Implement --hold

When specified, we don't exit when the slave/client process exits.

completions/zsh/_foot

@@ -7,6 +7,7 @@ _arguments \
     '(-t --term)'{-t,--term}'[value to set the environment variable TERM to (foot)]:term:->terms' \
     '(-g --geometry)'{-g,--geometry}'[window WIDTHxHEIGHT, in pixels (80x24 cells)]:geometry:()' \
     '(-s --server)'{-s,--server}'[run as server; open terminals by running footclient]:server:_files' \
+    '--hold[remain open after child process exits]:hold:()' \
     '(-v --version)'{-v,--version}'[show the version number and quit]' \
     '(-h --help)'{-h,--help}'[show help message and quit]'
 

config.c

@@ -511,6 +511,8 @@ config_load(struct config *conf, const char *conf_path)
 
         .render_worker_count = sysconf(_SC_NPROCESSORS_ONLN),
         .server_socket_path = get_server_socket_path(),
+        .presentation_timings = false,
+        .hold_at_exit = false,
     };
 
     char *default_path = NULL;

config.h

@@ -36,6 +36,7 @@ struct config {
     size_t render_worker_count;
     char *server_socket_path;
     bool presentation_timings;
+    bool hold_at_exit;
 };
 
 bool config_load(struct config *conf, const char *path);

doc/foot.1.scd

@@ -62,6 +62,9 @@ execute (instead of the shell).
 	*XDG\_RUNTIME\_DIR/foot.sock*. If you do so, you will need to use
 	the *--server-socket* option in *footclient*(1).
 
+*--hold*
+	Remain open after child process exits.
+
 *-v*,*--version*
 	Show the version number and quit.
 

main.c

@@ -47,6 +47,7 @@ print_usage(const char *prog_name)
         "  -g,--geometry=WIDTHxHEIGHT  set initial width and height\n"
         "  -s,--server[=PATH]          run as a server (use 'footclient' to start terminals).\n"
         "                              Without PATH, XDG_RUNTIME_DIR/foot.sock will be used.\n"
+        "     --hold                   remain open after child process exits\n"
         "  -v,--version                show the version number and quit\n",
         prog_name, prog_name);
 }
@@ -96,6 +97,7 @@ main(int argc, char *const *argv)
         {"font",                 required_argument, NULL, 'f'},
         {"geometry",             required_argument, NULL, 'g'},
         {"server",               optional_argument, NULL, 's'},
+        {"hold",                 no_argument,       NULL, 'H'},
         {"presentation-timings", no_argument,       NULL, 'p'}, /* Undocumented */
         {"version",              no_argument,       NULL, 'v'},
         {"help",                 no_argument,       NULL, 'h'},
@@ -110,6 +112,7 @@ main(int argc, char *const *argv)
     bool as_server = false;
     const char *conf_server_socket_path = NULL;
     bool presentation_timings = false;
+    bool hold = false;
 
     while (true) {
         int c = getopt_long(argc, argv, "c:tf:g:s::pvh", longopts, NULL);
@@ -169,6 +172,10 @@ main(int argc, char *const *argv)
             presentation_timings = true;
             break;
 
+        case 'H':
+            hold = true;
+            break;
+
         case 'v':
             printf("foot version %s\n", FOOT_VERSION);
             return EXIT_SUCCESS;
@@ -216,6 +223,7 @@ main(int argc, char *const *argv)
         conf.server_socket_path = strdup(conf_server_socket_path);
     }
     conf.presentation_timings = presentation_timings;
+    conf.hold_at_exit = hold;
 
     struct fdm *fdm = NULL;
     struct wayland *wayl = NULL;

terminal.c

@@ -36,6 +36,11 @@ static const char *const XCURSOR_HAND2 = "hand2";
 bool
 term_to_slave(struct terminal *term, const void *_data, size_t len)
 {
+    if (term->ptmx < 0) {
+        /* We're probably in "hold" */
+        return false;
+    }
+
     size_t async_idx = 0;
     if (tll_length(term->ptmx_buffer) > 0) {
         /* With a non-empty queue, EPOLLOUT has already been enabled */
@@ -128,25 +133,22 @@ fdm_ptmx(struct fdm *fdm, int fd, int events, void *data)
 {
     struct terminal *term = data;
 
-    bool pollin = events & EPOLLIN;
-    bool pollout = events & EPOLLOUT;
-    bool hup = events & EPOLLHUP;
-
-    if (hup) {
-        /* TODO: should we *not* ignore pollin? */
-        return term_shutdown(term);
-    }
+    const bool pollin = events & EPOLLIN;
+    const bool pollout = events & EPOLLOUT;
+    const bool hup = events & EPOLLHUP;
 
     if (pollout) {
         if (!fdm_ptmx_out(fdm, fd, events, data))
             return false;
     }
 
+#if 0
     if (!pollin)
         return true;
+#endif
 
     uint8_t buf[24 * 1024];
-    ssize_t count = read(term->ptmx, buf, sizeof(buf));
+    ssize_t count = pollin ? read(term->ptmx, buf, sizeof(buf)) : 0;
 
     if (count < 0) {
         LOG_ERRNO("failed to read from pseudo terminal");
@@ -225,9 +227,14 @@ fdm_ptmx(struct fdm *fdm, int fd, int events, void *data)
     } else
         term->render.pending = true;
 
-    if (events & EPOLLHUP)
-        return term_shutdown(term);
-
+    if (hup) {
+        if (term->hold_at_exit) {
+            fdm_del(fdm, fd);
+            term->ptmx = -1;
+            return true;
+        } else
+            return term_shutdown(term);
+    }
     return true;
 }
 
@@ -672,6 +679,7 @@ term_init(const struct config *conf, struct fdm *fdm, struct wayland *wayl,
             .lower_fd = delay_lower_fd,
             .upper_fd = delay_upper_fd,
         },
+        .hold_at_exit = conf->hold_at_exit,
         .shutdown_cb = shutdown_cb,
         .shutdown_data = shutdown_data,
         .foot_exe = strdup(foot_exe),

terminal.h

@@ -340,6 +340,7 @@ struct terminal {
         int upper_fd;
     } delayed_render_timer;
 
+    bool hold_at_exit;
     bool is_shutting_down;
     void (*shutdown_cb)(void *data, int exit_code);
     void *shutdown_data;