Fix bugs in piod_len return value processing in ReadMemory()
and WriteMemory() methods. In particular, add support for piod_len == 0
indicating EOF, and fix summing bytes_read/bytes_written when PT_IO does
partial reads/writes.
The EOF condition could happen if LLDB attempts to read past
vm.maxaddress, e.g. as a result of RBP containing large (invalid) value.
Previously, the 0 return caused the function to retry reading via PT_IO
indefinitely, effectively deadlooping lldb-server.
Partial reads probably did not occur in practice, yet they would cause
ReadMemory() to return incorrect bytes_read and/or overwrite previously
read data.
WriteMemory() suffered from analoguous problems.
Differential Revision: https://reviews.llvm.org/D61310
llvm-svn: 359572
io.piod_addr = dst + bytes_read;
Status error = NativeProcessNetBSD::PtraceWrapper(PT_IO, GetID(), &io);
- if (error.Fail())
+ if (error.Fail() || io.piod_len == 0)
return error;
- bytes_read = io.piod_len;
+ bytes_read += io.piod_len;
io.piod_len = size - bytes_read;
} while (bytes_read < size);
io.piod_offs = (void *)(addr + bytes_written);
Status error = NativeProcessNetBSD::PtraceWrapper(PT_IO, GetID(), &io);
- if (error.Fail())
+ if (error.Fail() || io.piod_len == 0)
return error;
- bytes_written = io.piod_len;
+ bytes_written += io.piod_len;
io.piod_len = size - bytes_written;
} while (bytes_written < size);