Adding a download function library plus basic testing

This is so that all downloads can take place through a single
function, regardless of OS or scenario.

Signed-off-by: Adam Farley <[email protected]>

sbin/common/lib/functionLibrary.sh

@@ -0,0 +1,219 @@
+#!/usr/bin/bash
+# This script contains a library of useful functions
+# Functions list:
+# downloadFile - Downloads a file and optionally checks it against a sha.
+# info - echoes any string sent to it, but only if it is enabled first.
+# checkFileSha - Checks whether a named file matches a supplied sha.
+# doesThisURLExist - Checks if a given URL exists.
+
+# This simple function takes a string, and echoes it if info-level logging is enabled.
+# Info-level logging can be enabled by simply passing the word "enable" to it as the sole argument.
+# This is handy for debug messages, as it can simply not be enabled for quiet runs.
+enableInfoLoggingBool=1
+
+function info() {
+  [ $# == 0 ] && echo "Warning: The library function \"info\" was called without an argument." && return 1
+  [[ $enableInfoLoggingBool == 0 ]] && echo $1 && return 0
+  [[ "${1}" == "enable" ]] && enableInfoLoggingBool=0 && return 0
+}
+
+# This function takes the supplied sha and compares it against the supplied file.
+# Example: checkFileSha 123456 /usr/bin/etc/exampleFile
+# Caution: I strongly advise against using relative paths.
+function checkFileSha() {
+  info "Checking if a file matches the sha256 checksum. Fails if there is no checksum."
+  if [ $# != 2 ]; then
+    echo "Error: checkFileSha() function was not supplied with exactly 2 arguments."
+    exit 1
+  fi
+
+  if [[ -z $1 ]]; then
+    info "No sha256 checksum found."
+    info "Check declared failed."
+    return 1
+  fi
+
+  if [[ ! -x $2 ]]; then
+    info "The file we're trying to check does not exist: ${2}"
+    return 1
+  fi
+
+  info "Checking if a file matches the checksum."
+  shaReturnCode=1
+  if command -v sha256sum &> /dev/null; then
+    echo "$1 $2" | sha256sum -c --quiet
+    shaReturnCode=$?
+  elif command -v shasum &> /dev/null; then
+    echo "$1 $2" | shasum -a 256 -c &> /dev/null -
+    shaReturnCode=$?
+  else
+    echo "Error: Neither sha256sum nor shasum is available on this machine."
+    exit 1
+  fi
+
+  if [ $shaReturnCode != 0 ]; then
+    echo "Warning: File ${2} does not match the supplied checksum."
+    return 1
+  else
+    info "File matches the checksum."
+    return 0
+  fi
+}
+
+# This function checks if a given URL (string argument) exists.
+function doesThisURLExist() {
+  info "Checking if a given URL exists."
+  if [ $# == 0 ]; then
+    echo "Error: doesThisURLExist() function was not supplied with a URL."
+    exit 1
+  fi
+
+  spiderOutput=1
+  if command -v wget &> /dev/null; then
+    wget --spider -q ${source} 2> /dev/null
+    spiderOutput=$?
+  elif command -v curl &> /dev/null; then
+    curl -I ${source} -s | grep "200 OK" -q
+    spiderOutput=$?
+  else
+    echo "Error: Neither wget nor curl could be found when downloading this file: ${source}"
+    exit 1
+  fi
+
+  return $spiderOutput
+}
+
+# This function downloads files
+# The accepted arguments are:
+# -source (mandatory: a web URL where the file is located)
+# -destination (mandatory: an existent folder where the file will be put)
+# -filename (optional: the new name of the file post-download)
+# -sha (optional: the anticipated sha of the downloaded file)
+function downloadFile() {
+  source=""
+  destination=""
+  filename=""
+  sha=""
+
+  arrayOfArgs=( "$@" )
+  x=0
+  while [[ ${#arrayOfArgs[@]} -gt $((x+1)) ]]; do
+    arg="${arrayOfArgs[x]}"
+    x="$((x+1))"
+    value="${arrayOfArgs[$x]}"
+    case "$arg" in
+      --source | -s )
+      source="${value}"
+      ;;
+
+      --destination | -d )
+      destination="${value}"
+      ;;
+
+      --filename | -f )
+      filename="${value}"
+      ;;
+
+      --sha | -sha )
+      sha="${value}"
+      ;;
+
+      *) echo >&2 "Invalid downloadFile argument: ${arg} ${value}"; exit 1;;
+    esac
+    x="$((x+1))"
+  done
+
+  info "File download requested."
+
+  if [[ "${source}" == "" || "${destination}" == "" ]]; then
+    echo "Error: function downloadFile requires both a source and a destination."
+    echo "Source detected: ${source}"
+    echo "Destination detected: ${destination}"
+    exit 1
+  fi
+
+  info "File details: "
+  info "- source: ${source}"
+  info "- destination: ${destination}"
+  info "- file name: ${filename}"
+  info "- sha256 checksum: ${sha}"
+
+  if [ -z ${filename} ]; then
+    filename="${source##*/}"
+  fi
+
+  info "Checking if source exists."
+  doesThisURLExist "${source}"
+  [[ $? != 0 ]] && echo "Error: File could not be found at source." && exit 1
+  info "Source exists."
+
+  info "Checking if destination folder exists."
+  [ ! -x ${destination} ] && echo "Error: Destination folder could not be found." && exit 1
+
+  info "Destination folder exists. Checking if file is already present."
+  if [ -x "${destination}/${filename}" ]; then
+    info "Warning: File already exists."
+    checkFileSha "${sha}" "${destination}/${filename}"
+    if [[ $? != 0 ]]; then
+      info "Warning: A file was found with the same name, and it does not match the supplied checksum. Removing file."
+      rm "${destination}/${filename}"
+      if [ $? != 0 ]; then
+        echo "Error: Could not remove file."
+        exit 1
+      fi
+    else
+      info "A file was found with the same name, and it matches the supplied checksum. Skipping download."
+      exit 0
+    fi
+  fi
+  if [ -x "${destination}/${source##*/}" ]; then
+    info "Warning: File already exists with the default file name: ${source##*/}"
+    checkFileSha "${sha}" "${destination}/${source##*/}"
+    if [[ $? != 0 ]]; then
+      info "Warning: A file was found with the same name, and it does not match the supplied checksum. Removing file."
+      rm "${destination}/${source##*/}"
+      if [ $? != 0 ]; then
+        echo "Error: Could not remove file."
+        exit 1
+      fi
+    else
+      info "A file was found with the same name, and it matches the supplied checksum. Skipping download."
+      mv "${destination}/${source##*/}" "${destination}/${filename}"
+      exit 0
+	fi
+  fi
+
+  info "File not already downloaded. Attempting file download."
+  if command -v wget &> /dev/null; then
+    info "Found wget. Using wget to download the file."
+    wget -q -P "${destination}" "${source}"
+  elif command -v curl &> /dev/null; then
+    info "Found curl. Using curl to download the file."
+    curl -s "${source}" -o "${destination}"
+  fi
+  if [ ! -x "${destination}/${filename}" ]; then
+    mv "${destination}/${source##*/}" "${destination}/${filename}"
+  fi
+
+  info "File download is complete."
+
+  if [[ -n $sha ]]; then
+    checkFileSha "${destination}/${filename}"
+    if [[ $? != 0 ]]; then
+      echo "Error: Checksum does not match the downloaded file. Removing file."
+      rm "${destination}/${filename}"
+      exit 1
+    fi
+  fi
+
+  info "File has been downloaded successfully."
+
+  info "Setting file permissions to 770."
+  chmod 770 "${destination}/${filename}"
+  [ $? != 0 ] && echo "Error: Checksum does not match the downloaded file. Removing file." && rm "${destination}/${filename}" && exit 1
+
+  info "File permissions set successfully."
+  info "File download script complete"
+
+  return 0
+}

