Add support for an optional offset when parsing the ID to replay.

The offset is a suffix in the form of @sec[.nanosec]

doc/sudoreplay.man.in

@@ -2,7 +2,7 @@
 .\"
 .\" SPDX-License-Identifier: ISC
 .\"
-.\" Copyright (c) 2009-2020 Todd C. Miller <Todd.Miller@sudo.ws>
+.\" Copyright (c) 2009-2021 Todd C. Miller <Todd.Miller@sudo.ws>
 .\"
 .\" Permission to use, copy, modify, and distribute this software for any
 .\" purpose with or without fee is hereby granted, provided that the above
@@ -16,7 +16,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.TH "SUDOREPLAY" "@mansectsu@" "May 26, 2021" "Sudo @PACKAGE_VERSION@" "System Manager's Manual"
+.TH "SUDOREPLAY" "@mansectsu@" "August 13, 2021" "Sudo @PACKAGE_VERSION@" "System Manager's Manual"
 .nh
 .if n .ad l
 .SH "NAME"
@@ -30,7 +30,7 @@
 [\fB\-f\fR\ \fIfilter\fR]
 [\fB\-m\fR\ \fInum\fR]
 [\fB\-s\fR\ \fInum\fR]
-ID
+ID[\fI@offset\fR]
 .HP 11n
 \fBsudoreplay\fR
 [\fB\-h\fR]
@@ -52,6 +52,16 @@ should either be a six character sequence of digits and
 upper case letters, e.g.,
 \fR0100A5\fR
 or a path name.
+The
+\fIID\fR
+may include an optional
+\fI@offset\fR
+suffix which may be used to start replaying at a specific time offset.
+The
+\fI@offset\fR
+is specified as a number in seconds since the start of the session
+with an optional decimal fraction.
+.PP
 Path names may be relative to the I/O log directory
 \fI@iolog_dir@\fR
 (unless overridden by the

doc/sudoreplay.mdoc.in

@@ -1,7 +1,7 @@
 .\"
 .\" SPDX-License-Identifier: ISC
 .\"
-.\" Copyright (c) 2009-2020 Todd C. Miller <Todd.Miller@sudo.ws>
+.\" Copyright (c) 2009-2021 Todd C. Miller <Todd.Miller@sudo.ws>
 .\"
 .\" Permission to use, copy, modify, and distribute this software for any
 .\" purpose with or without fee is hereby granted, provided that the above
@@ -15,7 +15,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd May 26, 2021
+.Dd August 13, 2021
 .Dt SUDOREPLAY @mansectsu@
 .Os Sudo @PACKAGE_VERSION@
 .Sh NAME
@@ -28,7 +28,7 @@
 .Op Fl f Ar filter
 .Op Fl m Ar num
 .Op Fl s Ar num
-ID
+.No ID Ns Op Ar @offset
 .Pp
 .Nm
 .Op Fl h
@@ -50,6 +50,16 @@ should either be a six character sequence of digits and
 upper case letters, e.g.,
 .Li 0100A5
 or a path name.
+The
+.Em ID
+may include an optional
+.Ar @offset
+suffix which may be used to start replaying at a specific time offset.
+The
+.Ar @offset
+is specified as a number in seconds since the start of the session
+with an optional decimal fraction.
+.Pp
 Path names may be relative to the I/O log directory
 .Pa @iolog_dir@
 (unless overridden by the

lib/iolog/iolog_timing.c

@@ -114,6 +114,11 @@ iolog_parse_delay(const char *cp, struct timespec *delay,
 
     /* Radix may be in user's locale for sudo < 1.7.4 so accept that too. */
     if (*ep != '.' && *ep != *decimal_point) {
+	if (*ep == '\0' || isspace((unsigned char)*ep)) {
+	    /* No fractional part. */
+	    delay->tv_nsec = 0;
+	    goto done;
+	}
 	sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
 	    "invalid characters after seconds: %s", ep);
 	debug_return_ptr(NULL);
@@ -152,6 +157,7 @@ iolog_parse_delay(const char *cp, struct timespec *delay,
     }
     delay->tv_nsec = (long)llval;
 
+done:
     /* Advance to the next field. */
     while (isspace((unsigned char)*ep))
 	ep++;

plugins/sudoers/sudoreplay.c

@@ -1,7 +1,7 @@
 /*
  * SPDX-License-Identifier: ISC
  *
- * Copyright (c) 2009-2020 Todd C. Miller <Todd.Miller@sudo.ws>
+ * Copyright (c) 2009-2021 Todd C. Miller <Todd.Miller@sudo.ws>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -82,6 +82,7 @@ struct replay_closure {
     struct sudo_event *sigquit_ev;
     struct sudo_event *sigterm_ev;
     struct sudo_event *sigtstp_ev;
+    struct timespec *offset;
     struct timespec *max_delay;
     struct timing_closure timing;
     int iolog_dir_fd;
@@ -176,8 +177,8 @@ static int parse_expr(struct search_node_list *, char **, bool);
 static void read_keyboard(int fd, int what, void *v);
 static void help(void) __attribute__((__noreturn__));
 static int replay_session(int iolog_dir_fd, const char *iolog_dir,
-    struct timespec *max_wait, const char *decimal, bool interactive,
+    struct timespec *offset, struct timespec *max_wait, const char *decimal,
-    bool suspend_wait);
+    bool interactive, bool suspend_wait);
 static void sudoreplay_cleanup(void);
 static void usage(int);
 static void write_output(int fd, int what, void *v);
@@ -195,7 +196,7 @@ static void setup_terminal(struct eventlog *evlog, bool interactive, bool resize
     isalnum((unsigned char)(s)[3]) && isalnum((unsigned char)(s)[4]) && \
     (s)[5] == '/' && \
     isalnum((unsigned char)(s)[6]) && isalnum((unsigned char)(s)[7]) && \
-    (s)[8] == '\0')
+    (s)[6] == '\0')
 
 sudo_dso_public int main(int argc, char *argv[]);
 
