[PATCH] Test for 50101

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

I included tests for all return values of sysread except "error in parameters".

That includes a couple of Xfail tests for the $REPLY value.  The doc says:

     ... The result of the read is stored in PARAM or
     REPLY if that is not given. ...
     If OUTFD is given, an attempt is made to write all the bytes just
     read to the file descriptor OUTFD.  If this fails, ...
     the bytes read but not written are stored in
     the parameter named by PARAM if supplied ....  If it was
     successful, COUNTVAR contains the full number of bytes transferred,
     as usual, and PARAM is not set.

This doesn't really specify what happens when $REPLY (or the PARAM)
already has a value before sysread is called.  As currently
implemented, the value (or unset-ness) is unchanged when the return
status does not require that anything be assigned, so it's necessary
to either carefully (un)set these parameters before calling sysread,
or to test the return status before using them.

diff --git a/Test/V14system.ztst b/Test/V14system.ztst
index ffdb730a4..81253324f 100644
--- a/Test/V14system.ztst
+++ b/Test/V14system.ztst
@@ -147,3 +147,69 @@ F:This timing test might fail due to process scheduling issues unrelated to zsh.
 0:zsystem flock successful wait test, fractional seconds
 ?elapsed time seems OK
 F:This timing test might fail due to process scheduling issues unrelated to zsh.
+
+  unset chars REPLY
+  print -n a few words | sysread -i 0 -c chars
+  ret=$?
+  print -- $chars x${REPLY}x
+  return ret
+0:sysread default
+>11 xa few wordsx
+
+  unset chars REPLY
+  sysread -i 9 -c chars
+  ret=$?
+  print -- $chars x${REPLY}x
+  return ret
+2:sysread read error
+>-1 xx
+
+  REPLY="say nothing"
+  sysread -i 9 -c chars
+  ret=$?
+  print -- $chars x${REPLY}x
+  return ret
+2f:sysread read error
+F:The value of $REPLY should be empty or unset when nothing is read?
+>-1 xx
+
+  unset chars REPLY
+  print -n a few words | sysread -i 0 -o 9 -c chars
+  ret=$?
+  print -- $chars x${REPLY}x
+  return ret
+3:sysread write error
+>11 xx
+
+  sleep 3 | sysread -i 0 -t 1
+4:sysread timeout
+
+  sysread -i 0 </dev/null
+5:sysread end of file
+
+  unset chars oration
+  print -n a few words | sysread -i 0 -o 9 -c chars oration
+  ret=$?
+  print $chars x${oration}x $REPLY
+  return ret
+3:regression test: sysread write error with both -o and a parameter
+>11 xa few wordsx
+
+  unset chars oration
+  print a few words | sysread -i 0 -o 1 -c chars oration
+  ret=$?
+  print -- $chars x${oration}x $REPLY
+  return ret
+0:regression test: sucessful sysread with both -o and a parameter
+>a few words
+>12 xx
+
+  oration="do not say these words"
+  print a few words | sysread -i 0 -o 1 -c chars oration
+  ret=$?
+  print -- $chars x${oration}x $REPLY
+  return ret
+0f:successful sysread with both -o and a parameter
+F:The value of $oration should be empty or unset when everything is written?
+>a few words
+>12 xx