Add a9 file submissions

Assignment9/.idea/runConfigurations/All_CTest.xml

@@ -0,0 +1,8 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="All CTest" type="CTestRunConfiguration" factoryName="CTestRun" PROGRAM_PARAMS="--extra-verbose" REDIRECT_INPUT="false" ELEVATE="false" USE_EXTERNAL_CONSOLE="false" EMULATE_TERMINAL="false" WORKING_DIR="file://$CMakeCurrentLocalGenerationDir$" PASS_PARENT_ENVS_2="true" CONFIG_NAME="Debug" RUN_PATH="$CTestCurrentExecutableName$" EXPLICIT_BUILD_TARGET_NAME="all" TEST_MODE="PATTERN">
+    <method v="2">
+      <option name="com.jetbrains.cidr.execution.CidrBuildBeforeRunTaskProvider$BuildBeforeRunTask" enabled="true" />
+      <option name="BeforeTestRunTask" enabled="true" />
+    </method>
+  </configuration>
+</component>

Assignment9/.idea/runConfigurations/images.xml

@@ -0,0 +1,8 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="images" type="CTestRunConfiguration" factoryName="CTestRun" PROGRAM_PARAMS="--extra-verbose" REDIRECT_INPUT="false" ELEVATE="false" USE_EXTERNAL_CONSOLE="false" EMULATE_TERMINAL="false" WORKING_DIR="file://$CMakeCurrentLocalGenerationDir$" PASS_PARENT_ENVS_2="true" CONFIG_NAME="Debug" RUN_PATH="$CTestCurrentExecutableName$" EXPLICIT_BUILD_TARGET_NAME="all" TEST_METHOD="images" TEST_MODE="SUITE_TEST">
+    <method v="2">
+      <option name="com.jetbrains.cidr.execution.CidrBuildBeforeRunTaskProvider$BuildBeforeRunTask" enabled="true" />
+      <option name="BeforeTestRunTask" enabled="true" />
+    </method>
+  </configuration>
+</component>

Assignment9/.idea/runConfigurations/output.xml

@@ -0,0 +1,8 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="output" type="CTestRunConfiguration" factoryName="CTestRun" PROGRAM_PARAMS="--extra-verbose" REDIRECT_INPUT="false" ELEVATE="false" USE_EXTERNAL_CONSOLE="false" EMULATE_TERMINAL="false" WORKING_DIR="file://$CMakeCurrentLocalGenerationDir$" PASS_PARENT_ENVS_2="true" CONFIG_NAME="Debug" RUN_PATH="$CTestCurrentExecutableName$" EXPLICIT_BUILD_TARGET_NAME="all" TEST_METHOD="output" TEST_MODE="SUITE_TEST">
+    <method v="2">
+      <option name="com.jetbrains.cidr.execution.CidrBuildBeforeRunTaskProvider$BuildBeforeRunTask" enabled="true" />
+      <option name="BeforeTestRunTask" enabled="true" />
+    </method>
+  </configuration>
+</component>

Assignment9/CMakeLists.txt

@@ -4,3 +4,7 @@ set(CMAKE_C_STANDARD 99)
 add_executable(Assignment9 src/main.c
         src/png.c
         src/png.h)
+
+enable_testing()
+add_test(NAME output COMMAND test_text.sh WORKING_DIRECTORY ../tests)
+add_test(NAME images COMMAND test_images.sh WORKING_DIRECTORY ../tests)

Assignment9/src/main.c

@@ -3,36 +3,38 @@
 #include <limits.h>
 #include <string.h>
 #include <stdbool.h>
-#include <unistd.h>
 #include "png.h"
 
