Merge remote-tracking branch 'toybox/master' into HEAD

Change-Id: Ib387b8d25ff1d36bff7a017fd59ef47fbc4e1adf

20 files changed, 257 insertions, 105 deletions

diff --git a/generated/flags.h b/generated/flags.h
index 09b34213..9c3145bd 100644
--- a/generated/flags.h
+++ b/generated/flags.h
@@ -2486,12 +2486,14 @@
 #undef FOR_sleep
 #endif
 
-// sntp   <1
+// sntp   sp:
 #undef OPTSTR_sntp
-#define OPTSTR_sntp "<1"
+#define OPTSTR_sntp "sp:"
 #ifdef CLEANUP_sntp
 #undef CLEANUP_sntp
 #undef FOR_sntp
+#undef FLAG_p
+#undef FLAG_s
 #endif
 
 // sort gS:T:mo:k*t:xVbMcszdfirun gS:T:mo:k*t:xVbMcszdfirun
@@ -3232,9 +3234,9 @@
 #undef FLAG_a
 #endif
 
-// xargs ^I:E:L#ptxrn#<1s#0[!0E] ^I:E:L#ptxrn#<1s#0[!0E]
+// xargs ^I:E:ptrn#<1s#0[!0E] ^I:E:ptrn#<1s#0[!0E]
 #undef OPTSTR_xargs
-#define OPTSTR_xargs "^I:E:L#ptxrn#<1s#0[!0E]"
+#define OPTSTR_xargs "^I:E:ptrn#<1s#0[!0E]"
 #ifdef CLEANUP_xargs
 #undef CLEANUP_xargs
 #undef FOR_xargs
@@ -3242,10 +3244,8 @@
 #undef FLAG_s
 #undef FLAG_n
 #undef FLAG_r
-#undef FLAG_x
 #undef FLAG_t
 #undef FLAG_p
-#undef FLAG_L
 #undef FLAG_E
 #undef FLAG_I
 #endif
@@ -5385,6 +5385,8 @@
 #ifndef TT
 #define TT this.sntp
 #endif
+#define FLAG_p (FORCED_FLAG<<0)
+#define FLAG_s (FORCED_FLAG<<1)
 #endif
 
 #ifdef FOR_sort
@@ -6013,12 +6015,10 @@
 #define FLAG_s (1<<1)
 #define FLAG_n (1<<2)
 #define FLAG_r (1<<3)
-#define FLAG_x (1<<4)
-#define FLAG_t (1<<5)
-#define FLAG_p (1<<6)
-#define FLAG_L (1<<7)
-#define FLAG_E (1<<8)
-#define FLAG_I (1<<9)
+#define FLAG_t (1<<4)
+#define FLAG_p (1<<5)
+#define FLAG_E (1<<6)
+#define FLAG_I (1<<7)
 #endif
 
 #ifdef FOR_xxd
diff --git a/generated/globals.h b/generated/globals.h
index 1ac1a5a4..a66ca10b 100644
--- a/generated/globals.h
+++ b/generated/globals.h
@@ -764,7 +764,7 @@ struct sh_data {
 // toys/pending/sntp.c
 
 struct sntp_data {
-  int unused;
+  char *p, *m;
 };
 
 // toys/pending/stty.c
@@ -1326,7 +1326,7 @@ struct wc_data {
 // toys/posix/xargs.c
 
 struct xargs_data {
-  long s, n, L;
+  long s, n;
   char *E, *I;
 
   long entries, bytes;
diff --git a/generated/help.h b/generated/help.h
index 472ee2ec..b1ba4a1f 100644
--- a/generated/help.h
+++ b/generated/help.h
@@ -108,7 +108,7 @@
 
 #define HELP_killall "usage: killall [-l] [-iqv] [-SIGNAL|-s SIGNAL] PROCESS_NAME...\n\nSend a signal (default: TERM) to all processes with the given names.\n\n-i	Ask for confirmation before killing\n-l	Print list of all available signals\n-q	Don't print any warnings or error messages\n-s	Send SIGNAL instead of SIGTERM\n-v	Report if the signal was successfully sent\n\n"
 
-#define HELP_hostname "usage: hostname [-bsf] [-F FILENAME] [newname]\n\nGet/set the current hostname.\n\n-b	Set hostname to 'localhost' if otherwise unset\n-d	Show DNS domain name (no host)\n-f	Show fully-qualified name (host+domain, FQDN)\n-F	Set hostname to contents of FILENAME\n-s	Show short host name (no domain)\n\n"
+#define HELP_hostname "usage: hostname [-bdsf] [-F FILENAME] [newname]\n\nGet/set the current hostname.\n\n-b	Set hostname to 'localhost' if otherwise unset\n-d	Show DNS domain name (no host)\n-f	Show fully-qualified name (host+domain, FQDN)\n-F	Set hostname to contents of FILENAME\n-s	Show short host name (no domain)\n\n"
 
 #define HELP_dmesg "usage: dmesg [-Cc] [-r|-t|-T] [-n LEVEL] [-s SIZE] [-w]\n\nPrint or control the kernel ring buffer.\n\n-C	Clear ring buffer without printing\n-c	Clear ring buffer after printing\n-n	Set kernel logging LEVEL (1-9)\n-r	Raw output (with <level markers>)\n-S	Use syslog(2) rather than /dev/kmsg\n-s	Show the last SIZE many bytes\n-T	Human readable timestamps\n-t	Don't print timestamps\n-w	Keep waiting for more output (aka --follow)\n\n"
 
