[distcc] Re: distcc 0.5

[Martin Pool]

On 26 Jun 2002, Frerich Raabe <raabe at kde.org> wrote:
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> 
> On Wednesday 26 June 2002 03:56, you wrote:
> > On 25 Jun 2002, Frerich Raabe <raabe at kde.org> wrote:
> > > just wanted to ask you whether you'd drop me a note before you go and
> > > release distcc 0.5.
> >
> > I'm not going to make many more changes before releasing 0.5.  I agree
> > with the approach you suggest.  Please go ahead and send patches.
> 
> Ok, here are the patches which seem to be required to get distcc CVS running 
> properly on FreeBSD:
> 
> patch-src::io.c - this patch to src/io.c honors the fact that FreeBSD provides 
> a sendfile() method as well, but with a different signature. Necessary to 
> make it compile.

Well, OK, I can agree that we need to support it, but that patch looks
pretty wierd to me.  Unix system calls don't normally return errno
values directly.

Index: io.c
===================================================================
RCS file: /cvsroot/distcc/src/io.c,v
retrieving revision 1.27
diff -u -3 -p -r1.27 io.c
--- io.c	13 Jun 2002 05:14:21 -0000	1.27
+++ io.c	26 Jun 2002 07:26:35 -0000
@@ -72,7 +72,11 @@
  **/
 int dcc_pump_sendfile(int ofd, int ifd, size_t size)
 {
+#ifdef __FreeBSD__
+    if (sendfile(ifd, ofd, 0, size, 0, 0, 0) == EAGAIN) {
+#else
     if (sendfile(ofd, ifd, 0, size) != (int) size) {
+#endif
 	rs_log_error("sendfile failed: %s", strerror(errno));
 	return -1;
     }

I looked in 

  http://www.freebsd.org/cgi/man.cgi?query=sendfile&sektion=2&apropos=0&manpath=FreeBSD+5.0-current

and it says that sendfile() returns -1 and sets errno on error; and
returns 0 on success.  Also because our sockets are not nonblocking I
don't think we need to handle EAGAIN.

My patch is below, please let me know if it works OK.

-- 
Martin 


--- io.c.~1.27.~	Thu Jun 13 15:14:21 2002
+++ io.c	Thu Jun 27 13:40:31 2002
@@ -1,4 +1,4 @@
-/* -*- c-file-style: "k&r"; c-basic-offset: 4; indent-tabs-mode: nil -*-
+/* -*- c-file-style: "java"; indent-tabs-mode: nil -*-
  * 
  * distcc -- A simple distributed compiler system
  * $Header: /data/cvs/distcc/src/io.c,v 1.27 2002/06/13 05:14:21 mbp Exp $ 
@@ -64,6 +64,33 @@
 #ifdef HAVE_SENDFILE
 /* If you don't have it, just use dcc_pump_readwrite */
 
+
+/**
+ * Map FreeBSD and Linux into something like the Linux interface.
+ *
+ * Our sockets are never non-blocking, so that seems to me to say that
+ * the kernel will never return EAGAIN -- we will always either send
+ * the whole thing or get an error.  Is that really true?
+ *
+ * How nice to have the function parameters reversed between platforms
+ * in a way that will not give a compiler warning.
+ *
+ * @return 0 for success (everything sent); -1 otherwise, with errno set.
+ *
+ * @sa http://www.freebsd.org/cgi/man.cgi?query=sendfile&sektion=2&apropos=0&manpath=FreeBSD+5.0-current
+ **/
+static int sys_sendfile(int ofd, int ifd, size_t size)
+{
+#ifdef __FreeBSD__
+    return sendfile(ifd, ofd, 0, size, 0, 0, 0);
+#else
+    /* Linux or something. */
+    off_t offset = 0;
+    return sendfile(ofd, ifd, &offset, size) == size ? 0 : -1;
+#endif
+}
+
+
 /**
  * Transmit the body of a file using sendfile().
  *
@@ -72,7 +99,7 @@
  **/
 int dcc_pump_sendfile(int ofd, int ifd, size_t size)
 {
-    if (sendfile(ofd, ifd, 0, size) != (int) size) {
+    if (sys_sendfile(ofd, ifd, size)) {
 	rs_log_error("sendfile failed: %s", strerror(errno));
 	return -1;
     }
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