explain_setregid(3)

💅 explain_setregid(3) — bestie's guide to decoding setregid(2) errors 💅

okay so. you called setregid(2) and it said no 💀 and now you're staring at errno like it owes you money. never fear: this is explain_setregid(3), straight outta the Library Functions Manual, and she is here to translate. 🫶✨

---

✨ NAME ✨

explain_setregid — she explains setregid(2) errors. that's it, that's the whole assignment. 💖

🌸 SYNOPSIS 🌸

#include <libexplain/setregid.h>
const char *explain_setregid(gid_t rgid, gid_t egid);
const char *explain_errno_setregid(int errnum, gid_t rgid, gid_t egid);
void explain_message_setregid(char *message, int message_size, gid_t rgid, gid_t egid);
void explain_message_errno_setregid(char *message, int message_size, int errnum, gid_t rgid, gid_t egid);

🦋 DESCRIPTION 🦋

These functions may be used to obtain explanations for errors returned by the setregid(2) system call. think of them as the group chat that actually tells you what went wrong instead of just leaving you on read. 📬

👑 explain_setregid

const char *explain_setregid(gid_t rgid, gid_t egid);

The explain_setregid function is used to obtain an explanation of an error returned by the setregid(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. so like, the bare minimum is strerror(errno), but she is not a bare-minimum girlie — she gives you the why. 💅

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

• rgid — The original rgid, exactly as passed to the setregid(2) system call. exactly. no edits. no vibes-based reinterpretation. 🫡
• egid — The original egid, exactly as passed to the setregid(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. so yeah, don't hold onto it like it's yours, because it is not. 😭

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

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

if (setregid(rgid, egid) < 0)
{
    fprintf(stderr, "%s\n", explain_setregid(rgid, egid));
    exit(EXIT_FAILURE);
}

The above code example is available pre-packaged as the explain_setregid_or_die(3) function. already done for you, no cap. 🎁

💜 explain_errno_setregid

const char *explain_errno_setregid(int errnum, gid_t rgid, gid_t egid);

The explain_errno_setregid function is used to obtain an explanation of an error returned by the setregid(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 as above, but this one lets you hand her the error value yourself. 🎀

• 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. yes, errno is slippery — grab it early or it's gone. 🙈
• rgid — The original rgid, exactly as passed to the setregid(2) system call.
• egid — The original egid, exactly as passed to the setregid(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. shared buffer, shared consequences. 🫠

Note: This function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library. that's the whole tea. ☕

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

if (setregid(rgid, egid) < 0)
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_setregid(err, rgid, egid));
    exit(EXIT_FAILURE);
}

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

🧚 explain_message_setregid

void explain_message_setregid(char *message, int message_size, gid_t rgid, gid_t egid);

The explain_message_setregid function is used to obtain an explanation of an error returned by the setregid(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 not gonna lowball you, she's gonna explain. 💬

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. bring your own buffer and suddenly it's ✨safe✨.
• message_size — The size in bytes of the location in which to store the returned message. size it right, bestie, no overflowing. 🍓
• rgid — The original rgid, exactly as passed to the setregid(2) system call.
• egid — The original egid, exactly as passed to the setregid(2) system call.

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

if (setregid(rgid, egid) < 0)
{
    char message[3000];
    explain_message_setregid(message, sizeof(message), rgid, egid);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

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

💀 explain_message_errno_setregid

void explain_message_errno_setregid(char *message, int message_size, int errnum, gid_t rgid, gid_t egid);

The explain_message_errno_setregid function is used to obtain an explanation of an error returned by the setregid(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 full combo: your buffer, your errnum, her explanation. iconic. 💅

• message — The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe. your buffer, your rules. 🎀
• 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. again: libc functions will mess with your errno, so save it first. 😤
• rgid — The original rgid, exactly as passed to the setregid(2) system call.
• egid — The original egid, exactly as passed to the setregid(2) system call.

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

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

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

---

👀 SEE ALSO 👀

• setregid(2) — set real and/or effective group ID
• explain_setregid_or_die(3) — set real and/or effective group ID and report errors

---

📜 COPYRIGHT 📜

libexplain version 1.4

Copyright (C) 2012 Peter Miller

---

and that's the whole page, bestie 🫶 go forth and debug your group IDs — this was explain_setregid(3) from libexplain version 1.4, with all the copyright love going to Peter Miller, Copyright (C) 2012. mwah. 💋✨