explain_setdomainname(3)

💖 explain_setdomainname — the bestie who explains your setdomainname(2) drama 💖

okay so real talk, this page lives in the Library Functions Manual, and it's all about a lil libexplain helper called explain_setdomainname(3). it doesn't do the syscall, bestie — it explains what went wrong when the syscall said no. ✨

---

🌸 NAME 🌸

explain_setdomainname — explain setdomainname(2) errors 🫶

like, it takes your confusion and hands you back a whole paragraph of "here's why, girl."

---

🎀 SYNOPSIS 🎀

#include <libexplain/setdomainname.h>
const char *explain_setdomainname(const char *data, size_t data_size);
const char *explain_errno_setdomainname(int errnum, const char *data,
size_t data_size);
void explain_message_setdomainname(char *message, int message_size,
const char *data, size_t data_size);
void explain_message_errno_setdomainname(char *message, int
message_size, int errnum, const char *data, size_t data_size);

---

✨ DESCRIPTION ✨

these functions are your lil translators, fr fr. you use them to obtain explanations for errors returned by the setdomainname(2) system call. that's the whole job. the vibe: syscall fails, you get a real answer instead of a cryptic number. 💅

---

🦋 explain_setdomainname 🦋

const char *explain_setdomainname(const char *data, size_t data_size);

the explain_setdomainname function is used to obtain an explanation of an error returned by the setdomainname(2) system call. the least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail. it's giving overachiever and we love that. 🔥

the errno global variable will be used to obtain the error value to be decoded.

• data — the original data, exactly as passed to the setdomainname(2) system call.
• data_size — the original data_size, exactly as passed to the setdomainname(2) system call.

Returns: the message explaining the error. this message buffer is shared by all libexplain functions which do not supply a buffer in their argument list. it will be overwritten by the next call to any libexplain function which shares this buffer, including other threads. so like, screenshot it or copy it, don't just point at it. 😭

Note: this function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library.

Example: this function is intended to be used in a fashion similar to the following example:

if (setdomainname(data, data_size) < 0)
{
    fprintf(stderr, "%s\n", explain_setdomainname(data,
    data_size));
    exit(EXIT_FAILURE);
}

the above code example is available pre‐packaged as the explain_setdomainname_or_die(3) function. (yes, "or die" — it's not mean, it's just honest. 💀)

---

🌈 explain_errno_setdomainname 🌈

const char *explain_errno_setdomainname(int errnum, const char *data,
size_t data_size);

the explain_errno_setdomainname function is used to obtain an explanation of an error returned by the setdomainname(2) system call. the least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail. same energy, but now you bring the errno. 👑

• errnum — the error value to be decoded, usually obtained from the errno global variable just before this function is called. this is necessary if you need to call any code between the system call to be explained and this function, because many libc functions will alter the value of errno. (they're messy like that, no cap.)
• data — the original data, exactly as passed to the setdomainname(2) system call.
• data_size — the original data_size, exactly as passed to the setdomainname(2) system call.

Returns: the message explaining the error. this message buffer is shared by all libexplain functions which do not supply a buffer in their argument list. this will be overwritten by the next call to any libexplain function which shares this buffer, including other threads.

Note: this function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library.

Example: this function is intended to be used in a fashion similar to the following example:

if (setdomainname(data, data_size) < 0)
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_setdomainname(err,
    data, data_size));
    exit(EXIT_FAILURE);
}

the above code example is available pre‐packaged as the explain_setdomainname_or_die(3) function.

---

🧚 explain_message_setdomainname 🧚

void explain_message_setdomainname(char *message, int message_size,
const char *data, size_t data_size);

the explain_message_setdomainname function is used to obtain an explanation of an error returned by the setdomainname(2) system call. the least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail. this one's the bring your own buffer edition. 🎀

the errno global variable will be used to obtain the error value to be decoded.

• message — the location in which to store the returned message. if a suitable message return buffer is supplied, this function is thread safe. (slay, we love a safe queen.)
• message_size — the size in bytes of the location in which to store the returned message.
• data — the original data, exactly as passed to the setdomainname(2) system call.
• data_size — the original data_size, exactly as passed to the setdomainname(2) system call.

Example: this function is intended to be used in a fashion similar to the following example:

if (setdomainname(data, data_size) < 0)
{
    char message[3000];
    explain_message_setdomainname(message, sizeof(message), data,
    data_size);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

the above code example is available pre‐packaged as the explain_setdomainname_or_die(3) function.

---

⭐ explain_message_errno_setdomainname ⭐

void explain_message_errno_setdomainname(char *message, int
message_size, int errnum, const char *data, size_t data_size);

the explain_message_errno_setdomainname function is used to obtain an explanation of an error returned by the setdomainname(2) system call. the least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail. this is the final boss form: your buffer and your errno. 👑

• message — the location in which to store the returned message. if a suitable message return buffer is supplied, this function is thread safe.
• message_size — the size in bytes of the location in which to store the returned message.
• errnum — the error value to be decoded, usually obtained from the errno global variable just before this function is called. this is necessary if you need to call any code between the system call to be explained and this function, because many libc functions will alter the value of errno.
• data — the original data, exactly as passed to the setdomainname(2) system call.
• data_size — the original data_size, exactly as passed to the setdomainname(2) system call.

Example: this function is intended to be used in a fashion similar to the following example:

if (setdomainname(data, data_size) < 0)
{
    int err = errno;
    char message[3000];
    explain_message_errno_setdomainname(message, sizeof(message),
    err, data, data_size);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

the above code example is available pre‐packaged as the explain_setdomainname_or_die(3) function.

---

💜 SEE ALSO 💜

• setdomainname(2) — set domain name
• explain_setdomainname_or_die(3) — set domain name and report errors

---

👑 COPYRIGHT 👑

libexplain version 1.4 Copyright (C) 2009 Peter Miller

---

and that's the whole page, bestie 🫶 this was explain_setdomainname(3) from the Library Functions Manual — go forth, decode your errnos, and stay thread safe (unless you're the shared-buffer ones, in which case… good luck babes 💅✨).