First test to read and edit the firmware, added defines for the required offsets etc

src/change_key.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <sys/stat.h>
+#include <string.h>
+#include <ctype.h>
+
+#include "../include/change_key.h"
+
+void set_key_value(char* firmware_buffer, int key, int value) {
+    memset(firmware_buffer + key, value, 1);
+}

src/firmware_handling.c

@@ -0,0 +1,49 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <string.h>
+#include <ctype.h>
+
+#include "../include/firmware_handling.h"
+
+fbuffer_t* get_firmware_buffer(char* filename) {
+    
+    fbuffer_t buffer;
+    fbuffer_t* p_fb = &buffer;
+
+    FILE *firmware = fopen(filename, "rb");
+    if(!firmware) {
+        perror("Error while reading in Firmware File.\r\nExiting.");
+        exit(EXIT_FAILURE);
+    }
+
+    struct stat sb;
+    if(stat(filename, &sb) == -1) {
+        perror("Error while reading Firmware metadata.\r\nExiting.");
+        exit(EXIT_FAILURE);
+    }
+    
+    p_fb->size = sb.st_size;
+    p_fb->buffer = malloc(p_fb->size);
+    fread(p_fb->buffer, p_fb->size, 1, firmware);
+
+    /* for testing if the buffer could be read correclty */
+    // printf("buffer size: %d", p_fb->size);
+
+    fclose(firmware);
+
+    return p_fb;
+}
+
+void write_firmware_buffer(char* filename, fbuffer_t* p_fb) {
+
+    FILE *firmware_file = fopen(filename, "wb+");
+    if(!firmware_file) {
+        perror("Error while opening in Firmware File.\r\nExiting.");
+        exit(EXIT_FAILURE);
+    }
+
+    fwrite(p_fb->buffer, p_fb->size, 1, firmware_file);
+
+    fclose(firmware_file);
+}

src/main.c

@@ -0,0 +1,27 @@
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+
+#include "../include/change_key.h"
+#include "../include/firmware_handling.h"
+
+int main (int argc, char *argv[])
+{
+    fbuffer_t* p_fb = get_firmware_buffer(argv[1]);
+
+    set_key_value(p_fb->buffer, KEY8, 0x1E);
+
+    /* for debugging -> print content of buffer to terminal */
+    /*
+    for(int i = 0; i<fb->size; i++){
+        putc(isprint(fb->buffer[i]) ? fb->buffer[i] : '.', stdout);
+    }
+    */
+    
+    char str[50];
+
+    sprintf(str, "new_%s", argv[1]);
+
+    write_firmware_buffer(str, p_fb);
+    return 0;
+}