Allow creating processes where only one of stdin or stdout is a PTY

* src/lisp.h (emacs_spawn):
* src/callproc.c (emacs_spawn): Add PTY_IN and PTY_OUT arguments to
specify which streams should be set up as a PTY.
(call_process): Adjust call to 'emacs_spawn'.

* src/process.h (Lisp_Process): Replace 'pty_flag' with 'pty_in' and
'pty_out'.

* src/process.c (is_pty_from_symbol): New function.
(make-process): Allow :connection-type to be a cons cell, and allow
using a stderr process with a PTY for stdin/stdout.
(create_process): Handle creating a process where only one of stdin or
stdout is a PTY.

* lisp/eshell/esh-proc.el (eshell-needs-pipe, eshell-needs-pipe-p):
Remove.
(eshell-gather-process-output): Use 'make-process' and set
':connection-type' as needed by the value of 'eshell-in-pipeline-p'.

* lisp/net/tramp.el (tramp-handle-make-process):
* lisp/net/tramp-adb.el (tramp-adb-handle-make-process):
* lisp/net/tramp-sh.el (tramp-sh-handle-make-process): Don't signal an
error when ':connection-type' is a cons cell.

* test/src/process-tests.el
(process-test-sentinel-wait-function-working-p): Allow passing PROC
in, and rework into...
(process-test-wait-for-sentinel): ... this.
(process-test-sentinel-accept-process-output)
(process-test-sentinel-sit-for, process-test-quoted-batfile)
(process-test-stderr-filter): Use 'process-test-wait-for-sentinel'.
(make/process/test-connection-type): New function.
(make-process/connection-type/pty, make-process/connection-type/pty-2)
(make-process/connection-type/pipe)
(make-process/connection-type/pipe-2)
(make-process/connection-type/in-pty)
(make-process/connection-type/out-pty)
(make-process/connection-type/pty-with-stderr-buffer)
(make-process/connection-type/out-pty-with-stderr-buffer): New tests.

* test/lisp/eshell/esh-proc-tests.el (esh-proc-test--detect-pty-cmd):
New variable.
(esh-proc-test/pipeline-connection-type/no-pipeline)
(esh-proc-test/pipeline-connection-type/first)
(esh-proc-test/pipeline-connection-type/middle)
(esh-proc-test/pipeline-connection-type/last): New tests.

* doc/lispref/processes.texi (Asynchronous Processes): Document new
':connection-type' behavior.
(Output from Processes): Remove caveat about ':stderr' forcing
'make-process' to use pipes.

* etc/NEWS: Announce this change (bug#56025).

1 files changed, 22 insertions, 15 deletions

diff --git a/src/callproc.c b/src/callproc.c
index dd162f36a6c..aec0a2f5a58 100644
--- a/src/callproc.c
+++ b/src/callproc.c
@@ -650,7 +650,7 @@ call_process (ptrdiff_t nargs, Lisp_Object *args, int filefd,
 
   child_errno
     = emacs_spawn (&pid, filefd, fd_output, fd_error, new_argv, env,
-                   SSDATA (current_dir), NULL, &oldset);
+                   SSDATA (current_dir), NULL, false, false, &oldset);
   eassert ((child_errno == 0) == (0 < pid));
 
   if (pid > 0)
@@ -1412,14 +1412,15 @@ emacs_posix_spawn_init_attributes (posix_spawnattr_t *attributes,
 int
 emacs_spawn (pid_t *newpid, int std_in, int std_out, int std_err,
              char **argv, char **envp, const char *cwd,
-             const char *pty, const sigset_t *oldset)
+             const char *pty_name, bool pty_in, bool pty_out,
+             const sigset_t *oldset)
 {
 #if USABLE_POSIX_SPAWN
   /* Prefer the simpler `posix_spawn' if available.  `posix_spawn'
      doesn't yet support setting up pseudoterminals, so we fall back
      to `vfork' if we're supposed to use a pseudoterminal.  */
 