@@ -340,7 +340,7 @@
 
 #define HELP_stty "usage: stty [-ag] [-F device] SETTING...\n\nGet/set terminal configuration.\n\n-F	Open device instead of stdin\n-a	Show all current settings (default differences from \"sane\")\n-g	Show all current settings usable as input to stty\n\nSpecial characters (syntax ^c or undef): intr quit erase kill eof eol eol2\nswtch start stop susp rprnt werase lnext discard\n\nControl/input/output/local settings as shown by -a, '-' prefix to disable\n\nCombo settings: cooked/raw, evenp/oddp/parity, nl, ek, sane\n\nN	set input and output speed (ispeed N or ospeed N for just one)\ncols N	set number of columns\nrows N	set number of rows\nline N	set line discipline\nmin N	set minimum chars per read\ntime N	set read timeout\nspeed	show speed only\nsize	show size only\n\n"
 
-#define HELP_sntp "usage: sntp SERVER...\n\nSimple Network Time Protocol client, set system clock from a server.\n\n"
+#define HELP_sntp "usage: sntp [-sm] [-p PORT] SERVER...\n\nSimple Network Time Protocol client, set system clock from a server.\n\n-p	Use PORT (default 123)\n-s	Serer\n\n"
 
 #define HELP_exit "usage: exit [status]\n\nExit shell.  If no return value supplied on command line, use value\nof most recent command, or 0 if none.\n\n"
 
@@ -438,7 +438,7 @@
 
 #define HELP_xargs_pedantic "This version supports insane posix whitespace handling rendered obsolete\nby -0 mode.\n\n\n"
 
-#define HELP_xargs "usage: xargs [-ptxr0] [-s NUM] [-n NUM] [-L NUM] [-E STR] COMMAND...\n\nRun command line one or more times, appending arguments from stdin.\n\nIf command exits with 255, don't launch another even if arguments remain.\n\n-s	Size in bytes per command line\n-n	Max number of arguments per command\n-0	Each argument is NULL terminated, no whitespace or quote processing\n#-p	Prompt for y/n from tty before running each command\n#-t	Trace, print command line to stderr\n#-x	Exit if can't fit everything in one command\n#-r	Don't run command with empty input\n#-L	Max number of lines of input per command\n-E	stop at line matching string\n\n"
+#define HELP_xargs "usage: xargs [-0prt] [-s NUM] [-n NUM] [-E STR] COMMAND...\n\nRun command line one or more times, appending arguments from stdin.\n\nIf command exits with 255, don't launch another even if arguments remain.\n\n-0	Each argument is NULL terminated, no whitespace or quote processing\n-E	Stop at line matching string\n-n	Max number of arguments per command\n-p	Prompt for y/n from tty before running each command\n-r	Don't run command with empty input\n-s	Size in bytes per command line\n-t	Trace, print command line to stderr\n\n"
 
 #define HELP_who "usage: who\n\nPrint logged user information on system\n\n"
 
diff --git a/generated/newtoys.h b/generated/newtoys.h
index 772b8c1f..faeefff7 100644
--- a/generated/newtoys.h
+++ b/generated/newtoys.h
@@ -225,7 +225,7 @@ USE_SHRED(NEWTOY(shred, "<1zxus#<1n#<1o#<0f", TOYFLAG_USR|TOYFLAG_BIN))
 USE_SKELETON(NEWTOY(skeleton, "(walrus)(blubber):;(also):e@d*c#b:a", TOYFLAG_USR|TOYFLAG_BIN))
 USE_SKELETON_ALIAS(NEWTOY(skeleton_alias, "b#dq", TOYFLAG_USR|TOYFLAG_BIN))
 USE_SLEEP(NEWTOY(sleep, "<1", TOYFLAG_BIN))
-USE_SNTP(NEWTOY(sntp, "<1", TOYFLAG_USR|TOYFLAG_BIN))
+USE_SNTP(NEWTOY(sntp, "sp:", TOYFLAG_USR|TOYFLAG_BIN))
 USE_SORT(NEWTOY(sort, USE_SORT_FLOAT("g")"S:T:m" "o:k*t:" "xVbMcszdfirun", TOYFLAG_USR|TOYFLAG_BIN))
 USE_SPLIT(NEWTOY(split, ">2a#<1=2>9b#<1l#<1[!bl]", TOYFLAG_USR|TOYFLAG_BIN))
 USE_START(NEWTOY(start, "", TOYFLAG_USR|TOYFLAG_SBIN))
@@ -289,7 +289,7 @@ USE_WGET(NEWTOY(wget, "f:", TOYFLAG_USR|TOYFLAG_BIN))
 USE_WHICH(NEWTOY(which, "<1a", TOYFLAG_USR|TOYFLAG_BIN))
 USE_WHO(NEWTOY(who, "a", TOYFLAG_USR|TOYFLAG_BIN))
 USE_WHOAMI(OLDTOY(whoami, logname, TOYFLAG_USR|TOYFLAG_BIN))
-USE_XARGS(NEWTOY(xargs, "^I:E:L#ptxrn#<1s#0[!0E]", TOYFLAG_USR|TOYFLAG_BIN))
+USE_XARGS(NEWTOY(xargs, "^I:E:ptrn#<1s#0[!0E]", TOYFLAG_USR|TOYFLAG_BIN))
 USE_XXD(NEWTOY(xxd, ">1c#l#o#g#<1=2iprs#[!rs]", TOYFLAG_USR|TOYFLAG_BIN))
 USE_XZCAT(NEWTOY(xzcat, NULL, TOYFLAG_USR|TOYFLAG_BIN))
 USE_YES(NEWTOY(yes, NULL, TOYFLAG_USR|TOYFLAG_BIN))
diff --git a/lib/lib.h b/lib/lib.h
index 546b32b3..ed31ffa9 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -360,12 +360,12 @@ void names_to_pid(char **names, int (*callback)(pid_t pid, char *name));
 pid_t __attribute__((returns_twice)) xvforkwrap(pid_t pid);
 #define XVFORK() xvforkwrap(vfork())
 
-// Wrapper to make xfuncs() return (via longjmp) instead of exiting.
+// Wrapper to make xfuncs() return (via siglongjmp) instead of exiting.
 // Assigns true/false "did it exit" value to first argument.
-#define WOULD_EXIT(y, x) do { jmp_buf _noexit; \
+#define WOULD_EXIT(y, x) do { sigjmp_buf _noexit; \
   int _noexit_res; \
   toys.rebound = &_noexit; \
-  _noexit_res = setjmp(_noexit); \
+  _noexit_res = sigsetjmp(_noexit, 1); \
   if (!_noexit_res) do {x;} while(0); \
   toys.rebound = 0; \
   y = _noexit_res; \
diff --git a/scripts/config2help.c b/scripts/config2help.c
index be53547d..edb1caea 100644
--- a/scripts/config2help.c
+++ b/scripts/config2help.c
@@ -19,7 +19,7 @@
 #include <poll.h>
 #include <sys/socket.h>
 
-/****************** functions copied from lib/*.c ********************/
+//****************** functions copied from lib/*.c ********************
 
 struct double_list {
   struct double_list *next, *prev;
@@ -107,7 +107,7 @@ struct double_list *dlist_add(struct double_list **list, char *data)
   return new;
 }
 
-/****************** end copies of lib/*.c *************/
+//****************** end copies of lib/*.c *************
 
 // Parse config files into data structures.
 
diff --git a/scripts/genconfig.sh b/scripts/genconfig.sh
index 3887b077..c4940dfd 100755
--- a/scripts/genconfig.sh
+++ b/scripts/genconfig.sh
@@ -6,6 +6,7 @@
 mkdir -p generated
 
 source configure
+source scripts/portability.sh
 
 probecc()
 {
@@ -129,7 +130,7 @@ genconfig()
     do
       # Grab the config block for Config.in
       echo "# $i"
-      sed -n '/^\*\//q;/^config [A-Z]/,$p' $i || return 1
+      $SED -n '/^\*\//q;/^config [A-Z]/,$p' $i || return 1
       echo
     done
 
@@ -144,7 +145,7 @@ genconfig > generated/Config.in || rm generated/Config.in
 toys()
 {
   grep 'TOY(.*)' "$@" | grep -v TOYFLAG_NOFORK | grep -v "0))" | \
-    sed -En 's/([^:]*):.*(OLD|NEW)TOY\( *([a-zA-Z][^,]*) *,.*/\1:\3/p'
+    $SED -En 's/([^:]*):.*(OLD|NEW)TOY\( *([a-zA-Z][^,]*) *,.*/\1:\3/p'
 }
 
 WORKING=
@@ -163,5 +164,5 @@ done &&
 echo -e "clean::\n\trm -f $WORKING $PENDING" &&
 echo -e "list:\n\t@echo $(echo $WORKING | tr ' ' '\n' | sort | xargs)" &&
 echo -e "list_pending:\n\t@echo $(echo $PENDING | tr ' ' '\n' | sort | xargs)" &&
-echo -e ".PHONY: $WORKING $PENDING" | sed 's/ \([^ ]\)/ test_\1/g'
+echo -e ".PHONY: $WORKING $PENDING" | $SED 's/ \([^ ]\)/ test_\1/g'
 ) > .singlemake
diff --git a/scripts/make.sh b/scripts/make.sh
index 45d6f1ca..388af651 100755
--- a/scripts/make.sh
+++ b/scripts/make.sh
@@ -6,6 +6,7 @@ export LANG=c
 export LC_ALL=C
 set -o pipefail
 source ./configure
+source scripts/portability.sh
 
 [ ! -z "$CROSS_COMPILE" ] && [ ! -e "$CROSS_COMPILE"cc ] &&
   echo "missing ${CROSS_COMPILE}cc" && exit 1
@@ -15,12 +16,7 @@ source ./configure
 UNSTRIPPED="generated/unstripped/$(basename "$OUTNAME")"
 
 # Try to keep one more cc invocation going than we have processors
-[ -z "$CPUS" ] && CPUS=$(($(nproc)+1))
-
-if [ -z "$SED" ]
-then
-  [ ! -z "$(which gsed 2>/dev/null)" ] && SED=gsed || SED=sed
-fi
+[ -z "$CPUS" ] && CPUS=$(($(nproc 2>/dev/null)+1))
 
 # Respond to V= by echoing command lines as well as running them
 DOTPROG=
@@ -102,7 +98,7 @@ genbuildsh()
 }
 
 if ! cmp -s <(genbuildsh 2>/dev/null | head -n 6 ; echo LINK="'"$LDOPTIMIZE $LDFLAGS) \
-          <(head -n 7 generated/build.sh 2>/dev/null | sed '7s/ -o .*//')
+          <(head -n 7 generated/build.sh 2>/dev/null | $SED '7s/ -o .*//')
 then
   echo -n "Library probe"
 
@@ -135,7 +131,8 @@ then
 
   # This long and roundabout sed invocation is to make old versions of sed
   # happy. New ones have '\n' so can replace one line with two without all
-  # the branches and tedious mucking about with hold space.
+  # the branches and tedious mucking about with hyperspace.
+  # TODO: clean this up to use modern stuff.
 
   $SED -n \
     -e 's/^# CONFIG_\(.*\) is not set.*/\1/' \
diff --git a/scripts/mkflags.c b/scripts/mkflags.c
index b28ae1e1..93294884 100644
--- a/scripts/mkflags.c
+++ b/scripts/mkflags.c
@@ -64,7 +64,7 @@ char *mark_gaps(char *flags, char *all)
     if (bare) bare = chrtype(c);
     if (*flags == c) {
       *(new++) = c;
-      *flags++;
+      flags++;
       continue;
     }
 
diff --git a/scripts/mktags.c b/scripts/mktags.c
index 9c23cf17..05494b2a 100644
--- a/scripts/mktags.c
+++ b/scripts/mktags.c
@@ -14,7 +14,7 @@ int main(int argc, char *argv[])
     char *line = 0, *s;
     ssize_t len;
 
-    len = getline(&line, &len, stdin);
+    len = getline(&line, (void *)&len, stdin);
     if (len<0) break;
     while (len && isspace(line[len-1])) line[--len]=0;
 
diff --git a/scripts/portability.sh b/scripts/portability.sh
new file mode 100644
index 00000000..fddd84ec
--- /dev/null
+++ b/scripts/portability.sh
@@ -0,0 +1,6 @@
+# sourced to find alternate names for things
+
+if [ -z "$SED" ]
+then
+  [ ! -z "$(which gsed 2>/dev/null)" ] && SED=gsed || SED=sed
+fi
diff --git a/scripts/test.sh b/scripts/test.sh
index 7e327a5d..a31021c6 100755
--- a/scripts/test.sh
+++ b/scripts/test.sh
@@ -1,6 +1,7 @@
 #!/bin/bash
 
-. scripts/runtest.sh
+source scripts/runtest.sh
+source scripts/portability.sh
 
 TOPDIR="$PWD"
 FILES="$PWD"/tests/files
@@ -26,7 +27,7 @@ cd testdir
 export LC_COLLATE=C
 
 [ -f "$TOPDIR/generated/config.h" ] &&
-  export OPTIONFLAGS=:$(echo $(sed -nr 's/^#define CFG_(.*) 1/\1/p' "$TOPDIR/generated/config.h") | sed 's/ /:/g')
+  export OPTIONFLAGS=:$(echo $($SED -nr 's/^#define CFG_(.*) 1/\1/p' "$TOPDIR/generated/config.h") | $SED 's/ /:/g')
 
 do_test()
 {
diff --git a/tests/xargs.test b/tests/xargs.test
index 407817cc..dce93ed3 100644
--- a/tests/xargs.test
+++ b/tests/xargs.test
@@ -27,6 +27,17 @@ rm one two three
 testing "-0 -n1" "printf 'a\0b\0c\0d\0e\0f' | xargs -0 -n1 echo _" "_ a\n_ b\n_ c\n_ d\n_ e\n_ f\n" "" ""
 testing "-0 -n2" "printf 'a\0b\0c\0d\0e\0f' | xargs -0 -n2 echo _" "_ a b\n_ c d\n_ e f\n" "" ""
 
+testing "-t" "xargs -t 2>stderr ; cat stderr ; rm stderr" "one two\necho one two \n" "" "one\ntwo\n"
+
+testing "-E END" "xargs -E END" "a b\n" "" "a\nb\nEND\nc\nd\n"
+
+testing "-r" "xargs -r echo x" "" "" ""
+
+# TODO: what exactly is -x supposed to do? why does coreutils output "one"?
+#testing "-x" "xargs -x -s 9 || echo expected" "one\nexpected\n" "" "one\ntwo\nthree"
+
+# TODO: test for -L? what exactly is the difference between -n and -L?
+
 #testing "-n exact match"
 #testing "-s exact match"
 #testing "-s 0"
diff --git a/toys.h b/toys.h
index 4083725a..9e49900b 100644
--- a/toys.h
+++ b/toys.h
@@ -108,7 +108,7 @@ extern struct toy_context {
   char wasroot;            // dropped setuid
 
   // This is at the end so toy_init() doesn't zero it.
-  jmp_buf *rebound;        // longjmp here instead of exit when do_rebound set
+  sigjmp_buf *rebound;     // siglongjmp here instead of exit when do_rebound
   struct arg_list *xexit;  // atexit() functions for xexit(), set by sigatexit()
   void *stacktop;          // nested toy_exec() call count, or 0 if vforked
 } toys;
diff --git a/toys/lsb/hostname.c b/toys/lsb/hostname.c
index c9fafa54..ac7f9163 100644
--- a/toys/lsb/hostname.c
+++ b/toys/lsb/hostname.c
@@ -10,7 +10,7 @@ config HOSTNAME
   bool "hostname"
   default y
   help
-    usage: hostname [-bsf] [-F FILENAME] [newname]
+    usage: hostname [-bdsf] [-F FILENAME] [newname]
 
     Get/set the current hostname.
 
@@ -36,13 +36,13 @@ void hostname_main(void)
   if (TT.F && (hostname = xreadfile(TT.F, 0, 0))) {
     if (!*chomp(hostname)) {
       if (CFG_TOYBOX_FREE) free(hostname);
-      if (!(toys.optflags&FLAG_b)) error_exit("empty '%s'", TT.F);
+      if (!FLAG(b)) error_exit("empty '%s'", TT.F);
       hostname = 0;
     }
   }
 
   // Implement -b.
-  if (!hostname && (toys.optflags&FLAG_b))
+  if (!hostname && FLAG(b))
     if (gethostname(toybuf, sizeof(toybuf)-1) || !*toybuf)
       hostname = "localhost";
 
@@ -55,9 +55,12 @@ void hostname_main(void)
 
   // Get the hostname.
   if (gethostname(toybuf, sizeof(toybuf)-1)) perror_exit("gethostname");
-  if (!(h = gethostbyname(toybuf))) perror_exit("gethostbyname");
-  snprintf(toybuf, sizeof(toybuf), "%s", h->h_name);
+  // We only do the DNS lookup for -d and -f.
+  if (FLAG(d) || FLAG(f)) {
+    if (!(h = gethostbyname(toybuf))) perror_exit("gethostbyname");
+    snprintf(toybuf, sizeof(toybuf), "%s", h->h_name);
+  }
   dot = strchr(toybuf, '.');
-  if (toys.optflags&FLAG_s) *dot = '\0';
-  xputs(toys.optflags&FLAG_d ? dot+1 : toybuf);
+  if (FLAG(s) && dot) *dot = '\0';
+  xputs(FLAG(d) ? dot+1 : toybuf);
 }
diff --git a/toys/pending/sh.c b/toys/pending/sh.c
index 0bfd32c5..8a9e93b6 100644
--- a/toys/pending/sh.c
+++ b/toys/pending/sh.c
@@ -205,13 +205,13 @@ static void run_pipeline(struct pipeline *line)
   // Is this command a builtin that should run in this process?
   if (tl && (tl->flags & TOYFLAG_NOFORK)) {
     struct toy_context temp;
-    jmp_buf rebound;
+    sigjmp_buf rebound;
 
