From 186819080baea53410ae8d8100179a3874ac1e32 Mon Sep 17 00:00:00 2001
From: Pierre Ossman <ossman@cendio.se>
Date: Tue, 19 May 2020 21:07:05 +0200
Subject: [PATCH] Simplify stream availability handling

Just have a simply number of bytes argument to avoid a lot of
complexity.
---
 common/rdr/BufferedInStream.cxx  | 17 ++++++---------
 common/rdr/BufferedInStream.h    |  2 +-
 common/rdr/BufferedOutStream.cxx | 17 +++++----------
 common/rdr/BufferedOutStream.h   |  2 +-
 common/rdr/HexInStream.cxx       |  2 +-
 common/rdr/HexOutStream.cxx      | 14 +++----------
 common/rdr/HexOutStream.h        |  2 +-
 common/rdr/InStream.h            | 36 +++++++++++++-------------------
 common/rdr/MemInStream.h         |  2 +-
 common/rdr/MemOutStream.h        | 10 ++++-----
 common/rdr/OutStream.h           | 34 +++++++++++++-----------------
 common/rdr/TLSInStream.cxx       |  4 ++--
 common/rdr/TLSOutStream.cxx      | 13 +++---------
 common/rdr/TLSOutStream.h        |  2 +-
 common/rdr/ZlibInStream.cxx      |  2 +-
 common/rdr/ZlibOutStream.cxx     | 15 ++++---------
 common/rdr/ZlibOutStream.h       |  2 +-
 common/rfb/JpegCompressor.cxx    |  2 +-
 common/rfb/JpegCompressor.h      |  4 ++--
 tests/perf/decperf.cxx           |  7 ++-----
 tests/perf/encperf.cxx           |  7 ++-----
 21 files changed, 70 insertions(+), 126 deletions(-)

diff --git a/common/rdr/BufferedInStream.cxx b/common/rdr/BufferedInStream.cxx
index 5083eb2d..5db3953a 100644
--- a/common/rdr/BufferedInStream.cxx
+++ b/common/rdr/BufferedInStream.cxx
@@ -44,12 +44,12 @@ size_t BufferedInStream::pos()
   return offset + ptr - start;
 }
 
-size_t BufferedInStream::overrun(size_t itemSize, size_t nItems, bool wait)
+bool BufferedInStream::overrun(size_t needed, bool wait)
 {
-  if (itemSize > bufSize)
+  if (needed > bufSize)
     throw Exception("BufferedInStream overrun: "
                     "requested size of %lu bytes exceeds maximum of %lu bytes",
-                    (long unsigned)itemSize, (long unsigned)bufSize);
+                    (long unsigned)needed, (long unsigned)bufSize);
 
   if (end - ptr != 0)
     memmove(start, ptr, end - ptr);
@@ -58,15 +58,10 @@ size_t BufferedInStream::overrun(size_t itemSize, size_t nItems, bool wait)
   end -= ptr - start;
   ptr = start;
 
-  while (avail() < itemSize) {
+  while (avail() < needed) {
     if (!fillBuffer(start + bufSize - end, wait))
-      return 0;
+      return false;
   }
 
-  size_t nAvail;
-  nAvail = avail() / itemSize;
-  if (nAvail < nItems)
-    return nAvail;
-
-  return nItems;
+  return true;
 }
diff --git a/common/rdr/BufferedInStream.h b/common/rdr/BufferedInStream.h
index fc62133e..61e57d65 100644
--- a/common/rdr/BufferedInStream.h
+++ b/common/rdr/BufferedInStream.h
@@ -38,7 +38,7 @@ namespace rdr {
   private:
     virtual bool fillBuffer(size_t maxSize, bool wait) = 0;
 
-    virtual size_t overrun(size_t itemSize, size_t nItems, bool wait);
+    virtual bool overrun(size_t needed, bool wait);
 
   private:
     size_t bufSize;
diff --git a/common/rdr/BufferedOutStream.cxx b/common/rdr/BufferedOutStream.cxx
index 76b0163b..69e877ad 100644
--- a/common/rdr/BufferedOutStream.cxx
+++ b/common/rdr/BufferedOutStream.cxx
@@ -71,22 +71,22 @@ void BufferedOutStream::flush()
     ptr = sentUpTo = start;
 }
 
-size_t BufferedOutStream::overrun(size_t itemSize, size_t nItems)
+void BufferedOutStream::overrun(size_t needed)
 {
-  if (itemSize > bufSize)
+  if (needed > bufSize)
     throw Exception("BufferedOutStream overrun: "
                     "requested size of %lu bytes exceeds maximum of %lu bytes",
-                    (long unsigned)itemSize, (long unsigned)bufSize);
+                    (long unsigned)needed, (long unsigned)bufSize);
 
