Forensic program that restores deleted JPEGs (only from FAT memory)

recover.c

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

//Defining new file type as a BYTE to represent 8 bit int
typedef uint8_t BYTE;

int main(int argc, char *argv[1])
{
    //Checks if there is exactly 1 argument
    if (argc != 2) {
        printf("Usage: ./recover image\n");
        return 1;
    }

    //opens the inputed file
    FILE *file = fopen(argv[1], "r");

    if (file == NULL) {
        printf("Critical error, file pointer == NULL");
        return 1;
    }

    //making an array to store 512 bytes
    BYTE buffer[512];

    //reads the first 512 bytes and captures it into the var
    size_t elements_count = fread(buffer, sizeof(BYTE), 512, file);
    int filename_count = 0;

    while (elements_count == 512) {

        //checks if the buffer contains the JPEG signature in the first 4 bytes
        if (
            buffer[0] == 0xff &&
            buffer[1] == 0xd8 &&
            buffer[2] == 0xff &&
            (buffer[3] & 0xf0) == 0xe0) {

                //dynamicically creates a string for file name
                char *filename = malloc(8);

                //in case dynamically allocated memory pointer filename is == NULL
                if (filename == NULL) {
                    printf("Critical error, pointer == NULL");
                    return 1;
                }

                //gives file name a 3 digit ordinal number
                sprintf(filename, "%03i.jpg", filename_count);
                //increases the file name ordinal number after it's created
                filename_count++;

                //opens the newly created .jpg file for writing
                FILE *img = fopen(filename, "w");
                //writes bytes from the buffen into the .jpg file
                fwrite(buffer, sizeof(BYTE), 512, img);
                //closes the .jpg file after it's done writing
                fclose(img);
                //reads next 512 bytes
                elements_count = fread(buffer, sizeof(BYTE), 512, file);

                //checks if the newly loaded bytes contain the start of JPEG
                if (elements_count == 512 &&
                    buffer[0] == 0xff &&
                    buffer[1] == 0xd8 &&
                    buffer[2] == 0xff &&
                    (buffer[3] & 0xf0) == 0xe0) {
                    //closes the current .jpg that's writing to
                    fclose(img);
                    //frees the allocated memory of .jpg
                    free(filename);
                }
                //in case end of file is reached
                else if (elements_count != 512) {
                    //closes the file that we're writing to
                    fclose(img);
                    //frees allocated memory of .jpg
                    free(filename);
                    break;
                }

                //if the newly loaded bytes doesn't contain start of JPEG
                else {
                    //continue writing newly loaded bytes into the file we opened at start
                    while (elements_count == 512) {
                        //breaks the loop if we reach the start of new JPEG
                        if (elements_count == 512 &&
                            buffer[0] == 0xff &&
                            buffer[1] == 0xd8 &&
                            buffer[2] == 0xff &&
                            (buffer[3] & 0xf0) == 0xe0) {
                                break;
                        }
                        //opens our .jpg file for appending
                        img = fopen(filename, "a");
                        //continue writing to our .jpg file
                        fwrite(buffer, sizeof(BYTE), 512, img);
                        //closes .jpg after it's done
                        fclose(img);
                        //reads next 512 bytes
                        elements_count = fread(buffer, sizeof(BYTE), 512, file);
                    }
                }

        }
        //if the buffers doesn't contain the start of JPEG file, read next 512 bytes
        else {
            //reads next 512 bytes
            elements_count = fread(buffer, sizeof(BYTE), 512, file);
        }
    }
    return 0;
}