I'm losing binary data when using fseek in c

I wrote a function that is responsible for moving to a binary file and editing its bytes

int replace(FILE *binaryFile, long offset, unsigned char *replaced, int length) {
    if (binaryFile != NULL) {
        for (int i = 0; i < length; i++) {
            fseek(binaryFile, offset + i, SEEK_SET);
            fwrite(&replaced[i], sizeof(*replaced), 1, binaryFile);
        }
        fclose(binaryFile);
        return 0;
    }
    else return -1;
}

When I use this function, I encounter a strange problem
All data in the file is filled with NULL bytes
And only one of the addresses in the file changes

Example:

FILE* fp = fopen("target.bin", "wb");

replace(fp, 0x57d8b0, "\x1E\xFF\x2F\xE1", 4);
replace(fp, 0x57c770, "\x01\x00\xA0\xE3\x1E\xFF\x2F\xE1", 8);

Result:

0x57c770: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
...
0x57d8a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x57d8b0: 1e ff 2f e1

Correct result:

0x57c770: 01 00 A0 E3 1E FF 2F E1 ...
...
0x57d8a0: 9c c4 0a ea 70 d2 68 00 44 d4 68 00 10 d1 68 00
0x57d8b0: 1e ff 2f e1 18 b0 8d e2 02 8b 2d ed 18 d0 4d e2

Please help me to solve the function problem or other problems.

Solution

wb is not correct. It clobbers the file.

From here,

Mode	Meaning	Explanation	If already exists	If does not exist
"r"	read	Open a file for reading	read from start	failure to open
"w"	write	Create a file for writing	destroy contents	create new
"a"	append	Append to a file	write to end	create new
"r+"	read extended	Open a file for read/write	read from start	error
"w+"	write extended	Create a file for read/write	destroy contents	create new
"a+"	append extended	Open a file for read/write	write to end	create new

You want r+b.

Also, you close the file handle in replace, which is premature. This should be done outside of replace, after you're done with the handle.

As an aside, you shouldn't be doing a number of seeks and writes of length one equal to length; you should be doing one seek and one write of length length.