add cargo-git.eclass to handle git dependencies for rust ebuilds

Signed-off-by: Alfred Wingate <parona@protonmail.com>

eclass/cargo-git.eclass

@@ -0,0 +1,103 @@
+# Copyright 1999-2021 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+# @ECLASS: cargo-git.eclass
+# @MAINTAINER:
+# parona@protonmail.com
+# @AUTHOR:
+# Alfred Wingate <parona@protonmail.com>
+# @SUPPORTED_EAPIS: 7
+# @BLURB: extend cargo.eclass to support git dependencies
+
+case "${EAPI:-0}" in
+	0|1|2|3|4|5|6)
+		die "Unsupported EAPI=${EAPI:-0} (too old) for ${ECLASS}"
+		;;
+	7)
+		;;
+	*)
+		die "Unsupported EAPI=${EAPI} (unknown) for ${ECLASS}"
+		;;
+esac
+
+inherit cargo git-r3
+
+EXPORT_FUNCTIONS src_unpack
+
+# @ECLASS-VARIABLE: CARGO_GIT
+# @DEFAULT_UNSET
+# @DESCRIPTION:
+# Array with the syntax "repourl oid identifier" (still not sure where the oid comes from :/)
+# Fetches the repo with git-r3 and then checksout them for cargo in ECARGO_HOME
+# Several checkouts arent possible at this moment, only one checkout per repository.
+
+# @FUNCTION: cargo-git_src_unpack
+# @DESCRIPTION:
+# Fetches and checksout git repositories specified in CARGO_GIT and sets up correct file structure for cargo so that it wont try to break the network sandbox
+cargo-git_src_unpack() {
+	debug-print-function ${FUNCNAME} "$@"
+
+	for line in "${CARGO_GIT[@]}"; do
+		local giturl oid identifier
+		read -r giturl oid identifier <<< "${line}"
+
+		git-r3_fetch "${giturl}" "${identifier}"
+	done
+
+	cargo_src_unpack
+
+	ECARGO_GIT="${ECARGO_HOME}/git"
+
+	for line in "${CARGO_GIT[@]}"; do
+		local giturl oid identifier
+		read -r giturl oid identifier <<< "${line}"
+
+		name=$(basename "${giturl}" .git || die)
+		repodir=$(get_gitdir "${giturl}" || die)
+		shortid=$(git --git-dir="${repodir}" rev-parse --short "${identifier}" || die)
+
+		git clone --bare "${repodir}"  "${ECARGO_GIT}/db/${name}-${oid}" || die
+
+		mkdir -p "${ECARGO_GIT}/checkouts/${name}-${oid}/${shortid}" || die
+		git-r3_checkout "${giturl}" "${ECARGO_GIT}/checkouts/${name}-${oid}/${shortid}"
+
+		# Make cargo happy with the checkout so that it doesnt try to update it
+		touch "${ECARGO_GIT}/checkouts/${name}-${oid}/${shortid}/.cargo-ok" || die
+	done
+}
+
+# @FUNCTION: get_gitdir
+# @DESCRIPTION:
+# Ripped out from git-r3.eclass to get the correct dir
+get_gitdir() {
+	debug-print-function ${FUNCNAME} "$@"
+
+	local repo_name=${1#*://*/}
+
+	# strip the trailing slash
+	repo_name=${repo_name%/}
+
+	# strip common prefixes to make paths more likely to match
+	# e.g. git://X/Y.git vs https://X/git/Y.git
+	# (but just one of the prefixes)
+	case "${repo_name}" in
+		# gnome.org... who else?
+		browse/*) repo_name=${repo_name#browse/};;
+		# cgit can proxy requests to git
+		cgit/*) repo_name=${repo_name#cgit/};;
+		# pretty common
+		git/*) repo_name=${repo_name#git/};;
+		# gentoo.org
+		gitroot/*) repo_name=${repo_name#gitroot/};;
+		# sourceforge
+		p/*) repo_name=${repo_name#p/};;
+		# kernel.org
+		pub/scm/*) repo_name=${repo_name#pub/scm/};;
+	esac
+	# ensure a .git suffix, same reason
+	repo_name=${repo_name%.git}.git
+	# now replace all the slashes
+	repo_name=${repo_name//\//_}
+
+	echo "${EGIT3_STORE_DIR}/${repo_name}"
+}