Aren
/
NetBSD
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Separate matched symbol functionality out of _rtld_symlook_obj() 

Simplifies the code and it will allow to use the matched symbol
functionality by other users.
This commit is contained in:
kamil 2020-02-29 04:21:42 +00:00
parent 8ad57d4b7d
commit e5a904478f
1 changed files with 118 additions and 103 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

221
libexec/ld.elf_so/symbol.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: symbol.c,v 1.69 2017/08/09 18:44:32 joerg Exp $ */
/* $NetBSD: symbol.c,v 1.70 2020/02/29 04:21:42 kamil Exp $ */
/*
* Copyright 1996 John D. Polstra.
@ -40,7 +40,7 @@
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: symbol.c,v 1.69 2017/08/09 18:44:32 joerg Exp $");
__RCSID("$NetBSD: symbol.c,v 1.70 2020/02/29 04:21:42 kamil Exp $");
#endif /* not lint */
#include <err.h>
@ -193,6 +193,119 @@ _rtld_symlook_needed(const char *name, unsigned long hash,
return def;
}
static bool
_rtld_symlook_obj_matched_symbol(const char *name,
const Obj_Entry *obj, u_int flags, const Ver_Entry *ventry,
unsigned long symnum, const Elf_Sym **vsymp, int *vcount)
{
const Elf_Sym *symp;
const char *strp;
Elf_Half verndx;
symp = obj->symtab + symnum;
strp = obj->strtab + symp->st_name;
rdbg(("check \"%s\" vs \"%s\" in %s", name, strp, obj->path));
if (name[1] != strp[1] || strcmp(name, strp))
return false;
#if defined(__mips__) || defined(__vax__)
if (symp->st_shndx == SHN_UNDEF)
continue;
#else
/*
* XXX DANGER WILL ROBINSON!
* If we have a function pointer in the executable's
* data section, it points to the executable's PLT
* slot, and there is NO relocation emitted. To make
* the function pointer comparable to function pointers
* in shared libraries, we must resolve data references
* in the libraries to point to PLT slots in the
* executable, if they exist.
*/
if (symp->st_shndx == SHN_UNDEF &&
((flags & SYMLOOK_IN_PLT) ||
symp->st_value == 0 ||
ELF_ST_TYPE(symp->st_info) != STT_FUNC))
return false;
#endif
if (ventry == NULL) {
if (obj->versyms != NULL) {
verndx = VER_NDX(obj->versyms[symnum].vs_vers);
if (verndx > obj->vertabnum) {
_rtld_error("%s: symbol %s references "
"wrong version %d", obj->path,
&obj->strtab[symnum], verndx);
return false;
}
/*
* If we are not called from dlsym (i.e. this
* is a normal relocation from unversioned
* binary), accept the symbol immediately
* if it happens to have first version after
* this shared object became versioned.
* Otherwise, if symbol is versioned and not
* hidden, remember it. If it is the only
* symbol with this name exported by the shared
* object, it will be returned as a match at the
* end of the function. If symbol is global
* (verndx < 2) accept it unconditionally.
*/
if (!(flags & SYMLOOK_DLSYM) &&
verndx == VER_NDX_GIVEN) {
*vsymp = symp;
return true;
} else if (verndx >= VER_NDX_GIVEN) {
if (!(obj->versyms[symnum].vs_vers & VER_NDX_HIDDEN)) {
if (*vsymp == NULL)
*vsymp = symp;
(*vcount)++;
}
return false;
}
}
*vsymp = symp;
return true;
} else {
if (obj->versyms == NULL) {
if (_rtld_object_match_name(obj, ventry->name)){
_rtld_error("%s: object %s should "
"provide version %s for symbol %s",
_rtld_objself.path, obj->path,
ventry->name, &obj->strtab[symnum]);
return false;
}
} else {
verndx = VER_NDX(obj->versyms[symnum].vs_vers);
if (verndx > obj->vertabnum) {
_rtld_error("%s: symbol %s references "
"wrong version %d", obj->path,
&obj->strtab[symnum], verndx);
return false;
}
if (obj->vertab[verndx].hash != ventry->hash ||
strcmp(obj->vertab[verndx].name, ventry->name)) {
/*
* Version does not match. Look if this
* is a global symbol and if it is not
* hidden. If global symbol (verndx < 2)
* is available, use it. Do not return
* symbol if we are called by dlvsym,
* because dlvsym looks for a specific
* version and default one is not what
* dlvsym wants.