sbin/common/lib/functionLibraryTests.sh

@@ -0,0 +1,70 @@
+#!/usr/bin/bash
+# A set of tests for the functionLibrary script
+
+source functionLibrary.sh
+
+sampleFileURL=https://github.com/adamfarley/temurin-build
+sampleFileName=sampleFileForTesting.txt
+sampleFileSha="12345"
+
+successTotal=0
+failureTotal=0
+
+# takes the name of the test and a boolean indicating whether it passed.
+function testResults() {
+  if [[ $2 == 0 ]]; then
+    echo "Success: $1 has passed."
+    successTotal=$((successTotal+1))
+  else
+    echo "Failure: $1 has failed."
+    failureTotal=$((failureTotal+1))
+  fi
+}
+
+# info
+function infoTests(){
+  # Does it work when it shouldn't?
+  [[ "$(info Test)" == "" ]]
+  testResults "infoTest 1" "$?"
+
+  # Does it work when it should?
+  info "enable"
+  [[ "$(info 123)" == "123" ]]
+  testResults "infoTest 2" "$?"
+}
+
+# checkFileSha
+function checkFileShaTests(){
+  return 0
+}
+
+# doesThisURLExist
+function doesThisURLExistTests(){
+  return 0
+}
+
+# downloadFile
+function downloadFileTests(){
+  return 0
+}
+
+echo "Test script start."
+echo ""
+
+# Test execution
+infoTests
+checkFileShaTests
+doesThisURLExistTests
+downloadFileTests
+
+echo ""
+echo "${successTotal} tests have passed."
+echo "${failureTotal} tests have failed."
+echo ""
+if [[ $failureTotal -eq 0 ]]; then
+  echo "This test script has passed."
+  exit 0
+else
+  echo "This test script has failed."
+  exit 1
+fi

sbin/common/lib/sampleFileForTesting.txt

@@ -0,0 +1,3 @@
+# A sample file which does not change. Used for download and sha256 testing.
+
+Sample file contents.