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: src/sys/sys/link_aout.h,v 1.24.8.1 2005/01/31 23:26:56 imp Exp $
   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 _SYS_LINK_AOUT_H_
   42 #define _SYS_LINK_AOUT_H_
   43 
   44 struct dl_info;
   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 };
   90 
   91 #define nz_un           nlist.n_un
   92 #define nz_strx         nlist.n_un.n_strx
   93 #define nz_name         nlist.n_un.n_name
   94 #define nz_type         nlist.n_type
   95 #define nz_value        nlist.n_value
   96 #define nz_desc         nlist.n_desc
   97 #define nz_other        nlist.n_other
   98 
   99 /*
  100  * The `section_dispatch_table' structure contains offsets to various data
  101  * structures needed to do run-time relocation.
  102  */
  103 struct section_dispatch_table {
  104         struct so_map *sdt_loaded;      /* List of loaded objects */
  105         long    sdt_sods;               /* List of shared objects descriptors */
  106         long    sdt_paths;              /* Library search paths */
  107         long    sdt_got;                /* Global offset table */
  108         long    sdt_plt;                /* Procedure linkage table */
  109         long    sdt_rel;                /* Relocation table */
  110         long    sdt_hash;               /* Symbol hash table */
  111         long    sdt_nzlist;             /* Symbol table itself */
  112         long    sdt_filler2;            /* Unused (was: stab_hash) */
  113         long    sdt_buckets;            /* Number of hash buckets */
  114         long    sdt_strings;            /* Symbol strings */
  115         long    sdt_str_sz;             /* Size of symbol strings */
  116         long    sdt_text_sz;            /* Size of text area */
  117         long    sdt_plt_sz;             /* Size of procedure linkage table */
  118 };
  119 
  120 /*
  121  * RRS symbol hash table, addressed by `sdt_hash' in section_dispatch_table.
  122  * Used to quickly lookup symbols of the shared object by hashing
  123  * on the symbol's name. `rh_symbolnum' is the index of the symbol
  124  * in the shared object's symbol list (`sdt_nzlist'), `rh_next' is
  125  * the next symbol in the hash bucket (in case of collisions).
  126  */
  127 struct rrs_hash {
  128         int     rh_symbolnum;           /* Symbol number */
  129         int     rh_next;                /* Next hash entry */
  130 };
  131 
  132 /*
  133  * `rt_symbols' is used to keep track of run-time allocated commons
  134  * and data items copied from shared objects.
  135  */
  136 struct rt_symbol {
  137         struct nzlist           *rt_sp;         /* The symbol */
  138         struct rt_symbol        *rt_next;       /* Next in linear list */
  139         struct rt_symbol        *rt_link;       /* Next in bucket */
  140         caddr_t                 rt_srcaddr;     /* Address of "master" copy */
  141         struct so_map           *rt_smp;        /* Originating map */
  142 };
  143 
  144 /*
  145  * Debugger interface structure.
  146  */
  147 struct so_debug {
  148         int     dd_version;             /* Version # of interface */
  149         int     dd_in_debugger;         /* Set when run by debugger */
  150         int     dd_sym_loaded;          /* Run-time linking brought more
  151                                            symbols into scope */
  152         char     *dd_bpt_addr;          /* Address of rtld-generated bpt */
  153         int     dd_bpt_shadow;          /* Original contents of bpt */
  154         struct rt_symbol *dd_cc;        /* Allocated commons/copied data */
  155 };
  156 
  157 /*
  158  * Version returned to crt0 from ld.so
  159  */
  160 #define LDSO_VERSION_NONE       0       /* FreeBSD2.0, 2.0.5 */
  161 #define LDSO_VERSION_HAS_DLEXIT 1       /* includes dlexit in ld_entry */
  162 #define LDSO_VERSION_HAS_DLSYM3 2       /* includes 3-argument dlsym */
  163 #define LDSO_VERSION_HAS_DLADDR 3       /* includes dladdr in ld_entry */
  164 
  165 /*
  166  * Entry points into ld.so - user interface to the run-time linker.
  167  * Entries are valid for the given version numbers returned by ld.so
  168  * to crt0.