   // First try to get rid of the data we have
   flush();
 
   // Still not enough space?
-  while (itemSize > avail()) {
+  while (needed > avail()) {
     // Can we shuffle things around?
     // (don't do this if it gains us less than 25%)
     if (((size_t)(sentUpTo - start) > bufSize / 4) &&
-        (itemSize < bufSize - (ptr - sentUpTo))) {
+        (needed < bufSize - (ptr - sentUpTo))) {
       memmove(start, sentUpTo, ptr - sentUpTo);
       ptr = start + (ptr - sentUpTo);
       sentUpTo = start;
@@ -105,11 +105,4 @@ size_t BufferedOutStream::overrun(size_t itemSize, size_t nItems)
         ptr = sentUpTo = start;
     }
   }
-
-  size_t nAvail;
-  nAvail = avail() / itemSize;
-  if (nAvail < nItems)
-    return nAvail;
-
-  return nItems;
 }
diff --git a/common/rdr/BufferedOutStream.h b/common/rdr/BufferedOutStream.h
index 092ea1f0..c33621b6 100644
--- a/common/rdr/BufferedOutStream.h
+++ b/common/rdr/BufferedOutStream.h
@@ -46,7 +46,7 @@ namespace rdr {
 
     virtual bool flushBuffer(bool wait) = 0;
 
-    virtual size_t overrun(size_t itemSize, size_t nItems);
+    virtual void overrun(size_t needed);
 
   private:
     size_t bufSize;
diff --git a/common/rdr/HexInStream.cxx b/common/rdr/HexInStream.cxx
index 0901afee..ab98298f 100644
--- a/common/rdr/HexInStream.cxx
+++ b/common/rdr/HexInStream.cxx
@@ -73,7 +73,7 @@ decodeError:
 
 
 bool HexInStream::fillBuffer(size_t maxSize, bool wait) {
-  if (!in_stream.check(2, 1, wait))
+  if (!in_stream.check(2, wait))
     return false;
 
   const U8* iptr = in_stream.getptr();
diff --git a/common/rdr/HexOutStream.cxx b/common/rdr/HexOutStream.cxx
index 6118c136..a44c3998 100644
--- a/common/rdr/HexOutStream.cxx
+++ b/common/rdr/HexOutStream.cxx
@@ -95,18 +95,10 @@ HexOutStream::flush() {
   out_stream.flush();
 }
 
-size_t
-HexOutStream::overrun(size_t itemSize, size_t nItems) {
-  if (itemSize > bufSize)
-    throw Exception("HexOutStream overrun: max itemSize exceeded");
+void HexOutStream::overrun(size_t needed) {
+  if (needed > bufSize)
+    throw Exception("HexOutStream overrun: buffer size exceeded");
 
   writeBuffer();
-
-  size_t nAvail;
-  nAvail = avail() / itemSize;
-  if (nAvail < nItems)
-    return nAvail;
-
-  return nItems;
 }
 
diff --git a/common/rdr/HexOutStream.h b/common/rdr/HexOutStream.h
index 92442a72..29827689 100644
--- a/common/rdr/HexOutStream.h
+++ b/common/rdr/HexOutStream.h
@@ -37,7 +37,7 @@ namespace rdr {
 
   private:
     void writeBuffer();
-    size_t overrun(size_t itemSize, size_t nItems);
+    virtual void overrun(size_t needed);
 
     OutStream& out_stream;
 
diff --git a/common/rdr/InStream.h b/common/rdr/InStream.h
index 665084f2..ce3a344d 100644
--- a/common/rdr/InStream.h
+++ b/common/rdr/InStream.h
@@ -43,31 +43,24 @@ namespace rdr {
       return end - ptr;
     }
 
-    // check() ensures there is buffer data for at least one item of size
-    // itemSize bytes.  Returns the number of items in the buffer (up to a
-    // maximum of nItems).  If wait is false, then instead of blocking to wait
-    // for the bytes, zero is returned if the bytes are not immediately
-    // available.
+    // check() ensures there is buffer data for at least needed bytes. Returns
+    // true once the data is available. If wait is false, then instead of
+    // blocking to wait for the bytes, false is returned if the bytes are not
+    // immediately available.
 
