I have yet to find the reason for the crash on reverseIndex reported …

…on bug #256, adding some logging rather than a crash, hoping to find out why
migueldeicaza · Feb 10, 2023 · 550a805 · 550a805
1 parent 71bc772
commit 550a805
Show file tree

Hide file tree

Showing 2 changed files with 30 additions and 7 deletions.
diff --git a/Sources/SwiftTerm/CircularList.swift b/Sources/SwiftTerm/CircularList.swift
@@ -162,12 +162,29 @@ class CircularList<T> {
         self.count -= count
     }
 
-    func shiftElements (start: Int, count: Int, offset: Int)
+    func shiftElements (start: Int, count: Int, offset: Int) -> Bool
     {
-        precondition (count > 0)
-        precondition (start >= 0)
-        precondition(start < self.count)
-        precondition (start+offset > 0)
+        func dumpState (_ msg: String) -> Bool {
+            print ("Assertion at start=\(start) count=\(count) offset=\(offset): \(msg)")
+            return false
+        }
+
+        if count < 0 {
+            return dumpState ("count < 0")
+        }
+        if start < 0 {
+            return dumpState ("start < 0")
+        }
+        if start >= self.count {
+            return dumpState ("start >= self.count")
+        }
+        if start+offset <= 0 {
+            return dumpState ("start+offset <= 0")
+        }
+//        precondition (count > 0)
+//        precondition (start >= 0)
+//        precondition (start < self.count)
+//        precondition (start+offset > 0)
         if offset > 0 {
             for i in (0..<count).reversed() {
                 self [start + i + offset] = self [start + i]
@@ -186,6 +203,7 @@ class CircularList<T> {
                 self [start + i + offset] = self [start + i]
             }
         }
+        return true
     }
 
     var isFull: Bool {

diff --git a/Sources/SwiftTerm/Terminal.swift b/Sources/SwiftTerm/Terminal.swift
@@ -4678,7 +4678,9 @@ open class Terminal {
             // scrollback, instead we can just shift them in-place.
             let scrollRegionHeight = bottomRow - topRow + 1 /*as it's zero-based*/
             if scrollRegionHeight > 1 {
-                buffer.lines.shiftElements (start: topRow + 1, count: scrollRegionHeight - 1, offset: -1)
+                if !buffer.lines.shiftElements (start: topRow + 1, count: scrollRegionHeight - 1, offset: -1) {
+                    print ("Assertion on scroll, state was: bottomRow=\(bottomRow) topRow=\(topRow) yDisp=\(buffer.yDisp) linesTop=\(buffer.linesTop) isAlternate=\(buffers.isAlternateBuffer)")
+                }
             }
             buffer.lines [bottomRow] = BufferLine (from: newLine)
         }
@@ -4980,13 +4982,16 @@ open class Terminal {
 
     func reverseIndex ()
     {
+        let buffer = self.buffer
         restrictCursor()
         if buffer.y == buffer.scrollTop {
             // possibly move the code below to term.reverseScroll()
             // test: echo -ne '\e[1;1H\e[44m\eM\e[0m'
             // blankLine(true) is xterm/linux behavior
             let scrollRegionHeight = buffer.scrollBottom - buffer.scrollTop
-            buffer.lines.shiftElements (start: buffer.y + buffer.yBase, count: scrollRegionHeight, offset: 1)
+            if !buffer.lines.shiftElements (start: buffer.y + buffer.yBase, count: scrollRegionHeight, offset: 1) {
+                print ("Assertion on reverseIndex, state was: y=\(buffer.y) scrollTop=\(buffer.scrollTop)  yDisp=\(buffer.yDisp) linesTop=\(buffer.linesTop) isAlternate=\(buffers.isAlternateBuffer)")
+            }
             buffer.lines [buffer.y + buffer.yBase] = buffer.getBlankLine (attribute: eraseAttr ())
             updateRange (startLine: buffer.scrollTop, endLine: buffer.scrollBottom)
         } else if buffer.y > 0 {