X-Git-Url: https://git.xandkar.net/?p=khatus.git;a=blobdiff_plain;f=x5%2Fkhatus.c;h=5407acde0b145131f038515d773e0a8d17bf2526;hp=382c8731aaeee3c6494955567ecbd806468bb783;hb=HEAD;hpb=900b9a6b1cf64ec6fc67bca260784ab93aec4fa1

diff --git a/x5/khatus.c b/x5/khatus.c
index 382c873..5407acd 100644
--- a/x5/khatus.c
+++ b/x5/khatus.c
@@ -5,6 +5,7 @@
 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -24,10 +25,12 @@
 }
 #define ERRMSG "ERROR"
 
+
 static const char errmsg[] = ERRMSG;
 static const int  errlen   = sizeof(ERRMSG) - 1;
 
-char *argv0;
+char *argv0 = NULL;
+int running = 1;
 
 /* TODO: Convert slot list to slot array. */
 typedef struct Slot Slot;
@@ -47,10 +50,11 @@ typedef struct Config Config;
 struct Config {
 	double interval;
 	char * separator;
+	char   expiry_character;
 	Slot * slots;
 	int    slot_count;
-	int    total_width;
-	int    output_to_x_root_window;
+	int    buf_width;
+	int    to_x_root;
 };
 
 enum read_status {
@@ -60,8 +64,54 @@ enum read_status {
 	FAILURE
 };
 
+char *
+buf_create(Config *cfg)
+{
+	int seplen;
+	char *buf;
+	Slot *s;
+
+	buf = calloc(1, cfg->buf_width + 1);
+	if (buf == NULL)
+		khlib_fatal(
+		    "[memory] Failed to allocate buffer of %d bytes",
+		    cfg->buf_width
+		);
+	memset(buf, ' ', cfg->buf_width);
+	buf[cfg->buf_width] = '\0';
+	seplen = strlen(cfg->separator);
+	/* Set the separators */
+	for (s = cfg->slots; s; s = s->next) {
+		/* Skip the first, left-most */
+		if (s->out_pos_lo) {
+			/* Copying only seplen ensures we omit the '\0' byte. */
+			strncpy(
+			    buf + (s->out_pos_lo - seplen),
+			    cfg->separator,
+			    seplen
+			);
+		}
+	}
+	return buf;
+}
+
+Slot *
+slots_rev(Slot *old)
+{
+	Slot *tmp = NULL;
+	Slot *new = NULL;
+
+	while (old) {
+		tmp       = old->next;
+		old->next = new;
+		new       = old;
+		old       = tmp;
+	}
+	return new;
+}
+
 void
-slot_print_one(Slot *s)
+slot_log(Slot *s)
 {
 	khlib_info("Slot "
 	    "{"
@@ -90,15 +140,277 @@ slot_print_one(Slot *s)
 }
 
