CS50 Recover runs and recovers all files except the first one - cs50

Question

My question is regarding the Recover assignment as part of CS50.
The code is running (finally) and it produces 50 JPEG files, and most of them are the correct images, except the first file is not an image, therefore it doesn't pass check50.
I have spent a long time trying to figure out what the problem is but I cannot pinpoint it so I am hoping someone might be able to help me out so I can move on.
Thanks in advance! Here is my code:
int main(int argc, char *argv[])
{
// ensure proper usage
if (argc != 2)
{
fprintf(stderr, "Usage: Name of Memory Card File\n");
return 1;
}
char *readfile = argv[1];
// open memory card file
FILE *card_ptr = fopen(readfile, "r");
if (card_ptr == NULL)
{
fprintf(stderr, "Could not open %s.\n", readfile);
return 2;
}
//Declare a buffer to read into
unsigned char *buffer = malloc(512);
//to check if we have already found a file
bool (jpgAlreadyNew) = false;
//declare counter for the number of files found and a file pointer
int filenumber = 0;
FILE *new_jpg_ptr = NULL;
char filename[8];
//read in bytes until reach EOF
while (fread(buffer, 1, 512, card_ptr) != 0x00)
{
//if we reach the header pattern of bytes
if (buffer [0] == 0xff && buffer [1] == 0xd8 && buffer [2] == 0xff && (buffer [3] & 0xf0) == 0xe0)
{
//if there is not already a JPEG file found
if (!jpgAlreadyNew)
{
//change the bool value
(jpgAlreadyNew) = true;
//open new file
sprintf(filename, "%03i.jpg", filenumber);
new_jpg_ptr = fopen(filename, "w");
if (new_jpg_ptr == NULL)
{
return 3;
}
//add to counter of files found
filenumber++;
//write files from buffer into new img file
fwrite(buffer, 1, 512, new_jpg_ptr);
}
//if there is already a JPEG file found
if (jpgAlreadyNew)
{
//close the previous file which would now be complete
fclose(new_jpg_ptr);
//open new file
sprintf(filename, "%03i.jpg", filenumber);
new_jpg_ptr = fopen(filename, "w");
if (new_jpg_ptr == NULL)
{
return 4;
}
//add to counter of files found
filenumber++;
//write files from buffer into new img file
fwrite(buffer, 1, 512, new_jpg_ptr);
}
}
// else if we do not see pattern of header bytes
else
{
//if already found a jpg file which is open then write the bytes to that file
if (jpgAlreadyNew)
{
fwrite(buffer, 1, 512, new_jpg_ptr);
}
//if no file found yet, discard and move on
if (!jpgAlreadyNew)
{
continue;
}
}
}
//free memory
free (buffer);
//close pointers and end program successfully
fclose(card_ptr);
fclose(new_jpg_ptr);
return 0;
}

Answer 1

Let's walk through the program starting with finding the first jpeg signature:
This if (!jpgAlreadyNew) evaluates to true, so it enters the if block; the first thing it does is (jpgAlreadyNew) = true;. When it is done creating the file and writing the first block, what happens next? This if (jpgAlreadyNew). Which also evaluates to true. So it closes 000.jpg and moves along.
Since jpgAlreadyNew is a boolean, an if {} else {} construct would suffice.