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

     /*
      * Copyright (c) 1993 Paul Kranenburg
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by Paul Kranenburg.
     * 4. The name of the author may not be used to endorse or promote products
     *    derived from this software without specific prior written permission
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     *
     * $FreeBSD$
     */
    
    /*
     * RRS section definitions.
     *
     * The layout of some data structures defined in this header file is
     * such that we can provide compatibility with the SunOS 4.x shared
     * library scheme.
     */
    
    #ifndef _LINK_H_
    #define _LINK_H_
    
    #if (defined(FREEBSD_ELF) || defined(__ELF__)) && !defined(FREEBSD_AOUT)
    
    #include <sys/types.h>
    
    /*
     * Flags that describe the origin of the entries in Dl_serinfo.
     * SunOS has these in <sys/link.h>, we follow the suit.
     */
    #define LA_SER_ORIG     0x01    /* original (needed) name */
    #define LA_SER_LIBPATH  0x02    /* LD_LIBRARY_PATH entry prepended */
    #define LA_SER_RUNPATH  0x04    /* runpath entry prepended */
    #define LA_SER_CONFIG   0x08    /* configuration entry prepended */
    #define LA_SER_DEFAULT  0x40    /* default path prepended */
    #define LA_SER_SECURE   0x80    /* default (secure) path prepended */
    
    typedef struct link_map {
            caddr_t         l_addr;                 /* Base Address of library */
    #ifdef __mips__
            caddr_t         l_offs;                 /* Load Offset of library */
    #endif
            const char      *l_name;                /* Absolute Path to Library */
            const void      *l_ld;                  /* Pointer to .dynamic in memory */
            struct link_map *l_next, *l_prev;       /* linked list of of mapped libs */
    } Link_map;
    
    struct r_debug {
            int             r_version;              /* not used */
            struct link_map *r_map;                 /* list of loaded images */
            void            (*r_brk)(struct r_debug *, struct link_map *);
                                                    /* pointer to break point */
            enum {
                RT_CONSISTENT,                      /* things are stable */
                RT_ADD,                             /* adding a shared library */
                RT_DELETE                           /* removing a shared library */
            }               r_state;
    };
    
    #else /* !__ELF__ */
    
    struct dl_info;
    
    /*
     * A `Shared Object Descriptor' describes a shared object that is needed
     * to complete the link edit process of the object containing it.
     * A list of such objects (chained through `sod_next') is pointed at
     * by `sdt_sods' in the section_dispatch_table structure.
     */
    
    struct sod {    /* Shared Object Descriptor */
            long    sod_name;               /* name (relative to load address) */
            u_int   sod_library  : 1,       /* Searched for by library rules */
                    sod_reserved : 31;
            short   sod_major;              /* major version number */
            short   sod_minor;              /* minor version number */
            long    sod_next;               /* next sod */
    };
   
   /*
    * `Shared Object Map's are used by the run-time link editor (ld.so) to
    * keep track of all shared objects loaded into a process' address space.
    * These structures are only used at run-time and do not occur within
    * the text or data segment of an executable or shared library.
    */
   struct so_map {         /* Shared Object Map */
           caddr_t         som_addr;       /* Address at which object mapped */
           char            *som_path;      /* Path to mmap'ed file */
           struct so_map   *som_next;      /* Next map in chain */
           struct sod      *som_sod;       /* Sod responsible for this map */
           caddr_t         som_sodbase;    /* Base address of this sod */
           u_int           som_write : 1;  /* Text is currently writable */
           struct _dynamic *som_dynamic;   /* _dynamic structure */
           caddr_t         som_spd;        /* Private data */
   };
   
   /*
    * Symbol description with size. This is simply an `nlist' with
    * one field (nz_size) added.
    * Used to convey size information on items in the data segment
    * of shared objects. An array of these live in the shared object's
    * text segment and is addressed by the `sdt_nzlist' field.
    */
   struct nzlist {
           struct nlist    nlist;
           u_long          nz_size;
   };
   
   #define nz_un           nlist.n_un
   #define nz_strx         nlist.n_un.n_strx
   #define nz_name         nlist.n_un.n_name
   #define nz_type         nlist.n_type
   #define nz_value        nlist.n_value
   #define nz_desc         nlist.n_desc
   #define nz_other        nlist.n_other
   