 void
-slot_print_all(Slot *head)
+slots_log(Slot *head)
+{
+	Slot *s = head;
+
+	for (; s; s = s->next) {
+		slot_log(s);
+	}
+}
+
+void
+slots_assert_fifos_exist(Slot *s)
+{
+	struct stat st;
+	int errors = 0;
+
+	for (; s; s = s->next) {
+		if (lstat(s->in_fifo, &st) < 0) {
+			khlib_error(
+			    "Cannot stat \"%s\". Error: %s\n",
+			    s->in_fifo,
+			    strerror(errno)
+			);
+			errors++;
+			continue;
+		}
+		if (!(st.st_mode & S_IFIFO)) {
+			khlib_error("\"%s\" is not a FIFO\n", s->in_fifo);
+			errors++;
+			continue;
+		}
+	}
+	if (errors)
+		khlib_fatal(
+		    "Encountered errors with given file paths. See log.\n"
+		);
+}
+
+void
+slot_close(Slot *s)
+{
+	close(s->in_fd);
+	s->in_fd        = -1;
+	s->out_pos_cur  = s->out_pos_lo;
+}
+
+void
+slots_close(Slot *s)
+{
+	for (; s; s = s->next)
+		if (s->in_fd > -1)
+			slot_close(s);
+}
+
+
+void
+slot_expire(Slot *s, struct timespec t, char expiry_character, char *buf)
 {
-	for (Slot *s = head; s; s = s->next) {
-		slot_print_one(s);
+	struct timespec td;
+
+	timespecsub(&t, &(s->in_last_read), &td);
+	if (timespeccmp(&td, &(s->out_ttl), >=)) {
+		memset(
+		    buf + s->out_pos_lo,
+		    expiry_character,
+		    s->out_width
+		);
+		khlib_warn("Slot expired: \"%s\"\n", s->in_fifo);
+	}
+}
+
+void
+slot_set_error(Slot *s, char *buf)
+{
+	char *b;
+	int i;
+
+	s->in_fd = -1;
+	b = buf + s->out_pos_lo;
+	/* Copy as much of the error message as possible.
+	 * EXCLUDING the terminating \0. */
+	for (i = 0; i < errlen && i < s->out_width; i++)
+		b[i] = errmsg[i];
+	/* Any remaining positions: */
+	memset(b + i, '_', s->out_width - i);
+}
+
+enum read_status
+slot_read(Slot *s, char *buf)
+{
+	char c;  /* Character read. */
+	int  r;  /* Remaining unused positions in buffer range. */
+
+	for (;;) {
+		switch (read(s->in_fd, &c, 1)) {
+		case -1:
+			khlib_error(
+			    "Failed to read: \"%s\". errno: %d, msg: %s\n",
+			    s->in_fifo,
+			    errno,
+			    strerror(errno)
+			);
+			switch (errno) {
+			case EINTR:
+			case EAGAIN:
+				return RETRY;
+			default:
+				return FAILURE;
+			}
+		case  0:
+			khlib_debug("%s: End of FILE\n", s->in_fifo);
+			s->out_pos_cur = s->out_pos_lo;
+			return END_OF_FILE;
+		case  1:
+			/* TODO: Consider making msg term char a CLI option */
+			if (c == '\n' || c == '\0') {
+				r = (s->out_pos_hi - s->out_pos_cur) + 1;
+				if (r > 0)
+					memset(buf + s->out_pos_cur, ' ', r);
+				return END_OF_MESSAGE;
+			} else {
+				if (s->out_pos_cur <= s->out_pos_hi)
+					buf[s->out_pos_cur++] = c;
+				else
+					/*
+					 * Force EOM beyond available range.
+					 * To ensure that a rogue large message
+					 * doesn't trap us here needlessly
+					 * long.
+					 */
+					return END_OF_MESSAGE;
+			}
+			break;
+		default:
+			assert(0);
+		}
+	}
+}
+
+void
+slots_read(Config *cfg, struct timespec *ti, char *buf)
+{
+	fd_set fds;
+	int maxfd = -1;
+	int ready = 0;
+	struct stat st;
+	struct timespec t;
+	Slot *s;
+
+	FD_ZERO(&fds);
+	for (s = cfg->slots; s; s = s->next) {