     // This fakes lots of what toybox_main() does.
     memcpy(&temp, &toys, sizeof(struct toy_context));
     memset(&toys, 0, sizeof(struct toy_context));
 
-    if (!setjmp(rebound)) {
+    if (!sigsetjmp(rebound, 1)) {
       toys.rebound = &rebound;
       toy_init(tl, cmd->argv);
       tl->toy_main();
diff --git a/toys/pending/sntp.c b/toys/pending/sntp.c
index f34c3da2..446e3f75 100644
--- a/toys/pending/sntp.c
+++ b/toys/pending/sntp.c
@@ -4,24 +4,30 @@
  *
  * See https://www.ietf.org/rfc/rfc4330.txt
 
-USE_SNTP(NEWTOY(sntp, "<1", TOYFLAG_USR|TOYFLAG_BIN))
+USE_SNTP(NEWTOY(sntp, "sp:", TOYFLAG_USR|TOYFLAG_BIN))
 
 config SNTP
   bool "sntp"
   default n
   help
-    usage: sntp SERVER...
+    usage: sntp [-sm] [-p PORT] SERVER...
 
     Simple Network Time Protocol client, set system clock from a server.
+
+    -p	Use PORT (default 123)
+    -s	Serer
 */
 
 #define FOR_sntp
 #include "toys.h"
 
 GLOBALS(
-  int unused;
+  char *p, *m;
 )
 
+// Seconds from 1900 to 1970, including appropriate leap days
+#define SEVENTIES 2208988800L
+
 union socksaddr {
   struct sockaddr_in in;
   struct sockaddr_in6 in6;
@@ -46,20 +52,123 @@ int xrecvwait(int fd, char *buf, int len, union socksaddr *sa, int timeout)
   return len;
 }
 
+/// hardwired getaddrinfo() variant for what we want here.
+static struct addrinfo *gai(char *server)
+{
+  return xgetaddrinfo(server, TT.p, AF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP, 0);
+}
+
+// Get time and return ntptime (saving timespec in pointer if not null)
+// NTP time is high 32 bits = seconds since 1970 (blame RFC 868), low 32 bits
+// fraction of a second.
+static unsigned long long lunchtime(struct timespec *television)
+{
+  struct timespec tv;
+
+  clock_gettime(CLOCK_REALTIME, &tv);
+
+  if (television) *television = tv;
+
+  // Unix time is 1970 but RFCs 868 and 958 said 1900, so add seconds 1900->1970
+  // If they'd done a 34/30 bit split the Y2036 problem would be centuries
+  // from now and still give us nanosecond accuracy, but no...
+  return ((tv.tv_sec+SEVENTIES)<<32)+(((long long)tv.tv_nsec)<<32)/1000000000;
+}
+
+// convert ntptime back to struct timespec.
+static void doublyso(unsigned long long now, struct timespec *tv)
+{
+  // Y2036 fixup: if time wrapped, it's in the future
+  tv->tv_sec = (now>>32) + (1L<<32)*!(now&(1L<<63));
+  tv->tv_sec -= SEVENTIES; // Force signed math for Y2038 fixup
+  tv->tv_nsec = ((now&((1L<<32)-1))*1000000000)>>32;
+}
+
+// return difference between two timespecs in nanosecs
+static long long nanodiff(struct timespec *old, struct timespec *new)
+{
+  return (new->tv_sec - old->tv_sec)*1000000000LL+(new->tv_nsec - old->tv_nsec);
+}
+
+// Adjust timespec by nanosecond offset
+static void nanomove(struct timespec *ts, long long offset)
+{
+  long long nano = ts->tv_nsec + offset, secs = nano/1000000000;
+
+  ts->tv_sec += secs;
+  nano %= 1000000000;
+  if (nano<0) {
+    ts->tv_sec--;
+    nano += 1000000000;
+  }
+  ts->tv_nsec = nano;
+}
+
+int multicast = 0;
+
 void sntp_main(void)
 {
+  struct timespec tv, tv2;
+  unsigned long long *pktime = (void *)toybuf, now, then, before;
+  long long diff;
   struct addrinfo *ai;
   union socksaddr sa;
-  int fd, len;
+  int fd, attempts;
+
+  if (!FLAG(s) && !*toys.optargs) error_exit("Need -s or SERVER");
 
-  ai = xgetaddrinfo(*toys.optargs, 0, AF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP, 0);
+  // Lookup address and open server or client UDP socket
+  if (!TT.p || !*TT.p) TT.p = "123";
+  ai = gai(*toys.optargs);
   // When root, bind to local server address
-  if (!getuid())
-    fd = xbind(xgetaddrinfo("", "123", AF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP, 0));
+  if (!getuid()) fd = xbind(gai(""));
   else fd = xsocket(ai->ai_family, SOCK_DGRAM, IPPROTO_UDP);
 
