coreutils 6.10-2, cygwin 1.5.25-15, cp -af loss of precision in timestamp

[Rob Walker]

I've found that cp -af doesn't preserve the least significant bits of 
the "Modify" field of a file time.

I ran into this issue while using "cp -af" to install files via GNU make.

Simple makefile:

    there.txt: hi.txt
        cp -af hi.txt there.txt

The above makefile never manages to finish updating there.txt if hi.txt 
has a finely grained timestamp, as hi.txt does below:

rwalker@pariah> stat hi.txt       
  File: `hi.txt'
  Size: 0               Blocks: 0          IO Block: 65536  regular 
empty file
Device: 27537939h/659781945d    Inode: 15199648742824059  Links: 1
Access: (0666/-rw-rw-rw-)  Uid: ( 1005/ rwalker)   Gid: (  513/    None)
Access: 2009-12-07 17:00:05.490875000 -0800
Modify: 2009-12-07 17:25:09.084000200 -0800
Change: 2009-12-08 09:29:04.756500000 -0800

After running make with the above makefile:

rwalker@pariah> stat there.txt
  File: `there.txt'
  Size: 0               Blocks: 0          IO Block: 65536  regular 
empty file
Device: 27537939h/659781945d    Inode: 17451448556568056  Links: 1
Access: (0666/-rw-rw-rw-)  Uid: ( 1005/ rwalker)   Gid: (  513/    None)
Access: 2009-12-07 17:00:05.490875000 -0800
Modify: 2009-12-07 17:25:09.084000000 -0800
Change: 2009-12-08 09:37:45.600250000 -0800

Note that Modify differs only in the 3 least significant digits (200 on 
foo.txt, 000 on there.txt).

Taking make out of the equation changes nothing.

Ending up with a file with a time stamp of the above fine-grained form 
is somewhat rare, I had to write a short Windows program to induce it.

Thanks in advance for any help.

-Rob







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