Merge pull request #23414 from shanemikel/nix-helper-scripts

add a script that "diffs" nix environment generations

1 files changed, 277 insertions, 0 deletions

diff --git a/maintainers/scripts/nix-diff.sh b/maintainers/scripts/nix-diff.sh
new file mode 100755
index 000000000000..9e85b116bc92
--- /dev/null
+++ b/maintainers/scripts/nix-diff.sh
@@ -0,0 +1,277 @@
+#!/usr/bin/env nix-shell
+#! nix-shell -i bash -p coreutils gnugrep gnused
+
+################################################################################
+# nix-diff.sh                                                                  #
+################################################################################
+# This script "diffs" Nix profile generations.                                 #
+#                                                                              #
+# Example:                                                                     #
+################################################################################
+# > nix-diff.sh 90 92                                                          #
+# + gnumake-4.2.1                                                              #
+# + gnumake-4.2.1-doc                                                          #
+# - htmldoc-1.8.29                                                             #
+################################################################################
+# The example shows that as of generation 92 and since generation 90,          #
+# gnumake-4.2.1 and gnumake-4.2.1-doc have been installed, while               #
+# htmldoc-1.8.29 has been removed.                                             #
+#                                                                              #
+# The example above shows the default, minimal output mode of this script.     #
+# For more features, run `nix-diff.sh -h` for usage instructions.              #
+################################################################################
+
+usage() {
+    cat <<EOF
+usage: nix-diff.sh [-h] [-p profile | -s] [range]
+-h:         print this message before exiting
+-q:         list the derivations installed in the parent generation
+-l:         diff every available intermediate generation between parent and
+            child
+-p profile: specify the Nix profile to use
+            * defaults to ~/.nix-profile
+-s:         use the system profile
+            * equivalent to: -p /nix/var/nix/profiles/system
+profile:    * should be something like /nix/var/nix/profiles/default, not a
+              generation link like /nix/var/nix/profiles/default-2-link
+range:      the range of generations to diff
+            * the following patterns are allowed, where A, B, and N are positive
+              integers, and G is the currently active generation:
+                A..B => diffs from generation A to generation B
+                ~N   => diffs from the Nth newest generation (older than G) to G
+                A    => diffs from generation A to G
+            * defaults to ~1
+EOF
+}
+
+usage_tip() {
+    echo 'run `nix-diff.sh -h` for usage instructions' >&2
+    exit 1
+}
+
+while getopts :hqlp:s opt; do
+    case $opt in
+        h)
+            usage
+            exit
+            ;;
+        q)
+            opt_query=1
+            ;;
+        l)
+            opt_log=1
+            ;;
+        p)
+            opt_profile=$OPTARG
+            ;;
+        s)
+            opt_profile=/nix/var/nix/profiles/system
+            ;;
+        \?)
+            echo "error: invalid option -$OPTARG" >&2
+            usage_tip
+            ;;
+    esac
+done
+shift $((OPTIND-1))
+
+if [ -n "$opt_profile" ]; then
+    if ! [ -L "$opt_profile" ]; then
+        echo "error: expecting \`$opt_profile\` to be a symbolic link" >&2
+        usage_tip
+    fi
+else
+    opt_profile=$(readlink ~/.nix-profile)
+    if (( $? != 0 )); then
+        echo 'error: unable to dereference `~/.nix-profile`' >&2
+        echo 'specify the profile manually with the `-p` flag' >&2
+        usage_tip
+    fi
+fi
+
+list_gens() {
