Use LF
This commit is contained in:
@@ -1,51 +1,51 @@
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#include <stdio.h>
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#include <stdlib.h>
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#include <limits.h>
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#include <string.h>
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#include <stdbool.h>
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#include <unistd.h>
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#include "png.h"
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int main(int argc, char *argv[]) {
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// Error handling
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if (argc != 2) {
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printf("Usage: %s <png file>\n", argv[0]);
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exit(EXIT_FAILURE);
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}
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if (strlen(argv[1]) > PATH_MAX) {
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printf("Path too long\n");
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exit(EXIT_FAILURE);
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}
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// Read file
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char *path = argv[1];
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char *png_buffer = load_file(path);
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if (!is_png(png_buffer)) {
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printf("It's not a PNG file\n");
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exit(EXIT_FAILURE);
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} else {
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printf("It's a PNG file\n");
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}
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png_chunk **chunks = get_png_chunks(png_buffer);
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free(png_buffer);
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// Done with buffer, as chunks are a structured way to access the data
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// Iterate over chunks to display info and "decrypt" IDAT chunks
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int size = get_number_of_chunks(chunks);
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for (int i = 0; i < size; i++) {
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// Check if header is IDAT or IEND
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bool is_idat = memcmp(chunks[i]->type, "IDAT", 4) == 0;
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bool is_iend = memcmp(chunks[i]->type, "IEND", 4) == 0;
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if (is_idat || is_iend) {
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printf("Found %.4s\n", chunks[i]->type);
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if (is_idat) {
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xor_data(chunks[i]);
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}
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} else {
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printf("Found unknown: %.4s\n", chunks[i]->type);
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}
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printf("Chunk size is:%d\n", chunks[i]->length);
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}
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// Write file and free memory
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write_png_chunks(path, chunks);
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destroy_chunks(chunks);
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return EXIT_SUCCESS;
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}
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#include <stdio.h>
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#include <stdlib.h>
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#include <limits.h>
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#include <string.h>
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#include <stdbool.h>
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#include <unistd.h>
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#include "png.h"
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int main(int argc, char *argv[]) {
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// Error handling
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if (argc != 2) {
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printf("Usage: %s <png file>\n", argv[0]);
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exit(EXIT_FAILURE);
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}
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if (strlen(argv[1]) > PATH_MAX) {
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printf("Path too long\n");
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exit(EXIT_FAILURE);
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}
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// Read file
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char *path = argv[1];
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char *png_buffer = load_file(path);
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if (!is_png(png_buffer)) {
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printf("It's not a PNG file\n");
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exit(EXIT_FAILURE);
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} else {
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printf("It's a PNG file\n");
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}
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png_chunk **chunks = get_png_chunks(png_buffer);
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free(png_buffer);
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// Done with buffer, as chunks are a structured way to access the data
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// Iterate over chunks to display info and "decrypt" IDAT chunks
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int size = get_number_of_chunks(chunks);
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for (int i = 0; i < size; i++) {
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// Check if header is IDAT or IEND
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bool is_idat = memcmp(chunks[i]->type, "IDAT", 4) == 0;
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bool is_iend = memcmp(chunks[i]->type, "IEND", 4) == 0;
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if (is_idat || is_iend) {
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printf("Found %.4s\n", chunks[i]->type);
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if (is_idat) {
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xor_data(chunks[i]);
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}
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} else {
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printf("Found unknown: %.4s\n", chunks[i]->type);
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}
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printf("Chunk size is:%d\n", chunks[i]->length);
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}
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// Write file and free memory
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write_png_chunks(path, chunks);
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destroy_chunks(chunks);
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return EXIT_SUCCESS;
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}
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@@ -1,159 +1,159 @@
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/*
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* Copyright Notice
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* ----------------
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* Copyright © 1998, 1999 by: Glenn Randers-Pehrson
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* This specification is a modification of the PNG 1.0 specification. It is being
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* provided by the copyright holder under the provisions of the 1996 MIT copyright and license:
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* 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 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
|
||||
* 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.
