CODEWITHSUNDEEP
cprocesschecksum
ATB
ATB

Reputation: 141

Calculate checksum of a file in c

I try to calculate the checksum of the file in c.

I have a file of around 100MB random and I want to calculate the checksum.

I try this code from here: https://stackoverflow.com/a/3464166/14888108

    int CheckSumCalc(char * filename){
    FILE *fp = fopen(filename,"rb");
    unsigned char checksum = 0;
    while (!feof(fp) && !ferror(fp)) {
        checksum ^= fgetc(fp);
    }
    fclose(fp);
    return checksum;
}

but I got a Segmentation fault. in this line "while (!feof(fp) && !ferror(fp))"

Any help will be appreciated.

Upvotes: 1

Views: 1092

Answers (1)

DotNetRussell
DotNetRussell

Reputation: 9857

The issue here is that you are not checking for the return value of fopen. fopen returns NULL if the file cannot be opened. This means that fp is an invalid pointer, causing the segmentation fault.

You should change the code to check for the return value of fopen and handle the error accordingly.

int CheckSumCalc(char * filename){
    FILE *fp = fopen(filename,"rb");
    if(fp == NULL)
    {
        //handle error here
        return -1;
    }
    unsigned char checksum = 0;
    while (!feof(fp) && !ferror(fp)) {
        checksum ^= fgetc(fp);
    }
    fclose(fp);
    return checksum;
}

Upvotes: 1

Related Questions