include/link_aout.h

   1 /*      $NetBSD: link_aout.h,v 1.21 2008/04/28 20:22:54 martin Exp $    */
   2
   3 /*-
   4  * Copyright (c) 1998 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Paul Kranenburg.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 /*
  33  * RRS section definitions.
  34  *
  35  * The layout of some data structures defined in this header file is
  36  * such that we can provide compatibility with the SunOS 4.x shared
  37  * library scheme.
  38  */
  39
  40 #ifndef _LINK_AOUT_H_
  41 #define _LINK_AOUT_H_
  42
  43 #include <dlfcn.h>                      /* for Dl_info */
  44 #include <a.out.h>                      /* for struct nlist */
  45
  46 /*
  47  * A `Shared Object Descriptor' describes a shared object that is needed
  48  * to complete the link edit process of the object containing it.
  49  * A list of such objects (chained through `sod_next') is pointed at
  50  * by `sdt_sods' in the section_dispatch_table structure.
  51  */
  52
  53 struct sod {    /* Shared Object Descriptor */
  54         long    sod_name;               /* name (relative to load address) */
  55         u_int   sod_library  : 1,       /* Searched for by library rules */
  56                 sod_reserved : 31;
  57         short   sod_major;              /* major version number */
  58         short   sod_minor;              /* minor version number */
  59         long    sod_next;               /* next sod */
  60 };
  61
  62 /*
  63  * `Shared Object Map's are used by the run-time link editor (ld.so) to
  64  * keep track of all shared objects loaded into a process' address space.
  65  * These structures are only used at run-time and do not occur within
  66  * the text or data segment of an executable or shared library.
  67  */
  68 struct so_map {         /* Shared Object Map */
  69         caddr_t         som_addr;       /* Address at which object mapped */
  70         char            *som_path;      /* Path to mmap'ed file */
  71         struct so_map   *som_next;      /* Next map in chain */
  72         struct sod      *som_sod;       /* Sod responsible for this map */
  73         caddr_t         som_sodbase;    /* Base address of this sod */
  74         u_int           som_write : 1;  /* Text is currently writable */
  75         struct _dynamic *som_dynamic;   /* _dynamic structure */
  76         caddr_t         som_spd;        /* Private data */
  77 };
  78
  79 /*
  80  * Symbol description with size. This is simply an `nlist' with
  81  * one field (nz_size) added.
  82  * Used to convey size information on items in the data segment
  83  * of shared objects. An array of these live in the shared object's
  84  * text segment and is addressed by the `sdt_nzlist' field.
  85  */
  86 struct nzlist {
  87         struct nlist    nlist;
  88         u_long          nz_size;
  89 #define nz_un           nlist.n_un
  90 #define nz_strx         nlist.n_un.n_strx
  91 #define nz_name         nlist.n_un.n_name
  92 #define nz_type         nlist.n_type
  93 #define nz_value        nlist.n_value
  94 #define nz_desc         nlist.n_desc
  95 #define nz_other        nlist.n_other
  96 };
  97
  98 #define N_AUX(p)        ((p)->n_other & 0xf)
  99 #define N_BIND(p)       (((unsigned int)(p)->n_other >> 4) & 0xf)
 100 #define N_OTHER(r, v)   (((unsigned int)(r) << 4) | ((v) & 0xf))
 101
 102 #define AUX_OBJECT      1
 103 #define AUX_FUNC        2
 104 #define AUX_LABEL       3
 105 /*#define BIND_LOCAL    0       not used */
 106 /*#define BIND_GLOBAL   1       not used */
 107 #define BIND_WEAK       2
 108
 109
 110 /*
 111  * The `section_dispatch_table' structure contains offsets to various data
 112  * structures needed to do run-time relocation.
