Add a9 file submissions

Before didn't write the final IEND chunk

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/Test_All.xml

@@ -0,0 +1,10 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="Test All" type="CMakeRunConfiguration" factoryName="Application" REDIRECT_INPUT="false" ELEVATE="false" USE_EXTERNAL_CONSOLE="false" EMULATE_TERMINAL="false" PASS_PARENT_ENVS_2="true" PROJECT_NAME="Assignment9" TARGET_NAME="Assignment9" CONFIG_NAME="Debug" RUN_TARGET_PROJECT_NAME="Assignment9" RUN_TARGET_NAME="Assignment9">
+    <method v="2">
+      <option name="com.jetbrains.cidr.execution.CidrBuildBeforeRunTaskProvider$BuildBeforeRunTask" enabled="true" />
+      <option name="RunConfigurationTask" enabled="false" run_configuration_name="Test1" run_configuration_type="CMakeRunConfiguration" />
+      <option name="RunConfigurationTask" enabled="true" run_configuration_name="Test3" run_configuration_type="CMakeRunConfiguration" />
+      <option name="RunConfigurationTask" enabled="true" run_configuration_name="Test4" run_configuration_type="CMakeRunConfiguration" />
+    </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

@@ -6,34 +6,45 @@
 #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 %s chunk\n", chunks[i]->type);
+			printf("Found %.4s\n", chunks[i]->type);
+			if (is_idat) {
+				xor_data(chunks[i]);
+			}
 		} else {
-			printf("Found unknown: %s\n", chunks[i]->type);
+			printf("Found unknown: %.4s\n", chunks[i]->type);
 		}
 		printf("Chunk size is:%d\n", chunks[i]->length);
 	}
+	// Write file and free memory
+	write_png_chunks(path, chunks);
+	destroy_chunks(chunks);
+	return EXIT_SUCCESS;
 }

Assignment9/src/png.c

@@ -16,14 +16,14 @@
  * THIS SPECIFICATION IS PROVIDED ”AS IS,” AND COPYRIGHT HOLD-ERS
  * MAKE NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR
  * IMPLIED. BY WAY OF EXAMPLE, BUT NOT LIMITATION, COPYRIGHT
- * HOLDERS MAKE NO REPRESENTATIONS OR WARRANTIES OF MER-CHANTABILITY
+ * HOLDERS MAKE NO REPRESENTATIONS OR WARRANTIES OF MERCHANTABILITY
  * OR FITNESS FOR ANY PARTICULAR PURPOSE OR
  * THAT THE USE OF THE SPECIFICATION WILL NOT INFRINGE ANY
  * THIRD PARTY PATENTS, COPYRIGHTS, TRADEMARKS OR OTHER
  * RIGHTS. COPYRIGHT HOLDERS WILL BEAR NO LIABILITY FOR ANY
  * USE OF THIS SPECIFICATION.
  * The name and trademarks of copyright holders may NOT be used in
- * ad-vertising or publicity pertaining to the specification without specific, written
+ * advertising or publicity pertaining to the specification without specific, written
  * prior permission. Title to copyright in this specification and any associated
  * documentation will at all times remain with copyright holders.
  */
@@ -31,49 +31,30 @@
 #include <arpa/inet.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <zlib.h>
 #include <string.h>
+#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);
-	// Iterate over buffer and convert from network byte order to host byte order
-	//for (int i = 0; i < size; i += 4) {
-	//	uint32_t *ptr = (uint32_t *)(buffer + i);
-	//	*ptr = ntohl(*ptr);
-	//}
 	fclose(fp);
 	return buffer;
 }
@@ -82,19 +63,20 @@ int is_png(char *buffer) {
 	return memcmp(buffer, PNG_SIGNATURE, PNG_SIGNATURE_SIZE) == 0;
 }
 
-png_chunk *get_png_chunk(char *buffer, int offset) {
+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);
@@ -105,42 +87,73 @@ png_chunk **get_png_chunks(char *buffer) {
 	png_chunk **chunks = malloc(sizeof(png_chunk *));
 	if (chunks == NULL) {
 		perror("malloc");
-		exit(1);
+		exit(EXIT_FAILURE);
 	}
-	int offset = PNG_SIGNATURE_SIZE;
+	// Running offset of the buffer
+	unsigned int offset = PNG_SIGNATURE_SIZE;
+	// Index of the current chunk
 	int i = 0;
-	while (1) {
+	while (true) {
 		chunks[i] = get_png_chunk(buffer, offset);
-		offset += chunks[i]->length;
+		// 12 = 4 (length) + 4 (type) + 4 (crc)
+		offset += 12 + chunks[i]->length;
 		if (memcmp(chunks[i]->type, "IEND", 4) == 0) {
 			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;
 }
 
