Make width/height limits consistent and cap out-of-bounds values

When resizing, ensure that the replacement sync marker does not become
visible if the buffer height is increased by more than the marker's margin
(currently 200 rows).

src/agent/Agent.cc

@@ -153,6 +153,10 @@ Agent::Agent(LPCWSTR controlPipeName,
 {
     trace("Agent::Agent entered");
 
+    ASSERT(initialCols >= 1 && initialRows >= 1);
+    initialCols = std::min(initialCols, MAX_CONSOLE_WIDTH);
+    initialRows = std::min(initialRows, MAX_CONSOLE_HEIGHT);
+
     const bool outputColor =
         !m_plainMode || (agentFlags & WINPTY_FLAG_COLOR_ESCAPES);
     const Coord initialSize(initialCols, initialRows);
@@ -413,8 +417,8 @@ void Agent::handleStartProcessPacket(ReadBuffer &packet)
 
 void Agent::handleSetSizePacket(ReadBuffer &packet)
 {
-    int cols = packet.getInt32();
-    int rows = packet.getInt32();
+    const int cols = packet.getInt32();
+    const int rows = packet.getInt32();
     packet.assertEof();
     resizeWindow(cols, rows);
     auto reply = newPacket();
@@ -515,15 +519,12 @@ std::unique_ptr<Win32ConsoleBuffer> Agent::openPrimaryBuffer()
     }
 }
 
-void Agent::resizeWindow(const int cols, const int rows)
+void Agent::resizeWindow(int cols, int rows)
 {
-    if (cols < 1 ||
-            cols > MAX_CONSOLE_WIDTH ||
-            rows < 1 ||
-            rows > BUFFER_LINE_COUNT - 1) {
-        trace("resizeWindow: invalid size: cols=%d,rows=%d", cols, rows);
-        return;
-    }
+    ASSERT(cols >= 1 && rows >= 1);
+    cols = std::min(cols, MAX_CONSOLE_WIDTH);
+    rows = std::min(rows, MAX_CONSOLE_HEIGHT);
+
     Win32Console::FreezeGuard guard(m_console, m_console.frozen());
     const Coord newSize(cols, rows);
     ConsoleScreenBufferInfo info;

src/agent/Scraper.cc

@@ -209,7 +209,11 @@ void Scraper::resizeImpl(const ConsoleScreenBufferInfo &origInfo)
             m_consoleBuffer->clearLines(0, origWindowRect.Top, origInfo);
             clearBufferLines(0, origWindowRect.Top, origInfo.wAttributes);
             if (m_syncRow != -1) {
-                createSyncMarker(m_syncRow);
+                createSyncMarker(std::min(
+                    m_syncRow,
+                    BUFFER_LINE_COUNT - rows
+                                      - SYNC_MARKER_LEN
+                                      - SYNC_MARKER_MARGIN));
             }
         }
 
@@ -452,8 +456,10 @@ bool Scraper::scrollingScrapeOutput(const ConsoleScreenBufferInfo &info,
     // Creating a new sync row requires clearing part of the console buffer, so
     // avoid doing it if there's already a sync row that's good enough.
     // TODO: replace hard-coded constants
-    const int newSyncRow = static_cast<int>(windowRect.top()) - 200;
-    const bool shouldCreateSyncRow = newSyncRow >= m_syncRow + 200;
+    const int newSyncRow =
+        static_cast<int>(windowRect.top()) - SYNC_MARKER_LEN - SYNC_MARKER_MARGIN;
+    const bool shouldCreateSyncRow =
+        newSyncRow >= m_syncRow + SYNC_MARKER_LEN + SYNC_MARKER_MARGIN;
     if (tentative && shouldCreateSyncRow) {
         // It's difficult even in principle to put down a new marker if the
         // console can scroll an arbitrarily amount while we're writing.

src/agent/Scraper.h

@@ -43,7 +43,9 @@ class Win32ConsoleBuffer;
 // hundred fewer characters than BUFFER_LINE_COUNT.
 const int BUFFER_LINE_COUNT = 3000;
 const int MAX_CONSOLE_WIDTH = 2500;
+const int MAX_CONSOLE_HEIGHT = 2000;
 const int SYNC_MARKER_LEN = 16;
+const int SYNC_MARKER_MARGIN = 200;
 
 class Scraper {
 public: