The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/sys/link_aout.h

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    1 /*
    2  * Copyright (c) 1993 Paul Kranenburg
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 3. All advertising materials mentioning features or use of this software
   14  *    must display the following acknowledgement:
   15  *      This product includes software developed by Paul Kranenburg.
   16  * 4. The name of the author may not be used to endorse or promote products
   17  *    derived from this software without specific prior written permission
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   21  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   22  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   24  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   28  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   29  *
   30  * $FreeBSD$
   31  */
   32 
   33 /*
   34  * RRS section definitions.
   35  *
   36  * The layout of some data structures defined in this header file is
   37  * such that we can provide compatibility with the SunOS 4.x shared
   38  * library scheme.
   39  */
   40 
   41 #ifndef _LINK_H_
   42 #define _LINK_H_
   43 
   44 #if (defined(FREEBSD_ELF) || defined(__ELF__)) && !defined(FREEBSD_AOUT)
   45 
   46 #include <sys/types.h>
   47 
   48 struct link_map {
   49         caddr_t         l_addr;                 /* Base Address of library */
   50 #ifdef __mips__
   51         caddr_t         l_offs;                 /* Load Offset of library */
   52 #endif
   53         const char      *l_name;                /* Absolute Path to Library */
   54         const void      *l_ld;                  /* Pointer to .dynamic in memory */
   55         struct link_map *l_next, *l_prev;       /* linked list of of mapped libs */
   56 };
   57 
   58 struct r_debug {
   59         int             r_version;              /* not used */
   60         struct link_map *r_map;                 /* list of loaded images */
   61         void            (*r_brk)(void);         /* pointer to break point */
   62         enum {
   63             RT_CONSISTENT,                      /* things are stable */
   64             RT_ADD,                             /* adding a shared library */
   65             RT_DELETE                           /* removing a shared library */
   66         }               r_state;
   67 };
   68 
   69 #else /* !__ELF__ */
   70 
   71 struct dl_info;
   72 
   73 /*
   74  * A `Shared Object Descriptor' describes a shared object that is needed
   75  * to complete the link edit process of the object containing it.
   76  * A list of such objects (chained through `sod_next') is pointed at
   77  * by `sdt_sods' in the section_dispatch_table structure.
   78  */
   79 
   80 struct sod {    /* Shared Object Descriptor */
   81         long    sod_name;               /* name (relative to load address) */
   82         u_int   sod_library  : 1,       /* Searched for by library rules */
   83                 sod_reserved : 31;
   84         short   sod_major;              /* major version number */
   85         short   sod_minor;              /* minor version number */
   86         long    sod_next;               /* next sod */
   87 };
   88 
   89 /*
   90  * `Shared Object Map's are used by the run-time link editor (ld.so) to
   91  * keep track of all shared objects loaded into a process' address space.
   92  * These structures are only used at run-time and do not occur within
   93  * the text or data segment of an executable or shared library.
   94  */
   95 struct so_map {         /* Shared Object Map */
   96         caddr_t         som_addr;       /* Address at which object mapped */
   97         char            *som_path;      /* Path to mmap'ed file */
   98         struct so_map   *som_next;      /* Next map in chain */
   99         struct sod      *som_sod;       /* Sod responsible for this map */
  100         caddr_t         som_sodbase;    /* Base address of this sod */
  101         u_int           som_write : 1;  /* Text is currently writable */
  102         struct _dynamic *som_dynamic;   /* _dynamic structure */
  103         caddr_t         som_spd;        /* Private data */
  104 };
  105 
  106 /*
  107  * Symbol description with size. This is simply an `nlist' with
  108  * one field (nz_size) added.
  109  * Used to convey size information on items in the data segment
  110  * of shared objects. An array of these live in the shared object's
  111  * text segment and is addressed by the `sdt_nzlist' field.
  112  */
  113 struct nzlist {
  114         struct nlist    nlist;
  115         u_long          nz_size;
  116 };
  117 
  118 #define nz_un           nlist.n_un
  119 #define nz_strx         nlist.n_un.n_strx
  120 #define nz_name         nlist.n_un.n_name
  121 #define nz_type         nlist.n_type
  122 #define nz_value        nlist.n_value
  123 #define nz_desc         nlist.n_desc
  124 #define nz_other        nlist.n_other
  125 
  126 /*
  127  * The `section_dispatch_table' structure contains offsets to various data
  128  * structures needed to do run-time relocation.