+		/* TODO: Create the FIFO if it doesn't already exist. */
+		if (lstat(s->in_fifo, &st) < 0) {
+			khlib_error(
+			    "Cannot stat \"%s\". Error: %s\n",
+			    s->in_fifo,
+			    strerror(errno)
+			);
+			slot_set_error(s, buf);
+			continue;
+		}
+		if (!(st.st_mode & S_IFIFO)) {
+			khlib_error("\"%s\" is not a FIFO\n", s->in_fifo);
+			slot_set_error(s, buf);
+			continue;
+		}
+		if (s->in_fd < 0) {
+			khlib_debug(
+			    "%s: closed. opening. in_fd: %d\n",
+			    s->in_fifo,
+			    s->in_fd
+			);
+			s->in_fd = open(s->in_fifo, O_RDONLY | O_NONBLOCK);
+		} else {
+			khlib_debug(
+			    "%s: already openned. in_fd: %d\n",
+			    s->in_fifo,
+			    s->in_fd
+			);
+		}
+		if (s->in_fd == -1) {
+			/* TODO Consider backing off retries for failed slots */
+			khlib_error("Failed to open \"%s\"\n", s->in_fifo);
+			slot_set_error(s, buf);
+			continue;
+		}
+		khlib_debug("%s: open. in_fd: %d\n", s->in_fifo, s->in_fd);
+		if (s->in_fd > maxfd)
+			maxfd = s->in_fd;
+		FD_SET(s->in_fd, &fds);
 	}
+	khlib_debug("selecting...\n");
+	ready = pselect(maxfd + 1, &fds, NULL, NULL, ti, NULL);
+	khlib_debug("ready: %d\n", ready);
+	clock_gettime(CLOCK_MONOTONIC, &t);
+	if (ready == -1) {
+		switch (errno) {
+		case EINTR:
+			khlib_error(
+			    "pselect interrupted: %d, errno: %d, msg: %s\n",
+			    ready,
+			    errno,
+			    strerror(errno)
+			);
+			/* TODO: Reconsider what to do here. */
+			return;
+		default:
+			khlib_fatal(
+			    "pselect failed: %d, errno: %d, msg: %s\n",
+			    ready,
+			    errno,
+			    strerror(errno)
+			);
+		}
+	}
+	/* At-least-once ensures that expiries are still checked on timeouts. */
+	do {
+		for (s = cfg->slots; s; s = s->next) {
+			if (s->in_fd < 0)
+				continue;
+			if (FD_ISSET(s->in_fd, &fds)) {
+				khlib_debug("reading: %s\n", s->in_fifo);
+				switch (slot_read(s, buf)) {
+				/*
+				 * ### MESSAGE LOSS ###
+				 * is introduced by closing at EOM in addition
+				 * to EOF, since there may be unread messages
+				 * remaining in the pipe. However,
+				 *
+				 * ### INTER-MESSAGE PUSHBACK ###
+				 * is also gained, since pipes block at the
+				 * "open" call.
+				 *
+				 * This is an acceptable trade-off because we
+				 * are a stateless reporter of a _most-recent_
+				 * status, not a stateful accumulator.
+				 *
+				 * ### LOSSLESS ALTERNATIVES ###
+				 * - Read each pipe until EOF before reading
+				 *   another.
+				 *   PROBLEM: a fast writer can trap us in the
+				 *   read loop.
+				 *
+				 * - Read each pipe until EOM, but close only
+				 *   at EOF.
+				 *   PROBLEM: a fast writer can fill the pipe
+				 *   faster than we can read it and we end-up
+				 *   displaying stale data.
+				 *
+				 */
+				case END_OF_MESSAGE:
+				case END_OF_FILE:
+				case FAILURE:
+					slot_close(s);
+					s->in_last_read = t;
+					ready--;
+					break;
+				case RETRY:
+					break;
+				default:
+					assert(0);
+				}
+			} else {
+				slot_expire(s, t, cfg->expiry_character, buf);
+			}
+		}
+	} while (ready);
+	assert(ready == 0);
 }
 