   /*
    * The `section_dispatch_table' structure contains offsets to various data
    * structures needed to do run-time relocation.
    */
   struct section_dispatch_table {
           struct so_map *sdt_loaded;      /* List of loaded objects */
           long    sdt_sods;               /* List of shared objects descriptors */
           long    sdt_paths;              /* Library search paths */
           long    sdt_got;                /* Global offset table */
           long    sdt_plt;                /* Procedure linkage table */
           long    sdt_rel;                /* Relocation table */
           long    sdt_hash;               /* Symbol hash table */
           long    sdt_nzlist;             /* Symbol table itself */
           long    sdt_filler2;            /* Unused (was: stab_hash) */
           long    sdt_buckets;            /* Number of hash buckets */
           long    sdt_strings;            /* Symbol strings */
           long    sdt_str_sz;             /* Size of symbol strings */
           long    sdt_text_sz;            /* Size of text area */
           long    sdt_plt_sz;             /* Size of procedure linkage table */
   };
   
   /*
    * RRS symbol hash table, addressed by `sdt_hash' in section_dispatch_table.
    * Used to quickly lookup symbols of the shared object by hashing
    * on the symbol's name. `rh_symbolnum' is the index of the symbol
    * in the shared object's symbol list (`sdt_nzlist'), `rh_next' is
    * the next symbol in the hash bucket (in case of collisions).
    */
   struct rrs_hash {
           int     rh_symbolnum;           /* Symbol number */
           int     rh_next;                /* Next hash entry */
   };
   
   /*
    * `rt_symbols' is used to keep track of run-time allocated commons
    * and data items copied from shared objects.
    */
   struct rt_symbol {
           struct nzlist           *rt_sp;         /* The symbol */
           struct rt_symbol        *rt_next;       /* Next in linear list */
           struct rt_symbol        *rt_link;       /* Next in bucket */
           caddr_t                 rt_srcaddr;     /* Address of "master" copy */
           struct so_map           *rt_smp;        /* Originating map */
   };
   
   /*
    * Debugger interface structure.
    */
   struct so_debug {
           int     dd_version;             /* Version # of interface */
           int     dd_in_debugger;         /* Set when run by debugger */
           int     dd_sym_loaded;          /* Run-time linking brought more
                                              symbols into scope */
           char     *dd_bpt_addr;          /* Address of rtld-generated bpt */
           int     dd_bpt_shadow;          /* Original contents of bpt */
           struct rt_symbol *dd_cc;        /* Allocated commons/copied data */
   };
   
   /*
    * Version returned to crt0 from ld.so
    */
   #define LDSO_VERSION_NONE       0       /* FreeBSD2.0, 2.0.5 */
   #define LDSO_VERSION_HAS_DLEXIT 1       /* includes dlexit in ld_entry */
   #define LDSO_VERSION_HAS_DLSYM3 2       /* includes 3-argument dlsym */
   #define LDSO_VERSION_HAS_DLADDR 3       /* includes dladdr in ld_entry */
   
   /*
    * Entry points into ld.so - user interface to the run-time linker.
    * Entries are valid for the given version numbers returned by ld.so
    * to crt0.
    */
   struct ld_entry {
           void    *(*dlopen) __P((const char *, int));    /* NONE */
           int     (*dlclose) __P((void *));               /* NONE */
           void    *(*dlsym) __P((void *, const char *));  /* NONE */
           const char *(*dlerror) __P((void));             /* NONE */
           void    (*dlexit) __P((void));                  /* HAS_DLEXIT */
           void    *(*dlsym3) __P((void *, const char *, void *)); /* HAS_DLSYM3 */
           int      (*dladdr) __P((const void *,
                                   struct dl_info *));     /* HAS_DLADDR */
   };
   
   /*
    * This is the structure pointed at by the __DYNAMIC symbol if an
    * executable requires the attention of the run-time link editor.
    * __DYNAMIC is given the value zero if no run-time linking needs to
    * be done (it is always present in shared objects).
    * The union `d_un' provides for different versions of the dynamic
    * linking mechanism (switched on by `d_version'). The last version
    * used by Sun is 3. We leave some room here and go to version number
    * 8 for NetBSD, the main difference lying in the support for the
    * `nz_list' type of symbols.
    */
   
   struct  _dynamic {
           int             d_version;      /* version # of this interface */
           struct so_debug *d_debug;
           union {
                   struct section_dispatch_table *d_sdt;
           } d_un;
           struct ld_entry *d_entry;       /* XXX */
   };
   
   #define LD_VERSION_SUN          (3)
   #define LD_VERSION_BSD          (8)
   #define LD_VERSION_NZLIST_P(v)  ((v) >= 8)
   
