stropts.h(7POSIX)

📦 version 2017a, in debian bookworm, debian trixie, ubuntu jammy, ubuntu noble, ubuntu resolute, ubuntu stonking

🌸 stropts.h — STREAMS interface (STREAMS) ✨

okay bestie, so this is stropts.h from the POSIX Programmer's Manual, and the manual section is 7POSIX (yes it's a header page in section 7, we love a niche section 💅). Also real talk before we start:

PROLOG — this manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux. so like. check first, okay? 😭

🦋 SYNOPSIS 🦋

#include <stropts.h>

✨ DESCRIPTION ✨

okay so <stropts.h> is THE STREAMS header. it defines a whole little friend group of structs, types, and constants. let's meet them all, one by one, no skips, we're doing the whole roll call 💖

🎀 the bandinfo structure

<stropts.h> shall define the bandinfo structure, which shall include at least the following members:

int            bi_flag  Flushing type.
unsigned char  bi_pri   Priority band.

🎀 the strpeek structure

<stropts.h> shall define the strpeek structure, which shall include at least the following members:

struct strbuf  ctlbuf   The control portion of the message.
struct strbuf  databuf  The data portion of the message.
t_uscalar_t    flags    RS_HIPRI or 0.

🎀 the strbuf structure

<stropts.h> shall define the strbuf structure, which shall include at least the following members:

char  *buf     Pointer to buffer.
int    len     Length of data.
int    maxlen  Maximum buffer length.

🎀 the strfdinsert structure

<stropts.h> shall define the strfdinsert structure, which shall include at least the following members:

struct strbuf  ctlbuf   The control portion of the message.
struct strbuf  databuf  The data portion of the message.
int            fildes   File descriptor of the other STREAM.
t_uscalar_t    flags    RS_HIPRI or 0.
int            offset   Relative location of the stored value.

🎀 the strioctl structure

<stropts.h> shall define the strioctl structure, which shall include at least the following members:

int    ic_cmd     ioctl() command.
char  *ic_dp      Pointer to buffer.
int    ic_len     Length of data.
int    ic_timout  Timeout for response.

🎀 the strrecvfd structure

<stropts.h> shall define the strrecvfd structure, which shall include at least the following members:

int    fd   Received file descriptor.
gid_t  gid  GID of sender.
uid_t  uid  UID of sender.

🎀 types, types, types

<stropts.h> shall define the uid_t and gid_t types through typedef, as described in <sys/types.h>. 🫶

<stropts.h> shall define the t_scalar_t and t_uscalar_t types, respectively, as signed and unsigned opaque types of equal length of at least 32 bits.

🎀 the str_list structure

<stropts.h> shall define the str_list structure, which shall include at least the following members:

struct str_mlist  *sl_modlist  STREAMS module names.
int                sl_nmods    Number of STREAMS module names.

🎀 the str_mlist structure

<stropts.h> shall define the str_mlist structure, which shall include at least the following member:

char  l_name[FMNAMESZ+1]  A STREAMS module name.

👑 the ioctl() request constants 👑

<stropts.h> shall define at least the following symbolic constants for use as the request argument to ioctl():

  • I_ATMARK — Is the top message ``marked''? 👀
  • I_CANPUT — Is a band writable?
  • I_CKBAND — See if any messages exist in a band.
  • I_FDINSERT — Send implementation-defined information about another STREAM.
  • I_FIND — Look for a STREAMS module. 🔍
  • I_FLUSH — Flush a STREAM.
  • I_FLUSHBAND — Flush one band of a STREAM.
  • I_GETBAND — Get the band of the top message on a STREAM.
  • I_GETCLTIME — Get close time delay.
  • I_GETSIG — Retrieve current notification signals.
  • I_GRDOPT — Get the read mode.
  • I_GWROPT — Get the write mode.
  • I_LINK — Connect two STREAMs. 🔗
  • I_LIST — Get all the module names on a STREAM.
  • I_LOOK — Get the top module name.
  • I_NREAD — Size the top message.
  • I_PEEK — Peek at the top message on a STREAM.
  • I_PLINK — Persistently connect two STREAMs.
  • I_POP — Pop a STREAMS module. 🫧
  • I_PUNLINK — Dismantle a persistent STREAMS link.
  • I_PUSH — Push a STREAMS module.
  • I_RECVFD — Get a file descriptor sent via I_SENDFD.
  • I_SENDFD — Pass a file descriptor through a STREAMS pipe.
  • I_SETCLTIME — Set close time delay.
  • I_SETSIG — Ask for notification signals.
  • I_SRDOPT — Set the read mode.
  • I_STR — Send a STREAMS ioctl().
  • I_SWROPT — Set the write mode.
  • I_UNLINK — Disconnect two STREAMs.

🌈 constants for I_LOOK 🌈

<stropts.h> shall define at least the following symbolic constant for use with I_LOOK:

  • FMNAMESZ — The minimum size in bytes of the buffer referred to by the arg argument.

