[llvm-commits] [llvm] r85922 - /llvm/trunk/lib/Support/MemoryBuffer.cpp

[Dan Gohman]

On Nov 3, 2009, at 12:08 PM, Duncan Sands wrote:

> Hi Dan,
> 
>>> --- llvm/trunk/lib/Support/MemoryBuffer.cpp (original)
>>> +++ llvm/trunk/lib/Support/MemoryBuffer.cpp Tue Nov  3 13:10:22 2009
>>> @@ -226,7 +226,7 @@
>>>  size_t BytesLeft = FileSize;
>>>  while (BytesLeft) {
>>>    ssize_t NumRead = ::read(FD, BufPtr, BytesLeft);
>>> -    if (NumRead != -1) {
>>> +    if (NumRead > 0) {
>>>      BytesLeft -= NumRead;
>>>      BufPtr += NumRead;
>>>    } else if (errno == EINTR) {
>> Given this, the code should explicitly set errno to 0 so that it doesn't
>> infinite loop if it reaches the end of the file and errno happens to
>> have the value EINTR.
> 
> if errno is EINTR, isn't it correct to go around again, even if zero bytes
> were read?

read could return 0 and leave errno unmodified. errno could be set to
EINTR by unrelated code before the first read call. If read keeps
returning 0 for some reason, the code wouldn't recover.

Dan