04-25-2007
locate holes in a sparse file.
Lets say my program reads one block (4096 bytes) at a time from a file. It needs to report whether that block is a hole.
The program currently uses read() to read 1 block into a 4KB buffer.
Now I know that even if that block is a hole, it will be replaced by a sequence of NULL bytes '\0' when read into a buffer. And there is no way to detect if a particular block is a hole.
So for every block thats read in I will need to check if it contains consecutive stretches of zeros, and if so then report it as a hole.
Can anyone think of a way to do this ???
(yes I know that incase that block was not a hole but actually had sequence of zeros stored, my program will incorrectly report it as a hole)
Thanks
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