d3980376e8
functions to be used by the dynamic linker. This can be called by threads packages at start-up time. I will add the call to libc_r soon. Also add a default locking method that is used up until dllockinit() is called. The default method works by blocking SIGVTALRM, SIGPROF, and SIGALRM in critical sections. It is based on the observation that most user-space threads packages implement thread preemption with one of these signals (usually SIGVTALRM). The dynamic linker has never been reentrant, but it became less reentrant in revision 1.34 of "src/libexec/rtld-elf/rtld.c". Starting with that revision, multiple threads each doing lazy binding could interfere with each other. The usual symptom was that a symbol was falsely reported as undefined at start-up time. It was rare but not unseen. This commit fixes it.
173 lines
6.4 KiB
C
173 lines
6.4 KiB
C
/*-
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* Copyright 1996-1998 John D. Polstra.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef RTLD_H /* { */
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#define RTLD_H 1
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#include <sys/types.h>
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#include <sys/queue.h>
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#include <link.h>
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#include <elf.h>
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#include <stddef.h>
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#include "rtld_machdep.h"
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#ifndef STANDARD_LIBRARY_PATH
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#define STANDARD_LIBRARY_PATH "/usr/lib/elf:/usr/lib"
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#endif
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#define NEW(type) ((type *) xmalloc(sizeof(type)))
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#define CNEW(type) ((type *) xcalloc(sizeof(type)))
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/* We might as well do booleans like C++. */
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typedef unsigned char bool;
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#define false 0
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#define true 1
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struct stat;
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struct Struct_Obj_Entry;
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typedef struct Struct_Objlist_Entry {
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STAILQ_ENTRY(Struct_Objlist_Entry) link;
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struct Struct_Obj_Entry *obj;
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} Objlist_Entry;
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typedef STAILQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
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typedef struct Struct_Needed_Entry {
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struct Struct_Needed_Entry *next;
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struct Struct_Obj_Entry *obj;
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unsigned long name; /* Offset of name in string table */
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} Needed_Entry;
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/*
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* Shared object descriptor.
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*
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* Items marked with "(%)" are dynamically allocated, and must be freed
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* when the structure is destroyed.
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*
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* CAUTION: It appears that the JDK port peeks into these structures.
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* It looks at "next" and "mapbase" at least. Don't add new members
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* near the front, until this can be straightened out.
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*/
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typedef struct Struct_Obj_Entry {
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/*
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* These two items have to be set right for compatibility with the
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* original ElfKit crt1.o.
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*/
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Elf_Word magic; /* Magic number (sanity check) */
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Elf_Word version; /* Version number of struct format */
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struct Struct_Obj_Entry *next;
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char *path; /* Pathname of underlying file (%) */
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int refcount;
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int dl_refcount; /* Number of times loaded by dlopen */
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/* These items are computed by map_object() or by digest_phdr(). */
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caddr_t mapbase; /* Base address of mapped region */
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size_t mapsize; /* Size of mapped region in bytes */
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size_t textsize; /* Size of text segment in bytes */
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Elf_Addr vaddrbase; /* Base address in shared object file */
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caddr_t relocbase; /* Relocation constant = mapbase - vaddrbase */
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const Elf_Dyn *dynamic; /* Dynamic section */
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caddr_t entry; /* Entry point */
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const Elf_Phdr *phdr; /* Program header if it is mapped, else NULL */
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size_t phsize; /* Size of program header in bytes */
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const char *interp; /* Pathname of the interpreter, if any */
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/* Items from the dynamic section. */
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Elf_Addr *pltgot; /* PLT or GOT, depending on architecture */
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const Elf_Rel *rel; /* Relocation entries */
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unsigned long relsize; /* Size in bytes of relocation info */
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const Elf_Rela *rela; /* Relocation entries with addend */
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unsigned long relasize; /* Size in bytes of addend relocation info */
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const Elf_Rel *pltrel; /* PLT relocation entries */
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unsigned long pltrelsize; /* Size in bytes of PLT relocation info */
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const Elf_Rela *pltrela; /* PLT relocation entries with addend */
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unsigned long pltrelasize; /* Size in bytes of PLT addend reloc info */
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const Elf_Sym *symtab; /* Symbol table */
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const char *strtab; /* String table */
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unsigned long strsize; /* Size in bytes of string table */
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const Elf_Addr *buckets; /* Hash table buckets array */
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unsigned long nbuckets; /* Number of buckets */
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const Elf_Addr *chains; /* Hash table chain array */
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unsigned long nchains; /* Number of chains */
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const char *rpath; /* Search path specified in object */
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Needed_Entry *needed; /* Shared objects needed by this one (%) */
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void (*init)(void); /* Initialization function to call */
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void (*fini)(void); /* Termination function to call */
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bool mainprog; /* True if this is the main program */
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bool rtld; /* True if this is the dynamic linker */
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bool textrel; /* True if there are relocations to text seg */
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bool symbolic; /* True if generated with "-Bsymbolic" */
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bool traced; /* Already printed in ldd trace output */
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struct link_map linkmap; /* for GDB */
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Objlist dldags; /* Object belongs to these dlopened DAGs (%) */
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Objlist dagmembers; /* DAG has these members (%) */
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dev_t dev; /* Object's filesystem's device */
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ino_t ino; /* Object's inode number */
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unsigned long mark; /* Set to "curmark" to avoid repeat visits */
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} Obj_Entry;
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#define RTLD_MAGIC 0xd550b87a
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#define RTLD_VERSION 1
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extern void _rtld_error(const char *, ...) __printflike(1, 2);
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extern Obj_Entry *map_object(int, const char *, const struct stat *);
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extern void *xcalloc(size_t);
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extern void *xmalloc(size_t);
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extern char *xstrdup(const char *);
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extern Elf_Addr _GLOBAL_OFFSET_TABLE_[];
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/*
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* Function declarations.
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*/
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int do_copy_relocations(Obj_Entry *);
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unsigned long elf_hash(const char *);
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const Elf_Sym *find_symdef(unsigned long, Obj_Entry *, const Obj_Entry **,
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bool);
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void init_pltgot(Obj_Entry *);
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void lockdflt_acquire(void *);
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void *lockdflt_create(void *);
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void lockdflt_destroy(void *);
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void lockdflt_release(void *);
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void obj_free(Obj_Entry *);
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Obj_Entry *obj_new(void);
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int reloc_non_plt(Obj_Entry *, Obj_Entry *);
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int reloc_plt(Obj_Entry *, bool);
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void _rtld_bind_start(void);
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const Elf_Sym *symlook_obj(const char *, unsigned long,
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const Obj_Entry *, bool);
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#endif /* } */
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