-int is_chunk_valid(png_chunk *chunk) {
-	uint32_t crc = htonl(chunk->crc);
-	//uint32_t calculated_crc = crc32(0, chunk->type, 4);
-	//calculated_crc = crc32(calculated_crc, chunk->data, chunk->length);
-	//return crc == calculated_crc;
-	return 1;
-}
-
-int is_chunk_critical(png_chunk *chunk) {
-	return chunk->type[0] >= 'A' && chunk->type[0] <= 'Z';
-}
-
 int get_number_of_chunks(png_chunk **chunks) {
 	int i = 0;
-	while (chunks[i] != NULL) {
+	while (memcmp(chunks[i]->type, "IEND", 4) != 0) {
 		i++;
 	}
-	return i;
+	// Add one for the IEND chunk
+	return ++i;
+}
+
+void xor_data(png_chunk *chunk) {
+	for (int i = 0; i < chunk->length; i++) {
+		chunk->data[i] ^= KEY;
+	}
+}
+
+void destroy_chunks(png_chunk **chunks) {
+	unsigned int size = get_number_of_chunks(chunks);
+	for (int i = 0; i < size; i++) {
+		free(chunks[i]->data);
+		free(chunks[i]);
+	}
+	free(chunks);
+}
+
+void write_png_chunks(char *path, png_chunk **chunks) {
+	FILE *fp = fopen(path, "wb");
+	if (fp == NULL) {
+		perror("fopen");
+		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);
+	}
+	fclose(fp);
 }

Assignment9/src/png.h

@@ -16,29 +16,30 @@
  * THIS SPECIFICATION IS PROVIDED ”AS IS,” AND COPYRIGHT HOLD-ERS
  * MAKE NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR
  * IMPLIED. BY WAY OF EXAMPLE, BUT NOT LIMITATION, COPYRIGHT
- * HOLDERS MAKE NO REPRESENTATIONS OR WARRANTIES OF MER-CHANTABILITY
+ * HOLDERS MAKE NO REPRESENTATIONS OR WARRANTIES OF MERCHANTABILITY
  * OR FITNESS FOR ANY PARTICULAR PURPOSE OR
  * THAT THE USE OF THE SPECIFICATION WILL NOT INFRINGE ANY
  * THIRD PARTY PATENTS, COPYRIGHTS, TRADEMARKS OR OTHER
  * RIGHTS. COPYRIGHT HOLDERS WILL BEAR NO LIABILITY FOR ANY
  * USE OF THIS SPECIFICATION.
  * The name and trademarks of copyright holders may NOT be used in
- * ad-vertising or publicity pertaining to the specification without specific, written
+ * advertising or publicity pertaining to the specification without specific, written
  * prior permission. Title to copyright in this specification and any associated
  * documentation will at all times remain with copyright holders.
  */
 
 #pragma once
 
+// Needed for uint types
 #include <arpa/inet.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <zlib.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 {
 	uint32_t length;
 	char type[4];
@@ -46,20 +47,17 @@ 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);
 
 // Get PNG chunk
-png_chunk *get_png_chunk(char *buffer, int offset);
+png_chunk *get_png_chunk(char *buffer, unsigned int offset);
 
 // Get all PNG chunks
 png_chunk **get_png_chunks(char *buffer);
@@ -67,8 +65,11 @@ png_chunk **get_png_chunks(char *buffer);
 // Get number of chunks
 int get_number_of_chunks(png_chunk **chunks);
 
-// Check if chunk is critical
-int is_chunk_critical(png_chunk *chunk);
+// XOR chunk with key
+void xor_data(png_chunk *chunk);
 
-// Is chunk valid?
-int is_chunk_valid(png_chunk *chunk);
+// Destroy all chunks
+void destroy_chunks(png_chunk **chunks);
+
+// Write PNG chunks to file
+void write_png_chunks(char *path, png_chunk **chunks);

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."