 113  */
 114 struct section_dispatch_table {
 115         struct so_map *sdt_loaded;      /* List of loaded objects */
 116         long    sdt_sods;               /* List of shared objects descriptors */
 117         long    sdt_paths;              /* Library search paths */
 118         long    sdt_got;                /* Global offset table */
 119         long    sdt_plt;                /* Procedure linkage table */
 120         long    sdt_rel;                /* Relocation table */
 121         long    sdt_hash;               /* Symbol hash table */
 122         long    sdt_nzlist;             /* Symbol table itself */
 123         long    sdt_filler2;            /* Unused (was: stab_hash) */
 124         long    sdt_buckets;            /* Number of hash buckets */
 125         long    sdt_strings;            /* Symbol strings */
 126         long    sdt_str_sz;             /* Size of symbol strings */
 127         long    sdt_text_sz;            /* Size of text area */
 128         long    sdt_plt_sz;             /* Size of procedure linkage table */
 129 };
 130
 131 /*
 132  * RRS symbol hash table, addressed by `sdt_hash' in section_dispatch_table.
 133  * Used to quickly lookup symbols of the shared object by hashing
 134  * on the symbol's name. `rh_symbolnum' is the index of the symbol
 135  * in the shared object's symbol list (`sdt_nzlist'), `rh_next' is
 136  * the next symbol in the hash bucket (in case of collisions).
 137  */
 138 struct rrs_hash {
 139         int     rh_symbolnum;           /* Symbol number */
 140         int     rh_next;                /* Next hash entry */
 141 };
 142
 143 /*
 144  * `rt_symbols' is used to keep track of run-time allocated commons
 145  * and data items copied from shared objects.
 146  */
 147 struct rt_symbol {
 148         struct nzlist           *rt_sp;         /* The symbol */
 149         struct rt_symbol        *rt_next;       /* Next in linear list */
 150         struct rt_symbol        *rt_link;       /* Next in bucket */
 151         caddr_t                 rt_srcaddr;     /* Address of "master" copy */
 152         struct so_map           *rt_smp;        /* Originating map */
 153 };
 154
 155 /*
 156  * Debugger interface structure.
 157  */
 158 struct so_debug {
 159         int     dd_version;             /* Version # of interface */
 160         int     dd_in_debugger;         /* Set when run by debugger */
 161         int     dd_sym_loaded;          /* Run-time linking brought more
 162                                            symbols into scope */
 163         char     *dd_bpt_addr;          /* Address of rtld-generated bpt */
 164         int     dd_bpt_shadow;          /* Original contents of bpt */
 165         struct rt_symbol *dd_cc;        /* Allocated commons/copied data */
 166 };
 167
 168 /*
 169  * Entry points into ld.so - user interface to the run-time linker.
 170  */
 171 struct ld_entry {
 172         void    *(*dlopen)(const char *, int);
 173         int     (*dlclose)(void *);
 174         void    *(*dlsym)(void *, const char *);
 175         int     (*dlctl)(void *, int, void *);
 176         void    (*dlexit)(void);
 177         int     (*dladdr)(const void *, Dl_info *);
 178         void    (*dlrsrvd[2])(void);
 179 };
 180
 181 /*
 182  * This is the structure pointed at by the __DYNAMIC symbol if an
 183  * executable requires the attention of the run-time link editor.
 184  * __DYNAMIC is given the value zero if no run-time linking needs to
 185  * be done (it is always present in shared objects).
 186  * The union `d_un' provides for different versions of the dynamic
 187  * linking mechanism (switched on by `d_version'). The last version
 188  * used by Sun is 3. We leave some room here and go to version number
 189  * 8 for NetBSD, the main difference lying in the support for the
 190  * `nz_list' type of symbols.
