include/dlfcn.h

   1 #ifndef _DLFCN_H
   2 #include <dlfcn/dlfcn.h>
   3 #ifndef _ISOMAC
   4 #include <link.h>               /* For ElfW.  */
   5 #include <stdbool.h>
   6
   7 /* Internally used flag.  */
   8 #define __RTLD_DLOPEN   0x80000000
   9 #define __RTLD_SPROF    0x40000000
  10 #define __RTLD_OPENEXEC 0x20000000
  11 #define __RTLD_CALLMAP  0x10000000
  12 #define __RTLD_AUDIT    0x08000000
  13 #define __RTLD_SECURE   0x04000000 /* Apply additional security checks.  */
  14 #define __RTLD_NOIFUNC  0x02000000 /* Suppress calling ifunc functions.  */
  15
  16 #define __LM_ID_CALLER  -2
  17
  18 #ifdef SHARED
  19 /* Locally stored program arguments.  */
  20 extern int __dlfcn_argc attribute_hidden;
  21 extern char **__dlfcn_argv attribute_hidden;
  22 #else
  23 /* These variables are defined and initialized in the startup code.  */
  24 extern int __libc_argc attribute_hidden;
  25 extern char **__libc_argv attribute_hidden;
  26
  27 # define __dlfcn_argc __libc_argc
  28 # define __dlfcn_argv __libc_argv
  29 #endif
  30
  31
  32 /* Now define the internal interfaces.  */
  33
  34 /* Use RTLD_NOW here because:
  35    1. In pthread_cancel_init we want to use RTLD_NOW to reduce the stack usage
  36       of future cancellation operations, particularly when the target thread
  37       is running with a small stack.  Likewise for consistency we do the same
  38       thing in __libgcc_s_init.  RTLD_NOW will rarely make a difference for
  39       __libgcc_s_init because unwinding is already in progress, so libgcc_s.so
  40       has already been loaded if its unwinder is used (Bug 22636).
  41    2. It allows us to provide robust fallback code at dlopen time for
  42       incorrectly configured systems that mix old libnss_* modules
  43       with newly installed libraries e.g. old libnss_dns.so.2 with new
  44       libresolv.so.2.  Using RTLD_LAZY here causes a failure at the
  45       time the symbol is called and at that point it is much harder to
  46       safely return an error (Bug 22766).
  47
  48    The use of RTLD_NOW also impacts gconv module loading, backtracing
  49    (where the unwinder form libgcc_s.so is used), and IDNA functions
  50    (which load libidn2), all of which load their respective DSOs on
  51    demand, and so should not impact program startup.  That is to say
  52    that the DSOs are loaded as part of an API call and therefore we
  53    will be calling that family of API functions shortly so RTLD_NOW or
  54    RTLD_LAZY is not a big difference in performance, but RTLD_NOW has
  55    better error handling semantics for the library.  */
  56 #define __libc_dlopen(name) \
  57   __libc_dlopen_mode (name, RTLD_NOW | __RTLD_DLOPEN)
  58 extern void *__libc_dlopen_mode  (const char *__name, int __mode);
  59 extern void *__libc_dlsym   (void *__map, const char *__name);
  60 extern void *__libc_dlvsym (void *map, const char *name, const char *version);
  61 extern int   __libc_dlclose (void *__map);
  62 libc_hidden_proto (__libc_dlopen_mode)
  63 libc_hidden_proto (__libc_dlsym)
  64 libc_hidden_proto (__libc_dlvsym)
  65 libc_hidden_proto (__libc_dlclose)
  66
  67 /* Locate shared object containing the given address.  */
  68 #ifdef ElfW
  69 extern int _dl_addr (const void *address, Dl_info *info,
  70                      struct link_map **mapp, const ElfW(Sym) **symbolp);
  71 libc_hidden_proto (_dl_addr)
  72 #endif
  73
  74 struct link_map;
  75
  76 /* Close an object previously opened by _dl_open.  */
  77 extern void _dl_close (void *map) attribute_hidden;
  78 /* Same as above, but without locking and safety checks for user
  79    provided map arguments.  */
  80 extern void _dl_close_worker (struct link_map *map, bool force)
  81     attribute_hidden;
  82
  83 /* Look up NAME in shared object HANDLE (which may be RTLD_DEFAULT or
  84    RTLD_NEXT).  WHO is the calling function, for RTLD_NEXT.  Returns
  85    the symbol value, which may be NULL.  */
  86 extern void *_dl_sym (void *handle, const char *name, void *who);
  87
  88 /* Look up version VERSION of symbol NAME in shared object HANDLE
  89    (which may be RTLD_DEFAULT or RTLD_NEXT).  WHO is the calling
  90    function, for RTLD_NEXT.  Returns the symbol value, which may be
  91    NULL.  */
  92 extern void *_dl_vsym (void *handle, const char *name, const char *version,
  93                        void *who);
  94
  95 /* Helper function for <dlfcn.h> functions.  Runs the OPERATE function via
  96    _dl_catch_error.  Returns zero for success, nonzero for failure; and
  97    arranges for `dlerror' to return the error details.
