syms(4)                                                   syms(4)



NAME
     syms - common object file symbol table format

SYNOPSIS
     #include <syms.h>

DESCRIPTION
     Common object files contain information to support symbolic
     software testing (see sdb(1)).  Line number entries,
     linenum(4), and extensive symbolic information permit
     testing at the C source level.  Every object file's symbol
     table is organized as shown.

     Filename 1.
          Function 1.
               Local symbols for function 1.
          Function 2.
               Local symbols for function 2.
          ...
          Static externs for file 1.

     Filename 2.
          Function 1.
               Local symbols for function 1.
          Function 2.
               Local symbols for function 2.
          ...
          Static externs for file 2.
     ...

     Defined global symbols.
     Undefined global symbols.

     The entry for a symbol is a fixed-length structure.  The
     members of the structure hold the name (null padded), its
     value, and other information.  The C structure is

     #define  SYMNMLEN   8
     #define  FILNMLEN   14
     #define  DIMNUM          4

     struct    syment
     {
      union                        /* ways to get a
                                      symbol name */
      {
        char   _n_name[SYMNMLEN] ; /* names less than
                                      8 chars */
        struct                     /* names 8 char
                                      or more */
        {
           long        _n_zeroes;   /* == 0L when in



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syms(4)                                                   syms(4)



                                       string table */
           long        _n_offset;   /* location of name in
                                       table */
        } _n_n;
        char           *_n_nptr[2]; /* allows overlaying */
     } _n;
        long           n_value ;    /* value of symbol */
        short          n_scnum ;    /* section number */
        unsigned short n_type ;     /* type and derived type */
        char           n_sclass ;   /*storage class */
        char           n_numaux ;   /* number of aux entries */
     };
     #define    n_name      _n._n_name
     #define    n_zeroes    _n._n_n._n_zeroes
     #define    n_offset    _n._n_n._n_offset
     #define    n_nptr      _n._n_nptr[1]


     Meaningful values and explanations are given in both syms.h
     and Common Object File Format.  Anyone who needs to
     interpret the entries should seek more information in these
     sources.  Some symbols require more information than a
     single entry; they are followed by auxiliary entries that
     are the same size as a symbol entry.  The format is as
     follows.

     union auxent
     {
          struct
          {
               long      x_tagndx;
               union
               {
                    struct
                    {
                         unsigned short x_lnno;
                         unsigned short x_size;
                    } x_lnsz;
                    long x_fsize;
               } x_misc;
               union
               {
                    struct
                    {
                         long x_lnnoptr;
                         long x_endndx;
                    }    x_fcn;
                    struct
                    {
                         unsigned short x_dimen[DIMNUM];
                    }    x_ary;
               }         x_fcnary;



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syms(4)                                                   syms(4)



               unsigned short  x_tvndx;
          }    x_sym;
          struct
          {
               char x_fname[FILNMLEN];
          }    x_file;
             struct
             {
                     long    x_scnlen;
                     unsigned short  x_nreloc;
                     unsigned short  x_nlinno;
             }       x_scn;

          struct
          {
               unsigned short x_tvlen;
               unsigned short x_tvran[2];
          }    x_tv;
     };


     Indexes of symbol table entries begin at zero.

WARNINGS
     In machines in which a long are equivalent to an int (M68000
     and VAX), the long is converted to int in the compiler to
     minimize the complexity of the compiler code generator.
     Thus, the information about which symbols are declared as
     long and which as int cannot be determined from the symbol
     table.

SEE ALSO
     a.out(4), linenum(4)

     sdb(1) in A/UX Command Reference

     ``COFF Reference'' in A/UX Programming Languages and Tools,
     Volume 2

















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