Pre-receive hook to limit maximum git file size (attempt 1 - only compares diff)

git-pre-receive-diff.sh

#!/bin/bash -e

GITCMD="git"
NULLSHA="0000000000000000000000000000000000000000"
MAXSIZE="10"
MAXBYTES=$(( $MAXSIZE * 1024 * 1024 ))
EXIT=0

# Read stdin for ref information
while read oldref newref refname; do
  # Skip branch deletions
  if [ "${newref}" = "${NULLSHA}" ]; then
    continue
  fi

  # Set oldref properly if this is branch creation.
  if [ "${oldref}" = "${NULLSHA}" ]; then
    oldref="HEAD"
  fi

  # Get list of files to look at using git diff
  for file in $($GITCMD diff --stat --name-only --diff-filter=ACMRT ${oldref}..${newref}); do
    # Get the size of this file
    size=$($GITCMD cat-file -s ${newref}:${file})
    # Check to see if for some reason we didn't get a size
    if [ ! -z "${size}" ]; then
      # Compare filesize to MAXBYTES
      if [ "${size}" -gt "${MAXBYTES}" ]; then
        # Display error header if this is the first file
        if [ "$EXIT" -eq "0" ]; then
          EXIT=1
          echo ""
          echo "---------------------------------------------------------------------------"
          echo "Your push was rejected because it contains files larger than ${MAXSIZE} MB."
          echo "Please rethink your actions, and consider using https://git-lfs.github.com/"
          echo "or an external data store."
          echo "---------------------------------------------------------------------------"
          echo
          echo "Offending files:"
        fi

        echo " - ${file}"
      fi
    fi
  done
done

if [ "$EXIT" -ne "0" ]; then echo; fi
exit ${EXIT}