Hi Christoph,
On Tuesday 24 April 2018 04:45 PM, Langer, Christoph wrote:
Hi Vyom,
I think, it is intentional to handle case where return "hostname" is to large to
fit in array. if you see the man page(http://man7.org/linux/man-
pages/man2/gethostname.2.html) it says that it is unspecified whether
returned buffer includes a terminating null byte.
current code will put null in case of large "hostname", What do you think ?
yes, I had read the man page and saw this point of the spec. But exactly for
this purpose there's this code:
// make sure string is null-terminated
hostname[NI_MAXHOST] = '\0';
If we only hand 'NI_MAXHOST' as size value into gethostname, then the function
might only write NI_MAXHOST - 1 characters of the hostname into the buffer.
doc says it will copy len bytes into buffer and will not copy null
character into the buffer.
################################
*C library/kernel differences*
The GNU C library does not employ the*gethostname*() system call;
instead, it implements*gethostname*() as a library function that calls
uname(2) <http://man7.org/linux/man-pages/man2/uname.2.html> and copies
up to/len/ bytes from the returned/nodename/ field
into/name/. Having performed the copy, the function then checks if
the length of the/nodename/ was greater than or equal to/len/, and if
it is, then the function returns -1 with/errno
<http://man7.org/linux/man-pages/man3/errno.3.html>/ set to*ENAMETOOLONG*;
in this case, a terminating null byte is not included in the returned
/name/.
############################################################
Just for curiosity, are we facing any issues with the current code ?. Your code
change looks logical but if nothing is broken then why to change code.
Thanks,
Vyom
Best regards
Christoph
