2005-02-16 Andrew J. Schorr <ajschorr@alumni.princeton.edu>
* stream.h: Declare new function stream_read_try suitable for use
with non-blocking file descriptors. Indicate that stream_read
and stream_read_unblock are deprecated.
* stream.c: (stream_read_try) New function for use with non-blocking
I/O.
(stream_recvmsg) Should return -1 if the stream is too small to
contain the data.
diff --git a/lib/stream.c b/lib/stream.c
index e15d042..7e75f0d 100644
--- a/lib/stream.c
+++ b/lib/stream.c
@@ -603,6 +603,31 @@
return nbytes;
}
+ssize_t
+stream_read_try(struct stream *s, int fd, size_t size)
+{
+ ssize_t nbytes;
+
+ STREAM_VERIFY_SANE(s);
+
+ if (STREAM_WRITEABLE(s) < size)
+ {
+ STREAM_BOUND_WARN (s, "put");
+ /* Fatal (not transient) error, since retrying will not help
+ (stream is too small to contain the desired data). */
+ return -1;
+ }
+
+ if ((nbytes = read(fd, s->data + s->endp, size)) >= 0)
+ {
+ s->endp += nbytes;
+ return nbytes;
+ }
+ /* Error: was it transient (return -2) or fatal (return -1)? */
+ return ((errno == EAGAIN) || (errno == EWOULDBLOCK) || (errno == EINTR)) ?
+ -2 : -1;
+}
+
/* Read up to smaller of size or SIZE_REMAIN() bytes to the stream, starting
* from endp.
* First iovec will be used to receive the data.
@@ -621,7 +646,9 @@
if (STREAM_WRITEABLE (s) < size)
{
STREAM_BOUND_WARN (s, "put");
- return 0;
+ /* This is a logic error in the calling code: the stream is too small
+ to hold the desired data! */
+ return -1;
}
iov = &(msgh->msg_iov[0]);