dlfcn/dlfcn.h

   1 /* User functions for run-time dynamic loading.
   2    Copyright (C) 1995-2022 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _DLFCN_H
  20 #define _DLFCN_H 1
  21
  22 #include <features.h>
  23 #define __need_size_t
  24 #include <stddef.h>
  25
  26 /* Collect various system dependent definitions and declarations.  */
  27 #include <bits/dlfcn.h>
  28
  29
  30 #ifdef __USE_GNU
  31 #include <bits/dl_find_object.h>
  32
  33 /* If the first argument of `dlsym' or `dlvsym' is set to RTLD_NEXT
  34    the run-time address of the symbol called NAME in the next shared
  35    object is returned.  The "next" relation is defined by the order
  36    the shared objects were loaded.  */
  37 # define RTLD_NEXT      ((void *) -1l)
  38
  39 /* If the first argument to `dlsym' or `dlvsym' is set to RTLD_DEFAULT
  40    the run-time address of the symbol called NAME in the global scope
  41    is returned.  */
  42 # define RTLD_DEFAULT   ((void *) 0)
  43
  44
  45 /* Type for namespace indices.  */
  46 typedef long int Lmid_t;
  47
  48 /* Special namespace ID values.  */
  49 # define LM_ID_BASE     0       /* Initial namespace.  */
  50 # define LM_ID_NEWLM    -1      /* For dlmopen: request new namespace.  */
  51 #endif
  52
  53
  54 __BEGIN_DECLS
  55
  56 /* Open the shared object FILE and map it in; return a handle that can be
  57    passed to `dlsym' to get symbol values from it.  */
  58 extern void *dlopen (const char *__file, int __mode) __THROWNL;
  59
  60 /* Unmap and close a shared object opened by `dlopen'.
  61    The handle cannot be used again after calling `dlclose'.  */
  62 extern int dlclose (void *__handle) __THROWNL __nonnull ((1));
  63
  64 /* Find the run-time address in the shared object HANDLE refers to
  65    of the symbol called NAME.  */
  66 extern void *dlsym (void *__restrict __handle,
  67                     const char *__restrict __name) __THROW __nonnull ((2));
  68
  69 #ifdef __USE_GNU
  70 /* Like `dlopen', but request object to be allocated in a new namespace.  */
  71 extern void *dlmopen (Lmid_t __nsid, const char *__file, int __mode) __THROWNL;
  72
  73 /* Find the run-time address in the shared object HANDLE refers to
  74    of the symbol called NAME with VERSION.  */
  75 extern void *dlvsym (void *__restrict __handle,
  76                      const char *__restrict __name,
  77                      const char *__restrict __version)
  78      __THROW __nonnull ((2, 3));
  79 #endif
  80
  81 /* When any of the above functions fails, call this function
  82    to return a string describing the error.  Each call resets
  83    the error string so that a following call returns null.  */
  84 extern char *dlerror (void) __THROW;
  85
  86
  87 #ifdef __USE_GNU
  88 /* Structure containing information about object searched using
  89    `dladdr'.  */
  90 typedef struct
  91 {
  92   const char *dli_fname;        /* File name of defining object.  */
  93   void *dli_fbase;              /* Load address of that object.  */
  94   const char *dli_sname;        /* Name of nearest symbol.  */
  95   void *dli_saddr;              /* Exact value of nearest symbol.  */
  96 } Dl_info;
  97
  98 /* Fill in *INFO with the following information about ADDRESS.
  99    Returns 0 iff no shared object's segments contain that address.  */
 100 extern int dladdr (const void *__address, Dl_info *__info)
 101      __THROW __nonnull ((2));
 102
 103 /* Same as `dladdr', but additionally sets *EXTRA_INFO according to FLAGS.  */
 104 extern int dladdr1 (const void *__address, Dl_info *__info,
 105                     void **__extra_info, int __flags) __THROW __nonnull ((2));
 106
 107 /* These are the possible values for the FLAGS argument to `dladdr1'.
 108    This indicates what extra information is stored at *EXTRA_INFO.
 109    It may also be zero, in which case the EXTRA_INFO argument is not used.  */
 110 enum
 111   {
 112     /* Matching symbol table entry (const ElfNN_Sym *).  */
 113     RTLD_DL_SYMENT = 1,
 114
 115     /* The object containing the address (struct link_map *).  */
 116     RTLD_DL_LINKMAP = 2
 117   };
 118
 119
 120 /* Get information about the shared object HANDLE refers to.
