Copyn
R=rsc
DELTA=34 (34 added, 0 deleted, 0 changed)
OCL=19541
CL=19545
diff --git a/src/lib/io.go b/src/lib/io.go
index 80f753a..699f919 100644
--- a/src/lib/io.go
+++ b/src/lib/io.go
@@ -76,3 +76,37 @@
}
return &FullRead{fd}
}
+
+// Copies n bytes (or until EOF is reached) from src to dst.
+// Returns the number of bytes copied and the error, if any.
+export func Copyn(src Read, dst Write, n int) (c int, err *os.Error) {
+ buf := new([]byte, 32*1024); // BUG 6g crashes on non-pointer array slices
+ c = 0;
+ for c < n {
+ l := n - c;
+ if l > len(buf) {
+ l = len(buf)
+ }
+ nr, er := src.Read(buf[0 : l]);
+ if nr > 0 {
+ nw, ew := dst.Write(buf[0 : nr]);
+ if nw != nr || ew != nil {
+ c += nw;
+ if ew == nil {
+ ew = os.EIO
+ }
+ err = ew;
+ break;
+ }
+ c += nr;
+ }
+ if er != nil {
+ err = er;
+ break;
+ }
+ if nr == 0 {
+ break;
+ }
+ }
+ return c, err
+}
