cs-3424: add solution to assignment 2

Summer-2024/CS-3424/Assignments/Assignment-2/.gitignore

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+result

Summer-2024/CS-3424/Assignments/Assignment-2/flake.lock

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+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1710146030,
+        "narHash": "sha256-SZ5L6eA7HJ/nmkzGG7/ISclqe6oZdOZTNoesiInkXPQ=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "b1d9ab70662946ef0850d488da1c9019f3a9752a",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1720955038,
+        "narHash": "sha256-GaliJqfFwyYxReFywxAa8orCO+EnDq2NK2F+5aSc8vo=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "aa247c0c90ecf4ae7a032c54fdc21b91ca274062",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

Summer-2024/CS-3424/Assignments/Assignment-2/flake.nix

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+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+  outputs =
+    inputs@{ self, ... }:
+    inputs.flake-utils.lib.eachDefaultSystem (
+      system:
+      let
+        pkgs = inputs.nixpkgs.legacyPackages.${system};
+      in
+      rec {
+        packages.assign2 = pkgs.writeShellApplication {
+          name = "assign2";
+          runtimeInputs = with pkgs; [
+            gnused
+            coreutils
+          ];
+          derivationArgs = {
+            src = ./src;
+            checkPhase =
+              let
+                check-redaction-valid = pkgs.writeShellApplication {
+                  name = "check-redaction-valid";
+                  runtimeInputs = with pkgs; [
+                    diffutils
+                    gnused
+                    coreutils
+                  ];
+                  text = ''
+                    set -eEuo pipefail
+                    cp "${./data/redactme.txt}" ./redactme-alterable.txt
+                    chmod 0600 ./redactme-alterable.txt
+                    # shellcheck disable=SC2154
+                    "$out/bin/assign2" ./redactme-alterable.txt
+                    diff \
+                      --color=auto \
+                      --ignore-matching-lines='^Date:.*$' \
+                      ./redactme-alterable.txt \
+                      "${./data/redactme-after.txt}"
+                  '';
+                };
+              in
+              ''
+                set -eEuo pipefail
+                ${pkgs.shellcheck}/bin/shellcheck ${self}/src/assign2.bash
+                ${pkgs.shfmt}/bin/shfmt -d ${self}/src/assign2.bash
+                ${check-redaction-valid}/bin/check-redaction-valid
+              '';
+          };
+          text = ''${pkgs.bash}/bin/bash ${self}/src/assign2.bash "$@"'';
+        };
+        packages.default = packages.assign2;
+        apps.default = {
+          type = "app";
+          program = "${packages.assign2}/bin/assign2";
+        };
+      }
+    );
+}

Summer-2024/CS-3424/Assignments/Assignment-2/src/assign2.bash

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+#!/usr/bin/env bash
+
+set -eEuo pipefail
+
+SCRIPT_PATH="${BASH_SOURCE[0]}"
+SCRIPT_DIR="$(dirname "$SCRIPT_PATH")"
+
+#######################################
+# Print the given message to STDERR
+#######################################
+err() {
+	printf "%s\n" "${*}" >&2
+}
+
+#######################################
+# End the script with a non-zero exit code and the given message
+# Arguments:
+#   msg: The message to print to STDERR before exiting
+#######################################
+die() {
+	local msg="${*}"
+	err "$msg"
+	exit 1
+}
+
+#######################################
+# Print a usage synopsis for the script to stdout
+#######################################
+usage() {
+	cat <<-__EOS__
+		Usage:
+		    ${SCRIPT_PATH} <input-files...>
+		Args:
+		    <input-files...>: One or more paths to files on the system
+		Example:
+		    ${SCRIPT_PATH} ./some/file/to/handle.txt ./another/file/to/handle.txt
+	__EOS__
+}
+
+#######################################
+# Replace all instances of <dstamp> or <date> with todays date in day/month/year
+# format in place for the given file
+# Arguments:
+#   file: The file to template in the date for
+#######################################
+replace_date_placeholders_in_file() {
+	local file="${1}"
+	local current_date
+	current_date="$(date +"%d\/%m\/%Y")"
+	sed -ri "s/(<dstamp>|<date>)/$current_date/g" "$file"
+
+}
+
+#######################################
+# Redact the given file with the included sed script in place for the given file
+# Arguments:
+#   file: The file to redact
+#######################################
+redact_file() {
+	local file="${1}"
+	sed -ri -f "${SCRIPT_DIR}/assign2.sed" "$file"
+}
+
+#######################################
+# Check that the given file can be used within the script. For example, check
+# that the current script/user has read & write permissions for the given file.
+# Arguments:
+# 	file: The file to check
+#######################################
+check_file() {
+	local file="${1}"
+	if ! [[ -r "$file" ]]; then
+		err "Unable to read '${file}', the current user lacks read permissions or the file does not exist!"
+		return 1
+	fi
+
+	if ! [[ -w "$file" ]]; then
+		err "Unable to modify '${file}', the current user lacks write permissions!"
+		return 1
+	fi
+}
+
+#######################################
+# Check all given files and return a single error code if any given check fails.
+# This is done so all errors for the given files are output to the user prior to
+# exiting.
+# Arguments:
+# 	files: an array of files to loop through and validate
+#######################################
+validate_files() {
+	local ret_code=0
+	local files=("${@}")
+	for file in "${files[@]}"; do
+		if ! check_file "$file"; then
+			ret_code=1
+		fi
+	done
+	return "$ret_code"
+}
+
+main() {
+	local files=("${@}")
+	if (("${#files[@]}" == 0)); then
+		usage
+		die "No arguments provided!"
+	fi
+
+	validate_files "${files[@]}" || die "File checks failed, refusing to run script!"
+
+	for file in "${files[@]}"; do
+		redact_file "$file"
+		replace_date_placeholders_in_file "$file"
+	done
+}
+
+main "${@}"

Summer-2024/CS-3424/Assignments/Assignment-2/src/assign2.sed

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+# Redact Driver's License numbers
+s/[a-zA-Z]{2}\s?DL [0-9]{6,8}/DL <redacted>/g
+
+# Redact Credit Card Numbers
+## Visa Cards
+s/4[0-9]{3}-?[0-9]{4}-?[0-9]{4}-?([0-9]{4})/VISA-\1/g
+## Master Cards
+s/5[0-9]{3}-?[0-9]{4}-?[0-9]{4}-?([0-9]{4})/MC-\1/g
+## Discover Cards
+s/6[0-9]{3}-?[0-9]{4}-?[0-9]{4}-?([0-9]{4})/DISC-\1/g
+## Amex Cards (Important that it comes last because it collides inside larger card lengths)
+s/3[47][0-9]{2}-?[0-9]{6}-?[0-9]([0-9]{4})/AMEX-\1/g
+
+# Redact license plates
+s/TX\s?[[:alnum:]]{3}-?([[:digit:]]{4}|[[:alnum:]]{3})/TX <redacted>/g
+
+# Template in the municipality name
+s/(<mname>|<muname>)/City of Brook Haven, Connecticut/g