 void
-config_print(Config *cfg)
+config_log(Config *cfg)
 {
 	khlib_info(
 	    "Config "
@@ -106,15 +418,34 @@ config_print(Config *cfg)
 	    " interval = %f,"
 	    " separator = %s,"
 	    " slot_count = %d,"
-	    " total_width = %d,"
+	    " buf_width = %d,"
 	    " slots = ..."
 	    " }\n",
 	    cfg->interval,
 	    cfg->separator,
 	    cfg->slot_count,
-	    cfg->total_width
+	    cfg->buf_width
 	);
-	slot_print_all(cfg->slots);
+	slots_log(cfg->slots);
+}
+
+void
+config_stretch_for_separators(Config *cfg)
+{
+	int seplen = strlen(cfg->separator);
+	int prefix = 0;
+	int nslots = 0;
+	Slot *s    = cfg->slots;
+
+	while (s) {
+		s->out_pos_lo  += prefix;
+		s->out_pos_hi  += prefix;
+		s->out_pos_cur  = s->out_pos_lo;
+		prefix         += seplen;
+		nslots++;
+		s = s->next;
+	}
+	cfg->buf_width += (seplen * (nslots - 1));
 }
 
 int
@@ -159,9 +490,12 @@ print_usage()
 	    "             | -s SEPARATOR\n"
 	    "             | -x (* Output to X root window *)\n"
 	    "             | -l LOG_LEVEL\n"
+	    "             | -e EXPIRY_CHARACTER\n"
 	    "  SEPARATOR  = string\n"
 	    "  INTERVAL   = float  (* (positive) number of seconds *)\n"
 	    "  LOG_LEVEL  = int  (* %d through %d *)\n"
+	    "  EXPIRY_CHARACTER = string  "
+	    "(* Character with which to fill the slot upon expiration. *)\n"
 	    "\n",
 	    argv0,
 	    Nothing,
@@ -224,6 +558,15 @@ parse_opts_opt_l(Config *cfg, int argc, char *argv[], int i)
 	opts_parse_any(cfg, argc, argv, i);
 }
 
+void
+parse_opts_opt_e(Config *cfg, int argc, char *argv[], int i)
+{
+	if (i >= argc)
+		usage("Option -e parameter is missing.\n");
+	cfg->expiry_character = argv[i++][0];
+	opts_parse_any(cfg, argc, argv, i);
+}
+
 void
 parse_opts_opt(Config *cfg, int argc, char *argv[], int i)
 {
@@ -237,13 +580,17 @@ parse_opts_opt(Config *cfg, int argc, char *argv[], int i)
 		parse_opts_opt_s(cfg, argc, argv, ++i);
 		break;
 	case 'x':
-		cfg->output_to_x_root_window = 1;
+		cfg->to_x_root = 1;
 		opts_parse_any(cfg, argc, argv, ++i);
 		break;
 	case 'l':
 		/* TODO: Generic set_int */
 		parse_opts_opt_l(cfg, argc, argv, ++i);
 		break;
+	case 'e':
+		/* TODO: Generic set_str */
+		parse_opts_opt_e(cfg, argc, argv, ++i);
+		break;
 	default :
 		usage("Option \"%s\" is invalid\n", argv[i]);
 	}
@@ -252,38 +599,44 @@ parse_opts_opt(Config *cfg, int argc, char *argv[], int i)
 void
 parse_opts_spec(Config *cfg, int argc, char *argv[], int i)
 {
+	char *n;
+	char *w;
+	char *t;
+	struct timespec in_last_read;
+	Slot *s;
+
 	if ((i + 3) > argc)
 		usage(
 		    "[spec] Parameter(s) missing for fifo \"%s\".\n",
 		    argv[i]
 		);
 
-	char *n = argv[i++];
-	char *w = argv[i++];
-	char *t = argv[i++];
-
-	struct timespec in_last_read;
+	n = argv[i++];
+	w = argv[i++];
+	t = argv[i++];
 
 	if (!is_pos_num(w))
 		usage("[spec] Invalid width: \"%s\", for fifo \"%s\"\n", w, n);
 	if (!is_decimal(t))
 		usage("[spec] Invalid TTL: \"%s\", for fifo \"%s\"\n", t, n);
+
 	in_last_read.tv_sec  = 0;
 	in_last_read.tv_nsec = 0;
-	Slot *s = calloc(1, sizeof(struct Slot));
+	s = calloc(1, sizeof(struct Slot));
+
 	if (s) {
 		s->in_fifo      = n;
 		s->in_fd        = -1;
-		s->out_width     = atoi(w);
-		s->out_ttl       = khlib_timespec_of_float(atof(t));
+		s->out_width    = atoi(w);
+		s->out_ttl      = khlib_timespec_of_float(atof(t));
 		s->in_last_read = in_last_read;
-		s->out_pos_lo  = cfg->total_width;
+		s->out_pos_lo   = cfg->buf_width;
 		s->out_pos_cur  = s->out_pos_lo;
-		s->out_pos_hi = s->out_pos_lo + s->out_width - 1;
-		s->next      = cfg->slots;
+		s->out_pos_hi   = s->out_pos_lo + s->out_width - 1;
+		s->next		= cfg->slots;
 
