include/dlfcn.h

   1 /* User functions for run-time dynamic loading.
   2    Copyright (C) 1995-2021 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 /* If the first argument of `dlsym' or `dlvsym' is set to RTLD_NEXT
  32    the run-time address of the symbol called NAME in the next shared
  33    object is returned.  The "next" relation is defined by the order
  34    the shared objects were loaded.  */
  35 # define RTLD_NEXT      ((void *) -1l)
  36
  37 /* If the first argument to `dlsym' or `dlvsym' is set to RTLD_DEFAULT
  38    the run-time address of the symbol called NAME in the global scope
  39    is returned.  */
  40 # define RTLD_DEFAULT   ((void *) 0)
  41
  42
  43 /* Type for namespace indices.  */
  44 typedef long int Lmid_t;
  45
  46 /* Special namespace ID values.  */
  47 # define LM_ID_BASE     0       /* Initial namespace.  */
  48 # define LM_ID_NEWLM    -1      /* For dlmopen: request new namespace.  */
  49 #endif
  50
  51
  52 __BEGIN_DECLS
  53
  54 /* Open the shared object FILE and map it in; return a handle that can be
  55    passed to `dlsym' to get symbol values from it.  */
  56 extern void *dlopen (const char *__file, int __mode) __THROWNL;
  57
  58 /* Unmap and close a shared object opened by `dlopen'.
  59    The handle cannot be used again after calling `dlclose'.  */
  60 extern int dlclose (void *__handle) __THROWNL __nonnull ((1));
  61
  62 /* Find the run-time address in the shared object HANDLE refers to
  63    of the symbol called NAME.  */
  64 extern void *dlsym (void *__restrict __handle,
  65                     const char *__restrict __name) __THROW __nonnull ((2));
  66
  67 #ifdef __USE_GNU
  68 /* Like `dlopen', but request object to be allocated in a new namespace.  */
  69 extern void *dlmopen (Lmid_t __nsid, const char *__file, int __mode) __THROWNL;
  70
  71 /* Find the run-time address in the shared object HANDLE refers to
  72    of the symbol called NAME with VERSION.  */
  73 extern void *dlvsym (void *__restrict __handle,
  74                      const char *__restrict __name,
  75                      const char *__restrict __version)
  76      __THROW __nonnull ((2, 3));
  77 #endif
  78
  79 /* When any of the above functions fails, call this function
  80    to return a string describing the error.  Each call resets
  81    the error string so that a following call returns null.  */
  82 extern char *dlerror (void) __THROW;
  83
  84
  85 #ifdef __USE_GNU
  86 /* Structure containing information about object searched using
  87    `dladdr'.  */
  88 typedef struct
  89 {
  90   const char *dli_fname;        /* File name of defining object.  */
  91   void *dli_fbase;              /* Load address of that object.  */
  92   const char *dli_sname;        /* Name of nearest symbol.  */
  93   void *dli_saddr;              /* Exact value of nearest symbol.  */
  94 } Dl_info;
  95
  96 /* Fill in *INFO with the following information about ADDRESS.
  97    Returns 0 iff no shared object's segments contain that address.  */
  98 extern int dladdr (const void *__address, Dl_info *__info)
  99      __THROW __nonnull ((2));
 100
 101 /* Same as `dladdr', but additionally sets *EXTRA_INFO according to FLAGS.  */
 102 extern int dladdr1 (const void *__address, Dl_info *__info,
 103                     void **__extra_info, int __flags) __THROW __nonnull ((2));
 104
 105 /* These are the possible values for the FLAGS argument to `dladdr1'.
 106    This indicates what extra information is stored at *EXTRA_INFO.
 107    It may also be zero, in which case the EXTRA_INFO argument is not used.  */
 108 enum
 109   {
 110     /* Matching symbol table entry (const ElfNN_Sym *).  */
 111     RTLD_DL_SYMENT = 1,
 112
 113     /* The object containing the address (struct link_map *).  */
 114     RTLD_DL_LINKMAP = 2
 115   };
 116
 117
 118 /* Get information about the shared object HANDLE refers to.