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||||
*/
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||||
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#include <arpa/inet.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdbool.h>
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#include "png.h"
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FILE *get_file(char *path) {
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FILE *fp = fopen(path, "rb");
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if (fp == NULL) {
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perror("fopen");
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exit(EXIT_FAILURE);
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}
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return fp;
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}
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char *load_file(char *path) {
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FILE *fp = get_file(path);
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fseek(fp, 0, SEEK_END);
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long size = ftell(fp);
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rewind(fp);
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char *buffer = malloc(size);
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if (buffer == NULL) {
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perror("malloc");
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exit(EXIT_FAILURE);
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}
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fread(buffer, 1, size, fp);
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fclose(fp);
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return buffer;
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}
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int is_png(char *buffer) {
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return memcmp(buffer, PNG_SIGNATURE, PNG_SIGNATURE_SIZE) == 0;
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}
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png_chunk *get_png_chunk(char *buffer, unsigned int offset) {
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png_chunk *chunk = malloc(sizeof(png_chunk));
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if (chunk == NULL) {
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perror("malloc");
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exit(EXIT_FAILURE);
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}
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memcpy(&chunk->length, buffer + offset + 0, 4);
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// Convert length to host byte order because PNG lengths is in network byte order/Big Endian
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chunk->length = ntohl(chunk->length);
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memcpy(&chunk->type, buffer + offset + 4, 4);
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chunk->data = malloc(chunk->length);
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if (chunk->data == NULL) {
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perror("malloc");
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exit(EXIT_FAILURE);
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}
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memcpy(chunk->data, buffer + offset + 8, chunk->length);
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memcpy(&chunk->crc, buffer + offset + 8 + chunk->length, 4);
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return chunk;
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}
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png_chunk **get_png_chunks(char *buffer) {
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png_chunk **chunks = malloc(sizeof(png_chunk *));
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if (chunks == NULL) {
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perror("malloc");
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exit(EXIT_FAILURE);
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}
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// Running offset of the buffer
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unsigned int offset = PNG_SIGNATURE_SIZE;
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// Index of the current chunk
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int i = 0;
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while (true) {
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chunks[i] = get_png_chunk(buffer, offset);
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// 12 = 4 (length) + 4 (type) + 4 (crc)
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offset += 12 + chunks[i]->length;
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if (memcmp(chunks[i]->type, "IEND", 4) == 0) {
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break;
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}
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i++;
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// Add one because realloc is 1-indexed when multiplying by sizeof
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png_chunk **err_check = realloc(chunks, sizeof(png_chunk *) * (i + 1));
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if (err_check == NULL) {
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destroy_chunks(chunks);
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perror("realloc");
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exit(EXIT_FAILURE);
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}
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chunks = err_check;
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}
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return chunks;
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}
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int get_number_of_chunks(png_chunk **chunks) {
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int i = 0;
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while (memcmp(chunks[i]->type, "IEND", 4) != 0) {
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i++;
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}
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// Add one for the IEND chunk
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return ++i;
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}
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void xor_data(png_chunk *chunk) {
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for (int i = 0; i < chunk->length; i++) {
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chunk->data[i] ^= KEY;
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}
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}
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void destroy_chunks(png_chunk **chunks) {
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unsigned int size = get_number_of_chunks(chunks);
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for (int i = 0; i < size; i++) {
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free(chunks[i]->data);
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free(chunks[i]);
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}
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free(chunks);
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}
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void write_png_chunks(char *path, png_chunk **chunks) {
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FILE *fp = fopen(path, "wb");
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if (fp == NULL) {
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perror("fopen");
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exit(EXIT_FAILURE);
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}
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fwrite(PNG_SIGNATURE, PNG_SIGNATURE_SIZE, 1, fp);
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unsigned int size = get_number_of_chunks(chunks);
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for (int i = 0; i < size; i++) {
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// Convert length to network byte order for writing
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chunks[i]->length = htonl(chunks[i]->length);
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fwrite(&chunks[i]->length, 4, 1, fp);
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fwrite(chunks[i]->type, 4, 1, fp);
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// Convert back so we can accurately use it to write the length of the data
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chunks[i]->length = ntohl(chunks[i]->length);
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fwrite(chunks[i]->data, chunks[i]->length, 1, fp);
|
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fwrite(&chunks[i]->crc, 4, 1, fp);
|
||||
}
|
||||
fclose(fp);
|
||||
}
|
||||
/*
|
||||
* 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 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
|
||||
* 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.
|
||||
*/
|
||||
|
||||
#include <arpa/inet.h>
|
||||
#include <stdio.h>
|
||||
#include <stdlib.h>
|
||||
#include <string.h>
|
||||
#include <stdbool.h>
|
||||
#include "png.h"
|
||||
|
||||
FILE *get_file(char *path) {
|
||||
FILE *fp = fopen(path, "rb");
|
||||
if (fp == NULL) {
|
||||
perror("fopen");
|
||||
exit(EXIT_FAILURE);
|
||||
}
|
||||
return fp;
|
||||
}
|
||||
|
||||
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(EXIT_FAILURE);
|
||||
}
|
||||
fread(buffer, 1, size, fp);
|
||||
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, unsigned int offset) {
|
||||
png_chunk *chunk = malloc(sizeof(png_chunk));
|
||||
if (chunk == NULL) {
|
||||
perror("malloc");
|
||||
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(EXIT_FAILURE);
|
||||
}
|
||||
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(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);
|
||||
// 12 = 4 (length) + 4 (type) + 4 (crc)
|
||||
offset += 12 + chunks[i]->length;
|
||||
if (memcmp(chunks[i]->type, "IEND", 4) == 0) {
|
||||
break;
|
||||
}
|
||||
i++;
|
||||
// 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(EXIT_FAILURE);
|
||||
}
|
||||
chunks = err_check;
|
||||
}
|
||||
return chunks;
|
||||
}
|
||||
|
||||
int get_number_of_chunks(png_chunk **chunks) {
|
||||
int i = 0;
|
||||
while (memcmp(chunks[i]->type, "IEND", 4) != 0) {
|
||||
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);
|
||||
}
|
||||
|
||||
@@ -1,75 +1,75 @@
|
||||
/*
|
||||
* 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 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
|
||||
* 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>
|
||||
|
||||
// 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];
|
||||
char *data;
|
||||
uint32_t crc;
|
||||
} png_chunk;
|
||||
|
||||
// Get FILE from path
|
||||
int get_fd(char *path);
|
||||
|
||||
// Store file in heap memory
|
||||
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, unsigned 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);
|
||||
|
||||
// XOR chunk with key
|
||||
void xor_data(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);
|
||||
/*
|
||||
* 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 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
|
||||
* 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>
|
||||
|
||||
// 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];
|
||||
char *data;
|
||||
uint32_t crc;
|
||||
} png_chunk;
|
||||
|
||||
// Get FILE from path
|
||||
int get_fd(char *path);
|
||||
|
||||
// Store file in heap memory
|
||||
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, unsigned 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);
|
||||
|
||||
// XOR chunk with key
|
||||
void xor_data(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);
|
||||
|
||||
Reference in New Issue
Block a user