-    inline size_t check(size_t itemSize, size_t nItems=1, bool wait=true)
+    inline size_t check(size_t needed, bool wait=true)
     {
-      size_t nAvail;
+      if (needed > avail())
+        return overrun(needed, wait);
 
-      if (itemSize > avail())
-        return overrun(itemSize, nItems, wait);
-
-      nAvail = avail() / itemSize;
-      if (nAvail < nItems)
-        return nAvail;
-
-      return nItems;
+      return true;
     }
 
     // checkNoWait() tries to make sure that the given number of bytes can
     // be read without blocking.  It returns true if this is the case, false
     // otherwise.  The length must be "small" (less than the buffer size).
 
-    inline bool checkNoWait(size_t length) { return check(length, 1, false)!=0; }
+    inline bool checkNoWait(size_t length) { return check(length, false); }
 
     // readU/SN() methods read unsigned and signed N-bit integers.
 
@@ -137,13 +130,12 @@ namespace rdr {
   private:
 
     // overrun() is implemented by a derived class to cope with buffer overrun.
-    // It ensures there are at least itemSize bytes of buffer data.  Returns
-    // the number of items in the buffer (up to a maximum of nItems).  itemSize
-    // is supposed to be "small" (a few bytes).  If wait is false, then
-    // instead of blocking to wait for the bytes, zero is returned if the bytes
-    // are not immediately available.
+    // It ensures there are at least needed bytes of buffer data. Returns true
+    // once the data is available. If wait is false, then instead of blocking
+    // to wait for the bytes, false is returned if the bytes are not
+    // immediately available.
 
-    virtual size_t overrun(size_t itemSize, size_t nItems, bool wait=true) = 0;
+    virtual bool overrun(size_t needed, bool wait=true) = 0;
 
   protected:
 
diff --git a/common/rdr/MemInStream.h b/common/rdr/MemInStream.h
index 3e9e77bc..83740dd9 100644
--- a/common/rdr/MemInStream.h
+++ b/common/rdr/MemInStream.h
@@ -53,7 +53,7 @@ namespace rdr {
 
   private:
 
-    size_t overrun(size_t itemSize, size_t nItems, bool wait) { throw EndOfStream(); }
+    bool overrun(size_t needed, bool wait) { throw EndOfStream(); }
     const U8* start;
     bool deleteWhenDone;
   };
diff --git a/common/rdr/MemOutStream.h b/common/rdr/MemOutStream.h
index a839473b..f8b4d93c 100644
--- a/common/rdr/MemOutStream.h
+++ b/common/rdr/MemOutStream.h
@@ -52,11 +52,11 @@ namespace rdr {
 
   protected:
 
-    // overrun() either doubles the buffer or adds enough space for nItems of
-    // size itemSize bytes.
+    // overrun() either doubles the buffer or adds enough space for
+    // needed bytes.
 
-    size_t overrun(size_t itemSize, size_t nItems) {
-      size_t len = ptr - start + itemSize * nItems;
+    virtual void overrun(size_t needed) {
+      size_t len = ptr - start + needed;
       if (len < (size_t)(end - start) * 2)
         len = (end - start) * 2;
 
@@ -69,8 +69,6 @@ namespace rdr {
       delete [] start;
       start = newStart;
       end = newStart + len;
-
-      return nItems;
     }
 
     U8* start;
diff --git a/common/rdr/OutStream.h b/common/rdr/OutStream.h
index 33381d9a..bb88f325 100644
--- a/common/rdr/OutStream.h
+++ b/common/rdr/OutStream.h
@@ -48,22 +48,12 @@ namespace rdr {
       return end - ptr;
     }
 
-    // check() ensures there is buffer space for at least one item of size
-    // itemSize bytes.  Returns the number of items which fit (up to a maximum
-    // of nItems).
+    // check() ensures there is buffer space for at least needed bytes.
 
-    inline size_t check(size_t itemSize, size_t nItems=1)
+    inline void check(size_t needed)
     {
-      size_t nAvail;
-
-      if (itemSize > avail())
-        return overrun(itemSize, nItems);
-
-      nAvail = avail() / itemSize;
-      if (nAvail < nItems)
-        return nAvail;
-
-      return nItems;
+      if (needed > avail())
+        overrun(needed);
     }
 
     // writeU/SN() methods write unsigned and signed N-bit integers.
@@ -95,7 +85,10 @@ namespace rdr {
 
     void writeBytes(const void* data, size_t length) {
       while (length > 0) {
-        size_t n = check(1, length);
+        check(1);
+        size_t n = length;
+        if (length > avail())
+          n = avail();
         memcpy(ptr, data, n);
         ptr += n;
         data = (U8*)data + n;
@@ -107,7 +100,10 @@ namespace rdr {
 
     void copyBytes(InStream* is, size_t length) {
       while (length > 0) {
-        size_t n = check(1, length);
+        check(1);
+        size_t n = length;
+        if (length > avail())
+          n = avail();
         is->readBytes(ptr, n);
         ptr += n;
         length -= n;
@@ -143,11 +139,9 @@ namespace rdr {
   private:
 