-  xsendto(fd, toybuf, 48, ai->ai_addr);
-  len = xrecvwait(fd, toybuf, sizeof(toybuf), &sa, 5000);
-  printf("%d\n", len);
-  if (len>0) write(1, toybuf, len);
+  // Try 3 times
+  for (attempts = 0; attempts < 3; attempts++) {
+    // Prepare outgoing NTP packet
+    memset(toybuf, 0, 48);
+    *toybuf = 0xe3; // li = 3 (unsynchronized), version = 4, mode = 3 (client)
+    toybuf[2] = 8;  // poll frequency 1<<8 = 256 seconds
+    pktime[5] = SWAP_BE64(before = lunchtime(&tv));
+
+    // Send and ye shall receive
+    xsendto(fd, toybuf, 48, ai->ai_addr);
+    then = (now = millitime())+4000;
+    while (now<then) {
+      // TODO: confirm sa matches
+      if (48 == xrecvwait(fd, toybuf, sizeof(toybuf), &sa, then-now)) {
+        if (multicast || pktime[3] == SWAP_BE64(before)) break;
+      }
+      now = millitime();
+    }
+    if (now < then) break;
+  }
+  lunchtime(&tv2);
+
+//printf("before) %ld %ld\n", (long)tv.tv_sec, (long)tv.tv_nsec);
+//printf("after) %ld %ld\n", (long)tv2.tv_sec, (long)tv2.tv_nsec);
+
+  // determine midpoint of packet transit time according to local clock
+  // (simple calculation: assume each direction took same time so midpoint
+  // is time reported by other clock)
+  diff = nanodiff(&tv, &tv2)/2;
+//printf("halfoff = %lld %llx\n", diff, diff);
+  nanomove(&tv, diff);
+//printf("midpoint) %ld %ld\n", (long)tv.tv_sec, (long)tv.tv_nsec);
+
+  doublyso(SWAP_BE64(pktime[5]), &tv2);
+  diff = nanodiff(&tv2, &tv);
+//printf("server) %ld %ld\n", (long)tv2.tv_sec, (long)tv2.tv_nsec);
+//printf("offby = %lld\n", diff);
+
+//int i;
+//for (i=0; i<48; ) {
+//  printf("%02x", toybuf[i]);
+//  if (!(++i&15)) printf("\n");
+//}
+
+  format_iso_time(toybuf, sizeof(toybuf)-1, &tv);
+  printf("%s offset %c%d.%09d secs\n", toybuf, (diff<0) ? '-' : '+',
+    abs(diff/1000000000), abs(diff%1000000000));
 }
diff --git a/toys/posix/ps.c b/toys/posix/ps.c
index f5e080c7..fef9c908 100644
--- a/toys/posix/ps.c
+++ b/toys/posix/ps.c
@@ -234,7 +234,7 @@ struct ofields {
  * struct procpid contains a slot[] array of 64 bit values, with the following
  * data at each position in the array. Most is read from /proc/$PID/stat (see
  * https://kernel.org/doc/Documentation/filesystems/proc.txt table 1-4) but
- * we we replace several fields with don't use with other data. */
+ * we replace several fields with don't use with other data. */
 
 enum {
  SLOT_pid,      /*process id*/            SLOT_ppid,      // parent process id
@@ -297,7 +297,7 @@ struct procpid {
  *        get the overflow back).
  *
  * slot: which slot[] out of procpid. Negative means it's a string field.
- *       Setting bit |64 requests extra display/sort processing.
+ *       value|XX requests extra display/sort processing.
  *
  * The TAGGED_ARRAY plumbing produces an enum of indexes, the "tag" is the
  * first string argument and the prefix is the first argument to TAGGED_ARRAY
@@ -308,8 +308,9 @@ struct procpid {
  *   if (TT.bits & _PS_NAME) printf("-o included PS_NAME");
  */
 
+#define XX 64 // force string representation for sorting, etc
+
 // TODO: Android uses -30 for LABEL, but ideally it would auto-size.
-// 64|slot means compare as string when sorting
 struct typography {
   char *name, *help;
   signed char width, slot;
@@ -349,13 +350,13 @@ struct typography {
 
   // user/group (may call getpwuid() or similar)
   {"UID", "User id", 5, SLOT_uid},
-  {"USER", "User name", -12, 64|SLOT_uid},
+  {"USER", "User name", -12, XX|SLOT_uid},
   {"RUID", "Real (before suid) user ID", 4, SLOT_ruid},
-  {"RUSER", "Real (before suid) user name", -8, 64|SLOT_ruid},
+  {"RUSER", "Real (before suid) user name", -8, XX|SLOT_ruid},
   {"GID", "Group ID", 8, SLOT_gid},
-  {"GROUP", "Group name", -8, 64|SLOT_gid},
+  {"GROUP", "Group name", -8, XX|SLOT_gid},
   {"RGID", "Real (before sgid) Group ID", 4, SLOT_rgid},
-  {"RGROUP", "Real (before sgid) group name", -8, 64|SLOT_rgid},
+  {"RGROUP", "Real (before sgid) group name", -8, XX|SLOT_rgid},
 
   // clock displays (00:00:00)
   {"TIME", "CPU time consumed", 8, SLOT_utime},
@@ -382,20 +383,19 @@ struct typography {
 
   // Misc (special cases)
   {"STIME", "Start time (ISO 8601)", 5, SLOT_starttime},
-  {"F", "Flags 1=FORKNOEXEC 4=SUPERPRIV", 1, 64|SLOT_flags},
+  {"F", "Flags 1=FORKNOEXEC 4=SUPERPRIV", 1, XX|SLOT_flags},
   {"S", "Process state:\n"
    "\t  R (running) S (sleeping) D (device I/O) T (stopped)  t (traced)\n"
    "\t  Z (zombie)  X (deader)   x (dead)       K (wakekill) W (waking)",
-   -1, 64},
+   -1, XX},
   {"STAT", "Process state (S) plus:\n"
    "\t  < high priority          N low priority L locked memory\n"
    "\t  s session leader         + foreground   l multithreaded",
-   -5, 64},
-  {"PCY", "Android scheduling policy", 3, 64|SLOT_pcy},
+   -5, XX},
+  {"PCY", "Android scheduling policy", 3, XX|SLOT_pcy},
 );
 
 // Show sorted "-o help" text for fields listed in toybuf[len]
-
 static void help_fields(int len, int multi)
 {
   int i, j, k, left = 0;
@@ -429,7 +429,7 @@ static void help_fields(int len, int multi)
   if (!multi && left) xputc('\n');
 }
 