@@ -207,6 +208,7 @@ main(int argc, char *argv[])
     bool interactive = true, suspend_wait = false, resize = true;
     const char *decimal, *id, *user = NULL, *pattern = NULL, *tty = NULL;
     char *cp, *ep, iolog_dir[PATH_MAX];
+    struct timespec offset = { 0, 0};
     struct eventlog *evlog;
     struct timespec max_delay_storage, *max_delay = NULL;
     double dval;
@@ -323,8 +325,16 @@ main(int argc, char *argv[])
 	iolog_files[IOFD_TTYOUT].enabled = true;
     }
 
-    /* 6 digit ID in base 36, e.g. 01G712AB or free-form name */
+    /* Check for offset in @sec.nsec form at the end of the id. */
     id = argv[0];
+    if ((cp = strchr(id, '@')) != NULL) {
+	ep = iolog_parse_delay(cp + 1, &offset, decimal);
+	if (ep == NULL || *ep != '\0')
+	    sudo_fatalx(U_("invalid time offset %s"), cp + 1);
+	*cp = '\0';
+    }
+
+    /* 6 digit ID in base 36, e.g. 01G712AB or free-form name */
     if (VALID_ID(id)) {
 	len = snprintf(iolog_dir, sizeof(iolog_dir), "%s/%.2s/%.2s/%.2s",
 	    session_dir, id, &id[2], &id[4]);
@@ -376,8 +386,8 @@ main(int argc, char *argv[])
     evlog = NULL;
 
     /* Replay session corresponding to iolog_files[]. */
-    exitcode = replay_session(iolog_dir_fd, iolog_dir, max_delay, decimal,
+    exitcode = replay_session(iolog_dir_fd, iolog_dir, &offset, max_delay,
-	interactive, suspend_wait);
+	decimal, interactive, suspend_wait);
 
     restore_terminal_size();
     sudo_term_restore(ttyfd, true);
@@ -774,6 +784,16 @@ get_timing_record(struct replay_closure *closure)
 	    closure->iobuf.toread = timing->u.nbytes;
 	}
 
+	if (sudo_timespecisset(closure->offset)) {
+	    if (sudo_timespeccmp(&timing->delay, closure->offset, >)) {
+		sudo_timespecsub(&timing->delay, closure->offset, &timing->delay);
+		sudo_timespecclear(closure->offset);
+	    } else {
+		sudo_timespecsub(closure->offset, &timing->delay, closure->offset);
+		sudo_timespecclear(&timing->delay);
+	    }
+	}
+
 	if (nodelay) {
 	    /* Already waited, fire immediately. */
 	    timing->delay.tv_sec = 0;
@@ -957,8 +977,8 @@ signal_cb(int signo, int what, void *v)
 
 static struct replay_closure *
 replay_closure_alloc(int iolog_dir_fd, const char *iolog_dir,
-    struct timespec *max_delay, const char *decimal, bool interactive,
+    struct timespec *offset, struct timespec *max_delay, const char *decimal,
-    bool suspend_wait)
+    bool interactive, bool suspend_wait)
 {
     struct replay_closure *closure;
     debug_decl(replay_closure_alloc, SUDO_DEBUG_UTIL);
@@ -969,6 +989,7 @@ replay_closure_alloc(int iolog_dir_fd, const char *iolog_dir,
     closure->iolog_dir_fd = iolog_dir_fd;
     closure->iolog_dir = iolog_dir;
     closure->interactive = interactive;
+    closure->offset = offset;
     closure->suspend_wait = suspend_wait;
     closure->max_delay = max_delay;
     closure->timing.decimal = decimal;
@@ -1042,7 +1063,7 @@ bad:
 }
 
 static int
-replay_session(int iolog_dir_fd, const char *iolog_dir,
+replay_session(int iolog_dir_fd, const char *iolog_dir, struct timespec *offset,
     struct timespec *max_delay, const char *decimal, bool interactive,
     bool suspend_wait)
 {
@@ -1051,8 +1072,8 @@ replay_session(int iolog_dir_fd, const char *iolog_dir,
     debug_decl(replay_session, SUDO_DEBUG_UTIL);
 
     /* Allocate the delay closure and read the first timing record. */
-    closure = replay_closure_alloc(iolog_dir_fd, iolog_dir, max_delay, decimal,
+    closure = replay_closure_alloc(iolog_dir_fd, iolog_dir, offset, max_delay,
-	interactive, suspend_wait);
+	decimal, interactive, suspend_wait);
     if (get_timing_record(closure) != 0) {
 	ret = 1;
 	goto done;