From bc4ced913952dd0e6d20c13dd27a7d515d7dcda2 Mon Sep 17 00:00:00 2001
From: pooryorick <com.digitalsmarties@pooryorick.com>
Date: Sun, 16 Apr 2023 23:10:16 +0000
Subject: [PATCH] Fix for [eabcbd08274f2d22], [read] error persists on channel
 with strict encoding after encoding is changed to binary.

---
 generic/tclIO.c |  4 +++-
 tests/io.test   | 24 ++++++++++++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/generic/tclIO.c b/generic/tclIO.c
index 4a88f52c66b..7e475cc2542 100644
--- a/generic/tclIO.c
+++ b/generic/tclIO.c
@@ -4616,7 +4616,7 @@ Tcl_GetsObj(
 
     if (GotFlag(statePtr, CHANNEL_ENCODING_ERROR)) {
 	UpdateInterest(chanPtr);
-	ResetFlag(statePtr, CHANNEL_ENCODING_ERROR);
+	ResetFlag(statePtr, CHANNEL_EOF|CHANNEL_BLOCKED);
 	Tcl_SetErrno(EILSEQ);
 	return TCL_INDEX_NONE;
     }
@@ -5941,6 +5941,7 @@ DoReadChars(
     int factor = UTF_EXPANSION_FACTOR;
 
     if (GotFlag(statePtr, CHANNEL_ENCODING_ERROR)) {
+	ResetFlag(statePtr, CHANNEL_EOF|CHANNEL_STICKY_EOF|CHANNEL_BLOCKED);
 	/* TODO: We don't need this call? */
 	UpdateInterest(chanPtr);
 	Tcl_SetErrno(EILSEQ);
@@ -6117,6 +6118,7 @@ DoReadChars(
 	 * succesfully red before the error.  Return an error so that callers
 	 * like [read] can also return an error.
 	*/
+	ResetFlag(statePtr, CHANNEL_EOF|CHANNEL_ENCODING_ERROR);
 	Tcl_SetErrno(EILSEQ);
 	copied = -1;
     }
diff --git a/tests/io.test b/tests/io.test
index f1966c791dc..764c77626d0 100644
--- a/tests/io.test
+++ b/tests/io.test
@@ -9322,6 +9322,30 @@ test io-75.8 {invalid utf-8 encoding eof handling (-profile strict)} -setup {
     removeFile io-75.8
 } -result {41 1 {}}
 
+test io-75.8.eoflater {invalid utf-8 encoding eof handling (-profile strict)} -setup {
+	set res {}
+    set fn [makeFile {} io-75.8]
+    set f [open $fn w+]
+    fconfigure $f -encoding binary
+    # \x81 is invalid in utf-8. -eofchar is not detected, because it comes later.
+    puts -nonewline $f A\x81\x1A
+    flush $f
+    seek $f 0
+    fconfigure $f -encoding utf-8 -buffering none -eofchar \x1A \
+	-translation lf -profile strict
+} -body {
+    after 1
+    set status [catch {read $f} cres copts]
+    lappend res $status
+    lappend res [eof $f]
+    chan configure $f -encoding iso8859-1
+    lappend res [read $f]
+    close $f
+    set res
+} -cleanup {
+    removeFile io-75.8
+} -result "1 0 \x81"
+
 test io-75.9 {unrepresentable character write passes and is replaced by ?} -setup {
     set fn [makeFile {} io-75.9]
     set f [open $fn w+]