Mesurer les trous

Cette annexe contient la partie intéressante du programme utilisé pour mesurer le potentiel de trous dans un système de fichiers. La distribution source du livre contient le code complet (sag/measure-holes/measure-holes.c).

int process(FILE *f, char *filename) {
        static char *buf = NULL;
        static long prev_block_size = -1;
        long zeroes;
        char *p;

        if (buf == NULL || prev_block_size != block_size) {
                free(buf);
                buf = xmalloc(block_size + 1);
                buf[block_size] = 1;
                prev_block_size = block_size;
        }
        zeroes = 0;
        while (fread(buf, block_size, 1, f) == 1) {
                for (p = buf; *p == '\0'; )
                        ++p;
                if (p == buf+block_size)
                        zeroes += block_size;
        }
        if (zeroes > 0)
                printf("%ld %s\n", zeroes, filename);
if (ferror(f)) {
                errormsg(0, -1, "read failed for`%s'", filename);
return -1;
        }
        return 0;
}