Manpage of ISASTREAM

ISASTREAM

Section: The OpenSS7 Project System Calls (2)
Updated: Sat, 18 May 2013 11:02:09 GMT
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NAME

isastream - test for a STREAMS special file

SYNOPSIS

#include <stropts.h>

int isastream(int fd);

ARGUMENTS

fd: the file descriptor to test.

DESCRIPTION

isastream() tests whether the open file associated with the file descriptor, fd, is a STREAMS special file.

USAGE

isastream() is normally used by an applications program to determine whether STREAMS input-output controls, streamio(7), are possible on a specific special file, fd. For example, isastream() can be used to determine whether the pipe returned by a call to pipe(2s) is a STREAMS-based pipe or a SVR 3-style pipe. Also, isastream() can be used to determine whether the pseudo-terminal returned by a call to openpt(3tty) is a STREAMS-based master pseudo-terminal or an SVR 3-style pseudo-terminal.

RETURN VALUE

isastream() returns true, (1), if the file associated with fd is a STREAMS special file; it return false, (0), if it is not, and returns minus one (-1), on failure and sets errno(3) to an appropriate error number.

ERRORS

When isastream() fails, it returns minus one (-1) and sets errno(3) to an appropriate error number as follows:

[EBADF]: The argument, fd, is not associted with an open file.

NOTICES

Multi-Threading

isastream() is thread-safe. isastream() does not contain an asynchrnous thread cancellation point, in accordance with POSIX[1]. Asynchronous thread cancellation is deferred across the call.

IMPLEMENTATION

isastream () is system call emulated by the libstreams(3) library by calling the I_ISASTREAM(7) STREAMS input-output control on fd, and adjusting the return value appropriately.

BUGS

isastream() has no known bugs. Behaviour is validated using the test-streams(8) test case executable and the The OpenSS7 Project autotest conformance test suite.

COMPATIBILITY

isastream() is compatible with SVR 4.2[2], and implementations based on SVR 4.2, with the following portability considerations:

---: isastream() is implemented as a STREAMS input-output control instead of a system call. This should not affect portablility.
---: isastream() conforms as closely as possible to the POSIX/SUSv3[1] specifications. Where a specific SVR 4.2-based implementation differs from POSIX/SUSv3, there will be differences with this The OpenSS7 Project implementation.
: Portable STREAMS application programs will expect conformance to POSIX/SUSv3.

If your Linux system is equipped with OpenGroup manual pages, see isastream(3p) for the equivalent POSIX/SUSv3 reference page.

CONFORMANCE

SVID[3], XID[4], SUSv2[5], SUSv3[1], POSIX 1003.1/2003[1]; Solaris®[6] and UnixWare®[7] documentation.

Conformance is testsed using the test-streams(8) test case executable and the The OpenSS7 Project autotest conformance test suite.

HISTORY

isastream() first appeared in SVR 4[8].

REFERENCES

[1]: SUS Version 3, Single UNIX Specification, OpenGroup, Open Group Publication. <http://www.opengroup.org/onlinepubs/>
[2]: SVR 4.2, UNIX® System V Release 4.2 Programmer's Manual, 1992, (Englewood Cliffs, New Jersey), AT&T UNIX System Laboratories, Inc., Prentice Hall.
[3]: SVID, System V, Interface Definition, Fourth Edition.
[4]: XBD Issue 5, X/Open System Interface Definitions, Issue 5, OpenGroup, Open Group Publication. <http://www.opengroup.org/onlinepubs/>
[5]: SUS Version 2, Single UNIX Specification, OpenGroup, Open Group Publication. <http://www.opengroup.org/onlinepubs/>
[6]: Solaris® 8, Solaris 8 Docmentation, 2001, (Santa Clara, California), Sun Microsystems, Inc., Sun. <http://docs.sun.com/>
[7]: UnixWare® 7.1.3, UnixWare 7.1.3 (OpenUnix 8) Documentation, 2002, (Lindon, Utah), Caldera International, Inc., Caldera. <http://uw713doc.sco.com/>
[8]: SVR 4, UNIX® System V Release 4 Programmer's Manual, 1990, (Englewood Cliffs, New Jersey), AT&T UNIX System Laboratories, Inc., Prentice Hall.