6.7 The .rsrc Section

Resources are indexed by a multiple level binary-sorted tree structure. The general design can incorporate 2**31 levels. By convention, however, Windows NT uses three levels:

  • Type

  • Name

  • Language

    A series of Resource Directory Tables relate all the levels in the following way: each directory table is followed by a series of directory entries, which give the name or ID for that level (Type, Name, or Language level) and an address of either a data description or another directory table. If a data description is pointed to, then the data is a leaf in the tree. If another directory table is pointed to, then that table lists directory entries at the next level down.

    A leaf's Type, Name, and Language IDs are determined by the path taken, through directory tables, to reach the leaf. The first table determines Type ID, the second table (pointed to by the directory entry in the first table) determines Name ID, and the third table determines Language ID.

    The general structure of the .rsrc section is:

    Data Description
    Resource Directory Tables (and Resource Directory Entries) A series of tables, one for each group of nodes in the tree. All top-level (Type) nodes are listed in the first table. Entries in this table point to second-level tables. Each second-level tree has the same Type identifier but different Name identifiers. Third-level trees have the same Type and Name identifiers but different Language identifiers.

    Each individual table is immediately followed by directory entries, in which each entry has: 1) a name or numeric identifier, and 2) a pointer to a data description or a table at the next lower level.
    Resource Directory Strings Two-byte-aligned Unicode™ strings, which serve as string data pointed to by directory entries.
    Resource Data Description An array of records, pointed to by tables, which describe the actual size and location of the resource data. These records are the leaves in the resource-description tree.
    Resource Data Raw data of the resource section. The size and location information in the Resource Data Descriptions delimit the individual regions of resource data.