From 262feb1ad0838bb585955b6ada5acbe106dbc9bf Mon Sep 17 00:00:00 2001
From: ajs <ajs>
Date: Wed, 16 Feb 2005 20:35:47 +0000
Subject: 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.
---
 lib/ChangeLog | 10 ++++++++++
 lib/stream.c  | 29 ++++++++++++++++++++++++++++-
 lib/stream.h  | 17 +++++++++++++++++
 3 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/lib/ChangeLog b/lib/ChangeLog
index 0627d206..ac05baba 100644
--- a/lib/ChangeLog
+++ b/lib/ChangeLog
@@ -1,3 +1,13 @@
+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.
+
 2005-02-16 Andrew J. Schorr <ajschorr@alumni.princeton.edu>
 
 	* network.c: (set_nonblocking) Should check return code from
diff --git a/lib/stream.c b/lib/stream.c
index e15d0426..7e75f0da 100644
--- a/lib/stream.c
+++ b/lib/stream.c
@@ -603,6 +603,31 @@ stream_read_unblock (struct stream *s, int fd, size_t size)
   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 @@ stream_recvmsg (struct stream *s, int fd, struct msghdr *msgh, int flags,
   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]);
diff --git a/lib/stream.h b/lib/stream.h
index fe45a4f5..54a16740 100644
--- a/lib/stream.h
+++ b/lib/stream.h
@@ -165,8 +165,25 @@ u_int32_t stream_get_ipv4 (struct stream *);
 
 #undef stream_read
 #undef stream_write
+
+/* Deprecated: assumes blocking I/O.  Will be removed. 
+   Use stream_read_try instead.  */
 int stream_read (struct stream *, int, size_t);
+
+/* Deprecated: all file descriptors should already be non-blocking.
+   Will be removed.  Use stream_read_try instead. */
 int stream_read_unblock (struct stream *, int, size_t);
+
+/* Read up to size bytes into the stream.
+   Return code:
+     >0: number of bytes read
+     0: end-of-file
+     -1: fatal error
+     -2: transient error, should retry later (i.e. EAGAIN or EINTR)
+   This is suitable for use with non-blocking file descriptors.
+ */
+extern ssize_t stream_read_try(struct stream *s, int fd, size_t size);
+
 int stream_recvmsg (struct stream *s, int fd, struct msghdr *,
                     int flags, size_t size);
 int stream_write (struct stream *, u_char *, size_t);
-- 
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