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Re: Opening a pty without a process
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From: |
Nick Roberts |
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Subject: |
Re: Opening a pty without a process |
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Date: |
Tue, 27 Nov 2007 09:27:49 +1300 |
Previously I wrote:
> I would like to associate a buffer with a pty without a process. How easy
> would it be able to adapt start-process to do this when given a nil value
> for program name:
>
> (start-process name buffer nil) or (start-process name buffer)
>
> Perhaps a new function would be better because I would like it to return the
> name of the pty, e.g,
>
> (open-pty-buffer buffer)
> ->"/dev/pts/1"
>
> Emacs would need then to monitor the file descriptor using select in
> wait_reading_process_output (process.c).
>
> and I would hook this up with a process using:
>
> M-x gdb
> Run gdb (like this): gdb -tty /dev/pts/1 -i=mi myprog
>
> (In practice it's more likely that Emacs will set a Lisp variable to the
> value of (open-pty-buffer buffer) and use it behind the users back.)
Here's a patch to sketch the ideas that I have. I would like it to be
considered for eventual inclusion on the trunk. With it if you evaluate
(start-process "mypty" "*mypty*" nil)
=> #<process mypty>
Then M-x list-processes gives something like:
Proc Status Buffer Tty Command
---- ------ ------ --- -------
mypty run *mypty* /dev/pts/1
shell run *shell* /dev/pts/3 /bin/bash --noediting -i
In buffer *mypty* do
M-x comint-mode
Start GDB as follows ("-annotate=3" won't work)
M-x gdb
Run gdb (like this): gdb --fullname myprog
where myprog is a program that does IO.
...
(gdb) tty /dev/pts/1
(gdb) run
Then your program output should appear in *mypty* and GDB should accept
input from there too.
It's still rough: ptys aren't closed when the buffer is killed, input gets
echoed in *mypty*, assumes ptys etc., but I would like feedback before
polishing it any further.
For GDB it means that a dummy process like:
(make-comint-in-buffer
"gdb-inferior" (current-buffer) "sleep" nil "1000000000"))
isn't needed. There must be other situations where this could be useful too.
--
Nick http://www.inet.net.nz/~nickrob
2007-11-26 Nick Roberts <address@hidden>
* process.c (create_pty): New function. Set pid == -2.
(list_processes_1): Check for no program.
(Fstart_process): Create a pty if PROGRAM is nil.
Condition for no program. Update doc string.
(start_process_unwind): Remove process if pid == -1.
*** process.c.~1.525~ 2007-11-27 09:15:17.000000000 +1300
--- process.c 2007-11-27 09:18:35.000000000 +1300
*************** static int keyboard_bit_set P_ ((SELECT_
*** 309,314 ****
--- 309,315 ----
static void deactivate_process P_ ((Lisp_Object));
static void status_notify P_ ((struct Lisp_Process *));
static int read_process_output P_ ((Lisp_Object, int));
+ static void create_pty P_ ((Lisp_Object));
/* If we support a window system, turn on the code to poll periodically
to detect C-g. It isn't actually used when doing interrupt input. */
*************** list_processes_1 (query_only)
*** 1522,1527 ****
--- 1523,1530 ----
while (1)
{
tem1 = Fcar (tem);
+ if (NILP (tem1))
+ break;
Finsert (1, &tem1);
tem = Fcdr (tem);
if (NILP (tem))
*************** at end of BUFFER, unless you specify an
*** 1571,1578 ****
function to handle the output. BUFFER may also be nil, meaning that
this process is not associated with any buffer.
! PROGRAM is the program file name. It is searched for in PATH.
! Remaining arguments are strings to give program as arguments.
If you want to separate standard output from standard error, invoke
the command through a shell and redirect one of them using the shell
--- 1574,1582 ----
function to handle the output. BUFFER may also be nil, meaning that
this process is not associated with any buffer.
! PROGRAM is the program file name. It is searched for in PATH. If nil,
! just associate a pty with the buffer. Remaining arguments are strings
! to give program as arguments.
