libbio: fix Bprint bug

Make Bprint work even when the amount of output
exceeds the available buffer space.

R=r
CC=golang-dev
https://golang.org/cl/1968041

diff --git a/src/libbio/bprint.c b/src/libbio/bprint.c
index 2e3867ae62ab4ed45fd77ce847b2aacacbaa68bb..b5d3e9ece01597e2581f3d851ace25e3cab06931 100644 (file)
--- a/src/libbio/bprint.c
+++ b/src/libbio/bprint.c
@@ -3,6 +3,7 @@ http://code.google.com/p/inferno-os/source/browse/libbio/bprint.c
 
        Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
        Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com).  All rights reserved.
+       Revisions Copyright © 2010 Google Inc.  All rights reserved.
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
@@ -30,25 +31,52 @@ THE SOFTWARE.
 int
 Bprint(Biobuf *bp, char *fmt, ...)
 {
-        va_list ap;
-        char *ip, *ep, *out;
-        int n;
-
-        ep = (char*)bp->ebuf;
-        ip = ep + bp->ocount;
-        va_start(ap, fmt);
-        out = vseprint(ip, ep, fmt, ap);
-        va_end(ap);
-        if(out == nil || out >= ep-5) {
-                Bflush(bp);
-                ip = ep + bp->ocount;
-                va_start(ap, fmt);
-                out = vseprint(ip, ep, fmt, ap);
-                va_end(ap);
-                if(out >= ep-5)
-                        return Beof;
-        }
-        n = out-ip;
-        bp->ocount += n;
-        return n;
+       int n;
+       va_list arg;
+
+       va_start(arg, fmt);
+       n = Bvprint(bp, fmt, arg);
+       va_end(arg);
+       return n;
+}
+
+static int
+bflush(Fmt *f)
+{
+       Biobuf *bp;
+       
+       if(f->stop == nil)
+               return 0;
+
+       bp = f->farg;
+       bp->ocount = (char*)f->to - (char*)f->stop;
+       if(Bflush(bp) < 0) {
+               f->stop = nil;
+               f->to = nil;
+               return 0;
+       }
+       f->to = (char*)f->stop + bp->ocount;
+       
+       return 1;
+}
+
+int
+Bvprint(Biobuf *bp, char *fmt, va_list arg)
+{
+       int n;
+       Fmt f;
+       
+       memset(&f, 0, sizeof f);
+       fmtlocaleinit(&f, nil, nil, nil);
+       f.stop = bp->ebuf;
+       f.to = (char*)f.stop + bp->ocount;
+       f.flush = bflush;
+       f.farg = bp;
+
+       n = fmtvprint(&f, fmt, arg);
+
+       if(f.stop != nil)
+               bp->ocount = (char*)f.to - (char*)f.stop;
+
+       return n;
 }