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/*
* Copyright (c) 2011, 2017, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code 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 General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#ifdef __APPLE__
#include "decoder_machO.hpp"
#include "jvm.h"
#include "memory/allocation.inline.hpp"
#include <cxxabi.h>
#include <mach-o/loader.h>
#include <mach-o/nlist.h>
bool MachODecoder::demangle(const char* symbol, char *buf, int buflen) {
int status;
char* result;
size_t size = (size_t)buflen;
// Don't pass buf to __cxa_demangle. In case of the 'buf' is too small,
// __cxa_demangle will call system "realloc" for additional memory, which
// may use different malloc/realloc mechanism that allocates 'buf'.
if ((result = abi::__cxa_demangle(symbol, NULL, NULL, &status)) != NULL) {
jio_snprintf(buf, buflen, "%s", result);
// call c library's free
::free(result);
return true;
}
return false;
}
bool MachODecoder::decode(address addr, char *buf,
int buflen, int *offset, const void *mach_base) {
if (addr == (address)(intptr_t)-1) {
// dladdr() in macOS12/Monterey returns success for -1, but that addr value
// won't work in this function. Should have been handled by the caller.
ShouldNotReachHere();
return false;
}
struct symtab_command * symt = (struct symtab_command *)
mach_find_command((struct mach_header_64 *)mach_base, LC_SYMTAB);
if (symt == NULL) {
DEBUG_ONLY(tty->print_cr("no symtab in mach file at 0x%lx", p2i(mach_base)));
return false;
}
uint32_t off = symt->symoff; /* symbol table offset (within this mach file) */
uint32_t nsyms = symt->nsyms; /* number of symbol table entries */
uint32_t stroff = symt->stroff; /* string table offset */
uint32_t strsize = symt->strsize; /* string table size in bytes */
// iterate through symbol table trying to match our offset
uint32_t addr_relative = (uintptr_t) mach_base - (uintptr_t) addr; // offset we seek in the symtab
void * symtab_addr = (void*) ((uintptr_t) mach_base + off);
struct nlist_64 *cur_nlist = (struct nlist_64 *) symtab_addr;
struct nlist_64 *last_nlist = cur_nlist; // no size stored in an entry, so keep previously seen nlist
int32_t found_strx = 0;
int32_t found_symval = 0;
for (uint32_t i=0; i < nsyms; i++) {
uint32_t this_value = cur_nlist->n_value;
if (addr_relative == this_value) {
found_strx = cur_nlist->n_un.n_strx;
found_symval = this_value;
break;
} else if (addr_relative > this_value) {
// gone past it, use previously seen nlist:
found_strx = last_nlist->n_un.n_strx;
found_symval = last_nlist->n_value;
break;
}
last_nlist = cur_nlist;
cur_nlist = cur_nlist + sizeof(struct nlist_64);
}
if (found_strx == 0) {
return false;
}
// write the offset:
*offset = addr_relative - found_symval;
// lookup found_strx in the string table
char * symname = mach_find_in_stringtable((char*) ((uintptr_t)mach_base + stroff), strsize, found_strx);
if (symname) {
strncpy(buf, symname, buflen);
buf[buflen - 1] = '\0';
return true;
}
DEBUG_ONLY(tty->print_cr("no string or null string found."));
return false;
}
void* MachODecoder::mach_find_command(struct mach_header_64 * mach_base, uint32_t command_wanted) {
// possibly verify it is a mach_header, use magic number.
// commands begin immediately after the header.
struct load_command *pos = (struct load_command *) mach_base + sizeof(struct mach_header_64);
for (uint32_t i = 0; i < mach_base->ncmds; i++) {
struct load_command *this_cmd = (struct load_command *) pos;
if (this_cmd->cmd == command_wanted) {
return pos;
}
int cmdsize = this_cmd->cmdsize;
pos += cmdsize;
}
return NULL;
}
char* MachODecoder::mach_find_in_stringtable(char *strtab, uint32_t tablesize, int strx_wanted) {
if (strx_wanted == 0) {
return NULL;
}
char *strtab_end = strtab + tablesize;
// find the first string, skip over the space char
// (or the four zero bytes we see e.g. in libclient)
if (*strtab == ' ') {
strtab++;
if (*strtab != 0) {
DEBUG_ONLY(tty->print_cr("string table has leading space but no following zero."));
return NULL;
}
strtab++;
} else {
if ((uint32_t) *strtab != 0) {
DEBUG_ONLY(tty->print_cr("string table without leading space or leading int of zero."));
return NULL;
}
strtab+=4;
}
// read the real strings starting at index 1
int cur_strx = 1;
while (strtab < strtab_end) {
if (cur_strx == strx_wanted) {
return strtab;
}
// find start of next string
while (*strtab != 0) {
strtab++;
}
strtab++; // skip the terminating zero
cur_strx++;
}
DEBUG_ONLY(tty->print_cr("string number %d not found.", strx_wanted));
return NULL;
}
#endif
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