From f5c47e4402864aa6d6f5f120c231c39423dcc360 Mon Sep 17 00:00:00 2001
From: "jan.nijtmans" <nijtmans@users.sourceforge.net>
Date: Mon, 20 Mar 2023 23:17:11 +0000
Subject: Proposed fix for [1bedc53c8c]: synchronous [read] with
 -strictencoding does not produce an error on invalid input

---
 generic/tclIO.c | 28 +++++++++++++++++++++++++++-
 tests/io.test   | 16 ++++++++++++++++
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/generic/tclIO.c b/generic/tclIO.c
index 9944787..7f74e2e 100644
--- a/generic/tclIO.c
+++ b/generic/tclIO.c
@@ -6078,6 +6078,23 @@ DoReadChars(
 		    statePtr->inQueueTail = NULL;
 		}
 	    }
+
+	    /*
+	     * If CHANNEL_ENCODING_ERROR and CHANNEL_STICKY_EOF are both set,
+	     * then CHANNEL_ENCODING_ERROR was caused by data that occurred
+	     * after the EOF character was encountered, so it doesn't count as
+	     * a real error.
+	     */
+
+	    if (GotFlag(statePtr, CHANNEL_ENCODING_ERROR)
+		    && !GotFlag(statePtr, CHANNEL_STICKY_EOF)
+		    && !GotFlag(statePtr, CHANNEL_NONBLOCKING)) {
+		/* Channel is blocking.  Return an error so that callers
+		 * like [read] can return an error.
+		*/
+		Tcl_SetErrno(EILSEQ);
+		goto finish;
+	    }
 	}
 
 	if (copiedNow < 0) {
@@ -6106,6 +6123,7 @@ DoReadChars(
 	}
     }
 
+finish:
     /*
      * Failure to fill a channel buffer may have left channel reporting a
      * "blocked" state, but so long as we fulfilled the request here, the
@@ -6139,6 +6157,11 @@ DoReadChars(
     assert(!(GotFlag(statePtr, CHANNEL_EOF|CHANNEL_BLOCKED)
             == (CHANNEL_EOF|CHANNEL_BLOCKED)));
     UpdateInterest(chanPtr);
+    if (GotFlag(statePtr, CHANNEL_ENCODING_ERROR)
+	    && (!copied || !GotFlag(statePtr, CHANNEL_NONBLOCKING))) {
+	Tcl_SetErrno(EILSEQ);
+	copied = -1;
+    }
     TclChannelRelease((Tcl_Channel)chanPtr);
     return copied;
 }
@@ -6769,11 +6792,14 @@ TranslateInputEOL(
 	 * EOF character was seen in EOL translated range. Leave current file
 	 * position pointing at the EOF character, but don't store the EOF
 	 * character in the output string.
+	 *
+	 * If CHANNEL_ENCODING_ERROR is set, it can only be because of data
+	 * encountered after the EOF character, so it is nonsense.  Unset it.
 	 */
 
 	SetFlag(statePtr, CHANNEL_EOF | CHANNEL_STICKY_EOF);
 	statePtr->inputEncodingFlags |= TCL_ENCODING_END;
-	ResetFlag(statePtr, CHANNEL_BLOCKED|INPUT_SAW_CR);
+	ResetFlag(statePtr, CHANNEL_BLOCKED|INPUT_SAW_CR|CHANNEL_ENCODING_ERROR);
     }
 }
 
diff --git a/tests/io.test b/tests/io.test
index cf90936..9246bd8 100644
--- a/tests/io.test
+++ b/tests/io.test
@@ -9171,6 +9171,22 @@ test io-75.6 {invalid utf-8 encoding gets is not ignored (-profile strict)} -set
     removeFile io-75.6
 } -match glob -returnCodes 1 -result {error reading "*": illegal byte sequence}
 
+test io-75.7 {invalid utf-8 encoding gets is not ignored (-profile strict)} -setup {
+    set fn [makeFile {} io-75.7]
+    set f [open $fn w+]
+    fconfigure $f -encoding binary
+    # \x81 is invalid in utf-8
+    puts -nonewline $f A\x81
+    flush $f
+    seek $f 0
+    fconfigure $f -encoding utf-8 -buffering none -eofchar "" -translation lf -profile strict
+} -body {
+    read $f
+} -cleanup {
+    close $f
+    removeFile io-75.7
+} -match glob -returnCodes 1 -result {error reading "*": illegal byte sequence}
+
 test io-75.8 {invalid utf-8 encoding eof handling (-profile strict)} -setup {
     set fn [makeFile {} io-75.8]
     set f [open $fn w+]
-- 
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