diff options
| -rw-r--r-- | sys/kern/sys_pipe.c | 59 |
1 files changed, 39 insertions, 20 deletions
diff --git a/sys/kern/sys_pipe.c b/sys/kern/sys_pipe.c index 66ddd50..396538a 100644 --- a/sys/kern/sys_pipe.c +++ b/sys/kern/sys_pipe.c @@ -16,7 +16,7 @@ * 4. Modifications may be freely made to this file if the above conditions * are met. * - * $Id: sys_pipe.c,v 1.48 1999/01/27 21:49:57 dillon Exp $ + * $Id: sys_pipe.c,v 1.49 1999/01/28 00:57:47 dillon Exp $ */ /* @@ -381,12 +381,39 @@ pipe_read(fp, uio, cred) #endif } else { /* + * If there is no more to read in the pipe, reset + * its pointers to the beginning. This improves + * cache hit stats. + * + * We get this over with now because it may block + * and cause the state to change out from under us, + * rather then have to re-test the state both before + * and after this fragment. + */ + + if ((error = pipelock(rpipe,1)) == 0) { + if (rpipe->pipe_buffer.cnt == 0) { + rpipe->pipe_buffer.in = 0; + rpipe->pipe_buffer.out = 0; + } + pipeunlock(rpipe); + + /* + * If pipe filled up due to pipelock + * blocking, loop back up. + */ + if (rpipe->pipe_buffer.cnt > 0) + continue; + } + + /* * detect EOF condition */ if (rpipe->pipe_state & PIPE_EOF) { /* XXX error = ? */ break; } + /* * If the "write-side" has been blocked, wake it up now. */ @@ -394,34 +421,26 @@ pipe_read(fp, uio, cred) rpipe->pipe_state &= ~PIPE_WANTW; wakeup(rpipe); } - if (nread > 0) + + /* + * break if error (signal via pipelock), or if some + * data was read + */ + if (error || nread > 0) break; + /* + * Handle non-blocking mode operation + */ + if (fp->f_flag & FNONBLOCK) { error = EAGAIN; break; } /* - * If there is no more to read in the pipe, reset - * its pointers to the beginning. This improves - * cache hit stats. + * Wait for more data */ - - if ((error = pipelock(rpipe,1)) == 0) { - if (rpipe->pipe_buffer.cnt == 0) { - rpipe->pipe_buffer.in = 0; - rpipe->pipe_buffer.out = 0; - } - pipeunlock(rpipe); - } else { - break; - } - - if (rpipe->pipe_state & PIPE_WANTW) { - rpipe->pipe_state &= ~PIPE_WANTW; - wakeup(rpipe); - } rpipe->pipe_state |= PIPE_WANTR; if ((error = tsleep(rpipe, PRIBIO|PCATCH, "piperd", 0)) != 0) { |
