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authorRoland McGrath <roland@gnu.org>1995-05-02 06:35:55 +0000
committerRoland McGrath <roland@gnu.org>1995-05-02 06:35:55 +0000
commitd66e34cd423425c348bcc83df127dd19711b0b9a (patch)
tree97058e776d3b4fe06ef54bc4951596991652183f /elf/link.h
parent08162fa888913a5153d2fcdc4e1a816b57b1fe56 (diff)
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* sysdeps/mach/i386/sysdep.h (SNARF_ARGS, CALL_WITH_SP): Rewritten.
* sysdeps/i386/dl-machine.h: New file. * sysdeps/stub/dl-machine.h: New file. * sysdeps/i386/dl-runtime.c: New file. * sysdeps/stub/dl-runtime.c: New file. * sysdeps/i386/elf/start.S: New file. * sysdeps/generic/dl-sysdep.c: New file. * sysdeps/mach/hurd/dl-sysdep.c: New file.
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+/* Run-time dynamic linker data structures for loaded ELF shared objects.
+Copyright (C) 1995 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB. If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA. */
+
+#ifndef _LINK_H
+#define _LINK_H 1
+
+#include <elf.h>
+
+
+/* Rendezvous structure used by the run-time dynamic linker to communicate
+ details of shared object loading to the debugger. If the executable's
+ dynamic section has a DT_DEBUG element, the run-time linker sets that
+ element's value to the address where this structure can be found. */
+
+struct r_debug
+ {
+ int r_version; /* Version number for this protocol. */
+
+ struct link_map *r_map; /* Head of the chain of loaded objects. */
+
+ /* This is the address of a function internal to the run-time linker,
+ that will always be called when the linker begins to map in a
+ library or unmap it, and again when the mapping change is complete.
+ The debugger can set a breakpoint at this address if it wants to
+ notice shared object mapping changes. */
+ Elf32_Addr r_brk;
+ enum
+ {
+ /* This state value describes the mapping change taking place when
+ the `r_brk' address is called. */
+ RT_CONSISTENT, /* Mapping change is complete. */
+ RT_ADD, /* Beginning to add a new object. */
+ RT_DELETE, /* Beginning to remove an object mapping. */
+ } r_state;
+
+ Elf32_Addr r_ldbase; /* Base address the linker is loaded at. */
+ };
+
+/* This symbol refers to the "dynamic structure" in the `.dynamic' section
+ of whatever module refers to `_DYNAMIC'. So, to find its own
+ `struct r_debug', a program could do:
+ for (dyn = _DYNAMIC; dyn->d_tag != DT_NULL)
+ if (dyn->d_tag == DT_DEBUG) r_debug = (struct r_debug) dyn->d_un.d_ptr;
+ */
+
+extern Elf32_Dyn _DYNAMIC[];
+
+
+/* Structure describing a loaded shared object. The `l_next' and `l_prev'
+ members form a chain of all the shared objects loaded at startup.
+
+ These data structures exist in space used by the run-time dynamic linker;
+ modifying them may have disastrous results. */
+
+struct link_map
+ {
+ /* These first few members are part of the protocol with the debugger.
+ This is the same format used in SVR4. */
+
+ Elf32_Addr l_addr; /* Base address shared object is loaded at. */
+ char *l_name; /* Absolute file name object was found in. */
+ Elf32_Dyn *l_ld; /* Dynamic section of the shared object. */
+ struct link_map *l_next, *l_prev; /* Chain of loaded objects. */
+
+ /* All following members are internal to the dynamic linker.
+ They may change without notice. */
+
+ const char *l_libname; /* Name requested (before search). */
+ Elf32_Dyn *l_info[DT_NUM]; /* Indexed pointers to dynamic section. */
+ const Elf32_Phdr *l_phdr; /* Pointer to program header table in core. */
+ Elf32_Word l_phnum; /* Number of program header entries. */
+
+ /* Symbol hash table. */
+ Elf32_Word l_nbuckets;
+ const Elf32_Word *l_buckets, *l_chain;
+
+ unsigned int l_opencount; /* Reference count for dlopen/dlclose. */
+ enum /* Where this object came from. */
+ {
+ lt_executable, /* The main executable program. */
+ lt_interpreter, /* The interpreter: the dynamic linker. */
+ lt_library, /* Library needed by main executable. */
+ lt_loaded, /* Extra run-time loaded shared object. */
+ } l_type:2;
+ unsigned int l_deps_loaded:1; /* Nonzero if DT_NEEDED items loaded. */
+ unsigned int l_relocated:1; /* Nonzero if object's relocations done. */
+ unsigned int l_init_called:1; /* Nonzero if DT_INIT function called. */
+ unsigned int l_init_running:1; /* Nonzero while DT_INIT function runs. */
+ };
+
+/* Internal functions of the run-time dynamic linker.
