Git

Revisions

The most basic element needed to interact with git is the concept of revisions:

	Description
`<sha1>`	the full sha1 of the object you need
`<refname>`	a symbolic ref name

Some useful reference are

Name	Description
`HEAD`
`FETCH_HEAD`
`ORIG_HEAD`
`MERGE_HEAD`
`CHERRY_PICK_HEAD`
`BISECT_HEAD`
`REVERT_HEAD`
`REJECT_NON_FF_HEAD`

Edit commit

 -> add to the index some changes
$ git commit --amend

Reset first commit

$ git update-ref -d HEAD

Edit commit in an interactive rebase

$ git rebase --interactive <ref>^
 -> change the operation for the desired commit to "edit" and close the editor
 -> now you are in the desired commit
$ git reset HEAD^
 -> you can now commit the changes in as many commits as you want
$ git rebase --continue

Set upstream for branch

(gp/falafel) $ git branch -u origin/kebab
Branch 'gp/falafel' set up to track remote branch 'kebab' from 'origin'.

Diffing

A part from the normal git diff and the options predates from diff(1), if you want colored output even in presence of a pipe, you must pass --color=always and use the -r option for less(1).

Rebase one commit onto

This is particular: you want to rebase the tip of <branch> to <upstream>, probably is the same as cherry-pick

$ git rebase <branch>^ <branch> --onto <upstream>

Rebase preserving merges

$ git rebase --preserve-merges <upstream>

Merge/rebase conflict resolution

When there are conflicts a few files are created

.BASE: the revision in common
.REMOTE: your code
.LOCAL: the code whose you are adapting your
.ORIG: the file containing the markers <<<<, ===== and >>>>

It's possible to use git mergetool in order to help with resolution, in particular with the flag --tool is possible to indicate which tool to use.

Resolving conflicts during a Git rebase

Show the nearest tag

It adds also a little more of data

$ git describe  --tags 
Ghidra_10.0.4_build-481-geab247707

in this example, 481 are the commits from the tag itself, and g<hash> contains the hash of the actual commit you are on.

Notes

$ git notes add <ref>
$ git notes edit <ref>
$ git notes append <ref>
$ git push origin ref/notes/commits
$ git fetch origin refs/notes/*:refs/notes/*

Follow function code evolution

$ git log -L:<function name>:<path file>

Search for functions

In some cases you need to look up in which function is present some string of your choice: the following shows the matching occurrence of the string plus a line with the function name containing it

$ git grep --show-function <some string>

otherwise is possible to search for a string obtaining all the code of the function containing it

$ git grep -W <some string>

Search across all branches

$ git grep <regex> $(git for-each-ref --format='%(refname:short)' refs/heads)

Submodules

This is the most hated functionality by me: the interface is really hard to remember and doesn't make sense.

Status

$ git submodule status
-7ada843c5bb0bb49c7f2bf5db72f9969e4091ba2 hardware/victims/firmware/crypto/secAES-ATmega8515
 715baf70fb04100a2c9da9764161a0019c3a9e41 jupyter (remotes/origin/cw5dev-74-g715baf7)
-9bebfcbda448fb39e8cf99aa75db4e345d56572e openadc
-1f79b63d485587d6ec5243f78b0fa86eaea9931c tutorials

- means the submodule needs to be initialized

Update

$ git submodule update --init
Submodule 'hardware/victims/firmware/crypto/secAES-ATmega8515' (https://github.com/jmichelp/secAES-ATmega8515.git) registered for path 'hardware/victims/firmware/crypto/secAES-ATmega8515'
Submodule 'openadc' (git://git.assembla.com/openadc.git) registered for path 'openadc'
Submodule 'tutorials' (https://github.com/newaetech/chipwhisperer-tutorials.git) registered for path 'tutorials'
Cloning into '/opt/chipwhisperer-git/hardware/victims/firmware/crypto/secAES-ATmega8515'...
Cloning into '/opt/chipwhisperer-git/openadc'...
Cloning into '/opt/chipwhisperer-git/tutorials'...
Submodule path 'hardware/victims/firmware/crypto/secAES-ATmega8515': checked out '7ada843c5bb0bb49c7f2bf5db72f9969e4091ba2'
Submodule path 'openadc': checked out '9bebfcbda448fb39e8cf99aa75db4e345d56572e'
Submodule path 'tutorials': checked out '1f79b63d485587d6ec5243f78b0fa86eaea9931c'

90% of the case you need only to update&init together!

Bundle

It's possible to use as transport for the repository the bundles

$ git bundle -h
usage: git bundle create [<options>] <file> <git-rev-list args>
   or: git bundle verify [<options>] <file>
   or: git bundle list-heads <file> [<refname>...]
   or: git bundle unbundle <file> [<refname>...]

    -v, --verbose         be verbose; must be placed before a subcommand

For example if you want to create a file bundle named kebab.bundle of your local repository with the objects contained in the branch kebab

$ git bundle create kebab.bundle kebab

the receiver needs only to fetch from it

$ git fetch kebab.bundle

Git