15 Aug
2016
15 Aug
'16
10:56 p.m.
On 15 Aug 2016 11:14 -0400, from random832(a)fastmail.com (Random832):
On Mon, Aug 15, 2016, at 10:04, Noel Chiappa wrote:
On Linux/glibc, based on the fstat(2) man page, it looks like the size
field is undefined for a FIFO:
But back to the original topic, it sounds like
there's a huge amount
of variance in the semantics of doing fstat() on a pipe. V6 doesn't
special-case it in any way, but it sounds as if other systems do.
I expect that the single important thing, the only thing that most
applications will rely on, is it returning successfully and indicating
that the file type is fifo. The st_size field gives the size of the file (if it is
a regular
file or a symbolic link) in bytes. The size of a symbolic link is
the length of the pathname it contains, without a terminating null
byte.
The mode field is used to hold the type of file:
The following POSIX macros are defined to check the
file type using
the st_mode field:
...
S_ISFIFO(m) FIFO (named pipe)?
...
The following flags are defined for the st_mode field:
...
S_IFIFO 0010000 FIFO
...
The above from Debian Wheezy.
--
Michael Kjörling • https://michael.kjorling.se • michael(a)kjorling.se
“People who think they know everything really annoy
those of us who know we don’t.” (Bjarne Stroustrup)