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-rw-r--r--include/dlfcn.h40
1 files changed, 31 insertions, 9 deletions
diff --git a/include/dlfcn.h b/include/dlfcn.h
index 2524292ebc..0dc57dbe22 100644
--- a/include/dlfcn.h
+++ b/include/dlfcn.h
@@ -31,20 +31,42 @@ extern char **__libc_argv attribute_hidden;
/* Now define the internal interfaces. */
+/* Use RTLD_NOW here because:
+ 1. In pthread_cancel_init we want to use RTLD_NOW to reduce the stack usage
+ of future cancellation operations, particularly when the target thread
+ is running with a small stack. Likewise for consistency we do the same
+ thing in __libgcc_s_init. RTLD_NOW will rarely make a difference for
+ __libgcc_s_init because unwinding is already in progress, so libgcc_s.so
+ has already been loaded if its unwinder is used (Bug 22636).
+ 2. It allows us to provide robust fallback code at dlopen time for
+ incorrectly configured systems that mix old libnss_* modules with newly
+ installed libraries e.g. old libnss_nis.so.2 with new libnsl.so.1. Using
+ RTLD_LAZY here causes a failure at the time the symbol is called and at
+ that point it is much harder to safely return an error (Bug 22766).
+
+ The use of RTLD_NOW also impacts gconv module loading, backtracing
+ (where the unwinder form libgcc_s.so is used), and IDNA functions
+ (which load libidn2), all of which load their respective DSOs on
+ demand, and so should not impact program startup. That is to say
+ that the DSOs are loaded as part of an API call and therefore we
+ will be calling that family of API functions shortly so RTLD_NOW or
+ RTLD_LAZY is not a big difference in performance, but RTLD_NOW has
+ better error handling semantics for the library. */
#define __libc_dlopen(name) \
- __libc_dlopen_mode (name, RTLD_LAZY | __RTLD_DLOPEN)
+ __libc_dlopen_mode (name, RTLD_NOW | __RTLD_DLOPEN)
extern void *__libc_dlopen_mode (const char *__name, int __mode);
extern void *__libc_dlsym (void *__map, const char *__name);
+extern void *__libc_dlvsym (void *map, const char *name, const char *version);
extern int __libc_dlclose (void *__map);
libc_hidden_proto (__libc_dlopen_mode)
libc_hidden_proto (__libc_dlsym)
+libc_hidden_proto (__libc_dlvsym)
libc_hidden_proto (__libc_dlclose)
/* Locate shared object containing the given address. */
#ifdef ElfW
extern int _dl_addr (const void *address, Dl_info *info,
- struct link_map **mapp, const ElfW(Sym) **symbolp)
- internal_function;
+ struct link_map **mapp, const ElfW(Sym) **symbolp);
libc_hidden_proto (_dl_addr)
#endif
@@ -60,23 +82,21 @@ extern void _dl_close_worker (struct link_map *map, bool force)
/* Look up NAME in shared object HANDLE (which may be RTLD_DEFAULT or
RTLD_NEXT). WHO is the calling function, for RTLD_NEXT. Returns
the symbol value, which may be NULL. */
-extern void *_dl_sym (void *handle, const char *name, void *who)
- internal_function;
+extern void *_dl_sym (void *handle, const char *name, void *who);
/* Look up version VERSION of symbol NAME in shared object HANDLE
(which may be RTLD_DEFAULT or RTLD_NEXT). WHO is the calling
function, for RTLD_NEXT. Returns the symbol value, which may be
NULL. */
extern void *_dl_vsym (void *handle, const char *name, const char *version,
- void *who)
- internal_function;
+ void *who);
/* Helper function for <dlfcn.h> functions. Runs the OPERATE function via
_dl_catch_error. Returns zero for success, nonzero for failure; and
arranges for `dlerror' to return the error details.
ARGS is passed as argument to OPERATE. */
extern int _dlerror_run (void (*operate) (void *), void *args)
- internal_function;
+ attribute_hidden;
#ifdef SHARED
# define DL_CALLER_DECL /* Nothing */
@@ -135,6 +155,8 @@ extern void __libc_register_dl_open_hook (struct link_map *map)
extern void __libc_register_dlfcn_hook (struct link_map *map)
attribute_hidden;
#endif
-#endif
+extern void __dlerror_main_freeres (void) attribute_hidden;
+
+#endif
#endif