If you want to separate standard output from standard error, invoke
the command through a shell and redirect one of them using the shell
*************** usage: (start-process NAME BUFFER PROGRA
*** 1628,1634 ****
program = args[2];
! CHECK_STRING (program);
proc = make_process (name);
/* If an error occurs and we can't start the process, we want to
--- 1632,1639 ----
program = args[2];
! if (!NILP (program))
! CHECK_STRING (program);
proc = make_process (name);
/* If an error occurs and we can't start the process, we want to
*************** usage: (start-process NAME BUFFER PROGRA
*** 1675,1681 ****
args2[0] = Qstart_process;
for (i = 0; i < nargs; i++) args2[i + 1] = args[i];
GCPRO2 (proc, current_dir);
! coding_systems = Ffind_operation_coding_system (nargs + 1, args2);
UNGCPRO;
if (CONSP (coding_systems))
val = XCAR (coding_systems);
--- 1680,1687 ----
args2[0] = Qstart_process;
for (i = 0; i < nargs; i++) args2[i + 1] = args[i];
GCPRO2 (proc, current_dir);
! if (!NILP (program))
! coding_systems = Ffind_operation_coding_system (nargs + 1, args2);
UNGCPRO;
if (CONSP (coding_systems))
val = XCAR (coding_systems);
*************** usage: (start-process NAME BUFFER PROGRA
*** 1693,1699 ****
args2[0] = Qstart_process;
for (i = 0; i < nargs; i++) args2[i + 1] = args[i];
GCPRO2 (proc, current_dir);
! coding_systems = Ffind_operation_coding_system (nargs + 1, args2);
UNGCPRO;
}
if (CONSP (coding_systems))
--- 1699,1706 ----
args2[0] = Qstart_process;
for (i = 0; i < nargs; i++) args2[i + 1] = args[i];
GCPRO2 (proc, current_dir);
! if (!NILP (program))
! coding_systems = Ffind_operation_coding_system (nargs + 1, args2);
UNGCPRO;
}
if (CONSP (coding_systems))
*************** usage: (start-process NAME BUFFER PROGRA
*** 1704,1784 ****
XPROCESS (proc)->encode_coding_system = val;
}
- #ifdef VMS
- /* Make a one member argv with all args concatenated
- together separated by a blank. */
- len = SBYTES (program) + 2;
- for (i = 3; i < nargs; i++)
- {
- tem = args[i];
- CHECK_STRING (tem);
- len += SBYTES (tem) + 1; /* count the blank */
- }
- new_argv = (unsigned char *) alloca (len);
- strcpy (new_argv, SDATA (program));
- for (i = 3; i < nargs; i++)
- {
- tem = args[i];
- CHECK_STRING (tem);
- strcat (new_argv, " ");
- strcat (new_argv, SDATA (tem));
- }
- /* Need to add code here to check for program existence on VMS */
-
- #else /* not VMS */
- new_argv = (unsigned char **) alloca ((nargs - 1) * sizeof (char *));
-
- /* If program file name is not absolute, search our path for it.
- Put the name we will really use in TEM. */
- if (!IS_DIRECTORY_SEP (SREF (program, 0))
- && !(SCHARS (program) > 1
- && IS_DEVICE_SEP (SREF (program, 1))))
- {
- struct gcpro gcpro1, gcpro2, gcpro3, gcpro4;
-
- tem = Qnil;
- GCPRO4 (name, program, buffer, current_dir);
- openp (Vexec_path, program, Vexec_suffixes, &tem, make_number (X_OK));
- UNGCPRO;
- if (NILP (tem))
- report_file_error ("Searching for program", Fcons (program, Qnil));
- tem = Fexpand_file_name (tem, Qnil);
- }
- else
- {
- if (!NILP (Ffile_directory_p (program)))
- error ("Specified program for new process is a directory");
- tem = program;
- }
-
- /* If program file name starts with /: for quoting a magic name,
- discard that. */
- if (SBYTES (tem) > 2 && SREF (tem, 0) == '/'
- && SREF (tem, 1) == ':')
- tem = Fsubstring (tem, make_number (2), Qnil);
-
- /* Encode the file name and put it in NEW_ARGV.
