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<H1><A NAME="SECTION001300000000000000000">Measuring Holes</A></H1>
 <A NAME="chapmeasureholes">&#160;</A>
<P>
This appendix contains the interesting part of the program used to measure
the potential for holes in a filesystem.  The source distribution of
the book contains the full source code
(<tt>sag/measure-holes/measure-holes.c</tt>).
<P>
<BLOCKQUOTE> 
<PRE>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 &gt; 0)
                printf(&quot;%ld %s\n&quot;, zeroes, filename);
        if (ferror(f)) {
                errormsg(0, -1, &quot;read failed for `%s'&quot;, filename);
                return -1;
        }
        return 0;
}</PRE>

</BLOCKQUOTE><BR> <HR>
<P><ADDRESS>
<I>Lars Wirzenius <BR>
Sat Nov 15 02:32:11 EET 1997</I>
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