term: don't double fork new terminal windows

Instead, register their PIDs with the new reaper module and let it
handle them.

CHANGELOG.md

@@ -25,6 +25,8 @@
   line is empty.
 * Number of lines to scroll is now always clamped to the number of
   lines in the scrolling region..
+* New terminal windows spawned with `ctrl`+`shift`+`n` is no longer
+  double forked.
 
 
 ### Deprecated

main.c

@@ -390,14 +390,14 @@ main(int argc, char *const *argv)
         goto out;
 
     if (!as_server && (term = term_init(
-                           &conf, fdm, wayl, "foot", cwd, argc, argv,
+                           &conf, fdm, reaper, wayl, "foot", cwd, argc, argv,
                            &term_shutdown_cb, &shutdown_ctx)) == NULL) {
         free(cwd);
         goto out;
     }
     free(cwd);
 
-    if (as_server && (server = server_init(&conf, fdm, wayl)) == NULL)
+    if (as_server && (server = server_init(&conf, fdm, reaper, wayl)) == NULL)
         goto out;
 
     /* Remember to restore signals in slave */

server.c

@@ -24,6 +24,7 @@ struct client;
 struct server {
     const struct config *conf;
     struct fdm *fdm;
+    struct reaper *reaper;
     struct wayland *wayl;
 
     int fd;
@@ -311,7 +312,7 @@ fdm_client(struct fdm *fdm, int fd, int events, void *data)
         client->conf.startup_mode = STARTUP_FULLSCREEN;
 
     client->term = term_init(
-        &client->conf, server->fdm, server->wayl,
+        &client->conf, server->fdm, server->reaper, server->wayl,
         "footclient", cwd, argc, argv, &term_shutdown_handler, client);
 
     if (client->term == NULL) {
@@ -406,7 +407,8 @@ err:
 }
 
 struct server *
-server_init(const struct config *conf, struct fdm *fdm, struct wayland *wayl)
+server_init(const struct config *conf, struct fdm *fdm, struct reaper *reaper,
+            struct wayland *wayl)
 {
     int fd = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
     if (fd == -1) {
@@ -448,6 +450,7 @@ server_init(const struct config *conf, struct fdm *fdm, struct wayland *wayl)
     *server = (struct server) {
         .conf = conf,
         .fdm = fdm,
+        .reaper = reaper,
         .wayl = wayl,
 
         .fd = fd,

server.h

@@ -5,5 +5,6 @@
 #include "wayland.h"
 
 struct server;
-struct server *server_init(const struct config *conf, struct fdm *fdm, struct wayland *wayl);
+struct server *server_init(const struct config *conf, struct fdm *fdm,
+                           struct reaper *reaper, struct wayland *wayl);
 void server_destroy(struct server *server);

terminal.c

@@ -23,6 +23,7 @@
 #include "config.h"
 #include "grid.h"
 #include "quirks.h"
+#include "reaper.h"
 #include "render.h"
 #include "selection.h"
 #include "sixel.h"
@@ -714,8 +715,9 @@ load_fonts_from_conf(const struct terminal *term, const struct config *conf,
 }
 
 struct terminal *
-term_init(const struct config *conf, struct fdm *fdm, struct wayland *wayl,
-          const char *foot_exe, const char *cwd, int argc, char *const *argv,
+term_init(const struct config *conf, struct fdm *fdm, struct reaper *reaper,
+          struct wayland *wayl, const char *foot_exe, const char *cwd,
+          int argc, char *const *argv,
           void (*shutdown_cb)(void *data, int exit_code), void *shutdown_data)
 {
     int ptmx = -1;
@@ -784,6 +786,7 @@ term_init(const struct config *conf, struct fdm *fdm, struct wayland *wayl,
     /* Initialize configure-based terminal attributes */
     *term = (struct terminal) {
         .fdm = fdm,
+        .reaper = reaper,
         .conf = conf,
         .quit = false,
         .ptmx = ptmx,
@@ -2221,69 +2224,59 @@ term_flash(struct terminal *term, unsigned duration_ms)
 bool
 term_spawn_new(const struct terminal *term)
 {
+    int pipe_fds[2] = {-1, -1};
+    if (pipe2(pipe_fds, O_CLOEXEC) < 0) {
+        LOG_ERRNO("failed to create pipe");
+        goto err;
+    }
+
     pid_t pid = fork();
     if (pid < 0) {
         LOG_ERRNO("failed to fork new terminal");
-        return false;
+        goto err;
     }
 