-  bool use_posix_spawn = pty == NULL;
+  bool use_posix_spawn = pty_name == NULL;
 
   posix_spawn_file_actions_t actions;
   posix_spawnattr_t attributes;
@@ -1473,7 +1474,9 @@ emacs_spawn (pid_t *newpid, int std_in, int std_out, int std_err,
   /* vfork, and prevent local vars from being clobbered by the vfork.  */
   pid_t *volatile newpid_volatile = newpid;
   const char *volatile cwd_volatile = cwd;
-  const char *volatile pty_volatile = pty;
+  const char *volatile ptyname_volatile = pty_name;
+  bool volatile ptyin_volatile = pty_in;
+  bool volatile ptyout_volatile = pty_out;
   char **volatile argv_volatile = argv;
   int volatile stdin_volatile = std_in;
   int volatile stdout_volatile = std_out;
@@ -1495,7 +1498,9 @@ emacs_spawn (pid_t *newpid, int std_in, int std_out, int std_err,
 
   newpid = newpid_volatile;
   cwd = cwd_volatile;
-  pty = pty_volatile;
+  pty_name = ptyname_volatile;
+  pty_in = ptyin_volatile;
+  pty_out = ptyout_volatile;
   argv = argv_volatile;
   std_in = stdin_volatile;
   std_out = stdout_volatile;
@@ -1506,13 +1511,12 @@ emacs_spawn (pid_t *newpid, int std_in, int std_out, int std_err,
   if (pid == 0)
 #endif /* not WINDOWSNT */
     {
-      bool pty_flag = pty != NULL;
       /* Make the pty be the controlling terminal of the process.  */
 #ifdef HAVE_PTYS
       dissociate_controlling_tty ();
 
       /* Make the pty's terminal the controlling terminal.  */
-      if (pty_flag && std_in >= 0)
+      if (pty_in && std_in >= 0)
         {
 #ifdef TIOCSCTTY
           /* We ignore the return value
@@ -1521,7 +1525,7 @@ emacs_spawn (pid_t *newpid, int std_in, int std_out, int std_err,
 #endif
         }
 #if defined (LDISC1)
-      if (pty_flag && std_in >= 0)
+      if (pty_in && std_in >= 0)
         {
           struct termios t;
           tcgetattr (std_in, &t);
@@ -1531,7 +1535,7 @@ emacs_spawn (pid_t *newpid, int std_in, int std_out, int std_err,
         }
 #else
 #if defined (NTTYDISC) && defined (TIOCSETD)
-      if (pty_flag && std_in >= 0)
+      if (pty_in && std_in >= 0)
         {
           /* Use new line discipline.  */
           int ldisc = NTTYDISC;
@@ -1548,18 +1552,21 @@ emacs_spawn (pid_t *newpid, int std_in, int std_out, int std_err,
      both TIOCSCTTY is defined.  */
         /* Now close the pty (if we had it open) and reopen it.
            This makes the pty the controlling terminal of the subprocess.  */
-      if (pty_flag)
+      if (pty_name)
         {
 
           /* I wonder if emacs_close (emacs_open (pty, ...))
              would work?  */
-          if (std_in >= 0)
+          if (pty_in && std_in >= 0)
             emacs_close (std_in);
-          std_out = std_in = emacs_open_noquit (pty, O_RDWR, 0);
-
+          int ptyfd = emacs_open_noquit (pty_name, O_RDWR, 0);
+          if (pty_in)
+            std_in = ptyfd;
+          if (pty_out)
+            std_out = ptyfd;
           if (std_in < 0)
             {
-              emacs_perror (pty);
+              emacs_perror (pty_name);
               _exit (EXIT_CANCELED);
             }
 
@@ -1599,7 +1606,7 @@ emacs_spawn (pid_t *newpid, int std_in, int std_out, int std_err,
       /* Stop blocking SIGCHLD in the child.  */
       unblock_child_signal (oldset);
 
-      if (pty_flag)
+      if (pty_out)
         child_setup_tty (std_out);
 #endif