spurious eof to M-x shell child stdin

[Thien-Thi Nguyen]

in a program initiated from the shell initiated w/ M-x shell, an input
line of 512 characters results in a spurious EOF to the program.  here
are three steps to reproduce the problem, and some additional actions to
compare the actual and expected behaviors:

(A) compile this C program:
cat > drain-stdin.c <<EOF
#include <stdio.h>
int
main (int argc, char *argv)
{
  int count = 0;
  int result;
  unsigned char byte;
  while (0 < (result = read (0, &byte, 1)))
    {
      count++;
      printf ("[%d:%d] %c\n", result, count, byte);
    }
  printf ("count: %d\n", count);
  return 0;
}
EOF
gcc -o /tmp/drain-stdin drain-stdin.c

(B) create a long input line:
(let ((s (apply 'concat (make-list 32 "0123456789ABCDEF")))
      (require-final-newline nil))
  (with-temp-buffer
    (insert s)
    (write-region (point-min) (point-max) "/tmp/.512")))

(C) run the program under M-x shell, giving it the input:
M-x shell
/tmp/drain-stdin RET
(insert-file-contents "/tmp/.512")
(end-of-line)
RET

(D) run the program noninteractively under M-x shell
/tmp/drain-stdin < /tmp/.512

(E) likewise, under a regular terminal (outside emacs):
/tmp/drain-stdin < /tmp/.512

(F) likewise, with M-x compile
/tmp/drain-stdin < /tmp/.512

for (C) i see output that ends with:
[1:503] 6
[1:504] 7
[1:505] 8
[1:506] 9
[1:507] A
[1:508] B
count: 508
$ bash: CDEF: command not found

for (D), (E) and (F), i see output that ends with:
[1:507] A
[1:508] B
[1:509] C
[1:510] D
[1:511] E
[1:512] F
count: 512

i believe (D), (E) and (F) are correct.  all behaviors were reproducible
w/ emacs from cvs and emacs 21.4, started with "-q --no-site-file".

thi




In GNU Emacs 22.0.98.2 (i686-pc-linux-gnu)
 of 2007-04-20 on ambire
Windowing system distributor `The XFree86 Project, Inc', version 11.0.40300001
configured using `configure  '--prefix' '/home/ttn/local' 
'CPPFLAGS=-DSITELOAD_PURESIZE_EXTRA=20000''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: C
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: C
  locale-coding-system: nil
  default-enable-multibyte-characters: t

Major mode: Man

Minor modes in effect:
  shell-dirtrack-mode: t
  display-time-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  auto-compression-mode: t
  transient-mark-mode: t

Recent input:
C-a C-a C-a C-a C-a C-x C-s M-m M-p RET C-x C-k C-x 
s M-p M-p <return> C-x i M-p <return> C-e <return> 
C-x C-f M-p RET C-x h M-w C-x C-f C-a C-f C-f C-k . 
e <backspace> b a s r h <backspace> <backspace> h r 
<tab> <return> C-x C-f . v a r <tab> RET C-s E M A 
C S C-s C-a C-a C-l M-: ( g e t e n v SPC " E M A C 
S " ) <return> C-x s e c h o SPC $ P A G E R <return> 
C-x b RET C-x C-b C-n C-n C-n RET C-x h M-w M-x r e 
p o <tab> r <tab> <return> s p u r i o u s SPC e o 
f SPC v i a SPC <backspace> <backspace> <backspace> 
<backspace> t h r o u g h <backspace> <backspace> <backspace> 
<backspace> <backspace> <backspace> <backspace> <backspace> 
SPC t o SPC M - x SPC s h e l l SPC c h i l <backspace> 
<backspace> <backspace> <backspace> c h i <backspace> 
<backspace> <backspace> c h i d l r e n SPC <backspace> 
<backspace> <backspace> <backspace> <backspace> <backspace> 
l d r e n SPC s t d i n <return> C-p C-p C-p C-p C-p 
C-n C-e M-b M-b M-f <backspace> <backspace> <backspace> 
M-> M-< C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n 
C-n C-p C-p C-p C-p C-p C-p C-p C-n C-x 1 C-p C-p C-p 
C-p C-p C-p C-n C-n C-n C-n C-n C-n C-h c C-c C-a C-x 
C-k C-x C-g M-x m a n <return> r e <backspace> <backspace> 
2 SPC r e a d <return> C-x 0 C-x b RET C-x b RET C-x 
b C-g M-x M-p M-p <return>

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