From: Philipp Stephani Date: Thu, 26 Mar 2020 16:22:25 +0000 (+0100) Subject: Add a module function to open a file descriptor connected to a pipe. X-Git-Tag: emacs-28.0.90~7716 X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=d28b00476890f791a89b65007e5f20682b3eaa0d;p=emacs.git Add a module function to open a file descriptor connected to a pipe. A common complaint about the module API is that modules can't communicate asynchronously with Emacs. While it isn't possible to call arbitrary Emacs functions asynchronously, writing to a pipe should always be fine and is a pretty low-hanging fruit. This patch implements a function that adapts an existing pipe process. That way, users can use familiar tools like process filters or 'accept-process-output'. * src/module-env-28.h: Add 'open_channel' module function. * src/emacs-module.c (module_open_channel): Provide definition for 'open_channel'. (initialize_environment): Use it. * src/process.c (open_channel_for_module): New helper function. (syms_of_process): Define necessary symbol. * test/src/emacs-module-tests.el (module/async-pipe): New unit test. * test/data/emacs-module/mod-test.c (signal_system_error): New helper function. (signal_errno): Use it. (write_to_pipe): New function running in the background. (Fmod_test_async_pipe): New test module function. (emacs_module_init): Export it. * doc/lispref/internals.texi (Module Misc): Document new module function. * doc/lispref/processes.texi (Asynchronous Processes): New anchor for pipe processes. * etc/NEWS: Document 'open_channel' function. --- diff --git a/doc/lispref/internals.texi b/doc/lispref/internals.texi index 442f6d156b6..0c24dac7775 100644 --- a/doc/lispref/internals.texi +++ b/doc/lispref/internals.texi @@ -2022,6 +2022,20 @@ variable values and buffer content may have been modified in arbitrary ways. @end deftypefn +@anchor{open_channel} +@deftypefun int open_channel (emacs_env *@var{env}, emacs_value @var{pipe_process}) +This function, which is available since Emacs 27, opens a channel to +an existing pipe process. @var{pipe_process} must refer to an +existing pipe process created by @code{make-pipe-process}. @ref{Pipe +Processes}. If successful, the return value will be a new file +descriptor that you can use to write to the pipe. Unlike all other +module functions, you can use the returned file descriptor from +arbitrary threads, even if no module environment is active. You can +use the @code{write} function to write to the file descriptor. Once +done, close the file descriptor using @code{close}. @ref{Low-Level +I/O,,,libc}. +@end deftypefun + @node Module Nonlocal @subsection Nonlocal Exits in Modules @cindex nonlocal exits, in modules diff --git a/doc/lispref/processes.texi b/doc/lispref/processes.texi index f515213615e..14cd079c563 100644 --- a/doc/lispref/processes.texi +++ b/doc/lispref/processes.texi @@ -743,6 +743,7 @@ Some file name handlers may not support @code{make-process}. In such cases, this function does nothing and returns @code{nil}. @end defun +@anchor{Pipe Processes} @defun make-pipe-process &rest args This function creates a bidirectional pipe which can be attached to a child process. This is useful with the @code{:stderr} keyword of diff --git a/etc/NEWS b/etc/NEWS index 910d9fa2d23..a2cb4b094e8 100644 --- a/etc/NEWS +++ b/etc/NEWS @@ -258,6 +258,10 @@ called when the function object is garbage-collected. Use 'set_function_finalizer' to set the finalizer and 'get_function_finalizer' to retrieve it. +** Modules can now open a channel to an existing pipe process using +the new module function 'open_channel'. Modules can use this +functionality to asynchronously send data back to Emacs. + ** 'file-modes', 'set-file-modes', and 'set-file-times' now have an optional argument specifying whether to follow symbolic links. diff --git a/src/emacs-module.c b/src/emacs-module.c index 60f16418efa..cdcbe061b53 100644 --- a/src/emacs-module.c +++ b/src/emacs-module.c @@ -88,6 +88,7 @@ To add a new module function, proceed as follows: #include "dynlib.h" #include "coding.h" #include "keyboard.h" +#include "process.h" #include "syssignal.h" #include "sysstdio.h" #include "thread.h" @@ -977,6 +978,13 @@ module_make_big_integer (emacs_env *env, int sign, return lisp_to_value (env, make_integer_mpz ()); } +static int +module_open_channel (emacs_env *env, emacs_value pipe_process) +{ + MODULE_FUNCTION_BEGIN (-1); + return open_channel_for_module (value_to_lisp (pipe_process)); +} + /* Subroutines. */ @@ -1391,6 +1399,7 @@ initialize_environment (emacs_env *env, struct emacs_env_private *priv) env->make_big_integer = module_make_big_integer; env->get_function_finalizer = module_get_function_finalizer; env->set_function_finalizer = module_set_function_finalizer; + env->open_channel = module_open_channel; Vmodule_environments = Fcons (make_mint_ptr (env), Vmodule_environments); return env; } diff --git a/src/module-env-28.h b/src/module-env-28.h index a2479a8f744..5d884c148c4 100644 --- a/src/module-env-28.h +++ b/src/module-env-28.h @@ -9,3 +9,6 @@ void (*set_function_finalizer) (emacs_env *env, emacs_value arg, void (*fin) (void *) EMACS_NOEXCEPT) EMACS_ATTRIBUTE_NONNULL (1); + + int (*open_channel) (emacs_env *env, emacs_value pipe_process) + EMACS_ATTRIBUTE_NONNULL (1); diff --git a/src/process.c b/src/process.c index e4e5e57aeee..07881d6c5d3 100644 --- a/src/process.c +++ b/src/process.c @@ -8200,6 +8200,17 @@ restore_nofile_limit (void) #endif } +int +open_channel_for_module (Lisp_Object process) +{ + CHECK_PROCESS (process); + CHECK_TYPE (PIPECONN_P (process), Qpipe_process_p, process); + int fd = dup (XPROCESS (process)->open_fd[SUBPROCESS_STDOUT]); + if (fd == -1) + report_file_error ("Cannot duplicate file descriptor", Qnil); + return fd; +} + /* This is not called "init_process" because that is the name of a Mach system call, so it would cause problems on Darwin systems. */ @@ -8446,6 +8457,7 @@ amounts of data in one go. */); DEFSYM (Qinterrupt_process_functions, "interrupt-process-functions"); DEFSYM (Qnull, "null"); + DEFSYM (Qpipe_process_p, "pipe-process-p"); defsubr (&Sprocessp); defsubr (&Sget_process); diff --git a/src/process.h b/src/process.h index 7884efc5494..a783a31cb86 100644 --- a/src/process.h +++ b/src/process.h @@ -300,6 +300,8 @@ extern Lisp_Object remove_slash_colon (Lisp_Object); extern void update_processes_for_thread_death (Lisp_Object); extern void dissociate_controlling_tty (void); +extern int open_channel_for_module (Lisp_Object); + INLINE_HEADER_END #endif /* EMACS_PROCESS_H */ diff --git a/test/data/emacs-module/mod-test.c b/test/data/emacs-module/mod-test.c index ec6948921f2..61733f1ef49 100644 --- a/test/data/emacs-module/mod-test.c +++ b/test/data/emacs-module/mod-test.c @@ -30,6 +30,9 @@ along with GNU Emacs. If not, see . */ #include #include +#include +#include + #ifdef HAVE_GMP #include #else @@ -320,9 +323,9 @@ Fmod_test_invalid_finalizer (emacs_env *env, ptrdiff_t nargs, emacs_value *args, } static void -signal_errno (emacs_env *env, const char *function) +signal_system_error (emacs_env *env, int error, const char *function) { - const char *message = strerror (errno); + const char *message = strerror (error); emacs_value message_value = env->make_string (env, message, strlen (message)); emacs_value symbol = env->intern (env, "file-error"); emacs_value elements[2] @@ -331,6 +334,12 @@ signal_errno (emacs_env *env, const char *function) env->non_local_exit_signal (env, symbol, data); } +static void +signal_errno (emacs_env *env, const char *function) +{ + signal_system_error (env, errno, function); +} + /* A long-running operation that occasionally calls `should_quit' or `process_input'. */ @@ -533,6 +542,49 @@ Fmod_test_function_finalizer_calls (emacs_env *env, ptrdiff_t nargs, return env->funcall (env, Flist, 2, list_args); } +static void * +write_to_pipe (void *arg) +{ + /* We sleep a bit to test that writing to a pipe is indeed possible + if no environment is active. */ + const struct timespec sleep = {0, 500000000}; + if (nanosleep (&sleep, NULL) != 0) + perror ("nanosleep"); + FILE *stream = arg; + if (fputs ("data from thread", stream) < 0) + perror ("fputs"); + if (fclose (stream) != 0) + perror ("close"); + return NULL; +} + +static emacs_value +Fmod_test_async_pipe (emacs_env *env, ptrdiff_t nargs, emacs_value *args, + void *data) +{ + assert (nargs == 1); + int fd = env->open_channel (env, args[0]); + if (env->non_local_exit_check (env) != emacs_funcall_exit_return) + return NULL; + FILE *stream = fdopen (fd, "w"); + if (stream == NULL) + { + signal_errno (env, "fdopen"); + return NULL; + } + pthread_t thread; + int error + = pthread_create (&thread, NULL, write_to_pipe, stream); + if (error != 0) + { + signal_system_error (env, error, "pthread_create"); + if (fclose (stream) != 0) + perror ("fclose"); + return NULL; + } + return env->intern (env, "nil"); +} + /* Lisp utilities for easier readability (simple wrappers). */ /* Provide FEATURE to Emacs. */ @@ -614,6 +666,7 @@ emacs_module_init (struct emacs_runtime *ert) Fmod_test_make_function_with_finalizer, 0, 0, NULL, NULL); DEFUN ("mod-test-function-finalizer-calls", Fmod_test_function_finalizer_calls, 0, 0, NULL, NULL); + DEFUN ("mod-test-async-pipe", Fmod_test_async_pipe, 1, 1, NULL, NULL); #undef DEFUN diff --git a/test/src/emacs-module-tests.el b/test/src/emacs-module-tests.el index 48d2e86a605..1f91795e1e6 100644 --- a/test/src/emacs-module-tests.el +++ b/test/src/emacs-module-tests.el @@ -424,4 +424,18 @@ See Bug#36226." ;; but at least one. (should (> valid-after valid-before))))) +(ert-deftest module/async-pipe () + "Check that writing data from another thread works." + (with-temp-buffer + (let ((process (make-pipe-process :name "module/async-pipe" + :buffer (current-buffer) + :coding 'utf-8-unix + :noquery t))) + (unwind-protect + (progn + (mod-test-async-pipe process) + (should (accept-process-output process 1)) + (should (equal (buffer-string) "data from thread"))) + (delete-process process))))) + ;;; emacs-module-tests.el ends here