/* bitchecker - verify numericity and quantumness of all bits in all files

   By Ben Hoyt (c) 2009 - http://benhoyt.com/

   Inspired by http://thedailywtf.com/Articles/Some-Crazy-Reason.aspx :-)
*/

#include <stdio.h>
#include <windows.h>

/* Return true if bit's numericity is wrong (bit is neither zero nor one). */
static inline int invalid_numericity(int bit)
{
    return bit != 0 && bit != 1;
}

/* Return true if bit's quantum-ness is wrong (i.e., bit is both zero and one
   at the same time). */
static inline int invalid_quantumness(int bit)
{
    return bit == 0 && bit == 1;
}

/* Check given file's bit integrity, displaying any errors. */
static void check_file(const char* dirname, const char* filename)
{
    char fullname[MAX_PATH];
    FILE *f;
    int byte;
    int bit;
    int pos;
    int i;

    strcpy(fullname, dirname);
    strcat(fullname, filename);
    printf("%s\n", fullname);

    f = fopen(fullname, "rb");
    if (!f)
        return;

    /* Hope that fgetc() is buffered */
    pos = 0;
    while((byte = fgetc(f)) != EOF) {
        for (i = 0; i < 8; i++) {
            bit = (byte >> i) & 1;
            if (invalid_numericity(bit) || invalid_quantumness(bit))
                printf("%s: bit %d is invalid!\n", fullname, pos * 8 + i);
        }
        pos++;
    }

    fclose(f);
}

/* Check all files in given base path and directory, recursively. */
static void check_dir(const char* base, const char* dir)
{
    char* path;
    HANDLE handle;
    WIN32_FIND_DATA data;

    path = (char*)malloc(MAX_PATH);
    if (!path)
        return;

    sprintf(path, "%s%s%s*.*", base, dir, (*dir ? "\\" : ""));
    handle = FindFirstFile(path, &data);
    if (handle != INVALID_HANDLE_VALUE) {
        /* Remove the "*.*" for later use */
        path[strlen(path) - 3] = '\0';

        /* Loop through all files/dirs in this directory */
        do {
            if (data.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
                if (strcmp(data.cFileName, ".") != 0 &&
                    strcmp(data.cFileName, "..") != 0) {
                    /* It's a directory, recurse */
                    check_dir(path, data.cFileName);
                }
            }
            else {
                /* It's a file, verify it */
                check_file(path, data.cFileName);
            }
         } while (FindNextFile(handle, &data) != 0);

        FindClose(handle);
    }

    free(path);
}

/* Check entire C: drive or given directory */
int main(int argc, char* argv[])
{
    check_dir((argc < 2 ? "c:\\" : argv[1]), "");
    return 0;
}