Repro script: check argc at the start

REPRODUCIBLE_BUILDS.md

@@ -1,15 +1,14 @@
-
 # Reproducible Builds
 
 ## Install Docker
 
 Download and install [Docker](https://www.docker.com/).
 
-## Download the App open-source code
+## Download the app's source code
 
 1. Make sure you have `git` installed
 2. Clone the Github repository
-3. Checkout the Tag that corresponds to the version of your app (e.g., 1.0.0)
+3. Checkout the tag that corresponds to the version of your app (e.g., 1.0.0)
 
 ```shell
 git clone https://github.com/admin-ch/CovidCertificate-App-Android.git ~/CovidCertificate-App-Android
@@ -118,7 +117,9 @@ python ../apkdiff.py verifier-built.apk verifier-store.apk
 
 ## Building and checking with script
 
-As an alternative you can also start the build and comparison process with the buildAndCompare.sh script. The script will ask you for the relevant input:
+As an alternative you can also run the build and comparison process with the buildAndCompare.sh script.
+The script expects the path to the APK to compare with and will ask you for all other inputs:
+
 ```shell
-./buildAndCompare.sh path/to/store/apk
-```
+./buildAndCompare.sh path/to/store.apk
+```

buildAndCompare.sh

@@ -1,35 +1,39 @@
 #!/bin/bash
 set -e
 
-echo "Which app would you like to build (type 'wallet' or 'verifier')?"
+if [[ $# -ne 1 ]]; then
+  echo "Pass the path/to/store.apk as an argument!"
+  exit 1
+fi
+
+echo "Which app would you like to build ('wallet' or 'verifier')?"
 read appName
 
-echo Please enter KeystoreFile name:
+echo "Please enter the keystore filename:"
 read keystoreFile
 
-echo Please enter Keystore Password:
+echo "Please enter the keystore password:"
 read -s keystorePassword
 
-echo Please enter KeyAlias:
+echo "Please enter the keyAlias:"
 read keyAlias
 
-echo Please enter KeyAlias Password:
+echo "Please enter the keyAlias password:"
 read -s keyAliasPassword
 
-echo Please enter Build Timestamp:
+echo "Please enter the build timestamp:"
 read buildTimestamp
 
-#make sure we have a full clean build
+# Make sure we have a full clean build
 rm -rf $appName/build
 rm -rf .gradle
 
+echo "Building apk from source..."
 docker build -t covidcertificate-builder .
 currentPath=`pwd`
 docker run --rm -v $currentPath:/home/covidcertificate -w /home/covidcertificate covidcertificate-builder gradle $appName:assembleProdRelease -PkeystorePassword=$keystorePassword -PkeyAlias=$keyAlias -PkeyAliasPassword=$keyAliasPassword -PkeystoreFile=$keystoreFile -PbuildTimestamp=$buildTimestamp
 
 cp $appName/build/outputs/apk/prod/release/$appName-prod-release.apk $appName-built.apk
 
-if [[ $# -eq 1 ]] ; then
-  echo Comparing the built APK with the reference:
-  python apkdiff.py $appName-built.apk $1
-fi
+echo "Comparing the APK built from source with the reference APK..."
+python apkdiff.py $appName-built.apk $1