From 11c5aacb08ce5bdbccf81e056fd61facb3097c9b Mon Sep 17 00:00:00 2001
From: nick black <dankamongmen@gmail.com>
Date: Tue, 21 Apr 2020 09:42:25 -0400
Subject: [PATCH] ncsubproc: move to big bad clone3() #310

---
 README.md          |  1 +
 src/lib/fd.c       | 25 +++++++++++++++++++------
 src/lib/internal.h |  1 +
 3 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index 4a969028e..49bf6506c 100644
--- a/README.md
+++ b/README.md
@@ -119,6 +119,7 @@ that fine library.
 * (OPTIONAL) (documentation) [pandoc](https://pandoc.org/index.html) 1.19.2+
 * (OPTIONAL) (python bindings): Python 3.7+, [CFFI](https://pypi.org/project/cffi/) 1.13.2+
 * (OPTIONAL) (rust bindings): rust 1.40.0+, cargo 0.40.0+, [bindgen](https://crates.io/crates/bindgen) 0.53.0+
+* (runtime) Linux 5.3+
 
 ### Building
 
diff --git a/src/lib/fd.c b/src/lib/fd.c
index 6cd809808..9190531e1 100644
--- a/src/lib/fd.c
+++ b/src/lib/fd.c
@@ -1,7 +1,9 @@
 #include <fcntl.h>
 #include <unistd.h>
+#include <asm/unistd.h>
 #include <pthread.h>
 #include <sys/wait.h>
+#include <linux/sched.h>
 #include "internal.h"
 
 // release the memory and fd, but don't join the thread (since we might be
@@ -90,12 +92,24 @@ int ncfdplane_destroy(ncfdplane* n){
 }
 
 static pid_t
-launch_pipe_process(int* pipe){
+launch_pipe_process(int* pipe, int* pidfd){
   int pipes[2];
   if(pipe2(pipes, O_CLOEXEC)){
     return -1;
   }
-  pid_t p = fork();
+  struct clone_args clargs = {
+    .flags = CLONE_CLEAR_SIGHAND | CLONE_FS | CLONE_PIDFD,
+    .pidfd = (uintptr_t)pidfd,
+    .child_tid = 0, // FIXME
+    .parent_tid = 0, // FIXME
+    .exit_signal = SIGCHLD,  // FIXME maybe switch it up for doctest?
+    .stack = 0,           // automatically created by clone3()
+    .stack_size = 0,         // automatically set by clone3()
+    .tls = 0, // FIXME
+    .set_tid = 0, // FIXME
+    .set_tid_size = 0, // FIXME
+  };
+  pid_t p = syscall(__NR_clone3, &clargs, sizeof(clargs));
   if(p == 0){
     if(dup2(pipes[1], STDOUT_FILENO) < 0 || dup2(pipes[1], STDERR_FILENO) < 0){
       return -1;
@@ -143,7 +157,6 @@ ncsubproc_thread(void* vncsp){
 static ncfdplane*
 ncsubproc_launch(ncplane* n, ncsubproc* ret, const ncsubproc_options* opts, int fd,
                  ncfdplane_callback cbfxn, ncfdplane_done_cb donecbfxn){
-  // FIXME need to pick up pidfd via clone() earlier in launch_pipe_process
   ret->nfp = ncfdplane_create_internal(n, &opts->popts, fd, cbfxn, donecbfxn, false);
   if(ret->nfp == NULL){
     return NULL;
@@ -166,7 +179,7 @@ ncsubproc* ncsubproc_createv(ncplane* n, const ncsubproc_options* opts,
   if(ret == NULL){
     return NULL;
   }
-  ret->pid = launch_pipe_process(&fd);
+  ret->pid = launch_pipe_process(&fd, &ret->pidfd);
   if(ret->pid == 0){
     execv(bin, arg);
     fprintf(stderr, "Error execv()ing %s\n", bin);
@@ -194,7 +207,7 @@ ncsubproc* ncsubproc_createvp(ncplane* n, const ncsubproc_options* opts,
   if(ret == NULL){
     return NULL;
   }
-  ret->pid = launch_pipe_process(&fd);
+  ret->pid = launch_pipe_process(&fd, &ret->pidfd);
   if(ret->pid == 0){
     execvp(bin, arg);
     fprintf(stderr, "Error execv()ing %s\n", bin);
@@ -222,7 +235,7 @@ ncsubproc* ncsubproc_createvpe(ncplane* n, const ncsubproc_options* opts,
   if(ret == NULL){
     return NULL;
   }
-  ret->pid = launch_pipe_process(&fd);
+  ret->pid = launch_pipe_process(&fd, &ret->pidfd);
   if(ret->pid == 0){
 #ifdef __FreeBSD__
     exect(bin, arg, env);
diff --git a/src/lib/internal.h b/src/lib/internal.h
index e0b537ef9..9e5c40071 100644
--- a/src/lib/internal.h
+++ b/src/lib/internal.h
@@ -201,6 +201,7 @@ typedef struct ncfdplane {
 typedef struct ncsubproc {
   ncfdplane* nfp;
   pid_t pid;                  // subprocess
+  int pidfd;                  // for signaling/watching the subprocess
 } ncsubproc;
 
 typedef struct ncmenu {