 121    REQUEST is from among the values below, and determines the use of ARG.
 122
 123    On success, returns zero.  On failure, returns -1 and records an error
 124    message to be fetched with `dlerror'.  */
 125 extern int dlinfo (void *__restrict __handle,
 126                    int __request, void *__restrict __arg)
 127      __THROW __nonnull ((1, 3));
 128
 129 /* These are the possible values for the REQUEST argument to `dlinfo'.  */
 130 enum
 131   {
 132     /* Treat ARG as `lmid_t *'; store namespace ID for HANDLE there.  */
 133     RTLD_DI_LMID = 1,
 134
 135     /* Treat ARG as `struct link_map **';
 136        store the `struct link_map *' for HANDLE there.  */
 137     RTLD_DI_LINKMAP = 2,
 138
 139     RTLD_DI_CONFIGADDR = 3,     /* Unsupported, defined by Solaris.  */
 140
 141     /* Treat ARG as `Dl_serinfo *' (see below), and fill in to describe the
 142        directories that will be searched for dependencies of this object.
 143        RTLD_DI_SERINFOSIZE fills in just the `dls_cnt' and `dls_size'
 144        entries to indicate the size of the buffer that must be passed to
 145        RTLD_DI_SERINFO to fill in the full information.  */
 146     RTLD_DI_SERINFO = 4,
 147     RTLD_DI_SERINFOSIZE = 5,
 148
 149     /* Treat ARG as `char *', and store there the directory name used to
 150        expand $ORIGIN in this shared object's dependency file names.  */
 151     RTLD_DI_ORIGIN = 6,
 152
 153     RTLD_DI_PROFILENAME = 7,    /* Unsupported, defined by Solaris.  */
 154     RTLD_DI_PROFILEOUT = 8,     /* Unsupported, defined by Solaris.  */
 155
 156     /* Treat ARG as `size_t *', and store there the TLS module ID
 157        of this object's PT_TLS segment, as used in TLS relocations;
 158        store zero if this object does not define a PT_TLS segment.  */
 159     RTLD_DI_TLS_MODID = 9,
 160
 161     /* Treat ARG as `void **', and store there a pointer to the calling
 162        thread's TLS block corresponding to this object's PT_TLS segment.
 163        Store a null pointer if this object does not define a PT_TLS
 164        segment, or if the calling thread has not allocated a block for it.  */
 165     RTLD_DI_TLS_DATA = 10,
 166
 167     RTLD_DI_MAX = 10
 168   };
 169
 170
 171 /* This is the type of elements in `Dl_serinfo', below.
 172    The `dls_name' member points to space in the buffer passed to `dlinfo'.  */
 173 typedef struct
 174 {
 175   char *dls_name;               /* Name of library search path directory.  */
 176   unsigned int dls_flags;       /* Indicates where this directory came from. */
 177 } Dl_serpath;
 178
 179 /* This is the structure that must be passed (by reference) to `dlinfo' for
 180    the RTLD_DI_SERINFO and RTLD_DI_SERINFOSIZE requests.  */
 181 typedef struct
 182 {
 183   size_t dls_size;              /* Size in bytes of the whole buffer.  */
 184   unsigned int dls_cnt;         /* Number of elements in `dls_serpath'.  */
 185 # if __GNUC_PREREQ (3, 0)
 186   /* The zero-length array avoids an unwanted array subscript check by
 187      the compiler, while the surrounding anonymous union preserves the
 188      historic size of the type.  At the time of writing, GNU C does
 189      not support structs with flexible array members in unions.  */
 190   __extension__ union
 191   {
 192     Dl_serpath dls_serpath[0]; /* Actually longer, dls_cnt elements.  */
 193     Dl_serpath __dls_serpath_pad[1];
 194   };
 195 # else
 196   Dl_serpath dls_serpath[1];    /* Actually longer, dls_cnt elements.  */
 197 # endif
 198 } Dl_serinfo;
 199
 200 struct dl_find_object
 201 {
 202   __extension__ unsigned long long int dlfo_flags;
 203   void *dlfo_map_start;         /* Beginning of mapping containing address.  */
 204   void *dlfo_map_end;           /* End of mapping.  */
 205   struct link_map *dlfo_link_map;
 206   void *dlfo_eh_frame;          /* Exception handling data of the object.  */
 207 # if DLFO_STRUCT_HAS_EH_DBASE
 208   void *dlfo_eh_dbase;          /* Base address for DW_EH_PE_datarel.  */
 209 #  if __WORDSIZE == 32
 210   unsigned int __dlfo_eh_dbase_pad;
 211 #  endif
 212 # endif
 213 # if DLFO_STRUCT_HAS_EH_COUNT
 214   int dlfo_eh_count;            /* Number of exception handling entries.  */
 215   unsigned int __dlfo_eh_count_pad;
 216 # endif
 217   __extension__ unsigned long long int __dflo_reserved[7];
 218 };
 219
 220 /* If ADDRESS is found in an object, fill in *RESULT and return 0.
 221    Otherwise, return -1.  */
 222 int _dl_find_object (void *__address, struct dl_find_object *__result) __THROW;
 223
 224 #endif /* __USE_GNU */
 225
 226
 227 __END_DECLS
 228
 229 #endif  /* dlfcn.h */