 		cfg->slots        = s;
-		cfg->total_width += s->out_width;
+		cfg->buf_width += s->out_width;
 		cfg->slot_count++;
 	} else {
 		khlib_fatal("[memory] Allocation failure.");
@@ -309,233 +662,15 @@ void
 opts_parse(Config *cfg, int argc, char *argv[])
 {
 	opts_parse_any(cfg, argc, argv, 1);
-
-	Slot *last = cfg->slots;
-	cfg->slots = NULL;
-	for (Slot *s = last; s; ) {
-		Slot *next = s->next;
-		s->next = cfg->slots;
-		cfg->slots = s;
-		s = next;
-	}
-}
-
-void
-slot_expire(Slot *s, struct timespec t, char *buf)
-{
-	struct timespec td;
-
-	timespecsub(&t, &(s->in_last_read), &td);
-	if (timespeccmp(&td, &(s->out_ttl), >=)) {
-		/* TODO: Maybe configurable expiry character. */
-		memset(buf + s->out_pos_lo, '_', s->out_pos_hi - s->out_pos_lo);
-		khlib_warn("Slot expired: \"%s\"\n", s->in_fifo);
-	}
-}
-
-void
-slot_read_error(Slot *s, char *buf)
-{
-	char *b;
-	int i;
-
-	b = buf + s->out_pos_lo;
-	/* Copy as much of the error message as possible.
-	 * EXCLUDING the terminating \0. */
-	for (i = 0; i < errlen && i < s->out_width; i++)
-		b[i] = errmsg[i];
-	/* Any remaining slots: */
-	for (; i < s->out_width; i++)
-		b[i] = '_';
-}
-
-enum read_status
-slot_read_one(Slot *s, struct timespec t, char *buf)
-{
-	char c;  /* Character read. */
-	int  r;  /* Remaining unused slots in buffer range. */
-
-	for (;;) {
-		switch (read(s->in_fd, &c, 1)) {
-		case -1:
-			khlib_error(
-			    "Failed to read: \"%s\". errno: %d, msg: %s\n",
-			    s->in_fifo,
-			    errno,
-			    strerror(errno)
-			);
-			switch (errno) {
-			case EINTR:
-			case EAGAIN:
-				return RETRY;
-			default:
-				return FAILURE;
-			}
-		case  0:
-			khlib_debug("%s: End of FILE\n", s->in_fifo);
-			s->out_pos_cur = s->out_pos_lo;
-			return END_OF_FILE;
-		case  1:
-			/* TODO: Consider making msg term char a CLI option */
-			if (c == '\n' || c == '\0') {
-				r = s->out_pos_hi - s->out_pos_cur;
-				if (r > 0)
-					memset(buf + s->out_pos_cur, ' ', r);
-				s->out_pos_cur = s->out_pos_lo;
-				s->in_last_read = t;
-				return END_OF_MESSAGE;
-			} else {
-				if (s->out_pos_cur <= s->out_pos_hi)
-					buf[s->out_pos_cur++] = c;
-				/* Drop beyond available range. */
-				/*
-				 * TODO Define max after which we stop reading.
-				 *      To ensure that a rogue large message
-				 *      doesn't trap us here.
-				 */
-			}
-			break;
-		default:
-			assert(0);
-		}
-	}
+	cfg->slots = slots_rev(cfg->slots);
+	config_log(cfg);
+	if (cfg->slots == NULL)
+		usage("No slot specs were given!\n");
 }
 
