diff options
Diffstat (limited to 'generic/tclIO.c')
| -rw-r--r-- | generic/tclIO.c | 88 |
1 files changed, 67 insertions, 21 deletions
diff --git a/generic/tclIO.c b/generic/tclIO.c index 0122ec9..c55c118 100644 --- a/generic/tclIO.c +++ b/generic/tclIO.c @@ -4414,6 +4414,17 @@ TclGetsObjBinary( if (bufPtr == NULL) { goto restore; } + } else { + /* + * There's something already in the buffer. If + * CHANNEL_STICKY_EOF is set we know that something begins + * with the eofchar. Otherwise, if CHANNEL_EOF is set, we + * know some earlier inputproc call returned zero bytes when + * we were trying to get more bytes to put in the buffer. + * which means..... ???? Place to probe with tests. + */ + assert (GotFlag(statePtr, CHANNEL_STICKY_EOF) + || !GotFlag(statePtr, CHANNEL_EOF) ); } dst = (unsigned char *) RemovePoint(bufPtr); @@ -4694,6 +4705,9 @@ FilterInputBytes( gsPtr->rawRead = 0; return -1; } + } else { + assert( GotFlag(statePtr, CHANNEL_STICKY_EOF) + || !GotFlag(statePtr, CHANNEL_EOF) ); } /* @@ -5018,6 +5032,7 @@ Tcl_ReadRaw( /* State info for channel */ int copied = 0; + assert(bytesToRead > 0); if (CheckChannelErrors(statePtr, TCL_READABLE | CHANNEL_RAW_MODE) != 0) { return -1; } @@ -5049,8 +5064,19 @@ Tcl_ReadRaw( } } - /* Go to the driver if more data needed. */ + /* + * Go to the driver only if we got nothing from pushback. + * Have to do it this way to avoid EOF mis-timings when we + * consider the ability that EOF may not be a permanent + * condition in the driver, and in that case we have to + * synchronize. + */ + + if (copied) { + return copied; + } + /* This test not needed. */ if (bytesToRead > 0) { int nread = ChanRead(chanPtr, readBuf, bytesToRead); @@ -5073,12 +5099,10 @@ Tcl_ReadRaw( if (!GotFlag(statePtr, CHANNEL_BLOCKED) || copied == 0) { copied = -1; } - } else if (copied > 0) { + } else { /* - * nread == 0. Driver is at EOF, but if copied>0 bytes - * from pushback, then we should not signal it yet. + * nread == 0. Driver is at EOF. Let that state filter up. */ - ResetFlag(statePtr, CHANNEL_EOF); } } return copied; @@ -6120,18 +6144,39 @@ GetInput( } /* - * For a channel at EOF do not bother allocating buffers; there's - * nothing more to read. Avoid calling the driver inputproc in - * case some of them do not react well to additional calls after - * they've reported an eof state.. - * TODO: Candidate for a can't happen panic. + * Strangely named "STICKY_EOF" really means we've seen the + * eofchar for this channel, and nothing since has reset it. + * (changed the eofchar, [seek]ed to a new offset, etc.) So, + * we know we're still poised to read that eofchar again, and + * there's no need to actually do it. */ - if (GotFlag(statePtr, CHANNEL_EOF)) { + if (GotFlag(statePtr, CHANNEL_STICKY_EOF)) { + assert(statePtr->inEofChar); + assert(statePtr->inQueueHead); + assert(RemovePoint(statePtr->inQueueHead)[0] == statePtr->inEofChar); return 0; } /* + * WARNING: There was once a comment here claiming that it was + * a bad idea to make another call to the inputproc of a channel + * driver when EOF has already been detected on the channel. Through + * much of Tcl's history, this warning was then completely negated + * by having all (most?) read paths clear the EOF setting before + * reaching here. So we had a guard that was never triggered. + * + * Don't be tempted to restore the guard. Even if EOF is set on + * the channel, continue through and call the inputproc again. This + * is the way to enable the ability to [read] again beyond the EOF, + * which seems a strange thing to do, but for which use cases exist + * [Tcl Bug 5adc350683] and which may even be essential for channels + * representing things like ttys or other devices where the stream + * might take the logical form of a series of 'files' separated by + * an EOF condition. + */ + + /* * First check for more buffers in the pushback area of the topmost * channel in the stack and use them. They can be the result of a * transformation which went away without reading all the information @@ -8848,16 +8893,6 @@ DoRead( ChannelBuffer *bufPtr = statePtr->inQueueHead; /* - * When there's no buffered data to read, and we're at EOF, - * escape to the caller. - */ - - if (GotFlag(statePtr, CHANNEL_EOF) - && (bufPtr == NULL || IsBufferEmpty(bufPtr))) { - break; - } - - /* * Don't read more data if we have what we need. */ @@ -8969,12 +9004,23 @@ DoRead( statePtr->inQueueTail = NULL; } RecycleBuffer(statePtr, bufPtr, 0); + bufPtr = statePtr->inQueueHead; } if (GotFlag(statePtr, CHANNEL_NONBLOCKING|CHANNEL_BLOCKED) == (CHANNEL_NONBLOCKING|CHANNEL_BLOCKED)) { break; } + + /* + * When there's no buffered data to read, and we're at EOF, + * escape to the caller. + */ + + if (GotFlag(statePtr, CHANNEL_EOF) + && (bufPtr == NULL || IsBufferEmpty(bufPtr))) { + break; + } } if (bytesToRead == 0) { ResetFlag(statePtr, CHANNEL_BLOCKED); |