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Add an implementation, still just trying to read

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Isaac Shoebottom 2023-12-04 18:39:21 -04:00
parent 18669ebf1c
commit 3aad46748a
10 changed files with 363 additions and 2 deletions
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7
Assignment9/.idea/runConfigurations/Assignment9.xml Normal file
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<component name="ProjectRunConfigurationManager">
<configuration default="false" name="Assignment9" 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" />
</method>
</configuration>
</component>

7
Assignment9/.idea/runConfigurations/Test1.xml Normal file
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<component name="ProjectRunConfigurationManager">
<configuration default="false" name="Test1" type="CMakeRunConfiguration" factoryName="Application" PROGRAM_PARAMS="../tests/test1.png" 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" />
</method>
</configuration>
</component>

7
Assignment9/.idea/runConfigurations/Test2.xml Normal file
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<component name="ProjectRunConfigurationManager">
<configuration default="false" name="Test2" type="CMakeRunConfiguration" factoryName="Application" PROGRAM_PARAMS="../tests/test2.png" 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" />
</method>
</configuration>
</component>

7
Assignment9/.idea/runConfigurations/Test3.xml Normal file
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<component name="ProjectRunConfigurationManager">
<configuration default="false" name="Test3" type="CMakeRunConfiguration" factoryName="Application" PROGRAM_PARAMS="../tests/test3.png" 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" />
</method>
</configuration>
</component>

7
Assignment9/.idea/runConfigurations/Test4.xml Normal file
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<component name="ProjectRunConfigurationManager">
<configuration default="false" name="Test4" type="CMakeRunConfiguration" factoryName="Application" PROGRAM_PARAMS="../tests/test4.png" 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" />
</method>
</configuration>
</component>

4
Assignment9/CMakeLists.txt
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cmake_minimum_required(VERSION 3.20)
project(Assignment9 C)
set(CMAKE_C_STANDARD 99)
add_executable(Assignment9 src/main.c)
add_executable(Assignment9 src/main.c
src/png.c
src/png.h)

68
Assignment9/documentation/EndiannessAndHomework9.c Normal file
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#include <stdio.h>
#include <stdlib.h>
#include <arpa/inet.h>
// FILE format is: 'header', then 2023 skipped bytes, then the number of interest
#define OURINT 1426915328
#define OFFSETTODATA 2023
int writeToFile(){
FILE* fp = fopen("toReadLater.txt","w+");
char c = 'h';
fwrite(&c, sizeof(char), 1, fp);
c = 'e';
fwrite(&c, sizeof(char), 1, fp);
c = 'a';
fwrite(&c, sizeof(char), 1, fp);
c = 'd';
fwrite(&c, sizeof(char), 1, fp);
c = 'e';
fwrite(&c, sizeof(char), 1, fp);
c = 'r';
fwrite(&c, sizeof(char), 1, fp);
unsigned int buf = OFFSETTODATA;
fwrite(&buf, sizeof(int), 1, fp);
fseek(fp, OFFSETTODATA, SEEK_CUR);
buf = OURINT;
fwrite(&buf, sizeof(int), 1, fp);
fclose(fp);
}
int readFromFile(){
FILE *fp = fopen("toReadLater.txt", "r+");
fseek(fp, 6 , SEEK_SET);
int skip = 0;
fread(&skip, sizeof(int), 1, fp);
// NOTE, in HW, the size of the section is a value in
// Big-Endian format, it will actually need conversion
fseek(fp, skip, SEEK_CUR);
unsigned int qBe = 0;
unsigned int qLe = 0;
int i;
unsigned char *c = (char *)(&qBe);
unsigned char *d = (char *)(&qLe);
for (i = 0; i < 4; i++)
{
c[i] = getc(fp);
printf("Byte %i: %i %x\n",i, c[i], c[i]);
}
for (i = 0; i < 4; i++)
{
d[4-i-1] = c[i];
}
printf("Translated using swapping the bytes order: %i\n", qLe);
qLe = ntohl(qBe);
printf("Translated using ntohl: %i\n", qLe);
fclose(fp);
}
int main (int argc, char** argv){
unsigned int wantToRead;
writeToFile();
printf("Sizeof (int) is:%li\n", sizeof(unsigned int));
readFromFile();
return 0;
}

