/*
* tkMacOSXDebug.c --
*
* Implementation of Macintosh specific functions for debugging MacOS
* events, regions, etc...
*
* Copyright 2001-2009, Apple Inc.
* Copyright (c) 2006-2009 Daniel A. Steffen <[email protected]>
*
* See the file "license.terms" for information on usage and redistribution
* of this file, and for a DISCLAIMER OF ALL WARRANTIES.
*/
#include "tkMacOSXPrivate.h"
#include "tkMacOSXDebug.h"
#ifdef TK_MAC_DEBUG
#include <mach-o/dyld.h>
#include <mach-o/nlist.h>
/*
*----------------------------------------------------------------------
*
* TkMacOSXGetNamedDebugSymbol --
*
* Dynamically acquire address of a named symbol from a loaded dynamic
* library, so that we can use API that may not be available on all OS
* versions. For debugging purposes, if we cannot find the symbol with
* the usual dynamic library APIs, we manually walk the symbol table of
* the loaded library. This allows access to unexported symbols such as
* private_extern internal debugging functions. If module is NULL or the
* empty string, search all loaded libraries (could be very expensive and
* should be avoided).
*
* THIS FUCTION IS ONLY TO BE USED FOR DEBUGGING PURPOSES, IT MAY BREAK
* UNEXPECTEDLY IN THE FUTURE!
*
* Results:
* Address of given symbol or NULL if unavailable.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
MODULE_SCOPE void *
TkMacOSXGetNamedDebugSymbol(
const char *module,
const char *symbol)
{
void *addr = TkMacOSXGetNamedSymbol(module, symbol);
#ifndef __LP64__
if (!addr) {
const struct mach_header *mh = NULL;
uint32_t i, n = _dyld_image_count();
size_t module_len = 0;
if (module && *module) {
module_len = strlen(module);
}
for (i = 0; i < n; i++) {
if (module && *module) {
/* Find image with given module name */
const char *name;
const char *path = _dyld_get_image_name(i);
if (!path) {
continue;
}
name = strrchr(path, '/') + 1;
if (strncmp(name, module, module_len) != 0) {
continue;
}
}
mh = _dyld_get_image_header(i);
if (mh) {
struct load_command *lc;
struct symtab_command *st = NULL;
struct segment_command *sg = NULL;
uint32_t j, m, nsect = 0, txtsectx = 0;
lc = (struct load_command*)((const char*) mh +
sizeof(struct mach_header));
m = mh->ncmds;
for (j = 0; j < m; j++) {
/* Find symbol table and index of __text section */
if (lc->cmd == LC_SEGMENT) {
/* Find last segment before symbol table */
sg = (struct segment_command*) lc;
if (!txtsectx) {
/* Count total sections until (__TEXT, __text) */
uint32_t k, ns = sg->nsects;
if (strcmp(sg->segname, SEG_TEXT) == 0) {
struct section *s = (struct section *)(
(char *)sg +
sizeof(struct segment_command));
for(k = 0; k < ns; k++) {
if (strcmp(s->sectname, SECT_TEXT) == 0) {
txtsectx = nsect+k+1;
break;
}
s++;
}
}
nsect += ns;
}
} else if (!st && lc->cmd == LC_SYMTAB) {
st = (struct symtab_command *) lc;
break;
}
lc = (struct load_command *)((char *) lc + lc->cmdsize);
}
if (st && sg && txtsectx) {
intptr_t base, slide = _dyld_get_image_vmaddr_slide(i);
char *strings;
struct nlist *sym;
uint32_t strsize = st->strsize;
int32_t strx;
/*
* Offset file positions by difference to actual position
* in memory of last segment before symbol table:
*/
base = (intptr_t) sg->vmaddr + slide - sg->fileoff;
strings = (char *) (base + st->stroff);
sym = (struct nlist *) (base + st->symoff);
m = st->nsyms;
for (j = 0; j < m; j++) {
/* Find symbol with given name in __text section */
strx = sym->n_un.n_strx;
if ((sym->n_type & N_TYPE) == N_SECT &&
sym->n_sect == txtsectx &&
strx > 0 && (uint32_t) strx < strsize &&
strcmp(strings + strx, symbol) == 0) {
addr = (char*) sym->n_value + slide;
break;
}
sym++;
}
}
}
if (module && *module) {
/* If given a module name, only search corresponding image */
break;
}
}
}
#endif /* __LP64__ */
return addr;
}
#endif /* TK_MAC_DEBUG */
/*
* Local Variables:
* mode: objc
* c-basic-offset: 4
* fill-column: 79
* coding: utf-8
* End:
*/
