From 14a54b903e952a9f99bf5a4bf4639ab2e105b1c4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gustavo=20Andr=C3=A9=20dos=20Santos=20Lopes?=
 <cataphract@php.net>
Date: Wed, 13 Oct 2010 03:13:29 +0000
Subject: [PATCH] - Fixed forward stream seeking emulation in streams that
 don't support seeking   in situations where the read operation gives back
 less data than requested   and when there was data in the buffer before the
 emulation started. Also made   more consistent its behavior -- should return
 failure every time less data   than was requested was skipped. - Small
 performance improvement by correcting off-by-one error that generate an  
 invalid call to the seek handler or read handler. in _php_stream_seek.

---
 NEWS                   |  5 +++++
 main/streams/streams.c | 16 +++++++---------
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/NEWS b/NEWS
index 235105ed6c5..2d3aa9b178e 100644
--- a/NEWS
+++ b/NEWS
@@ -28,6 +28,11 @@
 - Fixed inconsistent backlog default value (-1) in FPM on many systems. (fat)
 - Fixed bug in the Windows implementation of dns_get_record, where the two
   last parameters wouldn't be filled unless the type were DNS_ANY (Gustavo).
+- Fixed forward stream seeking emulation in streams that don't support seeking
+  in situations where the read operation gives back less data than requested
+  and when there was data in the buffer before the emulation started. Also made
+  more consistent its behavior -- should return failure every time less data
+  than was requested was skipped. (Gustavo)
 
 - Fixed bug #53021 (In html_entity_decode, failure to convert numeric entities
   with ENT_NOQUOTES and ISO-8859-1). Fixed and extended the fix of ENT_NOQUOTES 
diff --git a/main/streams/streams.c b/main/streams/streams.c
index c586d0110f8..023977d39ed 100755
--- a/main/streams/streams.c
+++ b/main/streams/streams.c
@@ -1097,8 +1097,8 @@ PHPAPI int _php_stream_seek(php_stream *stream, off_t offset, int whence TSRMLS_
 	if ((stream->flags & PHP_STREAM_FLAG_NO_BUFFER) == 0) {
 		switch(whence) {
 			case SEEK_CUR:
-				if (offset > 0 && offset < stream->writepos - stream->readpos) {
-					stream->readpos += offset;
+				if (offset > 0 && offset <= stream->writepos - stream->readpos) {
+					stream->readpos += offset; /* if offset = ..., then readpos = writepos */
 					stream->position += offset;
 					stream->eof = 0;
 					return 0;
@@ -1106,7 +1106,7 @@ PHPAPI int _php_stream_seek(php_stream *stream, off_t offset, int whence TSRMLS_
 				break;
 			case SEEK_SET:
 				if (offset > stream->position &&
-						offset < stream->position + stream->writepos - stream->readpos) {
+						offset <= stream->position + stream->writepos - stream->readpos) {
 					stream->readpos += offset - stream->position;
 					stream->position = offset;
 					stream->eof = 0;
@@ -1149,14 +1149,12 @@ PHPAPI int _php_stream_seek(php_stream *stream, off_t offset, int whence TSRMLS_
 	/* emulate forward moving seeks with reads */
 	if (whence == SEEK_CUR && offset > 0) {
 		char tmp[1024];
-		while(offset >= sizeof(tmp)) {
-			if (php_stream_read(stream, tmp, sizeof(tmp)) == 0) {
+		size_t didread;
+		while(offset > 0) {
+			if ((didread = php_stream_read(stream, tmp, MIN(offset, sizeof(tmp)))) == 0) {
 				return -1;
 			}
-			offset -= sizeof(tmp);
-		}
-		if (offset && (php_stream_read(stream, tmp, offset) == 0)) {
-			return -1;
+			offset -= didread;
 		}
 		stream->eof = 0;
 		return 0;