pre-commit: add files after fixing ending newlines.

2 files changed, 46 insertions, 28 deletions

diff --git a/dev/tools/check-eof-newline.sh b/dev/tools/check-eof-newline.sh
index c5a654e21..e244d9ab8 100755
--- a/dev/tools/check-eof-newline.sh
+++ b/dev/tools/check-eof-newline.sh
@@ -4,8 +4,9 @@
 # Detect missing end of file newlines for FILES.
 # Files are skipped if untracked by git and depending on gitattributes.
 # With --fix, automatically append a newline.
-# Exit status: 1 if any file had a missing newline, 0 otherwise
-# (regardless of --fix).
+# Exit status:
+# Without --fix: 1 if any file had a missing newline, 0 otherwise.
+# With --fix: 1 if any non writable file had a missing newline, 0 otherwise.
 
 FIX=
 if [ "$1" = --fix ];
@@ -22,12 +23,18 @@ for f in "$@"; do
     then
         if [ -n "$FIX" ];
         then
-            echo >> "$f"
-            echo "Newline appended to file $f!"
+            if [ -w "$f" ];
+            then
+                echo >> "$f"
+                echo "Newline appended to file $f!"
+            else
+                echo "File $f is missing a newline and not writable!"
+                CODE=1
+            fi
         else
             echo "No newline at end of file $f!"
+            CODE=1
         fi
-        CODE=1
     fi
 done
 
diff --git a/dev/tools/pre-commit b/dev/tools/pre-commit
index 0cd0a0b70..c5f6868d1 100755
--- a/dev/tools/pre-commit
+++ b/dev/tools/pre-commit
@@ -5,34 +5,42 @@
 
 set -e
 
-CODE=0
-git diff --cached --name-only -z | xargs -0 dev/tools/check-eof-newline.sh --fix || CODE=1
-
-if [ $CODE -ne 0 ]
-then
-    1>&2 echo "Some files had newline errors; they have been fixed in the working tree."
-    1>&2 echo "Make sure to add them before committing."
-    1>&2 echo "This may fix itself if you were using git commit -a, and you try again."
-    exit 1
-fi
-
-if git diff-index --check --cached HEAD >/dev/null 2>&1 ;
+if ! git diff --cached --name-only -z | xargs -0 dev/tools/check-eof-newline.sh ||
+        ! git diff-index --check --cached HEAD >/dev/null 2>&1 ;
 then
-    :
-else
     1>&2 echo "Auto fixing whitespace issues..."
 
-    TEMP=$(mktemp)
     # We fix whitespace in the index and in the working tree
     # separately to preserve non-added changes.
-    git diff-index -p --cached HEAD > "$TEMP"
-    git apply --cached -R "$TEMP"
-    git apply --cached --whitespace=fix "$TEMP"
-
-    git diff-index -p HEAD > "$TEMP"
-    git apply -R "$TEMP"
-    git apply --whitespace=fix "$TEMP"
-    rm "$TEMP"
+    index=$(mktemp "git-fix-ws-index.XXXXX")
+    fixed_index=$(mktemp "git-fix-ws-index-fixed.XXXXX")
+    tree=$(mktemp "git-fix-ws-tree.XXXXX")
+    1>&2 echo "Patches are saved in '$index', '$fixed_index' and '$tree'."
+    1>&2 echo "If an error destroys your changes you can recover using them."
+    1>&2 echo "(The files are cleaned up on success.)"
+
+    git diff-index -p --cached HEAD > "$index"
+    git diff-index -p HEAD > "$tree"
+
+    # reset work tree and index
+    # NB: untracked files which were not added are untouched
+    git apply --cached -R "$index"
+    git apply -R "$tree"
+
+    # Fix index
+    # For end of file newlines we must go through the worktree
+    git apply --cached --whitespace=fix "$index"
+    git apply --whitespace=fix "$index"
+    git diff --cached --name-only -z | xargs -0 dev/tools/check-eof-newline.sh --fix
+    git add -u
+
+    # reset work tree
+    git diff-index -p --cached HEAD > "$fixed_index"
+    git apply -R "$fixed_index"
+
+    # Fix worktree
+    git apply --whitespace=fix "$tree"
+    git diff --name-only -z | xargs -0 dev/tools/check-eof-newline.sh --fix
 
     # Check that we did fix whitespace
     if ! git diff-index --check --cached HEAD;
@@ -43,4 +51,7 @@ else
         exit 1
     fi
     1>&2 echo "Whitespace issues fixed!"
+
+    # clean up temporary files
+    rm "$index" "$tree" "$fixed_index"
 fi