# libxml2 {#setup-hook-libxml2}
Adds every file named `catalog.xml` found under the `xml/dtd` and `xml/xsl` subdirectories of each build input to the `XML_CATALOG_FILES` environment variable.
Title: libxml2 Configuration Hook
Summary
This configuration hook for libxml2 automatically identifies all 'catalog.xml' files located within the 'xml/dtd' and 'xml/xsl' subdirectories of each build input. It then appends the paths of these files to the `XML_CATALOG_FILES` environment variable.