From 2e628b79d9fe0fe590cbab9bea27c1fdf11082f9 Mon Sep 17 00:00:00 2001
From: "jan.nijtmans" <nijtmans@users.sourceforge.net>
Date: Tue, 14 Nov 2023 11:07:13 +0000
Subject: Add test for blocking mode

---
 generic/tclIO.c    | 29 ++++++++++++++++++++++++++++-
 generic/tclIOCmd.c | 12 ++++++------
 generic/tclInt.h   |  1 +
 tests/io.test      |  4 ++--
 4 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/generic/tclIO.c b/generic/tclIO.c
index bc1b1c6..0047f0b 100644
--- a/generic/tclIO.c
+++ b/generic/tclIO.c
@@ -4934,7 +4934,7 @@ Tcl_GetsObj(
 	     * two times, as gs.bytesWrote is not 0 on the first pass. This feels
 	     * once to much, as the data is anyway not used.
 	     */
-	     
+
 	    /* Set eol to the position that caused the encoding error, and then
 	     * continue to gotEOL, which stores the data that was decoded
 	     * without error to objPtr.  This allows the caller to do something
@@ -7616,6 +7616,33 @@ Tcl_Eof(
     return GotFlag(statePtr, CHANNEL_EOF) ? 1 : 0;
 }
 
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclChannelGetBlockingMode --
+ *
+ *	Returns 1 if the channel is in blocking mode (default), 0 otherwise.
+ *
+ * Results:
+ *	1 or 0, always.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+TclChannelGetBlockingMode(
+    Tcl_Channel chan)
+{
+    ChannelState *statePtr = ((Channel *) chan)->state;
+				/* State of real channel structure. */
+
+    return GotFlag(statePtr, CHANNEL_NONBLOCKING) ? 0 : 1;
+}
+
 /*
  *----------------------------------------------------------------------
  *
diff --git a/generic/tclIOCmd.c b/generic/tclIOCmd.c
index 0827858..9667419 100644
--- a/generic/tclIOCmd.c
+++ b/generic/tclIOCmd.c
@@ -459,11 +459,9 @@ Tcl_ReadObjCmd(
     TclChannelPreserve(chan);
     charactersRead = Tcl_ReadChars(chan, resultPtr, toRead, 0);
     if (charactersRead == TCL_IO_FAILURE) {
-
-	Tcl_Obj *returnOptsPtr = Tcl_NewDictObj();
-	/* check for blocking and encoding error */
-	/* TODO: check for blocking missing */
-	if ( Tcl_GetErrno() == EILSEQ ) {
+	Tcl_Obj *returnOptsPtr = NULL;
+	if (TclChannelGetBlockingMode(chan)) {
+	    returnOptsPtr = Tcl_NewDictObj();
 	    Tcl_DictObjPut(NULL, returnOptsPtr, Tcl_NewStringObj("-data", -1),
 		    resultPtr);
 	}
@@ -480,7 +478,9 @@ Tcl_ReadObjCmd(
 		    TclGetString(chanObjPtr), Tcl_PosixError(interp)));
 	}
 	TclChannelRelease(chan);
-	Tcl_SetReturnOptions(interp, returnOptsPtr);
+	if (returnOptsPtr) {
+	    Tcl_SetReturnOptions(interp, returnOptsPtr);
+	}
 	return TCL_ERROR;
     }
 
diff --git a/generic/tclInt.h b/generic/tclInt.h
index 3d8a702..f696ad2 100644
--- a/generic/tclInt.h
+++ b/generic/tclInt.h
@@ -3112,6 +3112,7 @@ MODULE_SCOPE int	TclByteArrayMatch(const unsigned char *string,
 MODULE_SCOPE double	TclCeil(const void *a);
 MODULE_SCOPE void	TclChannelPreserve(Tcl_Channel chan);
 MODULE_SCOPE void	TclChannelRelease(Tcl_Channel chan);
+MODULE_SCOPE int	TclChannelGetBlockingMode(Tcl_Channel chan);
 MODULE_SCOPE int	TclCheckArrayTraces(Tcl_Interp *interp, Var *varPtr,
 			    Var *arrayPtr, Tcl_Obj *name, int index);
 MODULE_SCOPE int	TclCheckBadOctal(Tcl_Interp *interp,
diff --git a/tests/io.test b/tests/io.test
index 0737c2d..75e30aa 100644
--- a/tests/io.test
+++ b/tests/io.test
@@ -9432,13 +9432,13 @@ test io-75.11 {shiftjis encoding error read results in error (strict profile)} -
 } -body {
     set d [read $f]
     binary scan $d H* hd
-    lappend hd [catch {set d [read $f]} msg data] $msg [dict get $data -data]
+    lappend hd [catch {set d [read $f]} msg data] $msg [dict exists $data -data]
 } -cleanup {
     close $f
     removeFile io-75.11
     unset d hd msg data f
 } -match glob -result {41 1 {error reading "file*":\
-    invalid or incomplete multibyte or wide character} {}}
+    invalid or incomplete multibyte or wide character} 0}
 
 test io-75.12 {invalid utf-8 encoding read is ignored} -setup {
     set fn [makeFile {} io-75.12]
-- 
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