  129  */
  130 struct section_dispatch_table {
  131         struct so_map *sdt_loaded;      /* List of loaded objects */
  132         long    sdt_sods;               /* List of shared objects descriptors */
  133         long    sdt_paths;              /* Library search paths */
  134         long    sdt_got;                /* Global offset table */
  135         long    sdt_plt;                /* Procedure linkage table */
  136         long    sdt_rel;                /* Relocation table */
  137         long    sdt_hash;               /* Symbol hash table */
  138         long    sdt_nzlist;             /* Symbol table itself */
  139         long    sdt_filler2;            /* Unused (was: stab_hash) */
  140         long    sdt_buckets;            /* Number of hash buckets */
  141         long    sdt_strings;            /* Symbol strings */
  142         long    sdt_str_sz;             /* Size of symbol strings */
  143         long    sdt_text_sz;            /* Size of text area */
  144         long    sdt_plt_sz;             /* Size of procedure linkage table */
  145 };
  146 
  147 /*
  148  * RRS symbol hash table, addressed by `sdt_hash' in section_dispatch_table.
  149  * Used to quickly lookup symbols of the shared object by hashing
  150  * on the symbol's name. `rh_symbolnum' is the index of the symbol
  151  * in the shared object's symbol list (`sdt_nzlist'), `rh_next' is
  152  * the next symbol in the hash bucket (in case of collisions).
  153  */
  154 struct rrs_hash {
  155         int     rh_symbolnum;           /* Symbol number */
  156         int     rh_next;                /* Next hash entry */
  157 };
  158 
  159 /*
  160  * `rt_symbols' is used to keep track of run-time allocated commons
  161  * and data items copied from shared objects.
  162  */
  163 struct rt_symbol {
  164         struct nzlist           *rt_sp;         /* The symbol */
  165         struct rt_symbol        *rt_next;       /* Next in linear list */
  166         struct rt_symbol        *rt_link;       /* Next in bucket */
  167         caddr_t                 rt_srcaddr;     /* Address of "master" copy */
  168         struct so_map           *rt_smp;        /* Originating map */
  169 };
  170 
  171 /*
  172  * Debugger interface structure.
  173  */
  174 struct so_debug {
  175         int     dd_version;             /* Version # of interface */
  176         int     dd_in_debugger;         /* Set when run by debugger */
  177         int     dd_sym_loaded;          /* Run-time linking brought more
  178                                            symbols into scope */
  179         char     *dd_bpt_addr;          /* Address of rtld-generated bpt */
  180         int     dd_bpt_shadow;          /* Original contents of bpt */
  181         struct rt_symbol *dd_cc;        /* Allocated commons/copied data */
  182 };
  183 
  184 /*
  185  * Version returned to crt0 from ld.so
  186  */
  187 #define LDSO_VERSION_NONE       0       /* FreeBSD2.0, 2.0.5 */
  188 #define LDSO_VERSION_HAS_DLEXIT 1       /* includes dlexit in ld_entry */
  189 #define LDSO_VERSION_HAS_DLSYM3 2       /* includes 3-argument dlsym */
  190 #define LDSO_VERSION_HAS_DLADDR 3       /* includes dladdr in ld_entry */
  191 
  192 /*
  193  * Entry points into ld.so - user interface to the run-time linker.
  194  * Entries are valid for the given version numbers returned by ld.so
  195  * to crt0.
  196  */
  197 struct ld_entry {
  198         void    *(*dlopen) __P((const char *, int));    /* NONE */
  199         int     (*dlclose) __P((void *));               /* NONE */
  200         void    *(*dlsym) __P((void *, const char *));  /* NONE */
  201         const char *(*dlerror) __P((void));             /* NONE */
  202         void    (*dlexit) __P((void));                  /* HAS_DLEXIT */
  203         void    *(*dlsym3) __P((void *, const char *, void *)); /* HAS_DLSYM3 */
  204         int      (*dladdr) __P((const void *,
  205                                 struct dl_info *));     /* HAS_DLADDR */
  206 };
  207 
  208 /*
  209  * This is the structure pointed at by the __DYNAMIC symbol if an
  210  * executable requires the attention of the run-time link editor.
  211  * __DYNAMIC is given the value zero if no run-time linking needs to
  212  * be done (it is always present in shared objects).
  213  * The union `d_un' provides for different versions of the dynamic
  214  * linking mechanism (switched on by `d_version'). The last version
  215  * used by Sun is 3. We leave some room here and go to version number
  216  * 8 for NetBSD, the main difference lying in the support for the
  217  * `nz_list' type of symbols.
