89 lines
2.5 KiB
Bash
Executable File
89 lines
2.5 KiB
Bash
Executable File
#! /bin/sh
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#
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# usage: fetchgit repo_name out_link
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#
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# Make the specified repository available as out_link.
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#
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set -euf
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repo_name=$1
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out_link=$2
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if test "$repo_name" != nixpkgs; then
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echo "fetchgit: cannot fetch $repo_name, yet" >&2
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exit -1
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fi
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git_rev=$(nixos-query nixpkgs.rev)
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git_url=$(nixos-query nixpkgs.url)
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dirty=$(nixos-query nixpkgs.dirty)
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case $dirty in true)
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ln -snf "$git_url" "$out_link"
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echo "fetchgit: using $git_url as it is" >&2
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exit
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esac
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# Put all bases in the same place as out_link.
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# Notice how out_link must not clash with cache_dir and work_dir.
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cache_base=$(dirname "$out_link")
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work_base=$(dirname "$out_link")
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# cache_dir points to a (maybe non-existent) directory, where a shared cache of
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# the repository should be maintained. The shared cache is used to create
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# multiple working trees of the repository.
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cache_dir=$cache_base/$(echo "$git_url" | urlencode)
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# work_dir points to a (maybe non-existent) directory, where a specific
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# revision of the repository is checked out.
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work_dir=$work_base/$(echo "$git_rev" | urlencode)
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cache_git() {
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git --git-dir="$cache_dir" "$@"
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}
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work_git() {
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git -C "$work_dir" "$@"
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}
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is_up_to_date() {
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test -d "$cache_dir" &&
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test -d "$work_dir" &&
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test "$(cache_git rev-parse --verify "$git_rev")" = "$git_rev" &&
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test "$(work_git rev-parse --verify HEAD)" = "$git_rev"
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}
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# Notice how the remote name "origin" has been chosen arbitrarily, but must be
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# kept in sync with the default value of nixpkgs.rev.
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if ! is_up_to_date; then
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if ! test -d "$cache_dir"; then
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mkdir -p "$cache_dir"
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cache_git init --bare
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fi
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if ! cache_git_url=$(cache_git config remote.origin.url); then
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cache_git remote add origin "$git_url"
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elif test "$cache_git_url" != "$git_url"; then
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cache_git remote set-url origin "$git_url"
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fi
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cache_git fetch origin
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if ! test -d "$work_dir"; then
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git clone -n --shared "$cache_dir" "$work_dir"
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fi
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commit_name=$(cache_git rev-parse --verify "$git_rev")
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work_git checkout "$commit_name" -- "$(readlink -f "$work_dir")"
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work_git checkout -q "$commit_name"
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work_git submodule init
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work_git submodule update
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fi
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work_git clean -dxf
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# Relative links are nicer, and actually we know that work_dir and out_link are
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# the same. But, for robustness, check anyway.. :)
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if test "$(dirname "$work_dir")" = "$(dirname "$out_link")"; then
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ln -snf "$(basename "$work_dir")" "$out_link"
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else
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ln -snf "$work_dir" "$out_link"
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fi
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echo "fetchgit: using $git_url $(work_git log --oneline -n1)" >&2
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