHub because it's the first hosted SCM that's free for open source with good social interaction I'm aware of. And GitHub is huge. Some might say that if you're not on GitHub, you don't exist as a project. Well this obviously isn't true, but you get the idea. You can get free Fossil hosting at Chisel, which is nice, but it's also not GitHub. Plus I like to be 100% self hosted.

So, to get myself on GitHub (as a mirror only), there needs to be a bridge between Fossil and Git. Fossil documentation implies this is quite easy. Sadly, this isn't the case as the <=Fossil-1.37 releases (note there is no guaranntee that future versions of follow will not have these flaws - my branch may not be comitted to trunk) have the following flaws:

  • Branch and Tag name mangling (dhcpcd-6 becomes dhcpcd_6)
  • Silent master branch renaming into trunk on inport, but not on export
  • No tag comments (Fossil lacks the feature) which means syncing tags back and forth results in tag conflict due to signature change

I submitted some initial patches the the Fossil mailing list and I now have a Fossil commit bit! You can find my branch here to fix the Fossil Git bridge.

But that's not the end of the story. A bridge has two ends. With my initial setup, the Git end was bare bones repository which I pushed to GitHub. This is no longer the case - I now need a staging repository to pull both ends. And this requires a script because Git needs a little more hand-holding to completely track a remote. The below script is tailored for my needs, yours may differ. It also reflects the above initial design and the subsequent change - as such it it may need editing if you need to create a git clone from fossil. This comes with no support, just as an idea of how you might implement such a bridge.

#!/bin/sh

fossildir=/var/fossil
# Cannot be a bare directory for git as we cannot write to the host directly.
# So we have a staging directory instead.
# This requires a bit of hand-holding to track all the branches.
gitdir=/var/git-staging

marksdir=/var/scm-marks

# Respect default naming at either end
fossil_export_opts="--rename-trunk master"
fossil_import_opts="--rename-master trunk"

# Only used when creating a git bare bones repo from Fossil.
export_fossil_to_git_new()
{

        rm -f "$fossilmarks" "$gitmarks"
        git init
        fossil export --git \
                --export-marks "$fossilmarks" \
                $fossil_export_opts "$fossildir/$fossilrepo" | \
                git fast-import \
                --export-marks="$gitmarks"
}

export_fossil_to_git()
{

        fossil export --git \
                --import-marks "$fossilmarks" --export-marks "$fossilmarks" \
                $fossil_export_opts "$fossildir/$fossilrepo" | \
                git fast-import \
                --import-marks="$gitmarks" --export-marks="$gitmarks"
}

export_git_to_fossil()
{

        git fast-export --all \
                --import-marks="$gitmarks" --export-marks="$gitmarks" | \
                fossil import --git --incremental \
                --import-marks "$fossilmarks" --export-marks "$fossilmarks" \
                $fossil_import_opts "$fossildir/$fossilrepo"
}

pull_git()
{
        local remote

        git fetch --all
        # Track all remote branches
        git branch -r | grep -v '\->' | while read remote; do
                if [ -z "$(git branch --list "${remote#origin/}")" ]; then
                        git branch --track "${remote#origin/}" "$remote"
                fi
        done
        git branch --list | sed -e 's/^\* //' | while read branch; do
                git checkout "$branch"
                git merge --ff-only
        done
}

push_git()
{

        git push --all
        git push --tags
        # Reset the current branch checkout.
        # If we don't, the next run will complain about unstashed changes.
        # This maybe a bug in git, but maybe not because the live checkout
        # *is* behind at this point as we just fast-imported.
        git reset --hard
}

echo "Syncing git and fossil."
for repo in "$fossildir"/*.fossil; do
        fossilrepo=${repo#${fossildir}/*}
        repo=${fossilrepo%.fossil}
        gitrepo="$repo"
        fossilmarks="$marksdir/$repo.fossil.marks"
        gitmarks="$marksdir/$repo.git.marks"

        # We just sync old fossil repos to new phab clones
        if [ -d "$gitdir/$gitrepo" ]; then
                cd "$gitdir/$gitrepo"
                pull_git # staging only
                export_git_to_fossil
                export_fossil_to_git
                push_git # staging only
# Enable the below if pusing to a bare git repo from fossil
#       else
#               export_fossil_to_git_new
        fi
done

