1.\" Copyright (c) 1980, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)stab.5 8.1 (Berkeley) 6/5/93 29.\" 30.Dd June 10, 2010 31.Dt STAB 5 32.Os 33.Sh NAME 34.Nm stab 35.Nd symbol table types 36.Sh SYNOPSIS 37.In stab.h 38.Sh DESCRIPTION 39The file 40.In stab.h 41defines some of the symbol table 42.Fa n_type 43field values for a.out files. 44These are the types for permanent symbols (i.e., not local labels, etc.\&) 45used by the old debugger 46.Em sdb 47and the Berkeley Pascal compiler 48.Xr pc 1 . 49Symbol table entries can be produced by the 50.Pa .stabs 51assembler directive. 52This allows one to specify a double-quote delimited name, a symbol type, 53one char and one short of information about the symbol, and an unsigned 54long (usually an address). 55To avoid having to produce an explicit label for the address field, 56the 57.Pa .stabd 58directive can be used to implicitly address the current location. 59If no name is needed, symbol table entries can be generated using the 60.Pa .stabn 61directive. 62The loader promises to preserve the order of symbol table entries produced 63by 64.Pa .stab 65directives. 66As described in 67.Xr a.out 5 , 68an element of the symbol table 69consists of the following structure: 70.Bd -literal 71/* 72* Format of a symbol table entry. 73*/ 74 75struct nlist { 76 union { 77 const char *n_name; /* for use when in-core */ 78 long n_strx; /* index into file string table */ 79 } n_un; 80 unsigned char n_type; /* type flag */ 81 char n_other; /* unused */ 82 short n_desc; /* see struct desc, below */ 83 unsigned n_value; /* address or offset or line */ 84}; 85.Ed 86.Pp 87The low bits of the 88.Fa n_type 89field are used to place a symbol into 90at most one segment, according to 91the following masks, defined in 92.In a.out.h . 93A symbol can be in none of these segments by having none of these segment 94bits set. 95.Bd -literal 96/* 97* Simple values for n_type. 98*/ 99 100#define N_UNDF 0x0 /* undefined */ 101#define N_ABS 0x2 /* absolute */ 102#define N_TEXT 0x4 /* text */ 103#define N_DATA 0x6 /* data */ 104#define N_BSS 0x8 /* bss */ 105 106#define N_EXT 01 /* external bit, or'ed in */ 107.Ed 108.Pp 109The 110.Fa n_value 111field of a symbol is relocated by the linker, 112.Xr ld 1 113as an address within the appropriate segment. 114.Fa N_value 115fields of symbols not in any segment are unchanged by the linker. 116In addition, the linker will discard certain symbols, according to rules 117of its own, unless the 118.Fa n_type 119field has one of the following bits set: 120.Bd -literal 121/* 122* Other permanent symbol table entries have some of the N_STAB bits set. 123* These are given in <stab.h> 124*/ 125 126#define N_STAB 0xe0 /* if any of these bits set, don't discard */ 127.Ed 128.Pp 129This allows up to 112 (7 \(** 16) symbol types, split between the various 130segments. 131Some of these have already been claimed. 132The old symbolic debugger, 133.Em sdb , 134uses the following n_type values: 135.Bd -literal 136#define N_GSYM 0x20 /* global symbol: name,,0,type,0 */ 137#define N_FNAME 0x22 /* procedure name (f77 kludge): name,,0 */ 138#define N_FUN 0x24 /* procedure: name,,0,linenumber,address */ 139#define N_STSYM 0x26 /* static symbol: name,,0,type,address */ 140#define N_LCSYM 0x28 /* .lcomm symbol: name,,0,type,address */ 141#define N_RSYM 0x40 /* register sym: name,,0,type,register */ 142#define N_SLINE 0x44 /* src line: 0,,0,linenumber,address */ 143#define N_SSYM 0x60 /* structure elt: name,,0,type,struct_offset */ 144#define N_SO 0x64 /* source file name: name,,0,0,address */ 145#define N_LSYM 0x80 /* local sym: name,,0,type,offset */ 146#define N_SOL 0x84 /* #included file name: name,,0,0,address */ 147#define N_PSYM 0xa0 /* parameter: name,,0,type,offset */ 148#define N_ENTRY 0xa4 /* alternate entry: name,linenumber,address */ 149#define N_LBRAC 0xc0 /* left bracket: 0,,0,nesting level,address */ 150#define N_RBRAC 0xe0 /* right bracket: 0,,0,nesting level,address */ 151#define N_BCOMM 0xe2 /* begin common: name,, */ 152#define N_ECOMM 0xe4 /* end common: name,, */ 153#define N_ECOML 0xe8 /* end common (local name): ,,address */ 154#define N_LENG 0xfe /* second stab entry with length information */ 155.Ed 156.Pp 157where the comments give 158.Em sdb 159conventional use for 160.Pa .stab 161.Fa s 162and the 163.Fa n_name , 164.Fa n_other , 165.Fa n_desc , 166and 167.Fa n_value 168fields 169of the given 170.Fa n_type . 171.Em Sdb 172uses the 173.Fa n_desc 174field to hold a type specifier in the form used 175by the Portable C Compiler, 176.Xr cc 1 ; 177see the header file 178.Pa pcc.h 179for details on the format of these type values. 180.Pp 181The Berkeley Pascal compiler, 182.Xr pc 1 , 183uses the following 184.Fa n_type 185value: 186.Bd -literal 187#define N_PC 0x30 /* global pascal symbol: name,,0,subtype,line */ 188.Ed 189.Pp 190and uses the following subtypes to do type checking across separately 191compiled files: 192.Bd -unfilled -offset indent 1931 source file name 1942 included file name 1953 global label 1964 global constant 1975 global type 1986 global variable 1997 global function 2008 global procedure 2019 external function 20210 external procedure 20311 library variable 20412 library routine 205.Ed 206.Sh SEE ALSO 207.Xr as 1 , 208.Xr ld 1 , 209.Xr a.out 5 210.Sh HISTORY 211The 212.Nm 213file appeared in 214.Bx 4.0 . 215.Sh BUGS 216More basic types are needed. 217