From 597bb3236aba9dbe1c799b8bde917c1228fd21a1 Mon Sep 17 00:00:00 2001
From: andreas_kupries <akupries@shaw.ca>
Date: Thu, 15 Jul 2004 20:46:17 +0000
Subject: * generic/tclIO.h (CHANNEL_INCLOSE): New flag. Set in
* generic/tclIO.c (Tcl_UnregisterChannel): 'Tcl_Close' while the *
generic/tclIO.c (Tcl_Close): close callbacks are run. Checked
in 'Tcl_Close' and 'Tcl_Unregister' to prevent recursive call of
'close' in the close-callbacks. This is a possible error made by
implementors of virtual filesystems based on 'tclvfs', thinking that
they have to close the channel in the close handler for the filesystem.
* generic/tclIO.c:
* generic/tclIO.h:
* Not reverting, but #ifdef'ing the changes from May 19, 2004 out
of the core. This removes the ***POTENTIAL INCOMPATIBILITY***
for channel drivers it introduced. This has become possible due
to Expect gaining a BlockModeProc and now handling blockingg and
non-blocking modes correctly. Thus [SF Tcl Bug 943274] is still
fixed if a recent enough version of Expect is used.
* doc/CrtChannel.3: Added warning about usage of a channel without
a BlockModeProc.
---
ChangeLog | 31 +++++++++++++++++++++++++++++--
doc/CrtChannel.3 | 10 +++++++++-
generic/tclIO.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++++-
generic/tclIO.h | 11 ++++++++++-
4 files changed, 96 insertions(+), 5 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 70bd297..99ffef6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,28 @@
+2004-07-14 Andreas Kupries <andreask@activestate.com>
+
+ * generic/tclIO.h (CHANNEL_INCLOSE): New flag. Set in
+ * generic/tclIO.c (Tcl_UnregisterChannel): 'Tcl_Close' while the
+ * generic/tclIO.c (Tcl_Close): close callbacks are
+ run. Checked in 'Tcl_Close' and 'Tcl_Unregister' to prevent
+ recursive call of 'close' in the close-callbacks. This is a
+ possible error made by implementors of virtual filesystems based
+ on 'tclvfs', thinking that they have to close the channel in the
+ close handler for the filesystem.
+
+2004-06-14 Andreas Kupries <andreask@activestate.com>
+
+ * generic/tclIO.c:
+ * generic/tclIO.h:
+ * Not reverting, but #ifdef'ing the changes from May 19, 2004 out
+ of the core. This removes the ***POTENTIAL INCOMPATIBILITY***
+ for channel drivers it introduced. This has become possible due
+ to Expect gaining a BlockModeProc and now handling blockingg and
+ non-blocking modes correctly. Thus [SF Tcl Bug 943274] is still
+ fixed if a recent enough version of Expect is used.
+
+ * doc/CrtChannel.3: Added warning about usage of a channel without
+ a BlockModeProc.
+
2004-07-15 Andreas Kupries <andreask@pliers.activestate.com>
* generic/tclIOCmd.c (Tcl_PutsObjCmd): Added length check to the
@@ -190,8 +215,8 @@
2004-05-19 Andreas Kupries <andreask@activestate.com>
- * tclIO.c: Fixed [SF Tcl Bug 943274]. This is the same problem as
- * tclIO.h: [SF Tcl Bug 462317], see ChangeLog entry
+ * generic/tclIO.c: Fixed [SF Tcl Bug 943274]. This is the same problem as
+ * generic/tclIO.h: [SF Tcl Bug 462317], see ChangeLog entry
2001-09-26. The fix done at that time is incomplete. It
is possible to get around it if the actual read
operation is defered and not executed in the event
@@ -202,6 +227,8 @@
actual data waiting. The flag is cleared by a short or
full read.
+ ***POTENTIAL INCOMPATIBILITY*** for channel drivers.
+
2004-05-18 Kevin B. Kenny <kennykb@acm.org>
* compat/strftime.c (_fmt, ISO8601Week):
diff --git a/doc/CrtChannel.3 b/doc/CrtChannel.3
index 477ef67..828b958 100644
--- a/doc/CrtChannel.3
+++ b/doc/CrtChannel.3
@@ -5,7 +5,7 @@
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\"
-'\" RCS: @(#) $Id: CrtChannel.3,v 1.16 2002/07/01 18:24:39 jenglish Exp $
+'\" RCS: @(#) $Id: CrtChannel.3,v 1.16.2.1 2004/07/15 20:46:17 andreas_kupries Exp $
.so man.macros
.TH Tcl_CreateChannel 3 8.3 Tcl "Tcl Library Procedures"
.BS
@@ -405,6 +405,14 @@ behavior must be emulated in the channel driver.
.PP
This value can be retrieved with \fBTcl_ChannelBlockModeProc\fR, which returns
a pointer to the function.