     // overrun() is implemented by a derived class to cope with buffer overrun.
-    // It ensures there are at least itemSize bytes of buffer space.  Returns
-    // the number of items which fit (up to a maximum of nItems).  itemSize is
-    // supposed to be "small" (a few bytes).
+    // It ensures there are at least needed bytes of buffer space.
 
-    virtual size_t overrun(size_t itemSize, size_t nItems) = 0;
+    virtual void overrun(size_t needed) = 0;
 
   protected:
 
diff --git a/common/rdr/TLSInStream.cxx b/common/rdr/TLSInStream.cxx
index 92c2f0c6..70303db0 100644
--- a/common/rdr/TLSInStream.cxx
+++ b/common/rdr/TLSInStream.cxx
@@ -36,7 +36,7 @@ ssize_t TLSInStream::pull(gnutls_transport_ptr_t str, void* data, size_t size)
   InStream *in = self->in;
 
   try {
-    if (!in->check(1, 1, false)) {
+    if (!in->check(1, false)) {
       gnutls_transport_set_errno(self->session, EAGAIN);
       return -1;
     }
@@ -84,7 +84,7 @@ size_t TLSInStream::readTLS(U8* buf, size_t len, bool wait)
   int n;
 
   if (gnutls_record_check_pending(session) == 0) {
-    n = in->check(1, 1, wait);
+    n = in->check(1, wait);
     if (n == 0)
       return 0;
   }
diff --git a/common/rdr/TLSOutStream.cxx b/common/rdr/TLSOutStream.cxx
index 089aa660..76f5dffe 100644
--- a/common/rdr/TLSOutStream.cxx
+++ b/common/rdr/TLSOutStream.cxx
@@ -93,19 +93,12 @@ void TLSOutStream::flush()
   out->flush();
 }
 
-size_t TLSOutStream::overrun(size_t itemSize, size_t nItems)
+void TLSOutStream::overrun(size_t needed)
 {
-  if (itemSize > bufSize)
-    throw Exception("TLSOutStream overrun: max itemSize exceeded");
+  if (needed > bufSize)
+    throw Exception("TLSOutStream overrun: buffer size exceeded");
 
   flush();
-
-  size_t nAvail;
-  nAvail = avail() / itemSize;
-  if (nAvail < nItems)
-    return nAvail;
-
-  return nItems;
 }
 
 size_t TLSOutStream::writeTLS(const U8* data, size_t length)
diff --git a/common/rdr/TLSOutStream.h b/common/rdr/TLSOutStream.h
index 71a7f3bf..9ce6eb6d 100644
--- a/common/rdr/TLSOutStream.h
+++ b/common/rdr/TLSOutStream.h
@@ -39,7 +39,7 @@ namespace rdr {
     size_t length();
 
   protected:
-    size_t overrun(size_t itemSize, size_t nItems);
+    virtual void overrun(size_t needed);
 
   private:
     size_t writeTLS(const U8* data, size_t length);
diff --git a/common/rdr/ZlibInStream.cxx b/common/rdr/ZlibInStream.cxx
index 675600d5..2e4e080b 100644
--- a/common/rdr/ZlibInStream.cxx
+++ b/common/rdr/ZlibInStream.cxx
@@ -94,7 +94,7 @@ bool ZlibInStream::fillBuffer(size_t maxSize, bool wait)
   zs->next_out = (U8*)end;
   zs->avail_out = maxSize;
 
-  size_t n = underlying->check(1, 1, wait);
+  size_t n = underlying->check(1, wait);
   if (n == 0) return false;
   zs->next_in = (U8*)underlying->getptr();
   zs->avail_in = underlying->avail();
diff --git a/common/rdr/ZlibOutStream.cxx b/common/rdr/ZlibOutStream.cxx
index f102980a..78abfc49 100644
--- a/common/rdr/ZlibOutStream.cxx
+++ b/common/rdr/ZlibOutStream.cxx
@@ -98,18 +98,18 @@ void ZlibOutStream::flush()
   ptr = start;
 }
 
-size_t ZlibOutStream::overrun(size_t itemSize, size_t nItems)
+void ZlibOutStream::overrun(size_t needed)
 {
 #ifdef ZLIBOUT_DEBUG
   vlog.debug("overrun");
 #endif
 
