Improve process doc. with respect to handling of large input (Bug#33191)

* src/process.c (Fprocess_send_region, Fprocess_send_string):
Document that process input longer than the process input
buffer may be split into bunches.  Remove an outdated
reference to a 500 character split boundary.
* doc/lispref/processes.texi (Asynchronous Processes): Remove
mention of "stray character injections" in PTY processes.  See
also the comment about ICANON in src/sysdep.c, function
child_setup_tty.

2 files changed, 12 insertions, 10 deletions

diff --git a/doc/lispref/processes.texi b/doc/lispref/processes.texi
index e7d61bd5faa..623be09cc63 100644
--- a/doc/lispref/processes.texi
+++ b/doc/lispref/processes.texi
@@ -604,10 +604,9 @@ these features.  However, for subprocesses used by Lisp programs for
 internal purposes (i.e., no user interaction with the subprocess is
 required), where significant amounts of data need to be exchanged
 between the subprocess and the Lisp program, it is often better to use
-a pipe, because pipes are more efficient, and because they are immune
-to stray character injections that ptys introduce for large (around
-500 byte) messages.  Also, the total number of ptys is limited on many
-systems, and it is good not to waste them unnecessarily.
+a pipe, because pipes are more efficient.  Also, the total number of
+ptys is limited on many systems, and it is good not to waste them
+unnecessarily.
 
 @defun make-process &rest args
 This function is the basic low-level primitive for starting
diff --git a/src/process.c b/src/process.c
index b0a327229c6..e306b2ae9ec 100644
--- a/src/process.c
+++ b/src/process.c
@@ -6456,9 +6456,11 @@ DEFUN ("process-send-region", Fprocess_send_region, Sprocess_send_region,
 PROCESS may be a process, a buffer, the name of a process or buffer, or
 nil, indicating the current buffer's process.
 Called from program, takes three arguments, PROCESS, START and END.
-If the region is more than 500 characters long,
-it is sent in several bunches.  This may happen even for shorter regions.
-Output from processes can arrive in between bunches.
+If the region is larger than the input buffer of the process (the
+length of which depends on the process connection type and the
+operating system), it is sent in several bunches.  This may happen
+even for shorter regions.  Output from processes can arrive in between
+bunches.
 
 If PROCESS is a non-blocking network process that hasn't been fully
 set up yet, this function will block until socket setup has completed.  */)
@@ -6489,9 +6491,10 @@ DEFUN ("process-send-string", Fprocess_send_string, Sprocess_send_string,
        doc: /* Send PROCESS the contents of STRING as input.
 PROCESS may be a process, a buffer, the name of a process or buffer, or
 nil, indicating the current buffer's process.
-If STRING is more than 500 characters long,
-it is sent in several bunches.  This may happen even for shorter strings.
-Output from processes can arrive in between bunches.
+If STRING is larger than the input buffer of the process (the length
+of which depends on the process connection type and the operating
+system), it is sent in several bunches.  This may happen even for
+shorter strings.  Output from processes can arrive in between bunches.
 
 If PROCESS is a non-blocking network process that hasn't been fully
 set up yet, this function will block until socket setup has completed.  */)