 void
-slot_read_all(Config *cfg, struct timespec *ti, char *buf)
-{
-	fd_set fds;
-	int maxfd = -1;
-	int ready = 0;
-	struct stat st;
-	struct timespec t;
-
-	FD_ZERO(&fds);
-	for (Slot *s = cfg->slots; s; s = s->next) {
-		/* TODO: Create the FIFO if it doesn't already exist. */
-		if (lstat(s->in_fifo, &st) < 0) {
-			khlib_error(
-			    "Cannot stat \"%s\". Error: %s\n",
-			    s->in_fifo,
-			    strerror(errno)
-			);
-			slot_read_error(s, buf);
-			continue;
-		}
-		if (!(st.st_mode & S_IFIFO)) {
-			khlib_error("\"%s\" is not a FIFO\n", s->in_fifo);
-			slot_read_error(s, buf);
-			continue;
-		}
-		if (s->in_fd < 0) {
-			khlib_debug(
-			    "%s: closed. opening. in_fd: %d\n",
-			    s->in_fifo,
-			    s->in_fd
-			);
-			s->in_fd = open(s->in_fifo, O_RDONLY | O_NONBLOCK);
-		} else {
-			khlib_debug(
-			    "%s: already openned. in_fd: %d\n",
-			    s->in_fifo,
-			    s->in_fd
-			);
-		}
-		if (s->in_fd == -1) {
-			/* TODO Consider backing off retries for failed slots */
-			khlib_error("Failed to open \"%s\"\n", s->in_fifo);
-			slot_read_error(s, buf);
-			continue;
-		}
-		khlib_debug("%s: open. in_fd: %d\n", s->in_fifo, s->in_fd);
-		if (s->in_fd > maxfd)
-			maxfd = s->in_fd;
-		FD_SET(s->in_fd, &fds);
-	}
-	khlib_debug("selecting...\n");
-	ready = pselect(maxfd + 1, &fds, NULL, NULL, ti, NULL);
-	khlib_debug("ready: %d\n", ready);
-	clock_gettime(CLOCK_MONOTONIC, &t);
-	if (ready == -1) {
-		switch (errno) {
-		case EINTR:
-			khlib_error(
-			    "pselect temp failure: %d, errno: %d, msg: %s\n",
-			    ready,
-			    errno,
-			    strerror(errno)
-			);
-			/* TODO: Reconsider what to do here. */
-			return;
-		default:
-			khlib_fatal(
-			    "pselect failed: %d, errno: %d, msg: %s\n",
-			    ready,
-			    errno,
-			    strerror(errno)
-			);
-		}
-	}
-	/* At-least-once ensures that expiries are still checked on timeouts. */
-	do {
-		for (Slot *s = cfg->slots; s; s = s->next) {
-			if (FD_ISSET(s->in_fd, &fds)) {
-				khlib_debug("reading: %s\n", s->in_fifo);
-				switch (slot_read_one(s, t, buf)) {
-				/*
-				 * ### MESSAGE LOSS ###
-				 * is introduced by closing at EOM in addition
-				 * to EOF, since there may be unread messages
-				 * remaining in the pipe. However,
-				 *
-				 * ### INTER-MESSAGE PUSHBACK ###
-				 * is also gained, since pipes block at the
-				 * "open" call.
-				 *
-				 * This is an acceptable trade-off because we
-				 * are a stateless reporter of a _most-recent_
-				 * status, not a stateful accumulator.
-				 */
-				case END_OF_MESSAGE:
-				case END_OF_FILE:
-				case FAILURE:
-					close(s->in_fd);
-					s->in_fd = -1;
-					ready--;
-					break;
-				case RETRY:
-					break;
-				default:
-					assert(0);
-				}
-			} else {
-				slot_expire(s, t, buf);
-			}
-		}
-	} while (ready);
-	assert(ready == 0);
-}
-
-int
-main(int argc, char *argv[])
+loop(Config *cfg, char *buf, Display *d)
 {
-	Config cfg = {
-		.interval    = 1.0,
-		.separator   = "|",
-		.slots       = NULL,
-		.slot_count  = 0,
-		.total_width = 0,
-		.output_to_x_root_window = 0,
-	};
-
-	int width  = 0;
-	int nslots = 0;
-	int seplen = 0;
-	int prefix = 0;
-	int errors = 0;
-	char *buf;
-	Display *d = NULL;
-	struct stat st;
 	struct timespec
 		t0,  /* time stamp. before reading slots */
 		t1,  /* time stamp. after  reading slots */
@@ -543,78 +678,11 @@ main(int argc, char *argv[])
 		td,  /* time interval measured   (t1 - t0) */
 		tc;  /* time interval correction (ti - td) when td < ti */
 
