From 173ca3e58e226b0e9f115c42371c2cb13415b53c Mon Sep 17 00:00:00 2001
From: pryon <pryon@users.noreply.github.com>
Date: Sat, 21 Sep 2024 20:02:58 +0200
Subject: [PATCH] Fix assertion failures on `str` operations

---
 code/client/cl_uimaprunner.cpp |  2 +-
 code/uilib/uimledit.cpp        | 28 +++++++++++++++++++++-------
 2 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/code/client/cl_uimaprunner.cpp b/code/client/cl_uimaprunner.cpp
index 40b0730d..20f4fbb9 100644
--- a/code/client/cl_uimaprunner.cpp
+++ b/code/client/cl_uimaprunner.cpp
@@ -83,7 +83,7 @@ void PickFile(const char *name, Listener *obj, Event& event)
     if (name && *name && strchr(name, '/')) {
         currentpath = name;
 
-        for (i = currentpath.length(); i > 0; i--) {
+        for (i = currentpath.length() - 1; i > 0; i--) {
             if (currentpath[i] == '/') {
                 break;
             }
diff --git a/code/uilib/uimledit.cpp b/code/uilib/uimledit.cpp
index 45463ab7..688e124f 100644
--- a/code/uilib/uimledit.cpp
+++ b/code/uilib/uimledit.cpp
@@ -646,12 +646,19 @@ void UIMultiLineEdit::DeleteSelection(void)
 
     for (i = 0, m_lines.IterateFromHead(); m_lines.IsCurrentValid() && i < topsel->line; i++, m_lines.IterateNext()) {}
 
+    // delete topmost line of the selection, but only up to topsel->column
     str& topline = m_lines.getCurrent();
-    topline.CapLength(topsel->column);
+    if (topline.length() > topsel->column) {
+        topline.CapLength(topsel->column);
+    }
     m_lines.IterateNext();
-    str& line = m_lines.getCurrent();
+    str line = m_lines.getCurrent();
+
+    // merge remainder of topmost line with the remainder after the end of selection
+    if (line.length() > botsel->column) {
+        topline += &line[botsel->column];
+    }
 
-    topline += &line[botsel->column];
     m_lines.RemoveCurrentSetPrev();
     *botsel = *topsel;
     m_vertscroll->setNumItems(m_lines.getCount());
@@ -691,8 +698,11 @@ void UIMultiLineEdit::CharEvent(int ch)
         m_changed = true;
 
         str& line      = LineFromLineNumber(m_selection.begin.line, false);
-        str  otherline = &line[m_selection.begin.column];
-        otherline.CapLength(m_selection.begin.column);
+        str otherline = "";
+        if (line.length() > m_selection.begin.column) {
+            otherline = &line[m_selection.begin.column];
+            line.CapLength(m_selection.begin.column);
+        }
 
         if (m_lines.IsCurrentValid()) {
             m_lines.InsertAfterCurrent(otherline);
@@ -730,7 +740,9 @@ void UIMultiLineEdit::CopySelection(void)
 
     line = LineFromLineNumber(topsel->line, true);
 
-    clipText += &line[topsel->column];
+    if (line.length() > topsel->column) {
+        clipText += &line[topsel->column];
+    }
 
     if (topsel->line == botsel->line) {
         clipText.CapLength(botsel->column - topsel->column);
@@ -740,7 +752,9 @@ void UIMultiLineEdit::CopySelection(void)
         }
 
         line = LineFromLineNumber(botsel->line, true);
-        line.CapLength(botsel->column);
+        if (line.length() > botsel->column) {
+            line.CapLength(botsel->column);
+        }
         clipText += "\n" + line;
     }