KWSys: Fix SystemTools::FileIsDirectory with long paths (#14176)

Allocate a buffer large enough to hold the input path when removing a
trailing slash.  Use a local stack buffer when it is large enough and
fall back to heap allocation otherwise.

1 files changed, 13 insertions, 4 deletions

diff --git a/Source/kwsys/SystemTools.cxx b/Source/kwsys/SystemTools.cxx
index 22bf193..8b25d60 100644
--- a/Source/kwsys/SystemTools.cxx
+++ b/Source/kwsys/SystemTools.cxx
@@ -2742,14 +2742,23 @@ bool SystemTools::FileIsDirectory(const char* name)
     }
 
   // Remove any trailing slash from the name.
-  char buffer[KWSYS_SYSTEMTOOLS_MAXPATH];
+  char local_buffer[KWSYS_SYSTEMTOOLS_MAXPATH];
+  std::string string_buffer;
   size_t last = length-1;
   if(last > 0 && (name[last] == '/' || name[last] == '\\')
     && strcmp(name, "/") !=0)
     {
-    memcpy(buffer, name, last);
-    buffer[last] = 0;
-    name = buffer;
+    if(last < sizeof(local_buffer))
+      {
+      memcpy(local_buffer, name, last);
+      local_buffer[last] = 0;
+      name = local_buffer;
+      }
+    else
+      {
+      string_buffer.append(name, last);
+      name = string_buffer.c_str();
+      }
     }
 
   // Now check the file node type.