.A File Format – Symbol index

System V and GNU static library

The first member of a library is an index from the public symbols to the object file that defines each one, so the linker need not read every member. The ranlib tool, or ar s, rebuilds it. Its member is named /.

Layout

  1. 0Number of symbols, big-endian4 bytes
  2. 4Offsets: for each symbol, the file offset of the member’s header, big-endian4 bytes each
  3. …Names: zero-terminated, in the same ordervaries
The symbol index.

/SYM64/

An archive with members past 4 GB uses a member named /SYM64/ instead, with the count and offsets 8 bytes each, still big-endian.