+.PP
+A channel driver \fBnot\fR supplying a \fIblockModeProc\fR has to be
+very, very careful. It has to tell the generic layer exactly which
+blocking mode is acceptable to it, and should this also document for
+the user so that the blocking mode of the channel is not changed to an
+inacceptable value. Any confusion here may lead the interpreter into a
+(spurious and difficult to find) deadlock.
+
.SH "CLOSEPROC AND CLOSE2PROC"
.PP
diff --git a/generic/tclIO.c b/generic/tclIO.c
index f1a3266..154bec0 100644
--- a/generic/tclIO.c
+++ b/generic/tclIO.c
@@ -10,7 +10,7 @@
* See the file "license.terms" for information on usage and redistribution
* of this file, and for a DISCLAIMER OF ALL WARRANTIES.
*
- * RCS: @(#) $Id: tclIO.c,v 1.61.2.6 2004/05/19 19:23:58 andreas_kupries Exp $
+ * RCS: @(#) $Id: tclIO.c,v 1.61.2.7 2004/07/15 20:46:18 andreas_kupries Exp $
*/
#include "tclInt.h"
@@ -772,6 +772,7 @@ Tcl_RegisterChannel(interp, chan)
}
Tcl_SetHashValue(hPtr, (ClientData) chanPtr);
}
+
statePtr->refCount++;
}
@@ -808,6 +809,17 @@ Tcl_UnregisterChannel(interp, chan)
{
ChannelState *statePtr; /* State of the real channel. */
+ statePtr = ((Channel *) chan)->state->bottomChanPtr->state;
+
+ if (statePtr->flags & CHANNEL_INCLOSE) {
+ if (interp != (Tcl_Interp*) NULL) {
+ Tcl_AppendResult(interp,
+ "Illegal recursive call to close through close-handler of channel",
+ (char *) NULL);
+ }
+ return TCL_ERROR;
+ }
+
if (DetachChannel(interp, chan) != TCL_OK) {
return TCL_OK;
}
@@ -2527,6 +2539,14 @@ Tcl_Close(interp, chan)
if (statePtr->refCount > 0) {
panic("called Tcl_Close on channel with refCount > 0");
}
+
+ if (statePtr->flags & CHANNEL_INCLOSE) {
+ Tcl_AppendResult(interp,
+ "Illegal recursive call to close through close-handler of channel",
+ (char *) NULL);
+ return TCL_ERROR;
+ }
+ statePtr->flags |= CHANNEL_INCLOSE;
/*
* When the channel has an escape sequence driven encoding such as
@@ -2551,6 +2571,8 @@ Tcl_Close(interp, chan)
ckfree((char *) cbPtr);
}
+ statePtr->flags &= ~CHANNEL_INCLOSE;
+
/*
* Ensure that the last output buffer will be flushed.
*/
@@ -4225,6 +4247,7 @@ Tcl_ReadRaw(chan, bufPtr, bytesToRead)
statePtr->flags &= (~(CHANNEL_BLOCKED));
}
+#ifdef TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING
/* [SF Tcl Bug 943274]. Better emulation of non-blocking
* channels for channels without BlockModeProc, by keeping
* track of true fileevents generated by the OS == Data
@@ -4240,6 +4263,7 @@ Tcl_ReadRaw(chan, bufPtr, bytesToRead)
nread = -1;
result = EWOULDBLOCK;
} else {
+#endif /* TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING */
/*
* Now go to the driver to get as much as is possible to
* fill the remaining request. Do all the error handling
@@ -4251,7 +4275,9 @@ Tcl_ReadRaw(chan, bufPtr, bytesToRead)
nread = (chanPtr->typePtr->inputProc)(chanPtr->instanceData,
bufPtr + copied, bytesToRead - copied, &result);
+#ifdef TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING
}
+#endif /* TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING */
if (nread > 0) {
/*
* If we get a short read, signal up that we may be
@@ -4265,11 +4291,13 @@ Tcl_ReadRaw(chan, bufPtr, bytesToRead)
statePtr->flags |= CHANNEL_BLOCKED;
}
+#ifdef TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING
if (nread <= (bytesToRead - copied)) {
/* [SF Tcl Bug 943274] We have read the available
* data, clear flag */
statePtr->flags &= ~CHANNEL_HAS_MORE_DATA;
}
+#endif /* TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING */
} else if (nread == 0) {
statePtr->flags |= CHANNEL_EOF;
statePtr->inputEncodingFlags |= TCL_ENCODING_END;
@@ -5310,6 +5338,7 @@ GetInput(chanPtr)
return 0;
}
+#ifdef TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING
/* [SF Tcl Bug 943274]. Better emulation of non-blocking channels
* for channels without BlockModeProc, by keeping track of true
* fileevents generated by the OS == Data waiting and reading if
@@ -5324,9 +5353,14 @@ GetInput(chanPtr)
nread = -1;
result = EWOULDBLOCK;
} else {
+#endif /* TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING */
+
nread = (chanPtr->typePtr->inputProc)(chanPtr->instanceData,
