pyrox.dev
1#! @bash@/bin/sh -e
2
3shopt -s nullglob
4
5export PATH=/empty
6for i in @path@; do PATH=$PATH:$i/bin; done
7
8usage() {
9 echo "usage: $0 -t <timeout> -c <path-to-default-configuration> [-d <boot-dir>] [-g <num-generations>] [-n <dtbName>] [-r]" >&2
10 exit 1
11}
12
13timeout= # Timeout in centiseconds
14default= # Default configuration
15target=/boot # Target directory
16numGenerations=0 # Number of other generations to include in the menu
17
18while getopts "t:c:d:g:n:r" opt; do
19 case "$opt" in
20 t) # U-Boot interprets '0' as infinite and negative as instant boot
21 if [ "$OPTARG" -lt 0 ]; then
22 timeout=0
23 elif [ "$OPTARG" = 0 ]; then
24 timeout=-10
25 else
26 timeout=$((OPTARG * 10))
27 fi
28 ;;
29 c) default="$OPTARG" ;;
30 d) target="$OPTARG" ;;
31 g) numGenerations="$OPTARG" ;;
32 n) dtbName="$OPTARG" ;;
33 r) noDeviceTree=1 ;;
34 \?) usage ;;
35 esac
36done
37
38[ "$timeout" = "" -o "$default" = "" ] && usage
39
40mkdir -p $target/nixos
41mkdir -p $target/extlinux
42
43# Convert a path to a file in the Nix store such as
44# /nix/store/<hash>-<name>/file to <hash>-<name>-<file>.
45cleanName() {
46 local path="$1"
47 echo "$path" | sed 's|^/nix/store/||' | sed 's|/|-|g'
48}
49
50# Copy a file from the Nix store to $target/nixos.
51declare -A filesCopied
52
53copyToKernelsDir() {
54 local src=$(readlink -f "$1")
55 local dst="$target/nixos/$(cleanName $src)"
56 # Don't copy the file if $dst already exists. This means that we
57 # have to create $dst atomically to prevent partially copied
58 # kernels or initrd if this script is ever interrupted.
59 if ! test -e $dst; then
60 local dstTmp=$dst.tmp.$$
61 cp -r $src $dstTmp
62 mv $dstTmp $dst
63 fi
64 filesCopied[$dst]=1
65 result=$dst
66}
67
68# Copy its kernel, initrd and dtbs to $target/nixos, and echo out an
69# extlinux menu entry
70addEntry() {
71 local path=$(readlink -f "$1")
72 local tag="$2" # Generation number or 'default'
73
74 if ! test -e $path/kernel -a -e $path/initrd; then
75 return
76 fi
77
78 copyToKernelsDir "$path/kernel"; kernel=$result
79 copyToKernelsDir "$path/initrd"; initrd=$result
80 dtbDir=$(readlink -m "$path/dtbs")
81 if [ -e "$dtbDir" ]; then
82 copyToKernelsDir "$dtbDir"; dtbs=$result
83 fi
84
85 timestampEpoch=$(stat -L -c '%Z' $path)
86
87 timestamp=$(date "+%Y-%m-%d %H:%M" -d @$timestampEpoch)
88 nixosLabel="$(cat $path/nixos-version)"
89 extraParams="$(cat $path/kernel-params)"
90
91 echo
92 echo "LABEL nixos-$tag"
93 if [ "$tag" = "default" ]; then
94 echo " MENU LABEL NixOS - Default"
95 else
96 echo " MENU LABEL NixOS - Configuration $tag ($timestamp - $nixosLabel)"
97 fi
98 echo " LINUX ../nixos/$(basename $kernel)"
99 echo " INITRD ../nixos/$(basename $initrd)"
100 echo " APPEND init=$path/init $extraParams"
101
102 if [ -n "$noDeviceTree" ]; then
103 return
104 fi
105
106 if [ -d "$dtbDir" ]; then
107 # if a dtbName was specified explicitly, use that, else use FDTDIR
108 if [ -n "$dtbName" ]; then
109 echo " FDT ../nixos/$(basename $dtbs)/${dtbName}"
110 else
111 echo " FDTDIR ../nixos/$(basename $dtbs)"
112 fi
113 else
114 if [ -n "$dtbName" ]; then
115 echo "Explicitly requested dtbName $dtbName, but there's no FDTDIR - bailing out." >&2
116 exit 1
117 fi
118 fi
119}
120
121tmpFile="$target/extlinux/extlinux.conf.tmp.$$"
122
123cat > $tmpFile <<EOF
124# Generated file, all changes will be lost on nixos-rebuild!
125
126# Change this to e.g. nixos-42 to temporarily boot to an older configuration.
127DEFAULT nixos-default
128
129MENU TITLE ------------------------------------------------------------
130TIMEOUT $timeout
131EOF
132
133addEntry $default default >> $tmpFile
134
135if [ "$numGenerations" -gt 0 ]; then
136 # Add up to $numGenerations generations of the system profile to the menu,
137 # in reverse (most recent to least recent) order.
138 for generation in $(
139 (cd /nix/var/nix/profiles && ls -d system-*-link) \
140 | sed 's/system-\([0-9]\+\)-link/\1/' \
141 | sort -n -r \
142 | head -n $numGenerations); do
143 link=/nix/var/nix/profiles/system-$generation-link
144 addEntry $link "${generation}-default"
145 for specialisation in $(
146 ls /nix/var/nix/profiles/system-$generation-link/specialisation \
147 | sort -n -r); do
148 link=/nix/var/nix/profiles/system-$generation-link/specialisation/$specialisation
149 addEntry $link "${generation}-${specialisation}"
150 done
151 done >> $tmpFile
152fi
153
154mv -f $tmpFile $target/extlinux/extlinux.conf
155
156# Remove obsolete files from $target/nixos.
157for fn in $target/nixos/*; do
158 if ! test "${filesCopied[$fn]}" = 1; then
159 echo "Removing no longer needed boot file: $fn"
160 chmod +w -- "$fn"
161 rm -rf -- "$fn"
162 fi
163done