🌈 constants for I_FLUSH 🌈

<stropts.h> shall define at least the following symbolic constants for use with I_FLUSH:

  • FLUSHR — Flush read queues.
  • FLUSHRW — Flush read and write queues.
  • FLUSHW — Flush write queues.

🌈 constants for I_SETSIG 🌈

<stropts.h> shall define at least the following symbolic constants for use with I_SETSIG:

  • S_BANDURG — When used in conjunction with S_RDBAND, SIGURG is generated instead of SIGPOLL when a priority message reaches the front of the STREAM head read queue.
  • S_ERROR — Notification of an error condition reaches the STREAM head.
  • S_HANGUP — Notification of a hangup reaches the STREAM head.
  • S_HIPRI — A high-priority message is present on a STREAM head read queue.
  • S_INPUT — A message, other than a high-priority message, has arrived at the head of a STREAM head read queue.
  • S_MSG — A STREAMS signal message that contains the SIGPOLL signal reaches the front of the STREAM head read queue.
  • S_OUTPUT — The write queue for normal data (priority band 0) just below the STREAM head is no longer full. This notifies the process that there is room on the queue for sending (or writing) normal data downstream.
  • S_RDBAND — A message with a non-zero priority band has arrived at the head of a STREAM head read queue.
  • S_RDNORM — A normal (priority band set to 0) message has arrived at the head of a STREAM head read queue.
  • S_WRBAND — The write queue for a non-zero priority band just below the STREAM head is no longer full.
  • S_WRNORM — Equivalent to S_OUTPUT.

🌈 constant for I_PEEK 🌈

<stropts.h> shall define at least the following symbolic constant for use with I_PEEK:

  • RS_HIPRI — Only look for high-priority messages.

🌈 constants for I_SRDOPT 🌈

<stropts.h> shall define at least the following symbolic constants for use with I_SRDOPT:

  • RMSGD — Message-discard mode.
  • RMSGN — Message-non-discard mode.
  • RNORM — Byte-STREAM mode, the default. 💅
  • RPROTDAT — Deliver the control part of a message as data when a process issues a read().
  • RPROTDIS — Discard the control part of a message, delivering any data part, when a process issues a read().
  • RPROTNORM — Fail read() with [EBADMSG] if a message containing a control part is at the front of the STREAM head read queue.

🌈 constant for I_SWOPT 🌈

<stropts.h> shall define at least the following symbolic constant for use with I_SWOPT:

  • SNDZERO — Send a zero-length message downstream when a write() of 0 bytes occurs.

🌈 constants for I_ATMARK 🌈

<stropts.h> shall define at least the following symbolic constants for use with I_ATMARK:

  • ANYMARK — Check if the message is marked.
  • LASTMARK — Check if the message is the last one marked on the queue.

<stropts.h> shall define at least the following symbolic constant for use with I_UNLINK:

  • MUXID_ALL — Unlink all STREAMs linked to the STREAM associated with fildes.

🌈 constants for getmsg(), getpmsg(), putmsg(), and putpmsg() 🌈

<stropts.h> shall define the following symbolic constants for getmsg(), getpmsg(), putmsg(), and putpmsg():

  • MORECTL — More control information is left in message.
  • MOREDATA — More data is left in message.
  • MSG_ANY — Receive any message.
  • MSG_BAND — Receive message from specified band.
  • MSG_HIPRI — Send/receive high-priority message.

🧚 extras, because of course 🧚

  • <stropts.h> may make visible all of the symbols from <unistd.h>.
  • <stropts.h> may also define macros for message types using names that start with M_.

🌟 the function squad 🌟

The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.

int    fattach(int, const char *);
int    fdetach(const char *);
int    getmsg(int, struct strbuf *restrict, struct strbuf *restrict,
           int *restrict);
int    getpmsg(int, struct strbuf *restrict, struct strbuf *restrict,
           int *restrict, int *restrict);
int    ioctl(int, int, ...);
int    isastream(int);
int    putmsg(int, const struct strbuf *, const struct strbuf *, int);
int    putpmsg(int, const struct strbuf *, const struct strbuf *, int,
           int);

The following sections are informative. 📝

💜 APPLICATION USAGE 💜

None.

💜 RATIONALE 💜

None.

💜 FUTURE DIRECTIONS 💜

None.

🔥 SEE ALSO 🔥

  • <sys_types.h>, <unistd.h>

The System Interfaces volume of POSIX.1‐2017, close(), fattach(), fcntl(), fdetach(), getmsg(), ioctl(), isastream(), open(), pipe(), read(), poll(), putmsg(), signal(), write()

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .

okay that's the whole page bestie, every struct, every constant, every function, nothing skipped, we ate and left no crumbs 💅✨

this was brought to you by IEEE/The Open Group, 2017 — stropts.h(7POSIX), mwah 🎀 bye!!
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