Improved directory management in git hooks

* Make git hooks always execute utilities relative to git repository root
* And make them fail if called from outside the git repository
* Make utilities save current directory and return after doing their
  things

git-hooks/post-checkout → git-hooks/post-checkout.in

 #!/bin/sh
 
+dir=`git rev-parse --show-toplevel`
+if [ -z $dir ]; then
+    exit 1
+fi
+
 echo -n Setting up hooks from git-hooks..
-`pwd`/util/sync_hooks.sh >/dev/null
+$dir/util/sync_hooks.sh >/dev/null
 if [ $? -eq 0 ]; then
     echo . done.
 else

git-hooks/pre-commit → git-hooks/pre-commit.in

 #!/bin/sh
 
+dir=`git rev-parse --show-toplevel`
+if [ -z $dir ]; then
+    exit 1
+fi
+
 echo -n Checking JSON parses..
-`pwd`/util/json_lint.sh
+$dir/util/json_lint.sh
 if [ $? -eq 0 ]; then
     echo . it does!
 else

util/json_lint.sh

 #!/bin/bash
+# A very simple check to see if the json files in the project at least compile.
+# If they do not, a cryptic message that might be helpful is produced.
+
+
+# Save current directory so we can come back; change to repo root
+STARTED_FROM=`pwd`
+cd $(git rev-parse --show-toplevel)
 
 # Do very basic syntax check of every json file to make sure it's valid format
 for file in `find . -iname '*.json'`; do 
@@ -8,9 +15,12 @@ for file in `find . -iname '*.json'`; do
         echo "JSON errors in $file"
         cat json_complaint.err
         rm -f json_complaint.err
+        cd $STARTED_FROM
         exit $retval;
     fi
 done
 
 # Everything went ok!
+rm -f json_complaint.err
+cd $STARTED_FROM
 exit 0

util/sync_hooks.sh

 #!/bin/bash
+# A small utility to symlink the files from git-hooks/ with filenames ending
+# like .in into the directory .git/hooks/
+#
+# It's intended this be run once near the start of a project by hand, and then
+# subsequently a hook that it installs keeps it running at project checkouts.
 
-# Are we running from the git root?
-GITHOOKSFOUND='false'
-if [ -d git-hooks ]; then
-    GITHOOKSFOUND='true';
-fi
-DOTGITHOOKSFOUND='false'
-if [ -d .git -a -d .git/hooks ]; then
-    DOTGITHOOKSFOUND='true';
-fi
+
+# Save current directory so we can come back; change to repo root
+STARTED_FROM=`pwd`
+cd $(git rev-parse --show-toplevel)
 
 # Sync git-hooks directory entries into .git/hooks/
-if [ 'true' = $GITHOOKSFOUND -a 'true' = $DOTGITHOOKSFOUND ]; then
-    for file in git-hooks/*; do
-        filepart=`echo $file | sed -e 's/git-hooks\/\(.*\)/\1/'`
+for file in git-hooks/*.in; do
+    filepart=`basename $file .in`
     if [ -e .git/hooks/$filepart -a ! -L .git/hooks/$filepart ]; then
         echo ".git/hooks/$filepart not link-managed; bailing..."
         echo "please examine your .git/hooks/ directory and repair inconsistencies manually"
+        cd $STARTED_FROM
         exit 1
     else
-            ln -v -s -b -f `pwd`/$file -t .git/hooks/
+        ln -v -s -b -f `pwd`/$file .git/hooks/$filepart
     fi
-    done
-else
-    echo "Not in git repository root, cannot continue."
-    exit 1
-fi
+done
 
-# Ok, everything went well
+# Ok, everything went well; restore previous context
+cd $STARTED_FROM
 exit 0