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mcookie: add --max-size option 

Just in case someone wants to add entropy from device with invocation
demonstrated below.

$ mcookie --file /dev/urandom --max-size 64k

[kzak@redhat.com: - use all-io.h]

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
Signed-off-by: Karel Zak <kzak@redhat.com>
This commit is contained in:
Sami Kerola 2014-03-08 15:43:30 -06:00 committed by Karel Zak
parent 46ae163a8e
commit f7bac5731b
2 changed files with 42 additions and 5 deletions
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15
misc-utils/mcookie.1
View File

@ -27,6 +27,21 @@ in this preference order.
Use additional file as a macig cookie random seed. When file is defined
as '-' character input is read from stdin.
.TP
\fB\-m\fR, \fB\-\-max\-size\fR=\fInumber\fR
Read form
.I FILE
only
.I number
of bytes. This option is meant to be used when reading additional
randomness from a device.
.IP
The
.I number
argument may be followed by the multiplicative suffixes KiB=1024,
MiB=1024*1024, and so on for GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is
optional, e.g., "K" has the same meaning as "KiB") or the suffixes
KB=1000, MB=1000*1000, and so on for GB, TB, PB, EB, ZB and YB.
.TP
\fB\-v\fR, \fB\-\-verbose\fR
Inform where randomness originated, with amount of entropy read from each
source.

32
misc-utils/mcookie.c
View File

@ -23,7 +23,9 @@
#include "nls.h"
#include "closestream.h"
#include "randutils.h"
#include "strutils.h"
#include "xalloc.h"
#include "all-io.h"
#include <fcntl.h>
#include <getopt.h>
@ -42,18 +44,29 @@ struct mcookie_control {
struct MD5Context ctx;
char **files;
size_t nfiles;
uint64_t maxsz;
unsigned int verbose:1;
};
/* The basic function to hash a file */
static size_t hash_file(struct mcookie_control *ctl, int fd)
static uint64_t hash_file(struct mcookie_control *ctl, int fd)
{
size_t count = 0;
ssize_t r;
unsigned char buf[BUFFERSIZE];
uint64_t wanted, count;
while ((r = read(fd, buf, sizeof(buf))) > 0) {
wanted = ctl->maxsz ? ctl->maxsz : sizeof(buf);
for (count = 0; count < wanted; ) {
size_t rdsz = sizeof(buf);
ssize_t r;
if (wanted - count < rdsz)
rdsz = wanted - count;
r = read_all(fd, (char *) buf, rdsz);
if (r < 0)
break;
MD5Update(&ctl->ctx, buf, r);
count += r;
}
@ -70,6 +83,7 @@ static void __attribute__ ((__noreturn__)) usage(FILE * out)
fputs(USAGE_OPTIONS, out);
fputs(_(" -f, --file <file> use file as a cookie seed\n"), out);
fputs(_(" -m, --max-size <num> limit how much is read from seed files\n"), out);
fputs(_(" -v, --verbose explain what is being done\n"), out);
fputs(USAGE_SEPARATOR, out);
@ -122,6 +136,7 @@ int main(int argc, char **argv)
static const struct option longopts[] = {
{"file", required_argument, NULL, 'f'},
{"max-size", required_argument, NULL, 'm'},
{"verbose", no_argument, NULL, 'v'},
{"version", no_argument, NULL, 'V'},
{"help", no_argument, NULL, 'h'},
@ -136,7 +151,7 @@ int main(int argc, char **argv)
if (2 < argc)
ctl.files = xmalloc(sizeof(char *) * argc);
while ((c = getopt_long(argc, argv, "f:vVh", longopts, NULL)) != -1) {
while ((c = getopt_long(argc, argv, "f:m:vVh", longopts, NULL)) != -1) {
switch (c) {
case 'v':
ctl.verbose = 1;
@ -144,6 +159,10 @@ int main(int argc, char **argv)
case 'f':
ctl.files[ctl.nfiles++] = optarg;
break;
case 'm':
ctl.maxsz = strtosize_or_err(optarg,
_("failed to parse length"));
break;
case 'V':
printf(UTIL_LINUX_VERSION);
return EXIT_SUCCESS;
@ -154,6 +173,9 @@ int main(int argc, char **argv)
}
}
if (ctl.maxsz && ctl.nfiles == 0)
warnx(_("--max-size ignored when used without --file."));
randomness_from_files(&ctl);
free(ctl.files);