1 files changed, 25 insertions, 6 deletions
diff --git a/tools/pre-commit b/tools/pre-commit
index 32fc7b9e..b1a3a187 100755
--- a/tools/pre-commit
+++ b/tools/pre-commit
@@ -1,29 +1,45 @@
 #!/bin/sh
 
-set -e
+if [ ! $(git rev-parse --symbolic-full-name HEAD) = refs/heads/master ]; then
+    exit 0
+fi
 
+# These are the locations I keep my temporary source and build trees in
 TMPDIR=$HOME/Products/ledger-pre-commit
 MIRROR=$HOME/Products/ledger-pre-commit-mirror
 
-# Checkout a copy of the current index into TMPDIR
+# Exit with status 1 if any command below fails
+set -e
+
+# Checkout a copy of the current index into MIRROR
 git checkout-index --prefix=$MIRROR/ -af
 
-# Remove files which are no longer present in the index
+# Remove files from MIRROR which are no longer present in the index
 git diff-index --cached --name-only --diff-filter=D -z HEAD | \
     (cd $MIRROR && xargs -0 rm -f --)
 
-# Copy over changes, ignoring timestamps
+# Copy only _changed files_ from MIRROR to TMPDIR, without copying timestamps.
+# This includes copying over new files, and deleting removed ones.  This way,
+# "make check" will only rebuild what is necessary to validate the commit.
 rsync -rlpgoDO --size-only --delete \
     --exclude-from=tools/excludes $MIRROR/ $TMPDIR/
 
+# Everything else happens in the temporary build tree
+if [ ! -f $TMPDIR/lib/utfcpp/source/utf8.h ]; then
+    rsync -a --delete lib/utfcpp/ $TMPDIR/lib/utfcpp/
+fi
 cd $TMPDIR
 
 # Make sure there is a current Makefile.  Regeneration of Makefile happens
 # automatically, but if myacprep or acprep changes, we want to regenerate
-# everything manually.
+# everything manually.  If the user doesn't have acprep or myacprep, look for
+# other common autoconf-related script files.
 if [ ! -f Makefile -o \
+     \( Makefile.am -nt Makefile -o \
+        configure.ac -nt Makefile \) -o \
      \( -f tools/myacprep -a -f acprep -a \
-     \( tools/myacprep -nt Makefile -o acprep -nt Makefile \) \) ]
+        \( tools/myacprep -nt Makefile -o \
+           acprep -nt Makefile \) \) ]
 then
     if [ -f tools/myacprep ]; then
 	tools/myacprep --local
@@ -36,4 +52,7 @@ then
     fi
 fi
 
+# Finally, (re)build this proposed source tree and see if it passes muster.
 nice -n 20 make check
+
+exit 0