problems with fseek and fread in C

I'm having an issue with fseek and fread. For some reason, using fseek (f, 0, SEEK_END); will not give me the end of my file, and instead go 1000 bytes farther, giving me junk data and generally being a pain... I have checked, if I open the same file with python, f=open("filename","r"); print(len(f.read())) will give me the correct result, but using ftell() in C after the line I wrote previously will be 1000 off, and I have no idea why. Here is the entire code for the function that is not working:

char* get_input(const char* path) {
    char* buffer = NULL;
    FILE* f = fopen(path, "r");

    if (f)
    {
        fseek (f, 0, SEEK_END);
        const long length = ftell(f);
        fseek (f, 0, SEEK_SET);
        printf("%d\n", length);
        buffer = malloc(length+1);
        if (buffer)
        {
            fread (buffer, 1, length, f);
            buffer[length+1] = '\0';
        }
        fclose (f);
    }
    return buffer;
}

(it's just trying to read the contents of the file as a char array...) The file I'm trying to open is just my day 2 input from advent of code(2024), that I copy-pasted to a text file as usual. I will not share it unless necessary as it is not good practice to do so.

With the help of the comments, I have found the two issues: The first one was: I read my file as text when I should have read it as binary. The second one was: I did not place my null terminator correctly.

The code I ended up using is:

char* get_input(const char* path) {
    char* buffer = NULL;
    FILE* f = fopen(path, "rb");

    if (f)
    {
        fseek (f, 0, SEEK_END);
        const long length = ftell(f);
        fseek (f, 0, SEEK_SET);
        buffer = malloc(length+1);
        if (buffer)
        {
            size_t bytes = fread (buffer, 1, length, f);
            buffer[bytes] = '\0';
        }
        fclose (f);
    }
    return buffer;
}