bool BacktraceCurrent::ReadWord(uintptr_t ptr, uint32_t* out_value) {
if (!VerifyReadWordArgs(ptr, out_value)) {
return false;
}
const backtrace_map_t* map = FindMap(ptr);
if (map && map->flags & PROT_READ) {
*out_value = *reinterpret_cast<uint32_t*>(ptr);
return true;
} else {
BACK_LOGW("pointer %p not in a readable map", reinterpret_cast<void*>(ptr));
*out_value = static_cast<uint32_t>(-1);
return false;
}
}
bool BacktracePtrace::ReadWord(uintptr_t ptr, word_t* out_value) {
#if defined(__APPLE__)
BACK_LOGW("MacOS does not support reading from another pid.");
return false;
#else
if (!VerifyReadWordArgs(ptr, out_value)) {
return false;
}
backtrace_map_t map;
FillInMap(ptr, &map);
if (!BacktraceMap::IsValid(map) || !(map.flags & PROT_READ)) {
return false;
}
return PtraceRead(Tid(), ptr, out_value);
#endif
}
bool BacktracePtrace::ReadWord(uintptr_t ptr, uint32_t* out_value) {
if (!VerifyReadWordArgs(ptr, out_value)) {
return false;
}
#if defined(__APPLE__)
BACK_LOGW("MacOS does not support reading from another pid.");
return false;
#else
// ptrace() returns -1 and sets errno when the operation fails.
// To disambiguate -1 from a valid result, we clear errno beforehand.
errno = 0;
*out_value = ptrace(PTRACE_PEEKTEXT, Tid(), reinterpret_cast<void*>(ptr), NULL);
if (*out_value == static_cast<uint32_t>(-1) && errno) {
BACK_LOGW("invalid pointer %p reading from tid %d, ptrace() strerror(errno)=%s",
reinterpret_cast<void*>(ptr), Tid(), strerror(errno));
return false;
}
return true;
#endif
}
