Usenet 1994 January/usenetsourcesnewsgroupsinfomagicjanuary1994.iso/sources/std_unix/volume.31/text0091.txt

Text File | 1993-07-15 | 1.5 KB | 52 lines

Submitted-by: [e-mail] (Eric Blood)

After going over pathconf(), I need something clarified.

In the Posix 1003.1 (90) document the return for pathconf is
documented as follows:

"If 'name' is an invalid value, the pathconf() and fpathconf() functions
shall return -1.

"If the variable corresponding to 'name' has no limit for that path or
file descriptor, the pathconf() and fpathconf() functions shall return
-1 without changing errno."

I have always gone on the assumption that you are never supposed to
set errno.  However, if it is allowed, then pathconf() could be used
as defined.  For example:

...
errno = 0;
if ((foo = pathconf("/tmp/bar", _PC_LINK_MAX)) < 0) {
  if (errno == 0) {
    ... /* No limit */
  } else {
    ... /* Invalid argument */
  }
} else {
  ... /* foo contains a valid limit */
}
...

The documentation for errno (in the same document) is as follows:

"The value of this variable ['errno'] shall be defined only after a
call to a function for which it is explicitly stated to be set and
until it is changed by the next function call.  The variable 'errno'
should only be examined when it is indicated to be valid by a
function's return value.  No function defined in this part of ISO/IEC
9945 sets errno to zero to indicate an error."

Does this mean I'm allowed to set the errno variable or not?  If I'm
able to, then I can use the example code with pathconf().  Otherwise,
what should I do?

--
Eric V. Blood
[e-mail]


Volume-Number: Volume 31, Number 93