explain_setgid(3)

💖 explain_setgid(3) 💖

okay bestie, gather round, because today we're talking about explain_setgid — a lil' library function from the Library Functions Manual that turns your cursed setgid(2) errors into actual explanations. no more staring at EPERM like it's a cryptic text from your ex. we're decoding it. periodt. ✨

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🌸 NAME 🌸

explain_setgid — explain setgid(2) errors 💅

like, it explains them. that's the whole job. and it ate. 👑

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✨ SYNOPSIS ✨

#include <libexplain/setgid.h>
const char *explain_setgid(gid_t gid);
const char *explain_errno_setgid(int errnum, gid_t gid);
void explain_message_setgid(char *message, int message_size, gid_t gid);
void explain_message_errno_setgid(char *message, int message_size, int
errnum, gid_t gid);

four functions. four besties. each one does the same glow-up but with slightly different energy. 🦋

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🎀 DESCRIPTION 🎀

so, the vibe: these functions may be used to obtain explanations for errors returned by the setgid(2) system call. that's it, that's the mission statement. they take your sad little error and give you lore. 📖

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💜 explain_setgid

const char *explain_setgid(gid_t gid);

The explain_setgid function is used to obtain an explanation of an error returned by the setgid(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. like, the bare minimum is a vibe, but bestie really went above and beyond. 🔥

The errno global variable will be used to obtain the error value to be decoded. it just knows. 🧚

• gid — The original gid, exactly as passed to the setgid(2) system call. yes, exactly. don't get cute and modify it. copy-paste energy only. 🙈

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. so like… it's one communal lip gloss and everyone's using it. 💄

Note: This function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library. screaming crying throwing up, but in a multithreaded way. 😭

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

if (setgid(gid) < 0)
{
    fprintf(stderr, "%s\n", explain_setgid(gid));
    exit(EXIT_FAILURE);
}

The above code example is available pre-packaged as the explain_setgid_or_die(3) function. ✨

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💖 explain_errno_setgid

const char *explain_errno_setgid(int errnum, gid_t gid);

The explain_errno_setgid function is used to obtain an explanation of an error returned by the setgid(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. she's thorough. she's that girl. 👑

• 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. so like, grab your errno before someone else snatches it. 🏃‍♀️
• gid — The original gid, exactly as passed to the setgid(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 (setgid(gid) < 0)
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_setgid(err, gid));
    exit(EXIT_FAILURE);
}

The above code example is available pre-packaged as the explain_setgid_or_die(3) function. 🌈

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🦋 explain_message_setgid

void explain_message_setgid(char *message, int message_size, gid_t gid);

The explain_message_setgid function is used to obtain an explanation of an error returned by the setgid(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 customer service voice but in a good way. 🎀

The errno global variable will be used to obtain the error value to be decoded. she read the room. 👀

• message — The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe. ooooh bestie said self-care and provided her own buffer. we love boundaries. 🫶
• message_size — The size in bytes of the location in which to store the returned message. like, how much room are we giving her to yap. 📏
• gid — The original gid, exactly as passed to the setgid(2) system call. 💅

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

if (setgid(gid) < 0)
{
    char message[3000];
    explain_message_setgid(message, sizeof(message), gid);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

The above code example is available pre-packaged as the explain_setgid_or_die(3) function. ⭐

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🌈 explain_message_errno_setgid

void explain_message_errno_setgid(char *message, int message_size, int
errnum, gid_t gid);

The explain_message_errno_setgid function is used to obtain an explanation of an error returned by the setgid(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. the final boss form. main character energy fr fr. 👑

• 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. once again: snag errno early or it's gone. 😤
• gid — The original gid, exactly as passed to the setgid(2) system call. 💜

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

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

The above code example is available pre-packaged as the explain_setgid_or_die(3) function. ✨

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👀 SEE ALSO 👀

• setgid(2) — set group identity. the original icon. the blueprint. 🫶
• explain_setgid_or_die(3) — set group identity and report errors. the pre-packaged version for when you don't feel like typing. 💅

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📜 COPYRIGHT 📜

libexplain version 1.4

Copyright (C) 2012 Peter Miller

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okay so that's the whole page bestie, every single detail intact, nothing skipped, no cap. 🎀 if you're out here debugging setgid(2) and you're confused, just call one of these four functions and let her explain. it's giving clarity. it's giving closure. it's giving explain_setgid(3), from the Library Functions Manual, libexplain version 1.4, Copyright (C) 2012 Peter Miller 💖✨🌸🦋💅👑💀🍓🧚💜