 119    REQUEST is from among the values below, and determines the use of ARG.
 120
 121    On success, returns zero.  On failure, returns -1 and records an error
 122    message to be fetched with `dlerror'.  */
 123 extern int dlinfo (void *__restrict __handle,
 124                    int __request, void *__restrict __arg)
 125      __THROW __nonnull ((1, 3));
 126
 127 /* These are the possible values for the REQUEST argument to `dlinfo'.  */
 128 enum
 129   {
 130     /* Treat ARG as `lmid_t *'; store namespace ID for HANDLE there.  */
 131     RTLD_DI_LMID = 1,
 132
 133     /* Treat ARG as `struct link_map **';
 134        store the `struct link_map *' for HANDLE there.  */
 135     RTLD_DI_LINKMAP = 2,
 136
 137     RTLD_DI_CONFIGADDR = 3,     /* Unsupported, defined by Solaris.  */
 138
 139     /* Treat ARG as `Dl_serinfo *' (see below), and fill in to describe the
 140        directories that will be searched for dependencies of this object.
 141        RTLD_DI_SERINFOSIZE fills in just the `dls_cnt' and `dls_size'
 142        entries to indicate the size of the buffer that must be passed to
 143        RTLD_DI_SERINFO to fill in the full information.  */
 144     RTLD_DI_SERINFO = 4,
 145     RTLD_DI_SERINFOSIZE = 5,
 146
 147     /* Treat ARG as `char *', and store there the directory name used to
 148        expand $ORIGIN in this shared object's dependency file names.  */
 149     RTLD_DI_ORIGIN = 6,
 150
 151     RTLD_DI_PROFILENAME = 7,    /* Unsupported, defined by Solaris.  */
 152     RTLD_DI_PROFILEOUT = 8,     /* Unsupported, defined by Solaris.  */
 153
 154     /* Treat ARG as `size_t *', and store there the TLS module ID
 155        of this object's PT_TLS segment, as used in TLS relocations;
 156        store zero if this object does not define a PT_TLS segment.  */
 157     RTLD_DI_TLS_MODID = 9,
 158
 159     /* Treat ARG as `void **', and store there a pointer to the calling
 160        thread's TLS block corresponding to this object's PT_TLS segment.
 161        Store a null pointer if this object does not define a PT_TLS
 162        segment, or if the calling thread has not allocated a block for it.  */
 163     RTLD_DI_TLS_DATA = 10,
 164
 165     RTLD_DI_MAX = 10
 166   };
 167
 168
 169 /* This is the type of elements in `Dl_serinfo', below.
 170    The `dls_name' member points to space in the buffer passed to `dlinfo'.  */
 171 typedef struct
 172 {
 173   char *dls_name;               /* Name of library search path directory.  */
 174   unsigned int dls_flags;       /* Indicates where this directory came from. */
 175 } Dl_serpath;
 176
 177 /* This is the structure that must be passed (by reference) to `dlinfo' for
 178    the RTLD_DI_SERINFO and RTLD_DI_SERINFOSIZE requests.  */
 179 typedef struct
 180 {
 181   size_t dls_size;              /* Size in bytes of the whole buffer.  */
 182   unsigned int dls_cnt;         /* Number of elements in `dls_serpath'.  */
 183 # if __GNUC_PREREQ (3, 0)
 184   /* The zero-length array avoids an unwanted array subscript check by
 185      the compiler, while the surrounding anonymous union preserves the
 186      historic size of the type.  At the time of writing, GNU C does
 187      not support structs with flexible array members in unions.  */
 188   __extension__ union
 189   {
 190     Dl_serpath dls_serpath[0]; /* Actually longer, dls_cnt elements.  */
 191     Dl_serpath __dls_serpath_pad[1];
 192   };
 193 # else
 194   Dl_serpath dls_serpath[1];    /* Actually longer, dls_cnt elements.  */
 195 # endif
 196 } Dl_serinfo;
 197 #endif /* __USE_GNU */
 198
 199
 200 __END_DECLS
 201
 202 #endif  /* dlfcn.h */