Spencer/PNG_CC
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2021-10-15 21:17:47 -04:00
parent 6166af2b41
commit 3c6c08429d
5 changed files with 109 additions and 86 deletions
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3
include/crc.h
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@@ -3,4 +3,5 @@ int check_file_header(char *addr);
int check_header_length(unsigned char *addr, long offset);
unsigned long first_idat(unsigned char *addr);
int total_idat(unsigned char *addr);
int change_idat_content(unsigned char *addr, unsigned char *message, int accuracy, unsigned long offset);
void build_png_file(struct PNG_FILE_STRUCT *png_file);;;
int change_idat_content(unsigned char *addr, struct PNG_FILE_STRUCT *png_file, unsigned char *message, int accuracy, unsigned long offset);

9
include/crc_util.h
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@@ -1,4 +1,5 @@
#include <stdio.h>
#include <stdint.h>
// PNG File Struct
struct PNG_START_FILE_STRUCT {
@@ -16,14 +17,18 @@ struct PNG_START_FILE_STRUCT {
};
struct PNG_IDAT_FILE_STRUCT {
unsigned char idat_length[4];
union{
unsigned char idat_length[4];
uint32_t idat_data_length;
};
unsigned char idat_header[4];
unsigned char idat_crc[4];
unsigned char idat_data[];
unsigned char *idat_data;
};
struct PNG_FILE_STRUCT {
struct PNG_START_FILE_STRUCT png_start_data;
struct PNG_IDAT_FILE_STRUCT png_idat_data;
};
extern const long png_signature[8];