  218  */
  219 
  220 struct  _dynamic {
  221         int             d_version;      /* version # of this interface */
  222         struct so_debug *d_debug;
  223         union {
  224                 struct section_dispatch_table *d_sdt;
  225         } d_un;
  226         struct ld_entry *d_entry;       /* XXX */
  227 };
  228 
  229 #define LD_VERSION_SUN          (3)
  230 #define LD_VERSION_BSD          (8)
  231 #define LD_VERSION_NZLIST_P(v)  ((v) >= 8)
  232 
  233 #define LD_GOT(x)       ((x)->d_un.d_sdt->sdt_got)
  234 #define LD_PLT(x)       ((x)->d_un.d_sdt->sdt_plt)
  235 #define LD_REL(x)       ((x)->d_un.d_sdt->sdt_rel)
  236 #define LD_SYMBOL(x)    ((x)->d_un.d_sdt->sdt_nzlist)
  237 #define LD_HASH(x)      ((x)->d_un.d_sdt->sdt_hash)
  238 #define LD_STRINGS(x)   ((x)->d_un.d_sdt->sdt_strings)
  239 #define LD_NEED(x)      ((x)->d_un.d_sdt->sdt_sods)
  240 #define LD_BUCKETS(x)   ((x)->d_un.d_sdt->sdt_buckets)
  241 #define LD_PATHS(x)     ((x)->d_un.d_sdt->sdt_paths)
  242 
  243 #define LD_GOTSZ(x)     ((x)->d_un.d_sdt->sdt_plt - (x)->d_un.d_sdt->sdt_got)
  244 #define LD_RELSZ(x)     ((x)->d_un.d_sdt->sdt_hash - (x)->d_un.d_sdt->sdt_rel)
  245 #define LD_HASHSZ(x)    ((x)->d_un.d_sdt->sdt_nzlist - (x)->d_un.d_sdt->sdt_hash)
  246 #define LD_STABSZ(x)    ((x)->d_un.d_sdt->sdt_strings - (x)->d_un.d_sdt->sdt_nzlist)
  247 #define LD_PLTSZ(x)     ((x)->d_un.d_sdt->sdt_plt_sz)
  248 #define LD_STRSZ(x)     ((x)->d_un.d_sdt->sdt_str_sz)
  249 #define LD_TEXTSZ(x)    ((x)->d_un.d_sdt->sdt_text_sz)
  250 
  251 /*
  252  * Interface to ld.so
  253  */
  254 struct crt_ldso {
  255         int             crt_ba;         /* Base address of ld.so */
  256         int             crt_dzfd;       /* "/dev/zero" file descriptor (SunOS) */
  257         int             crt_ldfd;       /* ld.so file descriptor */
  258         struct _dynamic *crt_dp;        /* Main's __DYNAMIC */
  259         char            **crt_ep;       /* environment strings */
  260         caddr_t         crt_bp;         /* Breakpoint if run from debugger */
  261         char            *crt_prog;      /* Program name (v3) */
  262         char            *crt_ldso;      /* Link editor name (v4) */
  263         struct ld_entry *crt_ldentry;   /* dl*() access (v4) */
  264         char            **crt_argv;     /* argument strings (v5) */
  265 };
  266 
  267 /*
  268  * Version passed from crt0 to ld.so (1st argument to _rtld()).
  269  */
  270 #define CRT_VERSION_SUN         1
  271 #define CRT_VERSION_BSD_2       2
  272 #define CRT_VERSION_BSD_3       3
  273 #define CRT_VERSION_BSD_4       4
  274 #define CRT_VERSION_BSD_5       5
  275 
  276 /*
  277  * Maximum number of recognized shared object version numbers.
  278  */
  279 #define MAXDEWEY        8
  280 
  281 /*
  282  * Header of the hints file.
  283  */
  284 struct hints_header {
  285         long            hh_magic;
  286 #define HH_MAGIC        011421044151
  287         long            hh_version;     /* Interface version number */
  288 #define LD_HINTS_VERSION_1      1
  289 #define LD_HINTS_VERSION_2      2
  290         long            hh_hashtab;     /* Location of hash table */
  291         long            hh_nbucket;     /* Number of buckets in hashtab */
  292         long            hh_strtab;      /* Location of strings */
  293         long            hh_strtab_sz;   /* Size of strings */
  294         long            hh_ehints;      /* End of hints (max offset in file) */
  295         long            hh_dirlist;     /* Colon-separated list of srch dirs */
  296 };
  297 
  298 #define HH_BADMAG(hdr)  ((hdr).hh_magic != HH_MAGIC)
  299 
  300 /*
  301  * Hash table element in hints file.
  302  */
  303 struct hints_bucket {
  304         /* namex and pathx are indices into the string table */
  305         int             hi_namex;               /* Library name */
  306         int             hi_pathx;               /* Full path */
  307         int             hi_dewey[MAXDEWEY];     /* The versions */
  308         int             hi_ndewey;              /* Number of version numbers */
  309 #define hi_major hi_dewey[0]
  310 #define hi_minor hi_dewey[1]
  311         int             hi_next;                /* Next in this bucket */
  312 };
  313 
  314 #define _PATH_LD_HINTS          "/var/run/ld.so.hints"
  315 
  316 #endif /* !__ELF__ */
  317 
  318 #endif /* _LINK_H_ */

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