Upstream patch for Bug #64565 	copy doesn't report failure on partial copy
    https://bugs.php.net/64565

Commit in PHP 5.4 branch:
http://git.php.net/?p=php-src.git;a=patch;h=6b4148bc9705d2668dd8589009215a8eb3076f31
http://git.php.net/?p=php-src.git;a=patch;h=8e8a75444cbb6bb108e212d48513343fe21c9255
http://git.php.net/?p=php-src.git;a=patch;h=731a5c51040042a0f344752fee1117701efa3cfd

--- php-5.3.3/main/streams/streams.c.copy	2013-04-08 12:50:55.336478801 +0200
+++ php-5.3.3/main/streams/streams.c	2013-04-08 12:50:55.445479336 +0200
@@ -1302,7 +1302,7 @@
 	char buf[CHUNK_SIZE];
 	size_t readchunk;
 	size_t haveread = 0;
-	size_t didread;
+	size_t didread, didwrite, towrite;
 	size_t dummy;
 	php_stream_statbuf ssbuf;
 
@@ -1337,16 +1337,16 @@
 		p = php_stream_mmap_range(src, php_stream_tell(src), maxlen, PHP_STREAM_MAP_MODE_SHARED_READONLY, &mapped);
 
 		if (p) {
-			mapped = php_stream_write(dest, p, mapped);
+			didwrite = php_stream_write(dest, p, mapped);
 
 			php_stream_mmap_unmap_ex(src, mapped);
 
-			*len = mapped;
+			*len = didwrite;
 
-			/* we've got at least 1 byte to read.
-			 * less than 1 is an error */
-
-			if (mapped > 0) {
+			/* we've got at least 1 byte to read
+			 * less than 1 is an error
+			 * AND read bytes match written */
+			if (mapped > 0 && mapped == didwrite) {
 				return SUCCESS;
 			}
 			return FAILURE;
@@ -1364,7 +1364,6 @@
 
 		if (didread) {
 			/* extra paranoid */
-			size_t didwrite, towrite;
 			char *writeptr;
 
 			towrite = didread;