Fix for [9ca87e6286262a62], sync fcopy buffers input in ReadChars().

2 files changed, 34 insertions, 6 deletions

diff --git a/generic/tclIO.c b/generic/tclIO.c
index 287a2f2..73d787a 100644
--- a/generic/tclIO.c
+++ b/generic/tclIO.c
@@ -196,7 +196,7 @@ static void		DiscardOutputQueued(ChannelState *chanPtr);
 static Tcl_Size		DoRead(Channel *chanPtr, char *dst, Tcl_Size bytesToRead,
 			    int allowShortReads);
 static Tcl_Size		DoReadChars(Channel *chan, Tcl_Obj *objPtr, Tcl_Size toRead,
-			    int appendFlag);
+			    int allowShortReads, int appendFlag);
 static int		FilterInputBytes(Channel *chanPtr,
 			    GetsState *statePtr);
 static int		FlushChannel(Tcl_Interp *interp, Channel *chanPtr,
@@ -5899,7 +5899,7 @@ Tcl_ReadChars(
 	return TCL_INDEX_NONE;
     }
 
-    return DoReadChars(chanPtr, objPtr, toRead, appendFlag);
+    return DoReadChars(chanPtr, objPtr, toRead, 0, appendFlag);
 }
 /*
  *---------------------------------------------------------------------------
@@ -5930,6 +5930,7 @@ DoReadChars(
     Tcl_Size toRead,		/* Maximum number of characters to store, or
 				 * TCL_INDEX_NONE to read all available data (up to EOF or
 				 * when channel blocks). */
+    int allowShortReads,	/* Allow half-blocking (pipes,sockets) */
     int appendFlag)		/* If non-zero, data read from the channel
 				 * will be appended to the object. Otherwise,
 				 * the data will replace the existing contents
@@ -6070,8 +6071,8 @@ DoReadChars(
 	    if (GotFlag(statePtr, CHANNEL_EOF)) {
 		break;
 	    }
-	    if (GotFlag(statePtr, CHANNEL_NONBLOCKING|CHANNEL_BLOCKED)
-		    == (CHANNEL_NONBLOCKING|CHANNEL_BLOCKED)) {
+	    if ((GotFlag(statePtr, CHANNEL_NONBLOCKING) || allowShortReads)
+		    && GotFlag(statePtr, CHANNEL_BLOCKED)) {
 		break;
 	    }
 	    result = GetInput(chanPtr);
@@ -9762,7 +9763,8 @@ CopyData(
                               !GotFlag(inStatePtr, CHANNEL_NONBLOCKING));
 	    } else {
 		size = DoReadChars(inStatePtr->topChanPtr, bufObj, sizeb,
-			0 /* No append */);
+			!GotFlag(inStatePtr, CHANNEL_NONBLOCKING)
+			,0 /* No append */);
 	    }
 	    underflow = (size >= 0) && ((size_t)size < sizeb);	/* Input underflow */
 	}
diff --git a/tests/io.test b/tests/io.test
index 96e5ea6..22b7482 100644
--- a/tests/io.test
+++ b/tests/io.test
@@ -8276,7 +8276,7 @@ test io-53.11 {Bug 2895565} -setup {
     removeFile out
     removeFile in
 } -result {40 bytes copied}
-test io-53.12 {CopyData: foreground short reads, aka bug 3096275} {stdio unix fcopy} {
+test io-53.12.0 {CopyData: foreground short reads, aka bug 3096275} {stdio unix fcopy} {
     file delete $path(pipe)
     set f1 [open $path(pipe) w]
     puts -nonewline $f1 {
@@ -8295,6 +8295,32 @@ test io-53.12 {CopyData: foreground short reads, aka bug 3096275} {stdio unix fc
     close $f1
     list $::done $ch
 } {ok A}
+test io-53.12.1 {
+    Issue 9ca87e6286262a62.
+    CopyData: foreground short reads via ReadChars().
+    Related to report 3096275 for ReadBytes().
+
+    Prior to the fix this test waited forever for read() to return.
+} {stdio unix fcopy} {
+    file delete $path(output)
+    set f1 [open $path(output) w]
+    puts -nonewline $f1 {
+	chan configure stdin -encoding iso8859-1 -translation lf -buffering none
+	fcopy stdin stdout
+    }
+    close $f1
+    set f1 [open "|[list [info nameofexecutable] $path(output)]" r+]
+    try {
+	chan configure $f1 -encoding utf-6  -buffering none
+	puts -nonewline $f1 A
+	set ch [read $f1 1]
+    } finally {
+	if {$f1 in [chan names]} {
+	    close $f1
+	}
+    }
+    lindex $ch
+} A
 test io-53.13 {TclCopyChannel: read error reporting} -setup {
     proc driver {cmd args} {
         variable buffer