Front page | perl.beginners |
Postings from December 2011
frank cui wrote: > Thanks John and Peter for the reply. > > Ok, to make this question more specific, the author of this book is making > a program to check if the files can be read off from the disk. > And he does so by checking two steps, first is making sure the meta data of > this file looks fine, Yes, but the stat fields he checks could be valid and still all have the value of zero. I would expect that only fields 0, 1 and 12 (DEV, INO and MODE) would normally be non-zero. > and secondly by reading byte by byte from this file > to actually check the file's content readability. You would probably only need to read one byte to see if the file is readable. He is checking that the operating system returns the same number of bytes that stat says the file contains. And you couldn't confirm that by seeking to the end of the file and reading one byte because there may be invalid disk sectors in the middle of the file that are unreadable. John -- Any intelligent fool can make things bigger and more complex... It takes a touch of genius - and a lot of courage to move in the opposite direction. -- Albert EinsteinThread Previous | Thread Next