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Error checking when finding file length using stat

This question is in reference to How can I get a file's size in C?

Most answers suggesting the use of the function stat to get the file length also comes with a tag to do error checking.

What kind of error checking do we need here?

Thanks.

Solution

  • Like many Unix/POSIX API functions, stat(2) returns a negative integer on failure. Unfortunately, this integer is always -1 for stat. Hence, you need to check the errno global variable (defined in <errno.h>) to see what the exact error was.

    Ben has listed some of the errors you can run into; the errno codes for these and other errors are listed in the stat manpage.