38
Assignment9/src/main.c
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#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <string.h>
#include <stdbool.h>
#include "png.h"
int main(int argc, char *argv[]) {
return 0;
if (argc != 2) {
printf("Usage: %s <png file>\n", argv[0]);
exit(1);
}
if (strlen(argv[1]) > PATH_MAX) {
printf("Path too long\n");
exit(1);
}
char *path = argv[1];
char* png_buffer = load_file(get_fd(path));
if (!is_png(png_buffer)) {
printf("It's not a PNG file\n");
exit(1);
} else {
printf("It's a PNG file\n");
}
png_chunk **chunks = get_png_chunks(png_buffer);
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);
} else {
printf("Found unknown: %s\n", chunks[i]->type);
}
printf("Chunk size is:%d\n", chunks[i]->length);
}
}

146
Assignment9/src/png.c Normal file
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/*
* Copyright Notice
* ----------------
* Copyright © 1998, 1999 by: Glenn Randers-Pehrson
* This specification is a modification of the PNG 1.0 specification. It is being
* provided by the copyright holder under the provisions of the 1996 MIT copyright and license:
* Copyright © 1996 by: Massachusetts Institute of Technology (MIT)
* This W3C specification is being provided by the copyright holders under
* the following license. By obtaining, using and/or copying this specification, you
* agree that you have read, understood, and will comply with the following terms
* and conditions:
* Permission to use, copy, and distribute this specification for any purpose
* and without fee or royalty is hereby granted, provided that the full text of
* this NOTICE appears on ALL copies of the specification or portions thereof,
* including modifications, that you make.
* 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
* 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
* prior permission. Title to copyright in this specification and any associated
* documentation will at all times remain with copyright holders.
*/
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <zlib.h>
#include <string.h>
#include "png.h"
int get_fd(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);
}
return fp;
}
char *load_file(int fd) {
FILE *fp = get_fp(fd);
fseek(fp, 0, SEEK_END);
long size = ftell(fp);
rewind(fp);
char *buffer = malloc(size);
if (buffer == NULL) {
perror("malloc");
exit(1);
}
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;
}
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 *chunk = malloc(sizeof(png_chunk));
if (chunk == NULL) {
perror("malloc");
exit(1);
}
memcpy(&chunk->length, buffer + offset + 0, 4);
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);
}
memcpy(chunk->data, buffer + offset + 8, chunk->length);
memcpy(&chunk->crc, buffer + offset + 8 + chunk->length, 4);
return chunk;
}
png_chunk **get_png_chunks(char *buffer) {
png_chunk **chunks = malloc(sizeof(png_chunk *));
if (chunks == NULL) {
perror("malloc");
exit(1);
}
int offset = PNG_SIGNATURE_SIZE;
int i = 0;
while (1) {
chunks[i] = get_png_chunk(buffer, offset);
offset += chunks[i]->length;
if (memcmp(chunks[i]->type, "IEND", 4) == 0) {
break;
}
i++;
chunks = realloc(chunks, sizeof(png_chunk *) * (i + 1));
if (chunks == NULL) {
perror("realloc");
exit(1);
}
}
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) {
i++;
}
return i;
}

74
Assignment9/src/png.h Normal file
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/*
* Copyright Notice
* ----------------
* Copyright © 1998, 1999 by: Glenn Randers-Pehrson
* This specification is a modification of the PNG 1.0 specification. It is being
* provided by the copyright holder under the provisions of the 1996 MIT copyright and license:
* Copyright © 1996 by: Massachusetts Institute of Technology (MIT)
* This W3C specification is being provided by the copyright holders under
* the following license. By obtaining, using and/or copying this specification, you
* agree that you have read, understood, and will comply with the following terms
* and conditions:
* Permission to use, copy, and distribute this specification for any purpose
* and without fee or royalty is hereby granted, provided that the full text of
* this NOTICE appears on ALL copies of the specification or portions thereof,
* including modifications, that you make.
* 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
* 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
* prior permission. Title to copyright in this specification and any associated
* documentation will at all times remain with copyright holders.
*/
#pragma once
#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
typedef struct png_chunk {
uint32_t length;
char type[4];
char *data;
uint32_t crc;
} png_chunk;
// Get file descriptor 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);
// Check if file is a PNG
int is_png(char *buffer);
// Get PNG chunk
png_chunk *get_png_chunk(char *buffer, int offset);
// Get all PNG chunks
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);
// Is chunk valid?
int is_chunk_valid(png_chunk *chunk);