diff options
| -rw-r--r-- | trans/fifo.c | 43 |
1 files changed, 40 insertions, 3 deletions
diff --git a/trans/fifo.c b/trans/fifo.c index 4fe50b74..72f48042 100644 --- a/trans/fifo.c +++ b/trans/fifo.c @@ -423,17 +423,54 @@ trivfs_S_io_seek (struct trivfs_protid *cred, /* SELECT_TYPE is the bitwise OR of SELECT_READ, SELECT_WRITE, and SELECT_URG. Block until one of the indicated types of i/o can be done "quickly", and return the types that are then available. ID_TAG is returned as passed; it -u is just for the convenience of the user in matching up reply messages with + is just for the convenience of the user in matching up reply messages with specific requests sent. */ error_t trivfs_S_io_select (struct trivfs_protid *cred, mach_port_t reply, mach_msg_type_name_t reply_type, int *select_type, int *tag) { + struct pipe *pipe; + error_t err = 0; + int ready = 0; + if (!cred) return EOPNOTSUPP; - *select_type &= SELECT_READ | SELECT_WRITE; - return pipe_pair_select (cred->hook, cred->hook, select_type, 1); + + pipe = cred->hook; + + if (*select_type & SELECT_READ) + if (cred->po->openmodes & O_READ) + { + mutex_lock (&pipe->lock); + if (pipe_wait_readable (pipe, 1, 1) != EWOULDBLOCK) + ready |= SELECT_READ; /* Data immediately readable (or error). */ + mutex_unlock (&pipe->lock); + } + else + ready |= SELECT_READ; /* Error immediately available... */ + + if (*select_type & SELECT_WRITE) + if (cred->po->openmodes & O_WRITE) + { + mutex_lock (&pipe->lock); + if (pipe_wait_writable (pipe, 1) != EWOULDBLOCK) + ready |= SELECT_WRITE; /* Data immediately writable (or error). */ + mutex_unlock (&pipe->lock); + } + else + ready |= SELECT_WRITE; /* Error immediately available... */ + + if (ready) + *select_type = ready; + else + /* Wait for something to change. */ + { + ports_interrupt_self_on_port_death (cred, reply); + err = pipe_pair_select (pipe, pipe, select_type, 1); + } + + return err; } /* ---------------------------------------------------------------- */ |