bufPtr->buf + bufPtr->nextAdded, toRead, &result);
+
+#ifdef TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING
}
+#endif /* TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING */
if (nread > 0) {
bufPtr->nextAdded += nread;
@@ -5342,11 +5376,13 @@ GetInput(chanPtr)
statePtr->flags |= CHANNEL_BLOCKED;
}
+#ifdef TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING
if (nread <= toRead) {
/* [SF Tcl Bug 943274] We have read the available data,
* clear flag */
statePtr->flags &= ~CHANNEL_HAS_MORE_DATA;
}
+#endif /* TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING */
} else if (nread == 0) {
statePtr->flags |= CHANNEL_EOF;
@@ -6740,6 +6776,7 @@ Tcl_NotifyChannel(channel, mask)
Channel* upChanPtr;
Tcl_ChannelType* upTypePtr;
+#ifdef TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING
/* [SF Tcl Bug 943274]
* For a non-blocking channel without blockmodeproc we keep track
* of actual input coming from the OS so that we can do a credible
@@ -6753,6 +6790,7 @@ Tcl_NotifyChannel(channel, mask)
statePtr->flags |= CHANNEL_HAS_MORE_DATA;
}
+#endif /* TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING */
/*
* In contrast to the other API functions this procedure walks towards
@@ -6993,6 +7031,7 @@ ChannelTimerProc(clientData)
statePtr->timer = Tcl_CreateTimerHandler(0, ChannelTimerProc,
(ClientData) chanPtr);
+#ifdef TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING
/* Set the TIMER flag to notify the higher levels that the
* driver might have no data for us. We do this only if we are
* in non-blocking mode and the driver has no BlockModeProc
@@ -7004,10 +7043,15 @@ ChannelTimerProc(clientData)
(Tcl_ChannelBlockModeProc(chanPtr->typePtr) == NULL)) {
statePtr->flags |= CHANNEL_TIMER_FEV;
}
+#endif /* TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING */
+
Tcl_Preserve((ClientData) statePtr);
Tcl_NotifyChannel((Tcl_Channel)chanPtr, TCL_READABLE);
+#ifdef TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING
statePtr->flags &= ~CHANNEL_TIMER_FEV;
+#endif /* TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING */
+
Tcl_Release((ClientData) statePtr);
} else {
statePtr->timer = NULL;
@@ -9239,8 +9283,11 @@ DumpFlags (str, flags)
if (flags & INPUT_NEED_NL) {buf[i] = '*';} else {buf [i]='_';}; i++;
if (flags & CHANNEL_DEAD) {buf[i] = 'D';} else {buf [i]='_';}; i++;
if (flags & CHANNEL_RAW_MODE) {buf[i] = 'R';} else {buf [i]='_';}; i++;
+#ifdef TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING
if (flags & CHANNEL_TIMER_FEV) {buf[i] = 'T';} else {buf [i]='_';}; i++;
if (flags & CHANNEL_HAS_MORE_DATA) {buf[i] = 'H';} else {buf [i]='_';}; i++;
+#endif /* TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING */
+ if (flags & CHANNEL_INCLOSE) {buf[i] = 'x';} else {buf [i]='_';}; i++;
buf [i] ='\0';
fprintf (stderr,"%s: %s\n", str, buf); fflush(stderr);
diff --git a/generic/tclIO.h b/generic/tclIO.h
index 7f2c421..ea3c6e4 100644
--- a/generic/tclIO.h
+++ b/generic/tclIO.h
@@ -10,7 +10,7 @@
* See the file "license.terms" for information on usage and redistribution
* of this file, and for a DISCLAIMER OF ALL WARRANTIES.
*
- * RCS: @(#) $Id: tclIO.h,v 1.5.4.1 2004/05/19 19:16:24 andreas_kupries Exp $
+ * RCS: @(#) $Id: tclIO.h,v 1.5.4.2 2004/07/15 20:46:19 andreas_kupries Exp $
*/
/*
@@ -296,6 +296,7 @@ typedef struct ChannelState {
* the state of the channel changes. */
#define CHANNEL_RAW_MODE (1<<16) /* When set, notes that the Raw API is
* being used. */
+#ifdef TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING
#define CHANNEL_TIMER_FEV (1<<17) /* When set the event we are
* notified by is a fileevent
* generated by a timer. We
@@ -323,6 +324,14 @@ typedef struct ChannelState {
* will be performed if the
* flag is set. This will
* reset the flag as well. */
+#endif /* TCL_IO_TRACK_OS_FOR_DRIVER_WITH_BAD_BLOCKING */
+
+#define CHANNEL_INCLOSE (1<<19) /* Channel is currently being
+ * closed. Its structures are
+ * still live and usable, but
+ * it may not be closed again
+ * from within the close handler.
+ */
/*
* For each channel handler registered in a call to Tcl_CreateChannelHandler,
--
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