When executing an Eshell pipeline, send input to the first process

Previously, input was sent to the last process in the pipeline,
resulting in unexpected behavior when running commands like
'tr a-z A-Z | rev'.

* lisp/eshell/esh-util.el (eshell-process-pair-p)
(eshell-make-process-pair): New functions.

* lisp/eshell/esh-cmd.el (eshell-last-async-proc): Rename to...
(eshell-last-async-procs): ... this, and store a pair of processes.
(eshell-interactive-process): Replace with...
(eshell-interactive-process-p, eshell-head-process)
(eshell-tail-process): ... these.
(eshell-cmd-initialize): Set 'eshell-last-async-procs'.
(eshell-do-pipelines): Set 'headproc'.
(eshell-execute-pipeline): Return 'headproc' and 'tailproc'.
(eshell-resume-eval): Use 'eshell-last-async-procs'.
(eshell-do-eval): Make sure we work with a pair of processes.

* lisp/eshell/esh-proc.el (eshell-send-eof-to-process): Move from
here...
* lisp/eshell/esh-mode.el (eshell-send-eof-to-process): ... to here,
and only send EOF to the head process.

* lisp/eshell/em-cmpl.el (eshell-complete-parse-arguments)
* lisp/eshell/esh-mode.el (eshell-intercept-commands)
(eshell-watch-for-password-prompt):
Use 'eshell-interactive-process-p'.

* lisp/eshell/em-rebind.el (eshell-delchar-or-maybe-eof)
* lisp/eshell/em-term.el (eshell-term-send-raw-string)
* lisp/eshell/esh-mode.el (eshell-self-insert-command)
(eshell-send-input, eshell-send-invisible):
Use 'eshell-head-process'.

* lisp/eshell/esh-cmd.el (eshell-as-subcommand):
Use 'eshell-tail-process'.

* lisp/eshell/eshell.el (eshell-command):
* test/lisp/eshell/eshell-tests-helpers.el
(eshell-wait-for-subprocess):
Use 'eshell-interactive-process-p' and 'eshell-tail-process'.

* test/lisp/eshell/eshell-tests.el (eshell-test/pipe-headproc-stdin):
New test.

1 files changed, 11 insertions, 0 deletions

diff --git a/test/lisp/eshell/eshell-tests.el b/test/lisp/eshell/eshell-tests.el
index 7658d5f5517..3b1bbe7188b 100644
--- a/test/lisp/eshell/eshell-tests.el
+++ b/test/lisp/eshell/eshell-tests.el
@@ -136,6 +136,17 @@ e.g. \"{(+ 1 2)} 3\" => 3"
    (eshell-command-result-p "*echo hi | echo bye"
                             "bye\nhi\n")))
 
+(ert-deftest eshell-test/pipe-headproc-stdin ()
+  "Check that standard input is sent to the head process in a pipeline"
+  (skip-unless (and (executable-find "tr")
+                    (executable-find "rev")))
+  (with-temp-eshell
+   (eshell-insert-command "tr a-z A-Z | rev")
+   (eshell-insert-command "hello")
+   (eshell-send-eof-to-process)
+   (eshell-wait-for-subprocess)
+   (eshell-match-result "OLLEH\n")))
+
 (ert-deftest eshell-test/window-height ()
   "$LINES should equal (window-height)"
   (should (eshell-test-command-result "= $LINES (window-height)")))