bool RDebug::Init() {
// The address of '_r_debug' is in the DT_DEBUG entry of the current
// executable.
init_ = true;
size_t dynamic_addr = 0;
size_t dynamic_size = 0;
String path;
// Find the current executable's full path, and its dynamic section
// information.
if (!FindExecutablePath(&path))
return false;
ProcMaps self_maps;
if (!FindElfDynamicSection(
path.c_str(), &self_maps, &dynamic_addr, &dynamic_size)) {
return false;
}
// Parse the dynamic table and find the DT_DEBUG entry.
const ELF::Dyn* dyn_section = reinterpret_cast<const ELF::Dyn*>(dynamic_addr);
while (dynamic_size >= sizeof(*dyn_section)) {
if (dyn_section->d_tag == DT_DEBUG) {
// Found it!
LOG("%s: Found DT_DEBUG entry inside %s at %p, pointing to %p\n",
__FUNCTION__,
path.c_str(),
dyn_section,
dyn_section->d_un.d_ptr);
if (dyn_section->d_un.d_ptr) {
r_debug_ = reinterpret_cast<r_debug*>(dyn_section->d_un.d_ptr);
LOG("%s: r_debug [r_version=%d r_map=%p r_brk=%p r_ldbase=%p]\n",
__FUNCTION__,
r_debug_->r_version,
r_debug_->r_map,
r_debug_->r_brk,
r_debug_->r_ldbase);
// Only version 1 of the struct is supported.
if (r_debug_->r_version != 1) {
LOG("%s: r_debug.r_version is %d, 1 expected.\n",
__FUNCTION__,
r_debug_->r_version);
r_debug_ = NULL;
}
// The linker of recent Android releases maps its link map entries
// in read-only pages. Determine if this is the case and record it
// for later. The first entry in the list corresponds to the
// executable.
int prot = self_maps.GetProtectionFlagsForAddress(r_debug_->r_map);
readonly_entries_ = (prot & PROT_WRITE) == 0;
LOG("%s: r_debug.readonly_entries=%s\n",
__FUNCTION__,
readonly_entries_ ? "true" : "false");
return true;
}
}
dyn_section++;
dynamic_size -= sizeof(*dyn_section);
}
LOG("%s: There is no non-0 DT_DEBUG entry in this process\n", __FUNCTION__);
return false;
}
/*
* vislib::sys::Path::FindExecutablePath
*/
vislib::StringW vislib::sys::Path::FindExecutablePath(
const vislib::StringW& filename) {
#ifdef _WIN32
bool found = false;
DWORD bufSize = MAX_PATH;
wchar_t *buffer = new wchar_t[bufSize];
// first try: "SearchPath"
DWORD rv = ::SearchPathW(NULL, filename.PeekBuffer(), NULL, bufSize,
buffer, NULL);
if (rv > 0) {
found = true;
if (rv + 1 > bufSize) {
bufSize = rv + 1;
delete[] buffer;
buffer = new wchar_t[bufSize];
rv = ::SearchPathW(NULL, filename.PeekBuffer(), NULL, bufSize,
buffer, NULL);
if (rv == 0) { // failed
found = false;
}
}
}
if (!found) {
// second try: "AssocQueryString"
// NOTE:
// AssocQueryString does not work as specified! It is not possible to ask
// for the size of the string buffer holding the value returned. Therefore
// this implementation increases the buffersize until the returned strings
// no longer grow.
DWORD bufLen = MAX_PATH;
HRESULT hr;
bufSize = MAX_PATH;
do {
hr = ::AssocQueryStringW(ASSOCF_INIT_BYEXENAME, ASSOCSTR_EXECUTABLE,
filename.PeekBuffer(), NULL, buffer, &bufSize);
if ((hr != E_POINTER) && (hr != S_OK)) { // error
break;
}
if (bufSize == bufLen) {
bufLen += MAX_PATH;
bufSize = bufLen;
delete[] buffer;
buffer = new wchar_t[bufSize];
} else {
found = true;
}
} while (bufSize == bufLen);
}
if (found) {
vislib::StringW retval(buffer);
delete[] buffer;
return retval;
} else {
return L"";
}
#else /* _WIN32 */
// linux is stupid
return A2W(FindExecutablePath(W2A(filename)));
#endif /* _WIN32 */
}