- That's where the child will use it to execute the program. */
- tem = ENCODE_FILE (tem);
- new_argv[0] = SDATA (tem);
-
- /* Here we encode arguments by the coding system used for sending
- data to the process. We don't support using different coding
- systems for encoding arguments and for encoding data sent to the
- process. */
-
- for (i = 3; i < nargs; i++)
- {
- tem = args[i];
- CHECK_STRING (tem);
- if (STRING_MULTIBYTE (tem))
- tem = (code_convert_string_norecord
- (tem, XPROCESS (proc)->encode_coding_system, 1));
- new_argv[i - 2] = SDATA (tem);
- }
- new_argv[i - 2] = 0;
- #endif /* not VMS */
-
XPROCESS (proc)->decoding_buf = make_uninit_string (0);
XPROCESS (proc)->decoding_carryover = 0;
XPROCESS (proc)->encoding_buf = make_uninit_string (0);
--- 1711,1716 ----
*************** usage: (start-process NAME BUFFER PROGRA
*** 1786,1792 ****
XPROCESS (proc)->inherit_coding_system_flag
= !(NILP (buffer) || !inherit_process_coding_system);
! create_process (proc, (char **) new_argv, current_dir);
return unbind_to (count, proc);
}
--- 1718,1804 ----
XPROCESS (proc)->inherit_coding_system_flag
= !(NILP (buffer) || !inherit_process_coding_system);
! if (!NILP (program))
! {
! #ifdef VMS
! /* Make a one member argv with all args concatenated
! together separated by a blank. */
! len = SBYTES (program) + 2;
! for (i = 3; i < nargs; i++)
! {
! tem = args[i];
! CHECK_STRING (tem);
! len += SBYTES (tem) + 1; /* count the blank */
! }
! new_argv = (unsigned char *) alloca (len);
! strcpy (new_argv, SDATA (program));
! for (i = 3; i < nargs; i++)
! {
! tem = args[i];
! CHECK_STRING (tem);
! strcat (new_argv, " ");
! strcat (new_argv, SDATA (tem));
! }
! /* Need to add code here to check for program existence on VMS */
!
! #else /* not VMS */
! new_argv = (unsigned char **) alloca ((nargs - 1) * sizeof (char *));
!
! /* If program file name is not absolute, search our path for it.
! Put the name we will really use in TEM. */
! if (!IS_DIRECTORY_SEP (SREF (program, 0))
! && !(SCHARS (program) > 1
! && IS_DEVICE_SEP (SREF (program, 1))))
! {
! struct gcpro gcpro1, gcpro2, gcpro3, gcpro4;
!
! tem = Qnil;
! GCPRO4 (name, program, buffer, current_dir);
! openp (Vexec_path, program, Vexec_suffixes, &tem, make_number (X_OK));
! UNGCPRO;
! if (NILP (tem))
! report_file_error ("Searching for program", Fcons (program, Qnil));
! tem = Fexpand_file_name (tem, Qnil);
! }
! else
! {
! if (!NILP (Ffile_directory_p (program)))
! error ("Specified program for new process is a directory");
! tem = program;
! }
!
! /* If program file name starts with /: for quoting a magic name,
! discard that. */
! if (SBYTES (tem) > 2 && SREF (tem, 0) == '/'
! && SREF (tem, 1) == ':')
! tem = Fsubstring (tem, make_number (2), Qnil);
!
! /* Encode the file name and put it in NEW_ARGV.
! That's where the child will use it to execute the program. */
! tem = ENCODE_FILE (tem);
! new_argv[0] = SDATA (tem);
!
! /* Here we encode arguments by the coding system used for sending
! data to the process. We don't support using different coding
! systems for encoding arguments and for encoding data sent to the
! process. */
!
! for (i = 3; i < nargs; i++)
! {
! tem = args[i];
! CHECK_STRING (tem);
! if (STRING_MULTIBYTE (tem))
! tem = (code_convert_string_norecord
! (tem, XPROCESS (proc)->encode_coding_system, 1));
! new_argv[i - 2] = SDATA (tem);
! }
! new_argv[i - 2] = 0;
! #endif /* not VMS */
!