+ These can be accessed if you link again the dynamic linker
+ as a shared library, as in `-lld' or `/lib/ld.so' explicitly;
+ but are not normally of interest to user programs.
+
+ The `-ldl' library functions in <dlfcn.h> provide a simple
+ user interface to run-time dynamic linking. */
+
+
+/* File descriptor referring to the zero-fill device. */
+extern int _dl_zerofd;
+
+/* OS-dependent function to open the zero-fill device. */
+extern int _dl_sysdep_open_zero_fill (void); /* dl-sysdep.c */
+
+/* OS-dependent function to give a fatal error message and exit
+ when the dynamic linker fails before the program is fully linked.
+ All arguments are `const char *'; args until a null pointer
+ are concatenated to form the message to print. */
+extern void _dl_sysdep_fatal (const char *string, ...)
+ __attribute__ ((__noreturn__));
+
+/* Nonzero if the program should be "secure" (i.e. it's setuid or somesuch).
+ This tells the dynamic linker to ignore environment variables. */
+extern int _dl_secure;
+
+/* This function is called by all the internal dynamic linker functions
+ when they encounter an error. ERRCODE is either an `errno' code
+ or zero; ERRSTRING is a string describing the specific problem. */
+
+extern void _dl_signal_error (int errcode, const char *errstring)
+ __attribute__ ((__noreturn__));
+
+/* Call OPERATE, catching errors from `dl_signal_error'. If there is no
+ error, *ERRSTRING is set to null. If there is an error, *ERRSTRING is
+ set to the string passed to _dl_signal_error, and the error code passed
+ is the return value. */
+extern int _dl_catch_error (const char **errstring, void (*operate) (void));
+
+
+/* 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. */
+extern int _dlerror_run (void (*operate) (void));
+
+
+/* Open the shared object NAME and map in its segments.
+ LOADER's DT_RPATH is used in searching for NAME.
+ If ENTRY_POINT is not null, fill it in with the object's entry point.
+ If the object is already opened, returns its existing map. */
+extern struct link_map *_dl_map_object (struct link_map *loader,
+ const char *name,
+ Elf32_Addr *entry_point);
+
+/* Cache the locations of MAP's hash table. */
+extern void _dl_setup_hash (struct link_map *map);
+
+
+/* Search loaded objects' symbol tables for a definition of the symbol
+ referred to by UNDEF. *SYM is the symbol table entry containing the
+ reference; it is replaced with the defining symbol, and the base load
+ address of the defining object is returned. SYMBOL_SCOPE is the head of
+ the chain used for searching. */
+extern Elf32_Addr _dl_lookup_symbol (const char *undef,
+ const Elf32_Sym **sym,
+ struct link_map *symbol_scope);
+
+
+/* List of objects currently loaded. */
+extern struct link_map *_dl_loaded;
+
+/* Tail of that list which were loaded at startup. */
+extern struct link_map *_dl_startup_loaded;
+
+/* Allocate a `struct link_map' for a new object being loaded,
+ and enter it into the _dl_loaded list. */
+extern struct link_map *_dl_new_object (char *realname, const char *libname,
+ int type);
+
+/* Relocate the given object (if it hasn't already been).
+ If LAZY is nonzero, don't relocate its PLT. */
+extern void _dl_relocate_object (struct link_map *map, int lazy);
+
+/* Return the address of the next initializer function not yet run.
+ When there are no more initializers to be run, this returns zero.
+ The functions are returned in the order they should be called. */
+extern Elf32_Addr _dl_init_next (void);
+
+/* Call the finalizer functions of all shared objects whose
+ initializer functions have completed. */
+extern void _dl_fini (void);
+
+/* The dynamic linker calls this function before and having changing
+ any shared object mappings. The `r_state' member of `struct r_debug'
+ says what change is taking place. This function's address is
+ the value of the `r_brk' member. */
+extern void _dl_r_debug_state (void);
+
+
+#endif /* link.h */