using lstat st_mode flags

This is a discussion on using lstat st_mode flags within the Linux Programming forums, part of the Platform Specific Boards category; hello everybody! i am a bit confused about the way the flags and masks defined for st_mode have to be ...

  1. #1
    Registered User
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    using lstat st_mode flags

    hello everybody!
    i am a bit confused about the way the flags and masks defined for st_mode have to be used..
    Suppose that I lstat-ed a file and want to retrieve first is permission in numeric format (eg 755) and then simply check if the owner has execute permission..
    In the second simplier case, I shall write something like:

    Code:
    if( (statbuff.st_mode & S_IRWXU) && S_IXUSR )
    isn't it?

    in the second case,isn't there a faster way to get the numbers 7 5 5 than making all the comparisons possible?


    thanks! Bye
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  2. #2
    Cat without Hat CornedBee's Avatar
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    and want to retrieve first is permission in numeric format (eg 755)
    What?

    (statbuff.st_mode & S_IRWXU) && S_IXUSR
    Assuming that S_IRWXU is a bitmask, this checks if any of those bits are set in st_mode and also if the constant S_IXUSR has a value other than 0 (I assume it has).
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

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