 int main(int argc, char *argv[]) {
+	// Error handling
 	if (argc != 2) {
 		printf("Usage: %s <png file>\n", argv[0]);
-		exit(1);
+		exit(EXIT_FAILURE);
 	}
 	if (strlen(argv[1]) > PATH_MAX) {
 		printf("Path too long\n");
-		exit(1);
+		exit(EXIT_FAILURE);
 	}
+	// Read file
 	char *path = argv[1];
-
-	char* png_buffer = load_file(get_fd(path));
+	char *png_buffer = load_file(path);
 	if (!is_png(png_buffer)) {
 		printf("It's not a PNG file\n");
-		exit(1);
+		exit(EXIT_FAILURE);
 	} else {
 		printf("It's a PNG file\n");
 	}
 	png_chunk **chunks = get_png_chunks(png_buffer);
 	free(png_buffer);
+	// Done with buffer, as chunks are a structured way to access the data
+	// Iterate over chunks to display info and "decrypt" IDAT chunks
 	int size = get_number_of_chunks(chunks);
 	for (int i = 0; i < size; i++) {
 		// Check if header is IDAT or IEND
 		bool is_idat = memcmp(chunks[i]->type, "IDAT", 4) == 0;
 		bool is_iend = memcmp(chunks[i]->type, "IEND", 4) == 0;
 		if (is_idat || is_iend) {
-			printf("Found %.4s chunk\n", chunks[i]->type);
+			printf("Found %.4s\n", chunks[i]->type);
 			if (is_idat) {
 				xor_data(chunks[i]);
 			}
@@ -41,11 +43,7 @@ int main(int argc, char *argv[]) {
 		}
 		printf("Chunk size is:%d\n", chunks[i]->length);
 	}
-	// Uncomment to not overwrite original file
-	//char new_path[PATH_MAX];
-	//getcwd(new_path, sizeof(new_path));
-	//strcat(new_path, "/output.png");
-	//write_png_chunks(new_path, chunks);
+	// Write file and free memory
 	write_png_chunks(path, chunks);
 	destroy_chunks(chunks);
 	return EXIT_SUCCESS;

Assignment9/src/png.c

@@ -35,38 +35,24 @@
 #include <stdbool.h>
 #include "png.h"
 
-int get_fd(char *path) {
+FILE *get_file(char *path) {
 	FILE *fp = fopen(path, "rb");
 	if (fp == NULL) {
 		perror("fopen");
-		exit(1);
-	}
-	int fd = fileno(fp);
-	if (fd == -1) {
-		perror("fileno");
-		exit(1);
-	}
-	return fd;
-}
-
-FILE *get_fp(int fd) {
-	FILE *fp = fdopen(fd, "rb");
-	if (fp == NULL) {
-		perror("fdopen");
-		exit(1);
+		exit(EXIT_FAILURE);
 	}
 	return fp;
 }
 
-char *load_file(int fd) {
-	FILE *fp = get_fp(fd);
+char *load_file(char *path) {
+	FILE *fp = get_file(path);
 	fseek(fp, 0, SEEK_END);
 	long size = ftell(fp);
 	rewind(fp);
 	char *buffer = malloc(size);
 	if (buffer == NULL) {
 		perror("malloc");
-		exit(1);
+		exit(EXIT_FAILURE);
 	}
 	fread(buffer, 1, size, fp);
 	fclose(fp);
@@ -81,15 +67,16 @@ png_chunk *get_png_chunk(char *buffer, unsigned int offset) {
 	png_chunk *chunk = malloc(sizeof(png_chunk));
 	if (chunk == NULL) {
 		perror("malloc");
-		exit(1);
+		exit(EXIT_FAILURE);
 	}
 	memcpy(&chunk->length, buffer + offset + 0, 4);
+	// Convert length to host byte order because PNG lengths is in network byte order/Big Endian
 	chunk->length = ntohl(chunk->length);
 	memcpy(&chunk->type, buffer + offset + 4, 4);
 	chunk->data = malloc(chunk->length);
 	if (chunk->data == NULL) {
 		perror("malloc");
-		exit(1);
+		exit(EXIT_FAILURE);
 	}
 	memcpy(chunk->data, buffer + offset + 8, chunk->length);
 	memcpy(&chunk->crc, buffer + offset + 8 + chunk->length, 4);
@@ -100,9 +87,11 @@ png_chunk **get_png_chunks(char *buffer) {
 	png_chunk **chunks = malloc(sizeof(png_chunk *));
 	if (chunks == NULL) {
 		perror("malloc");
-		exit(1);
+		exit(EXIT_FAILURE);
 	}
+	// Running offset of the buffer
 	unsigned int offset = PNG_SIGNATURE_SIZE;
+	// Index of the current chunk
 	int i = 0;
 	while (true) {
 		chunks[i] = get_png_chunk(buffer, offset);
@@ -112,11 +101,14 @@ png_chunk **get_png_chunks(char *buffer) {
 			break;
 		}
 		i++;
-		chunks = realloc(chunks, sizeof(png_chunk *) * (i + 1));
-		if (chunks == NULL) {
+		// Add one because realloc is 1-indexed when multiplying by sizeof
+		png_chunk **err_check = realloc(chunks, sizeof(png_chunk *) * (i + 1));
+		if (err_check == NULL) {
+			destroy_chunks(chunks);
 			perror("realloc");
-			exit(1);
+			exit(EXIT_FAILURE);
 		}
+		chunks = err_check;
 	}
 	return chunks;
 }
@@ -126,6 +118,7 @@ int get_number_of_chunks(png_chunk **chunks) {
 	while (memcmp(chunks[i]->type, "IEND", 4) != 0) {
 		i++;
 	}
+	// Add one for the IEND chunk
 	return ++i;
 }
 