     if (pid == 0) {
         /* Child */
-        int pipe_fds[2] = {-1, -1};
-        if (pipe2(pipe_fds, O_CLOEXEC) < 0) {
-            LOG_ERRNO("failed to create pipe");
-            goto err;
-        }
-
-        /* Double fork */
-        pid_t pid2 = fork();
-        if (pid2 < 0) {
-            LOG_ERRNO("failed to double fork new terminal");
-            goto err;
-        }
-
-        if (pid2 == 0) {
-            /* Child */
-            close(pipe_fds[0]);
-            if (chdir(term->cwd) < 0 ||
-                execlp(term->foot_exe, term->foot_exe, NULL) < 0)
-            {
-                (void)!write(pipe_fds[1], &errno, sizeof(errno));
-                _exit(errno);
-            }
-            assert(false);
+        close(pipe_fds[0]);
+        if (chdir(term->cwd) < 0 ||
+            execlp(term->foot_exe, term->foot_exe, NULL) < 0)
+        {
+            (void)!write(pipe_fds[1], &errno, sizeof(errno));
             _exit(errno);
         }
-
-        /* Parent */
-
-        close(pipe_fds[1]);
-
-        int _errno;
-        static_assert(sizeof(_errno) == sizeof(errno), "errno size mismatch");
-
-        ssize_t ret = read(pipe_fds[0], &_errno, sizeof(_errno));
-        close(pipe_fds[0]);
-
-        if (ret == 0)
-            _exit(0);
-        else if (ret < 0)
-            LOG_ERRNO("failed to read from pipe");
-        else {
-            LOG_ERRNO_P("%s: failed to spawn new terminal", _errno, term->foot_exe);
-            errno = _errno;
-            waitpid(pid2, NULL, 0);
-        }
-
-    err:
-        if (pipe_fds[0] != -1)
-            close(pipe_fds[0]);
+        assert(false);
         _exit(errno);
     }
 
-    int result;
-    waitpid(pid, &result, 0);
-    return WIFEXITED(result) && WEXITSTATUS(result) == 0;
+    /* Parent */
+    close(pipe_fds[1]);
+
+    int _errno;
+    static_assert(sizeof(_errno) == sizeof(errno), "errno size mismatch");
+
+    ssize_t ret = read(pipe_fds[0], &_errno, sizeof(_errno));
+    close(pipe_fds[0]);
+
+    if (ret == 0) {
+        reaper_add(term->reaper, pid);
+        return true;
+    } else if (ret < 0) {
+        LOG_ERRNO("failed to read from pipe");
+        return false;
+    } else {
+        LOG_ERRNO_P("%s: failed to spawn new terminal", _errno, term->foot_exe);
+        errno = _errno;
+        waitpid(pid, NULL, 0);
+        return false;
+    }
+
+err:
+    if (pipe_fds[0] != -1)
+        close(pipe_fds[0]);
+    if (pipe_fds[1] != -1)
+        close(pipe_fds[1]);
+    return false;
 }
 
 void

terminal.h

@@ -13,6 +13,7 @@
 
 //#include "config.h"
 #include "fdm.h"
+#include "reaper.h"
 #include "wayland.h"
 
 #define likely(c) __builtin_expect(!!(c), 1)
@@ -206,6 +207,7 @@ enum term_surface {
 
 struct terminal {
     struct fdm *fdm;
+    struct reaper *reaper;
     const struct config *conf;
 
     pid_t slave;
@@ -439,8 +441,9 @@ struct terminal {
 
 struct config;
 struct terminal *term_init(
-    const struct config *conf, struct fdm *fdm, struct wayland *wayl,
-    const char *foot_exe, const char *cwd, int argc, char *const *argv,
+    const struct config *conf, struct fdm *fdm, struct reaper *reaper,
+    struct wayland *wayl, const char *foot_exe, const char *cwd,
+    int argc, char *const *argv,
     void (*shutdown_cb)(void *data, int exit_code), void *shutdown_data);
 
 bool term_shutdown(struct terminal *term);