-  if (itemSize > bufSize)
-    throw Exception("ZlibOutStream overrun: max itemSize exceeded");
+  if (needed > bufSize)
+    throw Exception("ZlibOutStream overrun: buffer size exceeded");
 
   checkCompressionLevel();
 
-  while (avail() < itemSize) {
+  while (avail() < needed) {
     zs->next_in = start;
     zs->avail_in = ptr - start;
 
@@ -129,13 +129,6 @@ size_t ZlibOutStream::overrun(size_t itemSize, size_t nItems)
       ptr -= zs->next_in - start;
     }
   }
-
-  size_t nAvail;
-  nAvail = avail() / itemSize;
-  if (nAvail < nItems)
-    return nAvail;
-
-  return nItems;
 }
 
 void ZlibOutStream::deflate(int flush)
diff --git a/common/rdr/ZlibOutStream.h b/common/rdr/ZlibOutStream.h
index 11bb0468..aa1875c3 100644
--- a/common/rdr/ZlibOutStream.h
+++ b/common/rdr/ZlibOutStream.h
@@ -45,7 +45,7 @@ namespace rdr {
 
   private:
 
-    size_t overrun(size_t itemSize, size_t nItems);
+    virtual void overrun(size_t needed);
     void deflate(int flush);
     void checkCompressionLevel();
 
diff --git a/common/rfb/JpegCompressor.cxx b/common/rfb/JpegCompressor.cxx
index a4af92fa..4cb35a47 100644
--- a/common/rfb/JpegCompressor.cxx
+++ b/common/rfb/JpegCompressor.cxx
@@ -95,7 +95,7 @@ JpegEmptyOutputBuffer(j_compress_ptr cinfo)
   JpegCompressor *jc = dest->instance;
 
   jc->setptr(jc->getend());
-  jc->overrun(jc->getend() - jc->getstart(), 1);
+  jc->overrun(jc->getend() - jc->getstart());
   dest->pub.next_output_byte = jc->getptr();
   dest->pub.free_in_buffer = jc->avail();
 
diff --git a/common/rfb/JpegCompressor.h b/common/rfb/JpegCompressor.h
index 8fbb7a9e..ab0f9f85 100644
--- a/common/rfb/JpegCompressor.h
+++ b/common/rfb/JpegCompressor.h
@@ -49,8 +49,8 @@ namespace rfb {
 
     inline rdr::U8* getstart() { return start; }
 
-    inline int overrun(int itemSize, int nItems) {
-      return MemOutStream::overrun(itemSize, nItems);
+    inline virtual void overrun(int needed) {
+      return MemOutStream::overrun(needed);
     }
 
   private:
diff --git a/tests/perf/decperf.cxx b/tests/perf/decperf.cxx
index 687ac7a9..e1307070 100644
--- a/tests/perf/decperf.cxx
+++ b/tests/perf/decperf.cxx
@@ -52,7 +52,7 @@ public:
   virtual void flush();
 
 private:
-  virtual size_t overrun(size_t itemSize, size_t nItems);
+  virtual void overrun(size_t needed);
 
   int offset;
   rdr::U8 buf[131072];
@@ -99,12 +99,9 @@ void DummyOutStream::flush()
   ptr = buf;
 }
 
-size_t DummyOutStream::overrun(size_t itemSize, size_t nItems)
+void DummyOutStream::overrun(size_t needed)
 {
   flush();
-  if (itemSize * nItems > avail())
-    nItems = avail() / itemSize;
-  return nItems;
 }
 
 CConn::CConn(const char *filename)
diff --git a/tests/perf/encperf.cxx b/tests/perf/encperf.cxx
index 4665346f..6bcb6f74 100644
--- a/tests/perf/encperf.cxx
+++ b/tests/perf/encperf.cxx
@@ -76,7 +76,7 @@ public:
   virtual void flush();
 
 private:
-  virtual size_t overrun(size_t itemSize, size_t nItems);
+  virtual void overrun(size_t needed);
 
   int offset;
   rdr::U8 buf[131072];
@@ -156,12 +156,9 @@ void DummyOutStream::flush()
   ptr = buf;
 }
 
-size_t DummyOutStream::overrun(size_t itemSize, size_t nItems)
+void DummyOutStream::overrun(size_t needed)
 {
   flush();
-  if (itemSize * nItems > avail())
-    nItems = avail() / itemSize;
-  return nItems;
 }
 
 CConn::CConn(const char *filename)
-- 
2.39.5