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 with newly
  43       installed libraries e.g. old libnss_nis.so.2 with new libnsl.so.1.  Using
  44       RTLD_LAZY here causes a failure at the time the symbol is called and at
  45       that point it is much harder to safely return an error (Bug 22766).
  46
  47    The use of RTLD_NOW also impacts gconv module loading, backtracing
  48    (where the unwinder form libgcc_s.so is used), and IDNA functions
  49    (which load libidn2), all of which load their respective DSOs on
  50    demand, and so should not impact program startup.  That is to say
  51    that the DSOs are loaded as part of an API call and therefore we
  52    will be calling that family of API functions shortly so RTLD_NOW or
  53    RTLD_LAZY is not a big difference in performance, but RTLD_NOW has
  54    better error handling semantics for the library.  */
  55 #define __libc_dlopen(name) \
  56   __libc_dlopen_mode (name, RTLD_NOW | __RTLD_DLOPEN)
  57 extern void *__libc_dlopen_mode  (const char *__name, int __mode);
  58 extern void *__libc_dlsym   (void *__map, const char *__name);
  59 extern void *__libc_dlvsym (void *map, const char *name, const char *version);
  60 extern int   __libc_dlclose (void *__map);
  61 libc_hidden_proto (__libc_dlopen_mode)
  62 libc_hidden_proto (__libc_dlsym)
  63 libc_hidden_proto (__libc_dlvsym)
  64 libc_hidden_proto (__libc_dlclose)
  65
  66 /* Locate shared object containing the given address.  */
  67 #ifdef ElfW
  68 extern int _dl_addr (const void *address, Dl_info *info,
  69                      struct link_map **mapp, const ElfW(Sym) **symbolp);
  70 libc_hidden_proto (_dl_addr)
  71 #endif
  72
  73 struct link_map;
  74
  75 /* Close an object previously opened by _dl_open.  */
  76 extern void _dl_close (void *map) attribute_hidden;
  77 /* Same as above, but without locking and safety checks for user
  78    provided map arguments.  */
  79 extern void _dl_close_worker (struct link_map *map, bool force)
  80     attribute_hidden;
  81
  82 /* Look up NAME in shared object HANDLE (which may be RTLD_DEFAULT or
  83    RTLD_NEXT).  WHO is the calling function, for RTLD_NEXT.  Returns
  84    the symbol value, which may be NULL.  */
  85 extern void *_dl_sym (void *handle, const char *name, void *who);
  86
  87 /* Look up version VERSION of symbol NAME in shared object HANDLE
  88    (which may be RTLD_DEFAULT or RTLD_NEXT).  WHO is the calling
  89    function, for RTLD_NEXT.  Returns the symbol value, which may be
  90    NULL.  */
  91 extern void *_dl_vsym (void *handle, const char *name, const char *version,
  92                        void *who);
  93
  94 /* Helper function for <dlfcn.h> functions.  Runs the OPERATE function via
  95    _dl_catch_error.  Returns zero for success, nonzero for failure; and
  96    arranges for `dlerror' to return the error details.
  97    ARGS is passed as argument to OPERATE.  */
  98 extern int _dlerror_run (void (*operate) (void *), void *args)
  99     attribute_hidden;
 100
 101 #ifdef SHARED
 102 # define DL_CALLER_DECL /* Nothing */
 103 # define DL_CALLER RETURN_ADDRESS (0)
 104 #else
 105 # define DL_CALLER_DECL , void *dl_caller
 106 # define DL_CALLER dl_caller
 107 #endif
 108
 109 struct dlfcn_hook
 110 {
 111   void *(*dlopen) (const char *file, int mode, void *dl_caller);
 112   int (*dlclose) (void *handle);
 113   void *(*dlsym) (void *handle, const char *name, void *dl_caller);
 114   void *(*dlvsym) (void *handle, const char *name, const char *version,
 115                    void *dl_caller);
 116   char *(*dlerror) (void);
 117   int (*dladdr) (const void *address, Dl_info *info);
 118   int (*dladdr1) (const void *address, Dl_info *info,
 119                   void **extra_info, int flags);
 120   int (*dlinfo) (void *handle, int request, void *arg, void *dl_caller);
 121   void *(*dlmopen) (Lmid_t nsid, const char *file, int mode, void *dl_caller);
 122   void *pad[4];
 123 };
 124
 125 extern struct dlfcn_hook *_dlfcn_hook;
 126 libdl_hidden_proto (_dlfcn_hook)
 127
 128 extern void *__dlopen (const char *file, int mode DL_CALLER_DECL)
 129      attribute_hidden;
 130 extern void *__dlmopen (Lmid_t nsid, const char *file, int mode DL_CALLER_DECL)
 131      attribute_hidden;
 132 extern int __dlclose (void *handle)
 133      attribute_hidden;
 134 extern void *__dlsym (void *handle, const char *name DL_CALLER_DECL)
 135      attribute_hidden;
 136 extern void *__dlvsym (void *handle, const char *name, const char *version
 137                        DL_CALLER_DECL)
 138      attribute_hidden;
 139 extern char *__dlerror (void)
 140      attribute_hidden;
 141 extern int __dladdr (const void *address, Dl_info *info)
 142      attribute_hidden;
 143 extern int __dladdr1 (const void *address, Dl_info *info,
 144                       void **extra_info, int flags)
 145      attribute_hidden;
 146 extern int __dlinfo (void *handle, int request, void *arg DL_CALLER_DECL)
 147      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