filestat.par.lib

su 的源代码库

FILESTAT - Functions to determine and output the type of a file from file
		 descriptor

filestat - determine type of file from file descriptor
printstat - print the FileType as a string

Function Prototypes:
FileType filestat(int fd);
char *printstat(int fd);

filestat:
Input:
fd		file descriptor

Returns:	FileType filestat(fd)

printstat:
Input:
fd		file descriptor

Returns:	char *printstat(fd)

Notes:

Example:
	FileType ftype;
	...
	ftype = filestat(STDOUT)
	if (ftype = TTY) {
		...


BADFILETYPE is the error return and it is up to the calling program to
check for it.

FileType is defined in par.h as:
typedef enum {BADFILETYPE = -1,
   TTY, DISK, DIRECTORY, TAPE, PIPE, FIFO, SOCKET, SYMLINK} FileType;

SOCKETS and SYMLINKS are unlikely to be used.

Rochkind's Advanced Unix Programming assures us that the link count
for a pipe is 0.  But it's an old book.  It seems that PIPES are
sometimes implemented as FIFOs.  In most cases, the number of links for
a pipe is 0, even so.  But on NeXT (at least) the link count is 1.
In the code, I test for PIPE first and FIFO second, so for a PIPE
you'll actually get FIFO on machines that do it NeXT's way.

Portability: the code assumes that /dev/rmt0 and /dev/mt0
are tape devices on your system.  If not, make the obvious changes.
dev/null is handled as a special case and classified as a disk file.

The check on tapes allows either the raw or buffered version.
This is moot and easily changed.

If new types are added, the typedef "FileType" in par.h must be extended.


Authors:
SEP: Einar Kjartansson , Stew Levin
CWP: Jack Cohen