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> > There seems to be some confusing about empty lines.
yup.
> It seems that in child_input() on the "if (wc == '\n')" path before the
> 'continue' statement adding something like "(*buf)[l][c] = wc;" helps a bit.
yeah.
> But 'watch traceroute www.ripe.net' still is slightly strange: starting
> on the second invocation the 'traceroute to' header line appears.
That is because traceroute prints that to stderr. It just kinda shows
up anywhere, possibly quickly overwrittern. Officially "not a watch bug".
At least not at this point, obviously could be handled better.
This is the same as before, but preserves the \n in the buffer.
Index: watch.c
===================================================================
RCS file: /home/cvs/src/usr.bin/watch/watch.c,v
diff -u -p -r1.28 watch.c
--- watch.c 31 May 2025 08:26:26 -0000 1.28
+++ watch.c 21 Jun 2025 04:39:41 -0000
@@ -72,6 +72,7 @@ int start_line = 0, start_column = 0; /*
int pause_on_error = 0;
int paused = 0;
+int want_update;
int last_exitcode = 0;
time_t lastupdate;
int xflag = 0;
@@ -83,6 +84,15 @@ static char *cmdstr;
static size_t cmdlen;
static char **cmdv;
+struct child {
+ char buf[65000];
+ size_t bufsiz;
+ size_t pos;
+ pid_t pid;
+ int fd;
+ struct event evin;
+};
+
typedef wchar_t BUFFER[MAXLINE][MAXCOLUMN + 1];
BUFFER buf0, buf1;
BUFFER *cur_buf, *prev_buf;
@@ -93,17 +103,22 @@ struct event ev_timer;
#define ctrl(c) ((c) & 037)
int display(BUFFER *, BUFFER *, highlight_mode_t);
-void read_result(BUFFER *);
kbd_result_t kbd_command(int);
void show_help(void);
void untabify(wchar_t *, int);
void on_signal(int, short, void *);
+void on_sigchild(int, short, void *);
void timer(int, short, void *);
void input(int, short, void *);
void quit(void);
void usage(void);
void swap_buffers(void);
+struct child *running_child;
+void start_child();
+void child_input(int, short, void *);
+void child_done(struct child *);
+
int
set_interval(const char *str)
{
@@ -124,6 +139,7 @@ int
main(int argc, char *argv[])
{
struct event ev_sigint, ev_sighup, ev_sigterm, ev_sigwinch, ev_stdin;
+ struct event ev_sigchild;
size_t len, rem;
int i, ch;
char *p;
@@ -216,19 +232,19 @@ main(int argc, char *argv[])
signal_set(&ev_sighup, SIGHUP, on_signal, NULL);
signal_set(&ev_sigterm, SIGTERM, on_signal, NULL);
signal_set(&ev_sigwinch, SIGWINCH, on_signal, NULL);
+ signal_set(&ev_sigchild, SIGCHLD, on_sigchild, NULL);
signal_add(&ev_sigint, NULL);
signal_add(&ev_sighup, NULL);
signal_add(&ev_sigterm, NULL);
signal_add(&ev_sigwinch, NULL);
+ signal_add(&ev_sigchild, NULL);
event_set(&ev_stdin, STDIN_FILENO, EV_READ | EV_PERSIST, input, NULL);
event_add(&ev_stdin, NULL);
evtimer_set(&ev_timer, timer, NULL);
- evtimer_add(&ev_timer, &opt_interval.tv);
cur_buf = &buf0; prev_buf = &buf1;
- read_result(cur_buf);
- display(cur_buf, prev_buf, highlight_mode);
+ start_child();
event_dispatch();
@@ -379,21 +395,21 @@ display(BUFFER * cur, BUFFER * prev, hig
}
void
-read_result(BUFFER *buf)
+start_child()
{
- FILE *fp;
- int i, st, fds[2];
- pid_t pipe_pid, pid;
+ struct child *child;
+ int fds[2];
- /* Clear buffer */
- memset(buf, 0, sizeof(*buf));
+ child = calloc(1, sizeof(*child));
+ child->bufsiz = sizeof(child->buf);
if (pipe(fds) == -1)
err(1, "pipe()");
- if ((pipe_pid = vfork()) == -1)
- err(1, "vfork()");
- else if (pipe_pid == 0) {
+ child->pid = vfork();
