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rdate: make it do something remotely sane, facing 32-bit time overflow

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function                                             old     new   delta
rdate_main                                           251     254      +3
packed_usage                                       31029   31023      -6

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
2017-01-20 16:03:48 +01:00
parent 19e695ebad
commit 179e88bec9
2 changed files with 27 additions and 6 deletions
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31
util-linux/rdate.c
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@@ -21,11 +21,11 @@
//kbuild:lib-$(CONFIG_RDATE) += rdate.o
//usage:#define rdate_trivial_usage
//usage: "[-sp] HOST"
//usage: "[-s/-p] HOST"
//usage:#define rdate_full_usage "\n\n"
//usage: "Get and possibly set system time from a remote HOST\n"
//usage: "\n -s Set system time (default)"
//usage: "\n -p Print time"
//usage: "Set and print time from HOST using RFC 868\n"
//usage: "\n -s Only set system time"
//usage: "\n -p Only print time"
#include "libbb.h"
@@ -58,8 +58,22 @@ static time_t askremotedate(const char *host)
* the RFC 868 time 2,208,988,800 corresponds to 00:00 1 Jan 1970 GMT
* Subtract the RFC 868 time to get Linux epoch.
*/
nett = ntohl(nett) - RFC_868_BIAS;
return ntohl(nett) - RFC_868_BIAS;
if (sizeof(time_t) > 4) {
/* Now we have 32-bit lsb of a wider time_t
* Imagine that nett = 0x00000001,
* current time cur = 0x123ffffffff.
* Assuming our time is not some 40 years off,
* remote time must be 0x12400000001.
* Need to adjust out time by (int32_t)(nett - cur).
*/
time_t cur = time(NULL);
int32_t adjust = (int32_t)(nett - (uint32_t)cur);
return cur + adjust;
}
/* This is not going to work, but what can we do */
return (time_t)nett;
}
int rdate_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
@@ -73,6 +87,13 @@ int rdate_main(int argc UNUSED_PARAM, char **argv)
remote_time = askremotedate(argv[optind]);
/* Manpages of various Unixes are confusing. What happens is:
* (no opts) set and print time
* -s: set time ("do not print the time")
* -p: print time ("do not set, just print the remote time")
* -sp: print time (that's what we do, not sure this is right)
*/
if (!(flags & 2)) { /* no -p (-s may be present) */
time_t current_time;