  169  */
  170 struct ld_entry {
  171         void    *(*dlopen)(const char *, int);  /* NONE */
  172         int     (*dlclose)(void *);             /* NONE */
  173         void    *(*dlsym)(void *, const char *);        /* NONE */
  174         const char *(*dlerror)(void);           /* NONE */
  175         void    (*dlexit)(void);                        /* HAS_DLEXIT */
  176         void    *(*dlsym3)(void *, const char *, void *); /* HAS_DLSYM3 */
  177         int      (*dladdr)(const void *, struct dl_info *); /* HAS_DLADDR */
  178 };
  179 
  180 /*
  181  * This is the structure pointed at by the __DYNAMIC symbol if an
  182  * executable requires the attention of the run-time link editor.
  183  * __DYNAMIC is given the value zero if no run-time linking needs to
  184  * be done (it is always present in shared objects).
  185  * The union `d_un' provides for different versions of the dynamic
  186  * linking mechanism (switched on by `d_version'). The last version
  187  * used by Sun is 3. We leave some room here and go to version number
  188  * 8 for NetBSD, the main difference lying in the support for the
  189  * `nz_list' type of symbols.
  190  */
  191 
  192 struct _dynamic {
  193         int             d_version;      /* version # of this interface */
  194         struct so_debug *d_debug;
  195         union {
  196                 struct section_dispatch_table *d_sdt;
  197         } d_un;
  198         struct ld_entry *d_entry;       /* XXX */
  199 };
  200 
  201 #define LD_VERSION_SUN          (3)
  202 #define LD_VERSION_BSD          (8)
  203 #define LD_VERSION_NZLIST_P(v)  ((v) >= 8)
  204 
  205 #define LD_GOT(x)       ((x)->d_un.d_sdt->sdt_got)
  206 #define LD_PLT(x)       ((x)->d_un.d_sdt->sdt_plt)
  207 #define LD_REL(x)       ((x)->d_un.d_sdt->sdt_rel)
  208 #define LD_SYMBOL(x)    ((x)->d_un.d_sdt->sdt_nzlist)
  209 #define LD_HASH(x)      ((x)->d_un.d_sdt->sdt_hash)
  210 #define LD_STRINGS(x)   ((x)->d_un.d_sdt->sdt_strings)
  211 #define LD_NEED(x)      ((x)->d_un.d_sdt->sdt_sods)
  212 #define LD_BUCKETS(x)   ((x)->d_un.d_sdt->sdt_buckets)
  213 #define LD_PATHS(x)     ((x)->d_un.d_sdt->sdt_paths)
  214 
  215 #define LD_GOTSZ(x)     ((x)->d_un.d_sdt->sdt_plt - (x)->d_un.d_sdt->sdt_got)
  216 #define LD_RELSZ(x)     ((x)->d_un.d_sdt->sdt_hash - (x)->d_un.d_sdt->sdt_rel)
  217 #define LD_HASHSZ(x)    ((x)->d_un.d_sdt->sdt_nzlist - (x)->d_un.d_sdt->sdt_hash)
  218 #define LD_STABSZ(x)    ((x)->d_un.d_sdt->sdt_strings - (x)->d_un.d_sdt->sdt_nzlist)
  219 #define LD_PLTSZ(x)     ((x)->d_un.d_sdt->sdt_plt_sz)
  220 #define LD_STRSZ(x)     ((x)->d_un.d_sdt->sdt_str_sz)
  221 #define LD_TEXTSZ(x)    ((x)->d_un.d_sdt->sdt_text_sz)
  222 
  223 /*
  224  * Interface to ld.so
  225  */
  226 struct crt_ldso {
  227         int             crt_ba;         /* Base address of ld.so */
  228         int             crt_dzfd;       /* "/dev/zero" file descriptor (SunOS) */
  229         int             crt_ldfd;       /* ld.so file descriptor */
  230         struct _dynamic *crt_dp;        /* Main's __DYNAMIC */
  231         char            **crt_ep;       /* environment strings */
  232         caddr_t         crt_bp;         /* Breakpoint if run from debugger */
  233         char            *crt_prog;      /* Program name (v3) */
  234         char            *crt_ldso;      /* Link editor name (v4) */
  235         struct ld_entry *crt_ldentry;   /* dl*() access (v4) */
  236         char            **crt_argv;     /* argument strings (v5) */
  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 #define CRT_VERSION_BSD_5       5
  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 /* _SYS_LINK_AOUT_H_ */

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