-// Print help text for all -o field, with categories.
+// Print help text for each -o field, with categories.
 static void help_help(void)
 {
   int i, jump = PS_CMD+1-PS_COMM;
@@ -454,7 +454,7 @@ static void help_help(void)
   xexit();
 }
 
-// Return 0 to discard, nonzero to keep
+// process match filter for top/ps/pgrep: Return 0 to discard, nonzero to keep
 static int shared_match_process(long long *slot)
 {
   struct ptr_len match[] = {
@@ -478,8 +478,7 @@ static int shared_match_process(long long *slot)
   return ll ? 0 : -1;
 }
 
-
-// Return 0 to discard, nonzero to keep
+// process match filter for ps: Return 0 to discard, nonzero to keep
 static int ps_match_process(long long *slot)
 {
   int i = shared_match_process(slot);
@@ -497,12 +496,12 @@ static int ps_match_process(long long *slot)
   return 1;
 }
 
-// Convert field to string representation
+// Generate display string (260 bytes at end of toybuf) from struct ofield
 static char *string_field(struct procpid *tb, struct ofields *field)
 {
   char *buf = toybuf+sizeof(toybuf)-260, *out = buf, *s;
   int which = field->which, sl = typos[which].slot;
-  long long *slot = tb->slot, ll = (sl >= 0) ? slot[sl&63] : 0;
+  long long *slot = tb->slot, ll = (sl >= 0) ? slot[sl&(XX-1)] : 0;
 
   // numbers, mostly from /proc/$PID/stat
   if (which <= PS_BIT) {
@@ -536,7 +535,7 @@ static char *string_field(struct procpid *tb, struct ofields *field)
   // user/group
   } else if (which <= PS_RGROUP) {
     sprintf(out, "%lld", ll);
-    if (sl&64) {
+    if (sl&XX) {
       if (which > PS_RUSER) {
         struct group *gr = bufgetgrgid(ll);
 
@@ -576,7 +575,7 @@ static char *string_field(struct procpid *tb, struct ofields *field)
 
   // Percentage displays
   } else if (which <= PS__CPU) {
-    ll = slot[sl&63]*1000;
+    ll = slot[sl&(XX-1)]*1000;
     if (which==PS__VSZ || which==PS__MEM)
       ll /= slot[SLOT_totalram]/((which==PS__VSZ) ? 1024 : 4096);
     else if (slot[SLOT_upticks]) ll /= slot[SLOT_upticks];
@@ -624,7 +623,7 @@ static char *string_field(struct procpid *tb, struct ofields *field)
   return out;
 }
 
-// Display process data that get_ps() read from /proc, formatting with TT.fields
+// Display process data that get_ps() read from /proc, formatting via TT.fields
 static void show_ps(void *p)
 {
   struct procpid *tb = p;
@@ -687,7 +686,7 @@ static void show_ps(void *p)
   putchar(TT.time ? '\r' : '\n');
 }
 
-// dirtree callback: read data about process, then display or store it.
+// dirtree callback: read data about a process, then display or store it.
 // Fills toybuf with struct procpid and either DIRTREE_SAVEs a copy to ->extra
 // (in -k mode) or calls show_ps directly on toybuf (for low memory systems).
 static int get_ps(struct dirtree *new)
@@ -982,6 +981,7 @@ static int get_ps(struct dirtree *new)
   return DIRTREE_SAVE;
 }
 
+// wrapper for get_ps() that also collects threads under each processes
 static int get_threads(struct dirtree *new)
 {
   struct dirtree *dt;
@@ -1033,6 +1033,7 @@ static int get_threads(struct dirtree *new)
   return 0;
 }
 
+// Parse one FIELD argument (with optional =name :width) into struct ofields
 static char *parse_ko(void *data, char *type, int length)
 {
   struct ofields *field;
@@ -1100,6 +1101,8 @@ static char *parse_ko(void *data, char *type, int length)
   return 0;
 }
 
+// Write FIELD list into display header string (truncating at blen),
+// and return bitfield of which FIELDs are used.
 static long long get_headers(struct ofields *field, char *buf, int blen)
 {
   long long bits = 0;
@@ -1114,7 +1117,7 @@ static long long get_headers(struct ofields *field, char *buf, int blen)
   return bits;
 }
 
-// Parse -p -s -t -u -U -g -G
+// Parse command line options -p -s -t -u -U -g -G
 static char *parse_rest(void *data, char *str, int len)
 {
   struct ptr_len *pl = (struct ptr_len *)data;
@@ -1192,7 +1195,7 @@ static char *parse_rest(void *data, char *str, int len)
   return str;
 }
 
-// sort for -k
+// sort processes by FIELD(s) listed in option -k
 static int ksort(void *aa, void *bb)
 {
   struct ofields *field;
@@ -1203,7 +1206,7 @@ static int ksort(void *aa, void *bb)
     slot = typos[field->which].slot;
 
     // Can we do numeric sort?
-    if (!(slot&64)) {
+    if (!(slot&XX)) {
       if (ta->slot[slot]<tb->slot[slot]) ret = -1;
       if (ta->slot[slot]>tb->slot[slot]) ret = 1;
     }
@@ -1220,6 +1223,8 @@ static int ksort(void *aa, void *bb)
   return ret;
 }
 
+// Collect ->extra field from leaf nodes DIRTREE_SAVEd by get_ps() into array
+// (recursion because tree from get_thread() isn't flat list of siblings)
 static struct procpid **collate_leaves(struct procpid **tb, struct dirtree *dt) 
 {
   while (dt) {
@@ -1234,6 +1239,8 @@ static struct procpid **collate_leaves(struct procpid **tb, struct dirtree *dt)
   return tb;
 }
 
