*nix Documentation Project
·  Home
 +   man pages
·  Linux HOWTOs
·  FreeBSD Tips
·  *niX Forums

  man pages->OpenBSD man pages -> stab (5)              



NAME    [Toc]    [Back]

     stab - symbol table types

SYNOPSIS    [Toc]    [Back]

     #include <stab.h>

DESCRIPTION    [Toc]    [Back]

     The <stab.h> file defines some of the  symbol  table  n_type
field values
     for  a.out(5) files.  These are the types for permanent symbols (i.e., not
     local labels, etc.) used by the old  debugger  sdb  and  the
Berkeley Pascal
     compiler pc.

     Symbol  table  entries can be produced by the ``.stabs'' assembler directive.
  This allows one to specify a  double-quote  delimited
name, a symbol
     type,  one  char and one short of information about the symbol, as well as
     an unsigned long (usually an address).

     To avoid having to produce an explicit label for the address
field, the
     ``.stabd''  directive  can be used to implicitly address the
current location.
  If no name is needed, symbol  table  entries  can  be
generated using
     the  ``.stabn''  directive.  The loader promises to preserve
the order of
     symbol table entries produced by ``.stab''  directives.   As
described in
     a.out(5),  an  element  of  the symbol table consists of the
following structure:

     * Format of a symbol table entry.

     struct nlist {
             union {
                     char    *n_name;        /* for use when  incore */
                     long     n_strx;          /* index into file
string table */
             } n_un;
             unsigned char   n_type;         /* type flag */
             char            n_other;        /* unused */
             short           n_desc;         /* see struct  desc,
below */
             unsigned        n_value;        /* address or offset
or line */

     The low bits of the n_type field are used to place a  symbol
into at most
     one  segment,  according  to the following masks, defined in
<a.out.h>.  A
     symbol can be in none of these segments by  having  none  of
these segment
     bits set.

     * Simple values for n_type.

     #define N_UNDF  0x0     /* undefined */
     #define N_ABS   0x2     /* absolute */
     #define N_TEXT  0x4     /* text */
     #define N_DATA  0x6     /* data */
     #define N_BSS   0x8     /* bss */

     #define N_EXT   01      /* external bit, or'ed in */

     The  n_value  field  of a symbol is relocated by the linker,
ld(1), as an
     address within the appropriate segment.  n_value  fields  of
symbols not in
     any  segment  are unchanged by the linker.  In addition, the
linker will
     discard certain symbols, according to rules of its own,  unless the n_type
     field has one of the following bits set:

     *  Other  permanent  symbol  table  entries have some of the
N_STAB bits set.
     * These are given in <stab.h>

     #define N_STAB  0xe0    /* if any of these bits  set,  don't
discard */

     This  allows  up to 112 (7 * 16) symbol types, split between
the various
     segments.  Some of these have already been claimed.  The old
symbolic debugger,
 sdb, uses the following n_type values:

     #define N_GSYM  0x20    /* global symbol: name,,0,type,0 */
     #define  N_FNAME  0x22     /*  procedure  name (f77 kludge):
name,,0 */
     #define N_FUN   0x24    /* procedure: name,,0,linenumber,address */
     #define  N_STSYM  0x26    /* static symbol: name,,0,type,address */
     #define N_LCSYM 0x28    /* .lcomm  symbol:  name,,0,type,address */
     #define N_RSYM  0x40    /* register sym: name,,0,type,register */
     #define N_SLINE 0x44    /* src line: 0,,0,linenumber,address
     #define     N_SSYM      0x60        /*     structure    elt:
name,,0,type,struct_offset */
     #define N_SO    0x64    /* source file  name:  name,,0,0,address */
     #define N_LSYM  0x80    /* local sym: name,,0,type,offset */
     #define   N_SOL     0x84      /*   #included   file    name:
name,,0,0,address */
     #define N_PSYM  0xa0    /* parameter: name,,0,type,offset */
     #define N_ENTRY 0xa4    /*  alternate  entry:  name,linenumber,address */
     #define  N_LBRAC  0xc0    /* left bracket: 0,,0,nesting level,address */
     #define N_RBRAC 0xe0    /* right bracket: 0,,0,nesting  level,address */
     #define N_BCOMM 0xe2    /* begin common: name,, */
     #define N_ECOMM 0xe4    /* end common: name,, */
     #define  N_ECOML  0xe8     /* end common (local name): ,,address */
     #define N_LENG  0xfe    /* second stab entry with length information */

     where the comments give sdb conventional use for ``.stab s''
and the
     n_name, n_other, n_desc, and n_value  fields  of  the  given
n_type.  sdb uses
  the  n_desc  field  to hold a type specifier in the form
used by the
     Portable C Compiler, cc(1); see the header  file  pcc.h  for
details on the
     format of these type values.

     The  Berkeley Pascal compiler, pc, uses the following n_type

     #define   N_PC      0x30      /*   global   pascal   symbol:
name,,0,subtype,line */

     and  uses  the following subtypes to do type checking across
     compiled files:

           1       source file name
           2       included file name
           3       global label
           4       global constant
           5       global type
           6       global variable
           7       global function
           8       global procedure
           9       external function
           10      external procedure
           11      library variable
           12      library routine

SEE ALSO    [Toc]    [Back]

     as(1), gdb(1), ld(1), a.out(5)

HISTORY    [Toc]    [Back]

     The stab file appeared in 4.0BSD.

BUGS    [Toc]    [Back]

     More basic types are needed.

OpenBSD      3.6                           June      5,      1993
[ Back ]
 Similar pages
Name OS Title
ldgetname Tru64 retrieve symbol name for object file symbol table entry
ldgetname IRIX retrieve symbol name for object file symbol table entry
syms IRIX MIPS symbol table
stprint IRIX routines to print the symbol table
elf_getarsym IRIX retrieve archive symbol table
nm OpenBSD display name list (symbol table)
ranlib HP-UX regenerate archive symbol table
ksyms OpenBSD kernel symbol table device
nlist OpenBSD retrieve symbol table name list from an executable file
st_lang_str Tru64 translate symbol table codes to printable strings
Copyright © 2004-2005 DeniX Solutions SRL
newsletter delivery service