GETSOCKOPT(3P)

💖 GETSOCKOPT — get the socket options 💖

okay bestie, welcome to the POSIX Programmer's Manual page for getsockopt(). this is a POSIX joint, not a Linux joint, so listen up 👑

🎀 PROLOG 🎀

so real talk: this manual page is part of the POSIX Programmer's Manual. the Linux implementation of this interface may differ (like, go read the corresponding Linux manual page for the deets on Linux behavior, fr), or the interface might just… not be implemented on Linux at all 🙈. vibe check accordingly.

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✨ NAME ✨

getsockopt — get the socket options 💅

🦋 SYNOPSIS 🦋

#include <sys/socket.h>

int getsockopt(int socket, int level, int option_name,
    void *restrict option_value, socklen_t *restrict option_len);

🌸 DESCRIPTION 🌸

getsockopt() is the function that manipulates options associated with a socket. it's giving main character energy for socket options, periodt.

here's the tea ☕: getsockopt() shall retrieve the value for the option specified by the option_name argument, for the socket specified by the socket argument. and if the size of the option value is greater than option_len, the value stored in the object pointed to by the option_value argument shall be silently truncated 😭 (no warning, no nothing, she just clips it). otherwise, the object pointed to by the option_len argument shall be modified to indicate the actual length of the value. iconic behavior honestly.

the level argument specifies the protocol level at which the option resides. to retrieve options at the socket level, specify the level argument as SOL_SOCKET. to retrieve options at other levels, supply the appropriate level identifier for the protocol controlling the option. for example, to indicate that an option is interpreted by the TCP (Transmission Control Protocol), set level to IPPROTO_TCP as defined in the <netinet/in.h> header. iykyk 🧚

the socket in use may require the process to have appropriate privileges to use the getsockopt() function. so if you don't have the clearance, that's a you problem 💀.

the option_name argument specifies a single option to be retrieved. it can be one of the socket-level options defined in <sys_socket.h> and described in Section 2.10.16, Use of Options. yes, one option, singular, don't be greedy 🍓.

👑 RETURN VALUE 👑

upon successful completion, getsockopt() shall return 0 🎉. otherwise, -1 shall be returned and errno set to indicate the error. slay when it works, sigh when it doesn't.

💀 ERRORS 💀

the getsockopt() function shall fail if:

• EBADF — the socket argument is not a valid file descriptor. that's not a socket bestie, that's a random number 😭
• EINVAL — the specified option is invalid at the specified socket level. wrong level, wrong option, wrong energy.
• ENOPROTOOPT — the option is not supported by the protocol. she simply doesn't do that 💅
• ENOTSOCK — the socket argument does not refer to a socket. same energy as EBADF, different flavor.

the getsockopt() function may fail if:

• EACCES — the calling process does not have appropriate privileges. no permission, no peek 🙈
• EINVAL — the socket has been shut down. she's gone, she's resting, leave her alone.
• ENOBUFS — insufficient resources are available in the system to complete the function. the system is tired, give her a minute 😴

heads up: the following sections are informative. aka they're the chill ones, not the "you must obey" ones.

🌈 EXAMPLES 🌈

None.

(not me expecting examples and getting absolutely nothing 💀)

🫶 APPLICATION USAGE 🫶

None.

💜 RATIONALE 💜

None.

⭐ FUTURE DIRECTIONS ⭐

None.

🔥 SEE ALSO 🔥

• Section 2.10.16, Use of Options
• bind()
• close()
• endprotoent()
• setsockopt()
• socket()

and from the Base Definitions volume of POSIX.1‐2017:

• <sys_socket.h>
• <netinet_in.h>

🎀 COPYRIGHT 🎀

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 (she's the final boss, no cap). 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 .

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okay that's the whole page, we ate and left no crumbs 🍽️✨ this one's from IEEE/The Open Group, 2017, filed under GETSOCKOPT(3P) — mwah, go forth and read your socket options responsibly bestie 💖🦋