3 files changed, 173 insertions, 0 deletions
diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
index ab9725c96..2b6c167b7 100644
--- a/.github/CODEOWNERS
+++ b/.github/CODEOWNERS
@@ -338,3 +338,6 @@
 /dev/tools/pre-commit @SkySkimmer
 
 /dev/tools/sudo-apt-get-update @JasonGross
+
+/dev/tools/check-owners*.sh @SkySkimmer
+# Secondary maintainer @maximedenes
diff --git a/dev/tools/check-owners-pr.sh b/dev/tools/check-owners-pr.sh
new file mode 100755
index 000000000..d2910279b
--- /dev/null
+++ b/dev/tools/check-owners-pr.sh
@@ -0,0 +1,32 @@
+#!/usr/bin/env sh
+
+usage() {
+    { echo "usage: $0 PR [ARGS]..."
+      echo "A wrapper around check-owners.sh to check owners for a PR."
+      echo "Assumes upstream is the canonical Coq repository."
+      echo "Assumes the PR is against master."
+      echo
+      echo "  PR: PR number"
+      echo "  ARGS: passed through to check-owners.sh"
+    } >&2
+}
+
+case "$1" in
+    "--help"|"-h")
+        usage
+        if [ $# = 1 ]; then exit 0; else exit 1; fi;;
+    "")
+        usage
+        exit 1;;
+esac
+
+PR="$1"
+shift
+
+# this puts both refs in the FETCH_HEAD file but git rev-parse will use the first
+git fetch upstream "+refs/pull/$PR/head" master
+
+head=$(git rev-parse FETCH_HEAD)
+base=$(git merge-base upstream/master "$head")
+
+git diff --name-only -z "$base" "$head" | xargs -0 dev/tools/check-owners.sh "$@"
diff --git a/dev/tools/check-owners.sh b/dev/tools/check-owners.sh
new file mode 100755
index 000000000..1a97508ab
--- /dev/null
+++ b/dev/tools/check-owners.sh
@@ -0,0 +1,138 @@
+#!/usr/bin/env bash
+
+# Determine CODEOWNERS of the files given in argument
+# For a given commit range:
+# git diff --name-only -z COMMIT1 COMMIT2 | xargs -0 dev/tools/check-owners.sh [opts]
+
+# NB: gitignore files will be messed up if you interrupt the script.
+# You should be able to just move the .gitignore.bak files back manually.
+
+usage() {
+    { echo "usage: $0 [--show-patterns] [--owner OWNER] [FILE]..."
+      echo "  --show-patterns: instead of printing file names print the matching patterns (more compact)"
+      echo "  --owner: show only files/patterns owned by OWNER (use Nobody to see only non-owned files)"
+    } >&2
+}
+
+case "$1" in
+    "--help"|"-h")
+        usage
+        if [ $# = 1 ]; then exit 0; else exit 1; fi
+esac
+
+if ! [ -e .github/CODEOWNERS ]; then
+    >&2 echo "No CODEOWNERS set up or calling from wrong directory."
+    exit 1
+fi
+
+files=()
+show_patterns=false
+
+target_owner=""
+
+while [[ "$#" -gt 0 ]]; do
+    case "$1" in
+        "--show-patterns")
+            show_patterns=true
+            shift;;
+        "--owner")
+            if [[ "$#" = 1 ]]; then
+                >&2 echo "Missing argument to --owner"
+                usage
+                exit 1
+            elif [[ "$target_owner" != "" ]]; then
+                >&2 echo "Only one --owner allowed"
+                usage
+                exit 1
+            fi
+            target_owner="$2"
+            shift 2;;
+        *)
+            files+=("$@")
+            break;;
+    esac
+done
+
+# CODEOWNERS uses .gitignore patterns so we want to use git to parse it
+# The only available tool for that is git check-ignore
+# However it provides no way to use alternate .gitignore files
+# so we rename them temporarily
+
+find . -name .gitignore -print0 | while IFS= read -r -d '' f; do
+    if [ -e "$f.bak" ]; then
+        >&2 echo "$f.bak exists!"
+        exit 1
+    else
+        mv "$f" "$f.bak"
+    fi
+done
+
+# CODEOWNERS is not quite .gitignore patterns:
+# after the pattern is the owner (space separated)
+# git would interpret that as a big pattern containing spaces
+# so we create a valid .gitignore by removing all but the first field
+
+while read -r pat _; do
+    printf '%s\n' "$pat" >> .gitignore
+done < .github/CODEOWNERS
+
+# associative array [file => owner]
+declare -A owners
+
+for f in "${files[@]}"; do
+    data=$(git check-ignore --verbose --no-index "./$f")
+    code=$?
+
+    if [[ "$code" = 1 ]] || ! [[ "$data" =~ .gitignore:.* ]] ; then
+        # no match, or match from non tracked gitignore (eg global gitignore)
+        if [ "$target_owner" != "" ] && [ "$target_owner" != Nobody ] ; then
+            owner=""
+        else
+            owner="Nobody"
+            pat="$f" # no patterns for unowned files
+        fi
+    else
+        # data looks like [.gitignore:$line:$pattern $file]
+        # extract the line to look it up in CODEOWNERS
+        data=${data#'.gitignore:'}
+        line=${data%%:*}
+
+        # NB: supports multiple owners
+        # Does not support secondary owners declared in comment
+        read -r pat fowners < <(sed "${line}q;d" .github/CODEOWNERS)
+
+        owner=""
+        if [ "$target_owner" != "" ]; then
+            for o in $fowners; do # do not quote: multiple owners possible
+                if [ "$o" = "$target_owner" ]; then
+                    owner="$o"
+                fi
+            done
+        else
+            owner="$fowners"
+        fi
+    fi
+
+    if [ "$owner" != "" ]; then
+        if $show_patterns; then
+            owners[$pat]="$owner"
+        else
+            owners[$f]="$owner"
+        fi
+    fi
+done
+
+for f in "${!owners[@]}"; do
+    printf '%s: %s\n' "$f" "${owners[$f]}"
+done | sort -k 2 -k 1 # group by owner
+
+# restore gitignore files
+rm .gitignore
+find . -name .gitignore.bak -print0 | while IFS= read -r -d '' f; do
+    base=${f%.bak}
+    if [ -e "$base" ]; then
+        >&2 echo "$base exists!"
+    else
+        mv "$f" "$base"
+    fi
+done