recover compiles but has segmentation fault when running it with ./recover card.raw, could anyone take a look

Question

#include <stdio.h>
#include <stdlib.h>
#include <cs50.h>

int main(int argc, char *argv[])
{
    //this counter to keep track of how many jpegs found so far
    int counter = 0;

    //allocate a place with 8 characters for inputting the filename 
    char filename[8];
    //replace argv[1] with card
    char *card = argv[1];        
    //create a pointer called img 
    FILE *img;
    
    

    //check that if user did not give any inputs, to return
    if(argc !=2)
    {
        printf("Usage: ./recover image \n");
        return 1;
    }

    //open up file and read the file
    FILE *file = fopen(card,"r");
    if(!file)
    {
        printf("Could not open card\n");
        return 1;
    }

    //declare a buffer
    unsigned char buffer[512];

    //iterate over contents of the file till the end of the file
    while (fread(buffer, 512, 1, file) == 512)
    {
        //if first 4 bys of the array are as per the below
        if(buffer[0] == 0xff && buffer[1] == 0xd8 && buffer[2] == 0xff && (buffer[3] & 0xf0) == 0xe0)
        {
            //if this is the 1st JPEG that someone is working on
            if(counter == 0)
            {
                //create a new jpeg file
                sprintf(filename, "%03i.jpg", counter);
                counter++;


                //open this new jpeg file
                img = fopen(filename, "w");

                //start writing to this new jpeg, need a number that is based on how many times before the next "start" of the jpeg file
                fwrite(buffer, 512, 1, img);
            }
            
            //if this is not the 1st JPEG
            if(counter > 0)
            {
                //close the file at location img that was being written to 
                fclose(img);
                
                //create a new jpeg file
                sprintf(filename, "%03i.jpg", counter);
                counter++;


                //open this new jpeg file
                img = fopen(filename, "w");

                //start writing to this new jpeg, need a number that is based on how many times before the next "start" of the jpeg file
                fwrite(buffer, 512, 1, img);
                
            }
            
            
        }
        
        //to continue writing if there was a JPEG found before previously 
        else if (counter > 0 && fread(buffer, 512, 1, file) == 512)
        {
            //continue writing to this new jpeg
            fwrite(buffer, 512, 1, img);
        }
        
        //in case the first 512 bytes are not a jpeg, to ignore and continue with next set of 512 bytes 
        else
        {
            continue;
        }
    }


    //close file
    fclose(img);
    fclose(file);


}

Answer 1

change while (fread(buffer, 512, 1, file) == 512) to

size_t rd = 0;
while ((rd=fread(buffer, 1, 512, file))) {
   // now you have read rd bytes
}