*/
if ((flags & SYMLOOK_DLSYM) ||
(obj->versyms[symnum].vs_vers & VER_NDX_HIDDEN) ||
(verndx >= VER_NDX_GIVEN))
return false;
}
}
*vsymp = symp;
return true;
}
}
/*
* Search the symbol table of a single shared object for a symbol of
* the given name. Returns a pointer to the symbol, or NULL if no
@ -207,115 +320,17 @@ _rtld_symlook_obj(const char *name, unsigned long hash,
{
unsigned long symnum;
const Elf_Sym *vsymp = NULL;
Elf_Half verndx;
int vcount = 0;
for (symnum = obj->buckets[fast_remainder32(hash, obj->nbuckets,
obj->nbuckets_m, obj->nbuckets_s1, obj->nbuckets_s2)];
symnum != ELF_SYM_UNDEFINED;
symnum = obj->chains[symnum]) {
const Elf_Sym *symp;
const char *strp;
assert(symnum < obj->nchains);
symp = obj->symtab + symnum;
strp = obj->strtab + symp->st_name;
rdbg(("check \"%s\" vs \"%s\" in %s", name, strp, obj->path));
if (name[1] != strp[1] || strcmp(name, strp))
continue;
#if defined(__mips__) || defined(__vax__)
if (symp->st_shndx == SHN_UNDEF)
continue;
#else
/*
* XXX DANGER WILL ROBINSON!
* If we have a function pointer in the executable's
* data section, it points to the executable's PLT
* slot, and there is NO relocation emitted. To make
* the function pointer comparable to function pointers
* in shared libraries, we must resolve data references
* in the libraries to point to PLT slots in the
* executable, if they exist.
*/
if (symp->st_shndx == SHN_UNDEF &&
((flags & SYMLOOK_IN_PLT) ||
symp->st_value == 0 ||
ELF_ST_TYPE(symp->st_info) != STT_FUNC))
continue;
#endif
if (ventry == NULL) {
if (obj->versyms != NULL) {
verndx = VER_NDX(obj->versyms[symnum].vs_vers);
if (verndx > obj->vertabnum) {
_rtld_error("%s: symbol %s references "
"wrong version %d", obj->path,
&obj->strtab[symnum], verndx);
continue;
}
/*
* If we are not called from dlsym (i.e. this
* is a normal relocation from unversioned
* binary), accept the symbol immediately
* if it happens to have first version after
* this shared object became versioned.
* Otherwise, if symbol is versioned and not
* hidden, remember it. If it is the only
* symbol with this name exported by the shared
* object, it will be returned as a match at the
* end of the function. If symbol is global
* (verndx < 2) accept it unconditionally.
*/
if (!(flags & SYMLOOK_DLSYM) &&
verndx == VER_NDX_GIVEN) {
return symp;
} else if (verndx >= VER_NDX_GIVEN) {
if (!(obj->versyms[symnum].vs_vers & VER_NDX_HIDDEN)) {
if (vsymp == NULL)
vsymp = symp;
vcount++;
}
continue;
}
}
return symp;
} else {
if (obj->versyms == NULL) {
if (_rtld_object_match_name(obj, ventry->name)){
_rtld_error("%s: object %s should "
"provide version %s for symbol %s",
_rtld_objself.path, obj->path,
ventry->name, &obj->strtab[symnum]);
continue;
}
} else {
verndx = VER_NDX(obj->versyms[symnum].vs_vers);
if (verndx > obj->vertabnum) {
_rtld_error("%s: symbol %s references "
"wrong version %d", obj->path,
&obj->strtab[symnum], verndx);
continue;
}
if (obj->vertab[verndx].hash != ventry->hash ||
strcmp(obj->vertab[verndx].name, ventry->name)) {
/*
* Version does not match. Look if this
* is a global symbol and if it is not
* hidden. If global symbol (verndx < 2)
* is available, use it. Do not return
* symbol if we are called by dlvsym,
* because dlvsym looks for a specific
* version and default one is not what
* dlvsym wants.
*/
if ((flags & SYMLOOK_DLSYM) ||
(obj->versyms[symnum].vs_vers & VER_NDX_HIDDEN) ||
(verndx >= VER_NDX_GIVEN))
continue;
}
}
return symp;
if (_rtld_symlook_obj_matched_symbol(name, obj, flags,
ventry, symnum, &vsymp, &vcount)) {
return vsymp;
}
}
if (vcount == 1)