+ if (child->pid == -1)
+ err(1, "vfork");
+ if (child->pid == 0) {
close(fds[0]);
if (fds[1] != STDOUT_FILENO) {
dup2(fds[1], STDOUT_FILENO);
@@ -407,21 +423,56 @@ read_result(BUFFER *buf)
/* use warn(3) + _exit(2) not to call exit(3) */
warn("exec(%s)", cmdstr);
_exit(1);
-
/* NOTREACHED */
}
- if ((fp = fdopen(fds[0], "r")) == NULL)
- err(1, "fdopen()");
close(fds[1]);
+ child->fd = fds[0];
+
+ event_set(&child->evin, child->fd, EV_READ | EV_PERSIST, child_input, child);
+ event_add(&child->evin, NULL);
+
+ running_child = child;
+}
+
+void
+update()
+{
+ if (running_child) {
+ /* not yet */
+ want_update = 1;
+ return;
+ }
+ want_update = 0;
+ swap_buffers();
+ start_child();
+}
+
+void
+child_done(struct child *child)
+{
+ event_del(&child->evin);
+ close(child->fd);
+ free(child);
+ // assert(running_child == child);
+ if (running_child == child)
+ running_child = NULL;
+ if (want_update)
+ update();
+ else if (!paused)
+ evtimer_add(&ev_timer, &opt_interval.tv);
+}
+
+void
+on_sigchild(int sig, short event, void *arg)
+{
+ pid_t pid;
+ int st;
- /* Read command output and convert tab to spaces * */
- for (i = 0; i < MAXLINE && fgetws((*buf)[i], MAXCOLUMN, fp) != NULL;
- i++)
- untabify((*buf)[i], sizeof((*buf)[i]));
- fclose(fp);
do {
- pid = waitpid(pipe_pid, &st, 0);
+ pid = waitpid(WAIT_ANY, &st, 0);
} while (pid == -1 && errno == EINTR);
+ if (!running_child || running_child->pid != pid)
+ return;
/* Remember update time */
time(&lastupdate);
@@ -430,6 +481,47 @@ read_result(BUFFER *buf)
last_exitcode = WEXITSTATUS(st);
if (pause_on_error && last_exitcode)
paused = 1;
+
+ child_done(running_child);
+}
+
+void
+child_input(int sig, short event, void *arg)
+{
+ struct child *child = arg;
+ ssize_t n;
+
+ n = read(child->fd, child->buf + child->pos, child->bufsiz - child->pos);
+ if (n == -1)
+ return;
+ child->pos += n;
+
+ size_t l = 0, c = 0;
+ BUFFER *buf = cur_buf;
+ memset(*buf, 0, sizeof(*buf));
+ for (size_t i = 0; i < child->pos;/* i += len */) {
+ wchar_t wc;
+ int len = mbtowc(&wc, &child->buf[i], MB_CUR_MAX);
+ if (len == -1) {
+ wc = '?';
+ i += 1;
+ } else {
+ i += len;
+ }
+ if (wc == '\n') {
+ if (c < MAXCOLUMN)
+ (*buf)[l][c] = wc;
+ l++;
+ c = 0;
+ if (l == MAXLINE)
+ break;
+ continue;
+ }
+ if (c == MAXCOLUMN)
+ continue;
+ (*buf)[l][c++] = wc;
+ }
+ display(buf, prev_buf, highlight_mode);
}
kbd_result_t
@@ -534,12 +626,13 @@ kbd_command(int ch)
case 'p':
if (paused == 1) {
paused = 0;
- evtimer_del(&ev_timer);
- return (RSLT_REDRAW);
- } else {
- paused = 1;
evtimer_add(&ev_timer, &opt_interval.tv);
return (RSLT_UPDATE);
+ } else {
+ paused = 1;
+ want_update = 0;
+ evtimer_del(&ev_timer);
+ return (RSLT_REDRAW);
}
case 's':
@@ -687,11 +780,7 @@ on_signal(int sig, short event, void *ar
void
timer(int sig, short event, void *arg)
{
- swap_buffers();
- read_result(cur_buf);
- display(cur_buf, prev_buf, highlight_mode);
- if (!paused)
- evtimer_add(&ev_timer, &opt_interval.tv);
+ update();
}
void
@@ -704,11 +793,7 @@ input(int sig, short event, void *arg)
kbd_result_t result = kbd_command(ch);
switch (result) {
case RSLT_UPDATE: /* update buffer */
- swap_buffers();
- read_result(cur_buf);
- display(cur_buf, prev_buf, highlight_mode);
- if (!paused)
- evtimer_add(&ev_timer, &opt_interval.tv);
+ update();
break;
case RSLT_REDRAW: /* scroll with current buffer */
display(cur_buf, prev_buf, highlight_mode);
responsive watch wip