+    nix-env -p "$opt_profile" --list-generations \
+        | sed -r 's:^\s*::' \
+        | cut -d' ' -f1
+}
+
+current_gen() {
+    nix-env -p "$opt_profile" --list-generations \
+        | grep -E '\(current\)\s*$' \
+        | sed -r 's:^\s*::' \
+        | cut -d' ' -f1
+}
+
+neg_gen() {
+    local i=0 from=$1 n=$2 tmp
+    for gen in $(list_gens | sort -rn); do
+        if ((gen < from)); then
+            tmp=$gen
+            ((i++))
+            ((i == n)) && break
+        fi
+    done
+    if ((i < n)); then
+        echo -n "error: there aren't $n generation(s) older than" >&2
+        echo " generation $from" >&2
+        return 1
+    fi
+    echo $tmp
+}
+
+match() {
+    argv=("$@")
+    for i in $(seq $(($#-1))); do
+        if grep -E "^${argv[$i]}\$" <(echo "$1") >/dev/null; then
+            echo $i
+            return
+        fi
+    done
+    echo 0
+}
+
+case $(match "$1" '' '[0-9]+' '[0-9]+\.\.[0-9]+' '~[0-9]+') in
+    1)
+        diffTo=$(current_gen)
+        diffFrom=$(neg_gen $diffTo 1)
+        (($? == 1)) && usage_tip
+        ;;
+    2)
+        diffFrom=$1
+        diffTo=$(current_gen)
+        ;;
+    3)
+        diffFrom=${1%%.*}
+        diffTo=${1##*.}
+        ;;
+    4)
+        diffTo=$(current_gen)
+        diffFrom=$(neg_gen $diffTo ${1#*~})
+        (($? == 1)) && usage_tip
+        ;;
+    0)
+        echo 'error: invalid invocation' >&2
+        usage_tip
+        ;;
+esac
+
+dirA="${opt_profile}-${diffFrom}-link"
+dirB="${opt_profile}-${diffTo}-link"
+
+declare -a temp_files
+temp_length() {
+    echo -n ${#temp_files[@]}
+}
+temp_make() {
+    temp_files[$(temp_length)]=$(mktemp)
+}
+temp_clean() {
+    rm -f ${temp_files[@]}
+}
+temp_name() {
+    echo -n "${temp_files[$(($(temp_length)-1))]}"
+}
+trap 'temp_clean' EXIT
+
+temp_make
+versA=$(temp_name)
+refs=$(nix-store -q --references "$dirA")
+(( $? != 0 )) && exit 1
+echo "$refs" \
+    | grep -v env-manifest.nix \
+    | sort \
+          > "$versA"
+
+print_tag() {
+    local gen=$1
+    nix-env -p "$opt_profile" --list-generations \
+        | grep -E "^\s*${gen}" \
+        | sed -r 's:^\s*::' \
+        | sed -r 's:\s*$::'
+}
+
+if [ -n "$opt_query" ]; then
+    print_tag $diffFrom
+    cat "$versA" \
+        | sed -r 's:^[^-]+-(.*)$:    \1:'
+
+    print_line=1
+fi
+
+if [ -n "$opt_log" ]; then
+    gens=$(for gen in $(list_gens); do
+               ((diffFrom < gen && gen < diffTo)) && echo $gen
+           done)
+    # Force the $diffTo generation to be included in this list, instead of using
+    # `gen <= diffTo` in the preceding loop, so we encounter an error upon the
+    # event of its nonexistence.
+    gens=$(echo "$gens"
+           echo $diffTo)
+else
+    gens=$diffTo
+fi
+
+temp_make
+add=$(temp_name)
+temp_make
+rem=$(temp_name)
+temp_make
+out=$(temp_name)
+
+for gen in $gens; do
+
+    [ -n "$print_line" ] && echo
+
+    temp_make
+    versB=$(temp_name)
+
+    dirB="${opt_profile}-${gen}-link"
+    refs=$(nix-store -q --references "$dirB")
+    (( $? != 0 )) && exit 1
+    echo "$refs" \
+        | grep -v env-manifest.nix \
+        | sort \
+              > "$versB"
+
+    in=$(comm -3 -1 "$versA" "$versB")
+    sed -r 's:^[^-]*-(.*)$:\1+:' <(echo "$in") \
+        | sort -f \
+               > "$add"
+
+    un=$(comm -3 -2 "$versA" "$versB")
+    sed -r 's:^[^-]*-(.*)$:\1-:' <(echo "$un") \
+        | sort -f \
+               > "$rem"
+
+    cat "$rem" "$add" \
+        | sort -f \
+        | sed -r 's:(.*)-$:- \1:' \
+        | sed -r 's:(.*)\+$:\+ \1:' \
+        | grep -v '^$' \
+              > "$out"
+
+    if [ -n "$opt_query" -o -n "$opt_log" ]; then
+
+        lines=$(wc -l "$out" | cut -d' ' -f1)
+        tag=$(print_tag "$gen")
+        (( $? != 0 )) && exit 1
+        if [ $lines -eq 0 ]; then
+            echo "$tag   (no change)"
+        else
+            echo "$tag"
+        fi
+        cat "$out" \
+            | sed 's:^:    :'
+
+        print_line=1
+
+    else
+        echo "diffing from generation $diffFrom to $diffTo"
+        cat "$out"
+    fi
+
+    versA=$versB
+
+done
+
+exit 0