[LLDB] Fix Read/Write memory to be compatible with both endians

[mohit.bhakkad]

Summary

While copying a byte, copy a whole byte chunk instead of each bit, to make it compatible with both endians.

[tberghammer]

source/Plugins/Process/Linux/NativeProcessLinux.cpp

2549–2550 ↗

(On Diff #43505)

This will be a buffer overrun if "size % sizeof(long) != 0" (and also violating strict aliasing). I suggest to use memcpy instead what fixes both of these issue.

2601 ↗

(On Diff #43505)

Same here

[mohit.bhakkad]

Addressed comment.

[tberghammer]

LGTM

I can't accept it on the UI because of some bug, but you can commit it without waiting for Greg.

lldb/trunk/source/Plugins/Process/Linux/NativeProcessLinux.cpp

for (bytes_read = 0; bytes_read < size; bytes_read += remainder)
                 ProcessPOSIXLog::DecNestLevel();
             return error;
         }
 
         remainder = size - bytes_read;
         remainder = remainder > k_ptrace_word_size ? k_ptrace_word_size : remainder;
 
         // Copy the data into our buffer
-        for (unsigned i = 0; i < remainder; ++i)
-            dst[i] = ((data >> i*8) & 0xFF);
+        memcpy(dst, &data, remainder);
 
         if (log && ProcessPOSIXLog::AtTopNestLevel() &&
                 (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_LONG) ||
                         (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_SHORT) &&
                                 size <= POSIX_LOG_MEMORY_SHORT_BYTES)))
         {
             uintptr_t print_dst = 0;
             // Format bytes from data by moving into print_dst for log output
NativeProcessLinux::WriteMemory(lldb::addr_t addr, const void *buf, size_t size, size_t &bytes_written)
     for (bytes_written = 0; bytes_written < size; bytes_written += remainder)
     {
         remainder = size - bytes_written;
         remainder = remainder > k_ptrace_word_size ? k_ptrace_word_size : remainder;
 
         if (remainder == k_ptrace_word_size)
         {
             unsigned long data = 0;
-            for (unsigned i = 0; i < k_ptrace_word_size; ++i)
-                data |= (unsigned long)src[i] << i*8;
+            memcpy(&data, src, k_ptrace_word_size);
 
             if (log && ProcessPOSIXLog::AtTopNestLevel() &&
                     (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_LONG) ||
                             (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_SHORT) &&
                                     size <= POSIX_LOG_MEMORY_SHORT_BYTES)))
                 log->Printf ("NativeProcessLinux::%s() [%p]:0x%lx (0x%lx)", __FUNCTION__,
                         (void*)addr, *(const unsigned long*)src, data);