   #define LD_GOT(x)       ((x)->d_un.d_sdt->sdt_got)
   #define LD_PLT(x)       ((x)->d_un.d_sdt->sdt_plt)
   #define LD_REL(x)       ((x)->d_un.d_sdt->sdt_rel)
   #define LD_SYMBOL(x)    ((x)->d_un.d_sdt->sdt_nzlist)
   #define LD_HASH(x)      ((x)->d_un.d_sdt->sdt_hash)
   #define LD_STRINGS(x)   ((x)->d_un.d_sdt->sdt_strings)
   #define LD_NEED(x)      ((x)->d_un.d_sdt->sdt_sods)
   #define LD_BUCKETS(x)   ((x)->d_un.d_sdt->sdt_buckets)
   #define LD_PATHS(x)     ((x)->d_un.d_sdt->sdt_paths)
   
   #define LD_GOTSZ(x)     ((x)->d_un.d_sdt->sdt_plt - (x)->d_un.d_sdt->sdt_got)
   #define LD_RELSZ(x)     ((x)->d_un.d_sdt->sdt_hash - (x)->d_un.d_sdt->sdt_rel)
   #define LD_HASHSZ(x)    ((x)->d_un.d_sdt->sdt_nzlist - (x)->d_un.d_sdt->sdt_hash)
   #define LD_STABSZ(x)    ((x)->d_un.d_sdt->sdt_strings - (x)->d_un.d_sdt->sdt_nzlist)
   #define LD_PLTSZ(x)     ((x)->d_un.d_sdt->sdt_plt_sz)
   #define LD_STRSZ(x)     ((x)->d_un.d_sdt->sdt_str_sz)
   #define LD_TEXTSZ(x)    ((x)->d_un.d_sdt->sdt_text_sz)
   
   /*
    * Interface to ld.so
    */
   struct crt_ldso {
           int             crt_ba;         /* Base address of ld.so */
           int             crt_dzfd;       /* "/dev/zero" file descriptor (SunOS) */
           int             crt_ldfd;       /* ld.so file descriptor */
           struct _dynamic *crt_dp;        /* Main's __DYNAMIC */
           char            **crt_ep;       /* environment strings */
           caddr_t         crt_bp;         /* Breakpoint if run from debugger */
           char            *crt_prog;      /* Program name (v3) */
           char            *crt_ldso;      /* Link editor name (v4) */
           struct ld_entry *crt_ldentry;   /* dl*() access (v4) */
           char            **crt_argv;     /* argument strings (v5) */
   };
   
   /*
    * Version passed from crt0 to ld.so (1st argument to _rtld()).
    */
   #define CRT_VERSION_SUN         1
   #define CRT_VERSION_BSD_2       2
   #define CRT_VERSION_BSD_3       3
   #define CRT_VERSION_BSD_4       4
   #define CRT_VERSION_BSD_5       5
   
   /*
    * Maximum number of recognized shared object version numbers.
    */
   #define MAXDEWEY        8
   
   /*
    * Header of the hints file.
    */
   struct hints_header {
           long            hh_magic;
   #define HH_MAGIC        011421044151
           long            hh_version;     /* Interface version number */
   #define LD_HINTS_VERSION_1      1
   #define LD_HINTS_VERSION_2      2
           long            hh_hashtab;     /* Location of hash table */
           long            hh_nbucket;     /* Number of buckets in hashtab */
           long            hh_strtab;      /* Location of strings */
           long            hh_strtab_sz;   /* Size of strings */
           long            hh_ehints;      /* End of hints (max offset in file) */
           long            hh_dirlist;     /* Colon-separated list of srch dirs */
   };
   
   #define HH_BADMAG(hdr)  ((hdr).hh_magic != HH_MAGIC)
   
   /*
    * Hash table element in hints file.
    */
   struct hints_bucket {
           /* namex and pathx are indices into the string table */
           int             hi_namex;               /* Library name */
           int             hi_pathx;               /* Full path */
           int             hi_dewey[MAXDEWEY];     /* The versions */
           int             hi_ndewey;              /* Number of version numbers */
   #define hi_major hi_dewey[0]
   #define hi_minor hi_dewey[1]
           int             hi_next;                /* Next in this bucket */
   };
   
   #define _PATH_LD_HINTS          "/var/run/ld.so.hints"
   
   #endif /* !__ELF__ */
   
   #endif /* _LINK_H_ */

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