Direct download to script

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So finally I've moved all services from my old server to my Christmas Xen box! This was not without problems due to the fact it had to run NetBSD -current

  • gcc toolchain is broken for some packages which affected running any PHP build
  • clang toolchain was broken for my config (USE_SSP= yes and CPUFLAGS+= -march=core2)
  • clang compiles as a whole were broken due to a recent efiboot import

In hind-sight, I could have had the box up and running a lot sooner if I used NetBSD-7 guests (or maybe just a NetBSD-7 build box), but no, I just had to get -current running. It offers more than -7 and prior exerience told me that tracking -7 was very problematic ... but that could have been due to my settings and wanting to compile everything with clang. I've currently got 3 -current images there now ... the Xen DOM0, the actual server itself as Xen DomU (without any compiler or tools) and another Xen DomU which just builds stuff for other guests to use.

Anyway, the box itself is now up and running and all relevant services have been moved to it. During this move, I decided to modernise things a little and setup HTTP/2. If you're reading this then it's working :) As such, I've re-directed all basic HTTP traffic to HTTPS and it does seem to load a lot faster. One side effect of this is that I've stoped using my own self signed certificates and I'm now using the nice Let's Encrypt service. pkgsrc users should use the py-certbot package and don't bother searching for any letsencrypt package as it's been renamed. I found this quite confusing as there was no reference to the rename in pkgsrc I could find and wasted a little time on it.

But now it's live I can finally look into bringing online some other development utilities to play around with as the server has a lot more room to grow :)

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After starting the year with curses work, I decided to do some more!

Currently we lack Soft Label Key functions as specified by POSIX. What are these? Glad you asked! Soft Label Keys ripoff a line from the bottom of the screen and allow for up to 8 keys to be displayed there. You can define labels for them, colours, etc.

"BIG WHOOP!" I hear you say. "My app already does this, why should I care?"

Because SLK also works with the terminfo database to work out if the terminal natively supports labels (via plab_norm, label_on, etc)! This means a line doesn't have to be ripped off from the screen so no real-estate is lost. Sadly, no terminal actually seems to support these markings. But if one is ever made, it should work fine.

Now, not many curses apps actually use the SLK functions, probably for this very reason. But some do, and it is a standard so I've coded NetBSD to support this natively.

Sadly, this has uncovered a bug in the NetBSD curses library where cursor movement in a one line window at the bottom of the screen appears to push the window up. This is very visible with SLK and will have to be fixed for any apps that actually use it, but the SLK implementation itself is sound as resizing the terminal forces a redraw and it looks fine.

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Long trip up to Nunsmere Hall for a long over due but fantastic family lunch. The entire Marples and Coulbeck tribes actually managed to make it - not a single person missing!

Marples vs Coulbeck

We need to do this thing more often, especially in such a nice place where everyone was friendly and the food was just awesome. I think I managed to talk with everyone and have time to play with the kids. Speaking of the kids, they were absolute little gems the whole journey - 4 hours up and 4 hours down. Much better behaved than I was at a similar age no doubt ;)

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So over the holidays, I managed to get in some good quality family time and find some time to work on some Open Source stuff. I meant to work mainly on dhcpcd, but it turned out I spent most of my time working on NetBSD curses library so that Python Curses now works with it. Now, most people reading this blog may not care much for NetBSD or for curses, but it's important because ncurses is used pretty much everywhere by default ..... aside from NetBSD. And most readers should know, I go out of my way to promote interoperable software even when it's at a detriment to my own projects. That's just how I roll.

There is a apparently a thing called PD Curses but I don't know anywhere that actually uses it by default. If you know, please email me @ roy@marples.name or . I do know that the pkgsrc curses framework supports it.

And this is the thing I'm currently doing. As NetBSD curses supports more POSIX functions (and a few ncurses extensions, sadly) more and more packages now work alongside NetBSD curses, so I'm plowing through pkgsrc again moving things to the curses framework. This is important, because there is logic in devel/ncurses to use NetBSD curses when passing certain criteria, but sadly this always brings ncurses as a possibility to be linked or it's header used, both of which are quite bad for NetBSD curses so there is a method to my madness.

One interesting thing though is that since I started comitting my curses patches, it turns out that Sabotage Linux is using NetBSD curses and made it portable. I'm chatting with one of their devs and we're starting to merge of a few of their patches back into NetBSD.

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