FLUID: minor improvemnets to buffer handling (#1152)

The described crash can not be reproduced. The changes
improve the stability of the call that causes the crash.

fluid/undo.cxx

@@ -156,7 +156,7 @@ void undo_cb(Fl_Widget *, void *) {
     }
   }
   // Restore old browser position.
-  // Ideally, we would save the browser position insied the undo file.
+  // Ideally, we would save the browser position inside the undo file.
   if (widget_browser) widget_browser->restore_scroll_position();
 
   undo_current --;
@@ -178,7 +178,7 @@ void undo_checkpoint_once(int type) {
     undo_checkpoint();
     undo_once_type = type;
   } else {
-    // do not add more checkpoints for the same undo typw
+    // do not add more checkpoints for the same undo type
   }
 }
 

fluid/widget_browser.cxx

@@ -1,7 +1,7 @@
 //
 // Widget Browser code for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2023 by Bill Spitzak and others.
+// Copyright 1998-2024 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -143,8 +143,8 @@ void reveal_in_browser(Fl_Type *t) {
  \param[out] p return the resulting string in this buffer, terminated with
     a NUL byte
  \param[in] str copy this string; utf8 aware
- \param[in] maxl maximum number of letter to copy until we print
+ \param[in] maxl maximum number of letters to copy until we print
-    the elipsis (...)
+    the ellipsis (...)
  \param[in] quote if set, the resulting string is embedded in double quotes
  \param[in] trunc_lf if set, truncates at first newline
  \returns pointer to end of string (before terminating null byte).
@@ -159,16 +159,23 @@ static char *copy_trunc(char *p, const char *str, int maxl, int quote, int trunc
 {
   int size = 0;                         // truncated string size in characters
   int bs;                               // size of UTF-8 character in bytes
+  if (!p) return NULL;                  // bad buffer
+  if (!str) {                           // no input string
+    if (quote) { *p++='"'; *p++='"'; }
+    *p = 0;
+    return p;
+  }
   const char *end = str + strlen(str);  // end of input string
   if (quote) *p++ = '"';                // opening quote
   while (size < maxl) {                 // maximum <maxl> characters
     if (*str == '\n') {
       if (trunc_lf) {                   // handle trunc at \n
-        *p++ = 0;
+        if (quote) *p++ = '"';          // closing quote
+        *p = 0;
         return p;
       }
       *p++ = '\\'; *p++ = 'n';
-      str++; size++;
+      str++; size+=2;
       continue;
     }
     if (!(*str & (-32))) break;         // end of string (0 or control char)
@@ -197,7 +204,7 @@ static char *copy_trunc(char *p, const char *str, int maxl, int quote, int trunc
 
  \param[in] X, Y, W, H position and size of widget
  \param[in] l optional label
- \todo It would be nice to be able to grab one or more nodes and mmove them
+ \todo It would be nice to be able to grab one or more nodes and move them
     within the hierarchy.
  */
 Widget_Browser::Widget_Browser(int X,int Y,int W,int H,const char*l) :
@@ -305,7 +312,7 @@ void Widget_Browser::item_draw(void *v, int X, int Y, int, int) const {
   // cast to a more general type
   Fl_Type *l = (Fl_Type *)v;
 
-  char buf[340]; // edit buffer: large enough to hold 80 UTF-8 chars + nul
+  char buf[500]; // edit buffer: large enough to hold 80 UTF-8 chars + nul
 
   // calculate the horizontal start position of this item
   // 3 is the edge of the browser
@@ -446,7 +453,7 @@ void Widget_Browser::item_draw(void *v, int X, int Y, int, int) const {
  */
 int Widget_Browser::item_width(void *v) const {
 
-  char buf[340]; // edit buffer: large enough to hold 80 UTF-8 chars + nul
+  char buf[500]; // edit buffer: large enough to hold 80 UTF-8 chars + nul
 
   Fl_Type *l = (Fl_Type *)v;
 
@@ -562,7 +569,7 @@ int Widget_Browser::handle(int e) {
 }
 
 /**
- Save the current scrollbar postion during rebuild.
+ Save the current scrollbar position during rebuild.
  */
 void Widget_Browser::save_scroll_position() {
   saved_h_scroll_ = hposition();
@@ -570,7 +577,7 @@ void Widget_Browser::save_scroll_position() {
 }
 
 /**
- Restore the previous scrollbar postion after rebuild.
+ Restore the previous scrollbar position after rebuild.
  */
 void Widget_Browser::restore_scroll_position() {
   hposition(saved_h_scroll_);