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/* holes - find holes (= runs of zero bytes) in input files */
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
ssize_t minlen = 64;
char byte = 0;
int ret = 0;
char *argv0;
ssize_t total, totalz;
void
holes(FILE *input, char *filename)
{
off_t offset = 0;
off_t run = 0;
static char buf[16384];
int len;
int i;
char *d;
while ((len = fread(buf, 1, sizeof buf, input)) >= 1) {
if (run == 0) {
d = memchr(buf, byte, len);
if (!d) {
offset += len;
continue;
}
i = d - buf;
offset += i;
} else {
i = 0;
}
for (; i < len; i++) {
if (buf[i] == byte) {
run++;
} else {
if (run >= minlen) {
if (filename)
printf("%s: ", filename);
printf("%08lx %ld\n", offset - run, run);
totalz += run;
}
run = 0;
}
offset++;
}
}
if (ferror(input)) {
fprintf(stderr, "%s: can't read '%s': %s\n",
argv0, filename ? filename : "-", strerror(errno));
ret = 1;
return;
}
if (offset == 0 || // empty file
run >= minlen) {
if (filename)
printf("%s: ", filename);
printf("%08lx %ld\n", offset - run, run);
totalz += run;
}
total += offset;
}
int
main(int argc, char *argv[])
{
int c, i;
long b;
char *e;
int sflag = 0;
argv0 = argv[0];
while ((c = getopt(argc, argv, "b:n:s")) != -1)
switch (c) {
case 'b':
errno = 0;
b = strtol(optarg, &e, 0);
if (errno != 0 || *e || b < 0 || b > 256) {
fprintf(stderr,
"%s: can't parse byte '%s'.\n",
argv0, optarg);
exit(2);
}
byte = b;
break;
case 'n':
errno = 0;
minlen = strtoll(optarg, &e, 0);
if (errno != 0 || *e) {
fprintf(stderr,
"%s: can't parse length '%s'.\n",
argv0, optarg);
exit(2);
}
if (minlen < 1) {
fprintf(stderr,
"%s: MINLEN must not be smaller than 1.\n",
argv0);
exit(2);
}
break;
case 's': sflag++; break;
default:
fprintf(stderr,
"Usage: %s [-b BYTE] [-n MINLEN] [-s] [FILES...]\n",
argv0);
exit(2);
}
if (optind == argc)
holes(stdin, 0);
else
for (i = optind; i < argc; i++) {
FILE *input = (strcmp(argv[i], "-") == 0) ?
stdin : fopen(argv[i], "rb");
if (!input) {
fprintf(stderr, "%s: can't open file '%s': %s\n",
argv0, argv[i], strerror(errno));
ret = 1;
} else {
holes(input, argc - optind > 1 ? argv[i] : 0);
}
}
if (sflag)
printf("total %jd/%jd (%.2f%%)\n",
totalz, total,
total == 0 ? 0.0 : 100.0*totalz / total);
return ret;
}
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