Attachment 6850 Details for Bug 15235 – file.diff

[patch] file.diff

file.diff (text/plain), 3.41 KB, created by Tor Egge on 1999-12-03 04:30:01 UTC

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Creator: Tor Egge

Created: 1999-12-03 04:30:01 UTC

Size: 3.41 KB

patch

obsolete

>Index: sys/kern/sys_pipe.c
>===================================================================
>RCS file: /home/ncvs/src/sys/kern/sys_pipe.c,v
>retrieving revision 1.58
>diff -u -r1.58 sys_pipe.c
>--- sys_pipe.c	1999/11/08 03:28:48	1.58
>+++ sys_pipe.c	1999/12/02 18:18:21
>@@ -799,27 +799,13 @@
> 		space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
> 
> 		/* Writes of size <= PIPE_BUF must be atomic. */
>-		/* XXX perhaps they need to be contiguous to be atomic? */
> 		if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
> 			space = 0;
> 
> 		if (space > 0 && (wpipe->pipe_buffer.cnt < PIPE_SIZE)) {
>-			/*
>-			 * This set the maximum transfer as a segment of
>-			 * the buffer.
>-			 */
>-			int size = wpipe->pipe_buffer.size - wpipe->pipe_buffer.in;
>-			/*
>-			 * space is the size left in the buffer
>-			 */
>-			if (size > space)
>-				size = space;
>-			/*
>-			 * now limit it to the size of the uio transfer
>-			 */
>-			if (size > uio->uio_resid)
>-				size = uio->uio_resid;
> 			if ((error = pipelock(wpipe,1)) == 0) {
>+				int size;	/* Transfer size */
>+				int segsize;	/* first segment to transfer */
> 				/*
> 				 * It is possible for a direct write to
> 				 * slip in on us... handle it here...
>@@ -828,18 +814,73 @@
> 					pipeunlock(wpipe);
> 					goto retrywrite;
> 				}
>-				error = uiomove( &wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 
>-					size, uio);
>+				/* 
>+				 * If a process blocked in uiomove, our
>+				 * value for space might be bad.
>+				 */
>+				if (space > wpipe->pipe_buffer.size - 
>+				    wpipe->pipe_buffer.cnt) {
>+					pipeunlock(wpipe);
>+					goto retrywrite;
>+				}
>+
>+				/*
>+				 * Transfer size is minimum of uio transfer
>+				 * and free space in pipe buffer.
>+				 */
>+				if (space > uio->uio_resid)
>+					size = uio->uio_resid;
>+				else
>+					size = space;
>+				/*
>+				 * First segment to transfer is minimum of 
>+				 * transfer size and contiguous space in
>+				 * pipe buffer.  If first segment to transfer
>+				 * is less than the transfer size, we've got
>+				 * a wraparound in the buffer.
>+				 */
>+				segsize = wpipe->pipe_buffer.size - 
>+					wpipe->pipe_buffer.in;
>+				if (segsize > size)
>+					segsize = size;
>+				
>+				/* Transfer first segment */
>+
>+				error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 
>+						segsize, uio);
>+				
>+				if (error == 0 && segsize < size) {
>+					/* 
>+					 * Transfer remaining part now, to
>+					 * support atomic writes.  Wraparound
>+					 * happened.
>+					 */
>+					if (wpipe->pipe_buffer.in + segsize != 
>+					    wpipe->pipe_buffer.size)
>+						panic("Expected pipe buffer wraparound disappeared");
>+						
>+					error = uiomove(&wpipe->pipe_buffer.buffer[0],
>+							size - segsize, uio);
>+				}
>+				if (error == 0) {
>+					wpipe->pipe_buffer.in += size;
>+					if (wpipe->pipe_buffer.in >=
>+					    wpipe->pipe_buffer.size) {
>+						if (wpipe->pipe_buffer.in != size - segsize + wpipe->pipe_buffer.size)
>+							panic("Expected wraparound bad");
>+						wpipe->pipe_buffer.in = size - segsize;
>+					}
>+				
>+					wpipe->pipe_buffer.cnt += size;
>+					if (wpipe->pipe_buffer.cnt > wpipe->pipe_buffer.size)
>+						panic("Pipe buffer overflow");
>+				
>+				}
> 				pipeunlock(wpipe);
> 			}
> 			if (error)
> 				break;
> 
>-			wpipe->pipe_buffer.in += size;
>-			if (wpipe->pipe_buffer.in >= wpipe->pipe_buffer.size)
>-				wpipe->pipe_buffer.in = 0;
>-
>-			wpipe->pipe_buffer.cnt += size;
> 		} else {
> 			/*
> 			 * If the "read-side" has been blocked, wake it up now.

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Attachments on bug 15235: 6850