! create_process (proc, (char **) new_argv, current_dir);
! }
! else
! create_pty (proc);
return unbind_to (count, proc);
}
*************** start_process_unwind (proc)
*** 1803,1809 ****
abort ();
/* Was PROC started successfully? */
! if (XPROCESS (proc)->pid <= 0)
remove_process (proc);
return Qnil;
--- 1815,1821 ----
abort ();
/* Was PROC started successfully? */
! if (XPROCESS (proc)->pid == -1)
remove_process (proc);
return Qnil;
*************** create_process_sigchld ()
*** 1836,1841 ****
--- 1848,1939 ----
#endif
#endif
+ void
+ create_pty (process)
+ {
+ int inchannel, outchannel;
+
+ /* Use volatile to protect variables from being clobbered by longjmp. */
+ volatile int forkin, forkout;
+ volatile int pty_flag = 0;
+
+ inchannel = outchannel = -1;
+
+ #ifdef HAVE_PTYS
+ if (!NILP (Vprocess_connection_type))
+ outchannel = inchannel = allocate_pty ();
+
+ if (inchannel >= 0)
+ {
+ #if ! defined (USG) || defined (USG_SUBTTY_WORKS)
+ /* On most USG systems it does not work to open the pty's tty here,
+ then close it and reopen it in the child. */
+ #ifdef O_NOCTTY
+ /* Don't let this terminal become our controlling terminal
+ (in case we don't have one). */
+ forkout = forkin = emacs_open (pty_name, O_RDWR | O_NOCTTY, 0);
+ #else
+ forkout = forkin = emacs_open (pty_name, O_RDWR, 0);
+ #endif
+ if (forkin < 0)
+ report_file_error ("Opening pty", Qnil);
+ #if defined (RTU) || defined (UNIPLUS) || defined (DONT_REOPEN_PTY)
+ /* In the case that vfork is defined as fork, the parent process
+ (Emacs) may send some data before the child process completes
+ tty options setup. So we setup tty before forking. */
+ child_setup_tty (forkout);
+ #endif /* RTU or UNIPLUS or DONT_REOPEN_PTY */
+ #else
+ forkin = forkout = -1;
+ #endif /* not USG, or USG_SUBTTY_WORKS */
+ pty_flag = 1;
+ }
+ else
+ #endif /* HAVE_PTYS */
+
+ /* Stride people say it's a mystery why this is needed
+ as well as the O_NDELAY, but that it fails without this. */
+ #if defined (STRIDE) || (defined (pfa) && defined (HAVE_PTYS))
+ {
+ int one = 1;
+ ioctl (inchannel, FIONBIO, &one);
+ }
+ #endif
+
+ #ifdef O_NONBLOCK
+ fcntl (inchannel, F_SETFL, O_NONBLOCK);
+ fcntl (outchannel, F_SETFL, O_NONBLOCK);
+ #else
+ #ifdef O_NDELAY
+ fcntl (inchannel, F_SETFL, O_NDELAY);
+ fcntl (outchannel, F_SETFL, O_NDELAY);
+ #endif
+ #endif
+
+ /* Record this as an active process, with its channels.
+ As a result, child_setup will close Emacs's side of the pipes. */
+ chan_process[inchannel] = process;
+ XPROCESS (process)->infd = inchannel;
+ XPROCESS (process)->outfd = outchannel;
+
+ /* Previously we recorded the tty descriptor used in the subprocess.
+ It was only used for getting the foreground tty process, so now
+ we just reopen the device (see emacs_get_tty_pgrp) as this is
+ more portable (see USG_SUBTTY_WORKS above). */
+
+ XPROCESS (process)->pty_flag = pty_flag;
+ XPROCESS (process)->status = Qrun;
+ setup_process_coding_systems (process);
+
+ FD_SET (inchannel, &input_wait_mask);
+ FD_SET (inchannel, &non_keyboard_wait_mask);
+ if (inchannel > max_process_desc)
+ max_process_desc = inchannel;
+
+ XPROCESS (process)->pid = -2;
+ XPROCESS (process)->tty_name = build_string (pty_name);
+ }
+
#ifndef VMS /* VMS version of this function is in vmsproc.c. */
void
create_process (process, new_argv, current_dir)