 191  */
 192
 193 struct  _dynamic {
 194         int             d_version;      /* version # of this interface */
 195         struct so_debug *d_debug;
 196         union {
 197                 struct section_dispatch_table *d_sdt;
 198         } d_un;
 199         struct ld_entry *d_entry;       /* compat - now in crt_ldso */
 200 };
 201
 202 #define LD_VERSION_SUN          (3)
 203 #define LD_VERSION_BSD          (8)
 204 #define LD_VERSION_NZLIST_P(v)  ((v) >= 8)
 205
 206 #define LD_GOT(x)       ((x)->d_un.d_sdt->sdt_got)
 207 #define LD_PLT(x)       ((x)->d_un.d_sdt->sdt_plt)
 208 #define LD_REL(x)       ((x)->d_un.d_sdt->sdt_rel)
 209 #define LD_SYMBOL(x)    ((x)->d_un.d_sdt->sdt_nzlist)
 210 #define LD_HASH(x)      ((x)->d_un.d_sdt->sdt_hash)
 211 #define LD_STRINGS(x)   ((x)->d_un.d_sdt->sdt_strings)
 212 #define LD_NEED(x)      ((x)->d_un.d_sdt->sdt_sods)
 213 #define LD_BUCKETS(x)   ((x)->d_un.d_sdt->sdt_buckets)
 214 #define LD_PATHS(x)     ((x)->d_un.d_sdt->sdt_paths)
 215
 216 #define LD_GOTSZ(x)     ((x)->d_un.d_sdt->sdt_plt - (x)->d_un.d_sdt->sdt_got)
 217 #define LD_RELSZ(x)     ((x)->d_un.d_sdt->sdt_hash - (x)->d_un.d_sdt->sdt_rel)
 218 #define LD_HASHSZ(x)    ((x)->d_un.d_sdt->sdt_nzlist - (x)->d_un.d_sdt->sdt_hash)
 219 #define LD_STABSZ(x)    ((x)->d_un.d_sdt->sdt_strings - (x)->d_un.d_sdt->sdt_nzlist)
 220 #define LD_PLTSZ(x)     ((x)->d_un.d_sdt->sdt_plt_sz)
 221 #define LD_STRSZ(x)     ((x)->d_un.d_sdt->sdt_str_sz)
 222 #define LD_TEXTSZ(x)    ((x)->d_un.d_sdt->sdt_text_sz)
 223
 224 /*
 225  * Interface to ld.so
 226  */
 227 struct crt_ldso {
 228         int             crt_ba;         /* Base address of ld.so */
 229         int             crt_dzfd;       /* "/dev/zero" file descriptor (SunOS) */
 230         int             crt_ldfd;       /* ld.so file descriptor */
 231         struct _dynamic *crt_dp;        /* Main's __DYNAMIC */
 232         char            **crt_ep;       /* environment strings */
 233         caddr_t         crt_bp;         /* Breakpoint if run from debugger */
 234         char            *crt_prog;      /* Program name (v3) */
 235         char            *crt_ldso;      /* Link editor name (v4) */
 236         struct ld_entry *crt_ldentry;   /* dl*() access (v4) */
 237 };
 238
 239 /*
 240  * Version passed from crt0 to ld.so (1st argument to _rtld()).
 241  */
 242 #define CRT_VERSION_SUN         1
 243 #define CRT_VERSION_BSD_2       2
 244 #define CRT_VERSION_BSD_3       3
 245 #define CRT_VERSION_BSD_4       4
 246
 247
 248 /*
 249  * Maximum number of recognized shared object version numbers.
 250  */
 251 #define MAXDEWEY        8
 252
 253 /*
 254  * Header of the hints file.
 255  */
 256 struct hints_header {
 257         long            hh_magic;
 258 #define HH_MAGIC        011421044151
 259         long            hh_version;     /* Interface version number */
 260 #define LD_HINTS_VERSION_1      1
 261 #define LD_HINTS_VERSION_2      2
 262         long            hh_hashtab;     /* Location of hash table */
 263         long            hh_nbucket;     /* Number of buckets in hashtab */
 264         long            hh_strtab;      /* Location of strings */
 265         long            hh_strtab_sz;   /* Size of strings */
 266         long            hh_ehints;      /* End of hints (max offset in file) */
 267         long            hh_dirlist;     /* Colon-separated list of srch dirs */
 268 };
 269
 270 #define HH_BADMAG(hdr)  ((hdr).hh_magic != HH_MAGIC)
 271
 272 /*
 273  * Hash table element in hints file.
 274  */
 275 struct hints_bucket {
 276         /* namex and pathx are indices into the string table */
 277         int             hi_namex;               /* Library name */
 278         int             hi_pathx;               /* Full path */
 279         int             hi_dewey[MAXDEWEY];     /* The versions */
 280         int             hi_ndewey;              /* Number of version numbers */
 281 #define hi_major hi_dewey[0]
 282 #define hi_minor hi_dewey[1]
 283         int             hi_next;                /* Next in this bucket */
 284 };
 285
 286 #define _PATH_LD_HINTS          "/var/run/ld.so.hints"
 287
 288 #endif /* _LINK_AOUT_H_ */