xash3d-fwgs/engine/platform/android/dlsym-weak.cpp

99 lines
3.4 KiB
C++

/*
* Copyright (C) 2008, 2009 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if defined __ANDROID__ && !defined XASH_64BIT
#include <string.h>
#include <android/log.h>
#include "linker.h"
static Elf_Sym* soinfo_elf_lookup(soinfo* si, unsigned hash, const char* name) {
Elf_Sym* symtab = si->symtab;
const char* strtab = si->strtab;
if( si->nbucket == 0 )
return NULL;
for (unsigned n = si->bucket[hash % si->nbucket]; n != 0; n = si->chain[n]) {
Elf_Sym* s = symtab + n;
if (strcmp(strtab + s->st_name, name)) continue;
/* only concern ourselves with global and weak symbol definitions */
switch (ELF_ST_BIND(s->st_info)) {
case STB_GLOBAL:
case STB_WEAK:
if (s->st_shndx == SHN_UNDEF) {
continue;
}
return s;
}
}
return NULL;
}
static unsigned elfhash(const char* _name) {
const unsigned char* name = (const unsigned char*) _name;
unsigned h = 0, g;
while(*name) {
h = (h << 4) + *name++;
g = h & 0xf0000000;
h ^= g;
h ^= g >> 24;
}
return h;
}
/* This is used by dlsym(3). It performs symbol lookup only within the
specified soinfo object and not in any of its dependencies.
TODO: Only looking in the specified soinfo seems wrong. dlsym(3) says
that it should do a breadth first search through the dependency
tree. This agrees with the ELF spec (aka System V Application
Binary Interface) where in Chapter 5 it discuss resolving "Shared
Object Dependencies" in breadth first search order.
*/
static Elf_Sym* dlsym_handle_lookup(soinfo* si, const char* name) {
return soinfo_elf_lookup(si, elfhash(name), name);
}
extern "C" void* dlsym_weak(void* handle, const char* symbol) {
soinfo* found = NULL;
Elf_Sym* sym = NULL;
found = reinterpret_cast<soinfo*>(handle);
sym = dlsym_handle_lookup(found, symbol);
if (sym != NULL) {
return reinterpret_cast<void*>(sym->st_value + found->base/*load_bias*/);
}
__android_log_print(ANDROID_LOG_ERROR, "dlsym-weak", "Failed when looking up %s\n", symbol);
return NULL;
}
#endif