Pset 4 Recover - EM : \ expected an exit code of 0, not output of "image 16990724\n"

Question

I can retrieve all 50 photos, it works as far as I can see, but check50 won't let me pass. It says I don't recover any file correctly, it expects an exit code of 0 and my code doesn't produce that. I use a separate function to find the beginning of the first image, two file pointers are opened and closed. Then I open file pointers to write the first chunk of 512 bytes. I close the file pointers and reopen them for the rest. I use a while-loop and I open and close file pointers each time the code runs through the loop. So I guess, too many file pointers. But I have worked hard on this and I just don't know what else to do.

typedef uint8_t  BYTE;

int findFirstImage(char* fotoFile);

int main(int argc, char *argv[]) {
    if(argc != 2) {
        fprintf(stderr, "Please enter one single file name");
        return 1;
    }

    char *fotoFile = argv[1];

    // open the file, read until you find the beginning of a sentence    
    int image = findFirstImage(fotoFile);
    printf("image %i\n", image);

    BYTE writeImage[512] = {0};
    FILE* secondinptr = fopen(fotoFile, "r"); 
    if (secondinptr == NULL)
    {
        fprintf(stderr, "Could not open %s.\n", fotoFile);
        return 2;
    }


    fseek(secondinptr, (image - 4), SEEK_CUR);  
    fread(writeImage, 1, 512, secondinptr);
    fclose(secondinptr);

    // create name of file that will be written into
    char name[7];
    int tekst = 0;    
    sprintf(name, "%03i.jpg", tekst);

    //copy contents from beginning to end of first sentence in f
    FILE* outptr = fopen(name, "w"); 
    if (outptr == NULL)
    {
        fclose(secondinptr);
        fprintf(stderr, "Could not create %s.\n", name);
        return 3;
    }    

    fwrite(writeImage, 1, 512, outptr);        
    fclose(outptr);

    FILE* thirdinptr = fopen(fotoFile, "r");
    if (thirdinptr == NULL)
    {
        fprintf(stderr, "Could not open %s.\n", fotoFile);
        return 2;
    }

    int counter = 512;

    while(!feof(thirdinptr)) {    
        BYTE writeImage1[512] = {0};
        // set pointer at next chunk of code
        fseek(thirdinptr, (image - 4 + counter), SEEK_SET);   
        fread(writeImage1, 1, 512, thirdinptr);        

        if(writeImage1[0] == 0xFF && writeImage1[1] == 0xd8 && writeImage1[2] == 
            0xFF) {
            for (int b = 224; b < 240; b++) {
                if (writeImage1[3] == b) {             
                    tekst++;
                    sprintf(name, "%03i.jpg", tekst);
                    FILE* thirdoutptr = fopen(name, "w");  
                    if (thirdoutptr == NULL)
                    {
                        fclose(thirdinptr);
                        fprintf(stderr, "Could not create %s.\n", name);
                        return 3;
                    }                     
                    fwrite(writeImage1, 1, 512, thirdoutptr);
                    fclose(thirdoutptr);
                }
            }
        } else {
            FILE* secondoutptr = fopen(name, "a");
            if (secondoutptr == NULL)
            {
                fclose(thirdinptr);
                fprintf(stderr, "Could not create %s.\n", name);
                return 3;
            }            
            fwrite(writeImage1, 1, 512, secondoutptr);
            fclose(secondoutptr);
        }
        counter += 512;
    }

    fclose(thirdinptr); 
}    

// open the file, read until you find the beginning of a sentence 
int findFirstImage(char* fotoFile) { 
    FILE* inptr = fopen(fotoFile, "r");
    if (inptr == NULL)
    {
        fprintf(stderr, "Could not open %s.\n", fotoFile);
        return 2;
    }

    BYTE buffer[512] = {};
    while(!feof(inptr)) {
        fread(buffer, sizeof(BYTE), 4, inptr);
        if (buffer[0] == 0xFF && buffer[1] == 0xd8 && buffer[2] == 0xFF) {
            for (int b = 224; b < 240; b++) {
                if (buffer[3] == b) {
                    int firstImage = ftell(inptr);
                    return firstImage;
                }
            }    
        }
    }
    fclose(inptr);    
    return 1;
}

Answer 1

check50 is detecting output from printf("image %i\n", image);, which is causing the failure. The only screen output that is allowable is the error messages produced for bad "usage" or a file-not-found. You need to remove or at least comment that line. There could be other problems in the program, you'll have to see what check50 says.