@@ -135,8 +128,6 @@ void xor_data(png_chunk *chunk) {
 	}
 }
 
-
-
 void destroy_chunks(png_chunk **chunks) {
 	unsigned int size = get_number_of_chunks(chunks);
 	for (int i = 0; i < size; i++) {
@@ -150,14 +141,16 @@ void write_png_chunks(char *path, png_chunk **chunks) {
 	FILE *fp = fopen(path, "wb");
 	if (fp == NULL) {
 		perror("fopen");
-		exit(1);
+		exit(EXIT_FAILURE);
 	}
 	fwrite(PNG_SIGNATURE, PNG_SIGNATURE_SIZE, 1, fp);
 	unsigned int size = get_number_of_chunks(chunks);
 	for (int i = 0; i < size; i++) {
+		// Convert length to network byte order for writing
 		chunks[i]->length = htonl(chunks[i]->length);
 		fwrite(&chunks[i]->length, 4, 1, fp);
 		fwrite(chunks[i]->type, 4, 1, fp);
+		// Convert back so we can accurately use it to write the length of the data
 		chunks[i]->length = ntohl(chunks[i]->length);
 		fwrite(chunks[i]->data, chunks[i]->length, 1, fp);
 		fwrite(&chunks[i]->crc, 4, 1, fp);

Assignment9/src/png.h

@@ -30,15 +30,14 @@
 
 #pragma once
 
+// Needed for uint types
 #include <arpa/inet.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
 
 // http://www.libpng.org/pub/png/spec/1.2/PNG-Rationale.html#R.PNG-file-signature
 #define PNG_SIGNATURE "\211PNG\r\n\032\n"
 #define PNG_SIGNATURE_SIZE 8
 
+// The key used to "encrypt/decrypt" the PNG chunks
 #define KEY 42
 
 typedef struct png_chunk {
@@ -48,14 +47,11 @@ typedef struct png_chunk {
 	uint32_t crc;
 } png_chunk;
 
-// Get file descriptor from path
+// Get FILE from path
 int get_fd(char *path);
 
-// Get FILE* from file descriptor
-FILE *get_fp(int fd);
-
 // Store file in heap memory
-char *load_file(int fd);
+char *load_file(char *path);
 
 // Check if file is a PNG
 int is_png(char *buffer);

Assignment9/tests/test_images.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+
+# Executable path
+EXECUTABLE=../build/Assignment9
+
+
+test_reverse() {
+    start=$(date +%s)
+    cp "$1" in.png
+    cp in.png out.png
+    $EXECUTABLE out.png > /dev/null
+    $EXECUTABLE out.png > /dev/null
+    diff in.png out.png
+    rm in.png out.png
+    end=$(date +%s)
+    echo "Test $1 took $((end - start)) seconds"
+}
+
+test_reverse test1.png
+# test_reverse test2.png # This png is invalid, so it will fail
+test_reverse test3.png
+test_reverse test4.png

Assignment9/tests/test_text.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+
+EXECUTABLE=../build/Assignment9
+
+# Test the text output
+$EXECUTABLE test1.png | diff output1.txt -
+$EXECUTABLE test2.png | diff output2.txt -
+$EXECUTABLE test3.png | diff output3.txt -
+$EXECUTABLE test4.png | diff output4.txt -
+
+
+# Reverse the images
+$EXECUTABLE test1.png > /dev/null
+$EXECUTABLE test2.png > /dev/null
+$EXECUTABLE test3.png > /dev/null
+$EXECUTABLE test4.png > /dev/null
+
+echo "If there is no diff output, then the test passed."