  98    ARGS is passed as argument to OPERATE.  */
  99 extern int _dlerror_run (void (*operate) (void *), void *args)
 100     attribute_hidden;
 101
 102 #ifdef SHARED
 103 # define DL_CALLER_DECL /* Nothing */
 104 # define DL_CALLER RETURN_ADDRESS (0)
 105 #else
 106 # define DL_CALLER_DECL , void *dl_caller
 107 # define DL_CALLER dl_caller
 108 #endif
 109
 110 struct dlfcn_hook
 111 {
 112   void *(*dlopen) (const char *file, int mode, void *dl_caller);
 113   int (*dlclose) (void *handle);
 114   void *(*dlsym) (void *handle, const char *name, void *dl_caller);
 115   void *(*dlvsym) (void *handle, const char *name, const char *version,
 116                    void *dl_caller);
 117   char *(*dlerror) (void);
 118   int (*dladdr) (const void *address, Dl_info *info);
 119   int (*dladdr1) (const void *address, Dl_info *info,
 120                   void **extra_info, int flags);
 121   int (*dlinfo) (void *handle, int request, void *arg);
 122   void *(*dlmopen) (Lmid_t nsid, const char *file, int mode, void *dl_caller);
 123   void *pad[4];
 124 };
 125
 126 extern struct dlfcn_hook *_dlfcn_hook;
 127 libdl_hidden_proto (_dlfcn_hook)
 128
 129 extern void *__dlopen (const char *file, int mode DL_CALLER_DECL)
 130      attribute_hidden;
 131 extern void *__dlmopen (Lmid_t nsid, const char *file, int mode DL_CALLER_DECL)
 132      attribute_hidden;
 133 extern int __dlclose (void *handle)
 134      attribute_hidden;
 135 extern void *__dlsym (void *handle, const char *name DL_CALLER_DECL)
 136      attribute_hidden;
 137 extern void *__dlvsym (void *handle, const char *name, const char *version
 138                        DL_CALLER_DECL)
 139      attribute_hidden;
 140 extern char *__dlerror (void)
 141      attribute_hidden;
 142 extern int __dladdr (const void *address, Dl_info *info)
 143      attribute_hidden;
 144 extern int __dladdr1 (const void *address, Dl_info *info,
 145                       void **extra_info, int flags)
 146      attribute_hidden;
 147 extern int __dlinfo (void *handle, int request, void *arg) attribute_hidden;
 148
 149 #ifndef SHARED
 150 struct link_map;
 151 extern void * __libc_dlsym_private (struct link_map *map, const char *name)
 152      attribute_hidden;
 153 extern void __libc_register_dl_open_hook (struct link_map *map)
 154      attribute_hidden;
 155 extern void __libc_register_dlfcn_hook (struct link_map *map)
 156      attribute_hidden;
 157 #endif
 158
 159 extern void __dlerror_main_freeres (void) attribute_hidden;
 160
 161 #endif
 162 #endif