-	argv0 = argv[0];
-
-	opts_parse(&cfg, argc, argv);
-	khlib_debug("argv0 = %s\n", argv0);
-	config_print(&cfg);
-
-	ti = khlib_timespec_of_float(cfg.interval);
-
-	if (cfg.slots == NULL)
-		usage("No slot specs were given!\n");
-
-	/* 1st pass to check file existence and type */
-	for (Slot *s = cfg.slots; s; s = s->next) {
-		if (lstat(s->in_fifo, &st) < 0) {
-			khlib_error(
-			    "Cannot stat \"%s\". Error: %s\n",
-			    s->in_fifo,
-			    strerror(errno)
-			);
-			errors++;
-			continue;
-		}
-		if (!(st.st_mode & S_IFIFO)) {
-			khlib_error("\"%s\" is not a FIFO\n", s->in_fifo);
-			errors++;
-			continue;
-		}
-	}
-	if (errors)
-		khlib_fatal(
-		    "Encountered errors with given file paths. See log.\n"
-		);
-
-	width  = cfg.total_width;
-	seplen = strlen(cfg.separator);
-
-	/* 2nd pass to make space for separators */
-	for (Slot *s = cfg.slots; s; s = s->next) {
-		s->out_pos_lo  += prefix;
-		s->out_pos_hi += prefix;
-		s->out_pos_cur = s->out_pos_lo;
-		prefix += seplen;
-		nslots++;
-	}
-	width += (seplen * (nslots - 1));
-	buf = calloc(1, width + 1);
-	if (buf == NULL)
-		khlib_fatal(
-		    "[memory] Failed to allocate buffer of %d bytes",
-		    width
-		);
-	memset(buf, ' ', width);
-	buf[width] = '\0';
-	/* 3rd pass to set the separators */
-	for (Slot *s = cfg.slots; s; s = s->next) {
-		if (s->out_pos_lo) {  /* Skip the first, left-most */
-			/* Copying only seplen ensures we omit the '\0' byte. */
-			strncpy(
-			    buf + (s->out_pos_lo - seplen),
-			    cfg.separator,
-			    seplen
-			);
-		}
-	}
-
-	if (cfg.output_to_x_root_window && !(d = XOpenDisplay(NULL)))
-		khlib_fatal("XOpenDisplay failed with: %p\n", d);
-	/* TODO: Handle signals */
-	for (;;) {
+	ti = khlib_timespec_of_float(cfg->interval);
+	while (running) {
 		clock_gettime(CLOCK_MONOTONIC, &t0); // FIXME: check errors
-		slot_read_all(&cfg, &ti, buf);
-		if (cfg.output_to_x_root_window) {
+		slots_read(cfg, &ti, buf);
+		if (cfg->to_x_root) {
 			if (XStoreName(d, DefaultRootWindow(d), buf) < 0)
 				khlib_fatal("XStoreName failed.\n");
 			XFlush(d);
@@ -630,16 +698,53 @@ main(int argc, char *argv[])
 		    td.tv_nsec
 		);
 		if (timespeccmp(&td, &ti, <)) {
-			/* Pushback on data producers by refusing to read the
+			/*
+			 * Pushback on data producers by refusing to read the
 			 * pipe more frequently than the interval.
 			 */
 			timespecsub(&ti, &td, &tc);
-			khlib_debug("khlib_sleep YES\n");
 			khlib_sleep(&tc);
-		} else {
-			khlib_debug("khlib_sleep NO\n");
 		}
 	}
+}
+
+void
+terminate(int s)
+{
+	khlib_debug("terminating due to signal %d\n", s);
+	running = 0;
+}
 
+int
+main(int argc, char *argv[])
+{
+	argv0 = argv[0];
+
+	Config cfg = {
+		.interval    = 1.0,
+		.separator   = "|",
+		.expiry_character = '_',
+		.slots       = NULL,
+		.slot_count  = 0,
+		.buf_width   = 0,
+		.to_x_root   = 0,
+	};
+	char *buf;
+	Display *d = NULL;
+	struct sigaction sa;
+
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_handler = terminate;
+	sigaction(SIGTERM, &sa, NULL);
+	sigaction(SIGINT , &sa, NULL);
+
+	opts_parse(&cfg, argc, argv);
+	slots_assert_fifos_exist(cfg.slots);
+	config_stretch_for_separators(&cfg);
+	buf = buf_create(&cfg);
+	if (cfg.to_x_root && !(d = XOpenDisplay(NULL)))
+		khlib_fatal("XOpenDisplay failed with: %p\n", d);
+	loop(&cfg, buf, d);
+	slots_close(cfg.slots);
 	return EXIT_SUCCESS;
 }