Apple

I’ve found what I consider to be a stream IO bug. Here’s what’s happening:

Open a file for writing (using fopen(…, “w”) ) and write some data to the file
Flush the writer using fflush()
Open a second stream to the file for reading only using fopen(…., “r”)
Read some bytes using fseek() & fread() to confirm the reader can see the data written in step 1
Have the writer update 1 byte using fwrite()
Flush the writer using fflush()
Using the read stream, read the byte written by the writer in step 5 using fseek() / fread()
You will get the wrong answer here. The read should return the byte written in step 5 but instead returns the old value written in step 1.

Is this is a bug? Are there any work arounds?

I wrote a simple test case to demonstrate this problem, which passes on Solaris.

Norm Green