From fe6bedfb5dc360ce601af0f4a049d620b5992e77 Mon Sep 17 00:00:00 2001
From: "Ivan A. Melnikov" <imelnikov@griddynamics.com>
Date: Mon, 24 Jun 2013 12:34:20 +0400
Subject: [PATCH] tools/pre-commit: Don't use stashes

Using stashes in pre-commit hook had the following demerits:
- when stash was not needed, it was not created, so some other stash
  created by user was poped on exit -- this was a source of great
  confusion;
- files with unstaged changes were touched, which caused unwanted
  side effects with some tools like editors or build systems.

This commit changes the way we get the clean source by checking out
index tree to temporary dir without modifying working tree. This
might be a bit slower for large repositories, but in my tests for
this repo it is within 5%.

Change-Id: Ic32fc2f52958b63131fcbe363ea47fca13099ea3
---
 tools/pre-commit | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/tools/pre-commit b/tools/pre-commit
index 4201b88a..c6410c7c 100755
--- a/tools/pre-commit
+++ b/tools/pre-commit
@@ -3,11 +3,30 @@
 # install me this way:
 # cp pre-commit "$(git rev-parse --git-dir)/hooks/"
 
-git stash -q --keep-index
-trap 'git stash pop -q' EXIT
 
-STATUS=0
-FILES="$(git diff --cached --name-only --diff-filter=AM | grep -E '\.py$')"
+gitdir="$(readlink -f $(git rev-parse --git-dir))"
+
+tmpdir=
+cleanup_tmpdir()
+{
+        [ -z "$tmpdir" ] || rm -rf -- "$tmpdir"
+        exit "$@"
+}
+tmpdir=$(mktemp -dt "${0##*/}.XXXXXXXX")
+trap 'cleanup_tmpdir $?' EXIT
+trap 'clenaup_tmpdir 143' HUP INT QUIT PIPE TERM
+
+
+
+git checkout-index -a --prefix="$tmpdir/"
+cd "$tmpdir"
+
+indexed_files()
+{
+    git --git-dir="$gitdir" diff --cached --name-only --diff-filter=AM
+}
+
+FILES="$(indexed_files | grep -E '\.py$')"
 if [ -n "$FILES" ]; then
     pylint $FILES || STATUS=1
     if grep -nEH --color '(import pdb|pdb.set_trace)' $FILES; then
@@ -16,7 +35,7 @@ if [ -n "$FILES" ]; then
     fi
 fi
 
-FILES="$(git diff --cached --name-only --diff-filter=AM | grep -E '\.(py|html|js)$')"
+FILES="$(indexed_files | grep -E '\.(py|html|js)$')"
 if [ -n "$FILES" ]; then
     if grep -nEH --color '\s+$' $FILES; then
         echo "Please remove trailing spaces"