time,ns: add --time to set specific clocks

bst.1.scd

@@ -109,6 +109,14 @@ Users of bst may choose to opt-out of some of the isolation.
 
 	You cannot use this option with _--share=uts_.
 
+\--time <name-or-id>=<seconds>[.<nanoseconds>]
+	Set the value of the specified clock for the inner process' time namespace.
+
+	Valid clock names are the same as the ones described in *time_namespaces*(7).
+	Alternatively, the numerical clock IDs can be supplied.
+
+	You cannot use this option with _--share=time_.
+
 # SEE ALSO
 
 *namespaces*(7), *mount*(1), *setarch*(1)

main.c

@@ -4,7 +4,9 @@
  * in the LICENSE file.
  */
 
+#include <ctype.h>
 #include <err.h>
+#include <errno.h>
 #include <getopt.h>
 #include <limits.h>
 #include <signal.h>
@@ -28,6 +30,7 @@ enum {
 	OPTION_ARGV0,
 	OPTION_HOSTNAME,
 	OPTION_DOMAIN,
+	OPTION_TIME,
 };
 
 /* Usage is generated from usage.txt. Note that the array is not null-terminated,
@@ -69,10 +72,16 @@ int main(int argc, char *argv[], char *envp[])
 		{ "argv0",      required_argument,  NULL,           OPTION_ARGV0    },
 		{ "hostname",   required_argument,  NULL,           OPTION_HOSTNAME },
 		{ "domainname", required_argument,  NULL,           OPTION_DOMAIN   },
+		{ "time",       required_argument,  NULL,           OPTION_TIME     },
 
 		{ 0, 0, 0, 0 }
 	};
 
+	static const char *clocknames[MAX_CLOCK + 1] = {
+		[CLOCK_MONOTONIC] = "monotonic",
+		[CLOCK_BOOTTIME]  = "boottime",
+	};
+
 	char *argv0 = NULL;
 
 	int error = 0;
@@ -147,6 +156,57 @@ int main(int argc, char *argv[], char *envp[])
 				opts.domainname = optarg;
 				break;
 
+			case OPTION_TIME:
+			{
+				const char *name  = strtok(optarg, "=");
+				const char *secs  = strtok(NULL, ".");
+				const char *nsecs = strtok(NULL, "");
+
+				clockid_t clock = -1;
+				for (clockid_t id = 0; id < MAX_CLOCK + 1; ++id) {
+					if (clocknames[id] && strcmp(clocknames[id], name) == 0) {
+						clock = id;
+						break;
+					}
+				}
+
+				if (clock == -1 && isdigit(name[0])) {
+					errno = 0;
+					clock = strtol(name, NULL, 10);
+					if (errno != 0) {
+						clock = -1;
+					}
+				}
+
+				if (clock < 0 || clock > MAX_CLOCK) {
+					errx(2, "%s is not a valid clock ID or name", name);
+				}
+
+				struct timespec ts = {0, 0};
+				errno = 0;
+				ts.tv_sec  = strtol(secs, NULL, 10);
+				if (errno != 0) {
+					err(2, "%s is not a valid number of seconds", secs);
+				}
+				if (ts.tv_sec < 0) {
+					errx(2, "%s must be a positive number of seconds", secs);
+				}
+				if (nsecs && nsecs[0] != '\0') {
+					errno = 0;
+					ts.tv_nsec = strtol(nsecs, NULL, 10);
+					if (errno != 0) {
+						err(2, "%s is not a valid number of nanoseconds", nsecs);
+					}
+					if (ts.tv_nsec < 0 || ts.tv_nsec >= SEC_IN_NS) {
+						errx(2, "%s as nanoseconds is out of range (must be "
+								"between 0 and 999.999.999)", nsecs);
+					}
+				}
+
+				opts.clockspecs[clock] = ts;
+				break;
+			}
+
 			case 'r':
 				opts.root = optarg;
 				break;

timens.c

@@ -11,10 +11,6 @@
 #include <time.h>
 #include "timens.h"
 
-enum {
-    GIGA = 1000000000,
-};
-
 void init_clocks(int fd, const struct timespec *times, size_t nclocks)
 {
 	FILE *clocks = fdopen(fd, "w");
@@ -37,10 +33,10 @@ void init_clocks(int fd, const struct timespec *times, size_t nclocks)
 		}
 
 		tp.tv_sec  = times[clock].tv_sec - tp.tv_sec - 1;
-		tp.tv_nsec = GIGA - tp.tv_nsec + times[clock].tv_nsec;
-		while (tp.tv_nsec > GIGA) {
+		tp.tv_nsec = SEC_IN_NS - tp.tv_nsec + times[clock].tv_nsec;
+		while (tp.tv_nsec > SEC_IN_NS) {
 			tp.tv_sec += 1;
-			tp.tv_nsec -= GIGA;
+			tp.tv_nsec -= SEC_IN_NS;
 		}
 
 		fprintf(clocks, "%d %ld %ld\n", clock, tp.tv_sec, tp.tv_nsec);

timens.h

@@ -9,6 +9,8 @@
 
 enum {
 	MAX_CLOCK = 11, // CLOCK_TAI
+
+	SEC_IN_NS = 1000000000,
 };
 
 typedef long clockspecs[MAX_CLOCK];

usage.c

@@ -76,6 +76,11 @@ unsigned char usage_txt[] = {
   0x68, 0x20, 0x3c, 0x61, 0x72, 0x63, 0x68, 0x3e, 0x3a, 0x20, 0x20, 0x20,
   0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x53, 0x65, 0x74, 0x20, 0x74,
   0x68, 0x65, 0x20, 0x65, 0x78, 0x65, 0x63, 0x75, 0x74, 0x69, 0x6f, 0x6e,
-  0x20, 0x64, 0x6f, 0x6d, 0x61, 0x69, 0x6e, 0x2e, 0x0a
+  0x20, 0x64, 0x6f, 0x6d, 0x61, 0x69, 0x6e, 0x2e, 0x0a, 0x09, 0x2d, 0x2d,
+  0x74, 0x69, 0x6d, 0x65, 0x20, 0x3c, 0x6e, 0x61, 0x6d, 0x65, 0x3e, 0x3d,
+  0x3c, 0x73, 0x3e, 0x5b, 0x2e, 0x6e, 0x73, 0x5d, 0x3a, 0x20, 0x53, 0x65,
+  0x74, 0x20, 0x74, 0x68, 0x65, 0x20, 0x74, 0x69, 0x6d, 0x65, 0x20, 0x6f,
+  0x66, 0x20, 0x61, 0x20, 0x73, 0x70, 0x65, 0x63, 0x69, 0x66, 0x69, 0x63,
+  0x20, 0x63, 0x6c, 0x6f, 0x63, 0x6b, 0x2e, 0x0a
 };
-unsigned int usage_txt_len = 849;
+unsigned int usage_txt_len = 908;

usage.txt

@@ -18,3 +18,4 @@ Options:
 	--gid <gid>:            Set group ID.
 	--groups <gid,gid,...>: Set additional groups.
 	--arch <arch>:          Set the execution domain.
+	--time <name>=<s>[.ns]: Set the time of a specific clock.