+// Allocate struct procpid array of length count and populate it with ->extra
+// fields from dirtree leaf nodes. (top diffs old & new array to show changes)
 static struct procpid **collate(int count, struct dirtree *dt)
 {
   struct procpid **tbsort = xmalloc(count*sizeof(struct procpid *));
@@ -1243,6 +1250,7 @@ static struct procpid **collate(int count, struct dirtree *dt)
   return tbsort;
 } 
 
+// parse command line arguments (ala -k -o) with a comma separated FIELD list
 static void default_ko(char *s, void *fields, char *err, struct arg_list *arg)
 {
   struct arg_list def;
@@ -1320,7 +1328,7 @@ void ps_main(void)
 
     for (field = TT.fields; field; field = field->next) {
       if (FLAG(n) && field->which>=PS_UID
-        && field->which<=PS_RGROUP && (typos[field->which].slot&64))
+        && field->which<=PS_RGROUP && (typos[field->which].slot&XX))
           field->which--;
     }
   }
@@ -1585,7 +1593,7 @@ static void top_common(
           pos = stpcpy(toybuf, "Totals:");
           for (field = TT.fields; field; field = field->next) {
             long long ll, bits = 0;
-            int slot = typos[field->which].slot&63;
+            int slot = typos[field->which].slot&(XX-1);
 
             if (field->which<PS_C || field->which>PS_DIO) continue;
             ll = 1LL<<field->which;
diff --git a/toys/posix/xargs.c b/toys/posix/xargs.c
index d25a2e3f..e23d14c4 100644
--- a/toys/posix/xargs.c
+++ b/toys/posix/xargs.c
@@ -5,28 +5,28 @@
  * See http://opengroup.org/onlinepubs/9699919799/utilities/xargs.html
  *
  * TODO: Rich's whitespace objection, env size isn't fixed anymore.
+ * TODO: -x	Exit if can't fit everything in one command
+ * TODO: -L	Max number of lines of input per command
 
-USE_XARGS(NEWTOY(xargs, "^I:E:L#ptxrn#<1s#0[!0E]", TOYFLAG_USR|TOYFLAG_BIN))
+USE_XARGS(NEWTOY(xargs, "^I:E:ptrn#<1s#0[!0E]", TOYFLAG_USR|TOYFLAG_BIN))
 
 config XARGS
   bool "xargs"
   default y
   help
-    usage: xargs [-ptxr0] [-s NUM] [-n NUM] [-L NUM] [-E STR] COMMAND...
+    usage: xargs [-0prt] [-s NUM] [-n NUM] [-E STR] COMMAND...
 
     Run command line one or more times, appending arguments from stdin.
 
     If command exits with 255, don't launch another even if arguments remain.
 
-    -s	Size in bytes per command line
-    -n	Max number of arguments per command
     -0	Each argument is NULL terminated, no whitespace or quote processing
-    #-p	Prompt for y/n from tty before running each command
-    #-t	Trace, print command line to stderr
-    #-x	Exit if can't fit everything in one command
-    #-r	Don't run command with empty input
-    #-L	Max number of lines of input per command
-    -E	stop at line matching string
+    -E	Stop at line matching string
+    -n	Max number of arguments per command
+    -p	Prompt for y/n from tty before running each command
+    -r	Don't run command with empty input
+    -s	Size in bytes per command line
+    -t	Trace, print command line to stderr
 
 config XARGS_PEDANTIC
   bool "TODO xargs pedantic posix compatability"
@@ -41,7 +41,7 @@ config XARGS_PEDANTIC
 #include "toys.h"
 
 GLOBALS(
-  long s, n, L;
+  long s, n;
   char *E, *I;
 
   long entries, bytes;
@@ -134,6 +134,8 @@ void xargs_main(void)
 
   // Loop through exec chunks.
   while (data || !done) {
+    int doit = 1;
+
     TT.entries = 0;
     TT.bytes = bytes;
 
@@ -163,6 +165,8 @@ void xargs_main(void)
       break;
     }
 
+    if (TT.entries == 0 && FLAG(r)) continue;
+
     // Accumulate cally thing
 
     if (data && !TT.entries) error_exit("argument too long");
@@ -176,13 +180,25 @@ void xargs_main(void)
     for (dtemp = dlist; dtemp; dtemp = dtemp->next)
       handle_entries(dtemp->data, out+entries);
 
-    if (!(pid = XVFORK())) {
-      xclose(0);
-      open("/dev/null", O_RDONLY);
-      xexec(out);
+    if (FLAG(p) || FLAG(t)) {
+      int i;
+
+      for (i = 0; out[i]; ++i) fprintf(stderr, "%s ", out[i]);
+      if (FLAG(p)) {
+        fprintf(stderr, "?");
+	doit = yesno(0);
+      } else fprintf(stderr, "\n");
+    }
+
+    if (doit) {
+      if (!(pid = XVFORK())) {
+        xclose(0);
+        open("/dev/null", O_RDONLY);
+        xexec(out);
+      }
+      waitpid(pid, &status, 0);
+      status = WIFEXITED(status) ? WEXITSTATUS(status) : WTERMSIG(status)+127;
     }
-    waitpid(pid, &status, 0);
-    status = WIFEXITED(status) ? WEXITSTATUS(status) : WTERMSIG(status)+127;
 
     // Abritrary number of execs, can't just leak memory each time...
     while (dlist) {
diff --git a/www/code.html b/www/code.html
index b1b17ef5..953c53bb 100644
--- a/www/code.html
+++ b/www/code.html
@@ -653,7 +653,7 @@ and change the exit code to indicate error, lets our toys.exit function
 change happen for signal exit paths and lets us remove the functions
 after we've called them.</p>
 
-<p>You can intercept our exit by assigning a setjmp/longjmp buffer to
+<p>You can intercept our exit by assigning a sigsetjmp/siglongjmp buffer to
 toys.rebound (set it back to zero to restore the default behavior).
 If you do this, cleaning up resource leaks is your problem.</p>