explain_getpgrp(3)

🎀 explain_getpgrp 🎀

okay so bestie, you found the manual page for explain_getpgrp(3) — it lives in the Library Functions Manual section of your friendly neighborhood libexplain docs, and it's here to make your error messages actually make sense. no more staring at a bare strerror like 👁️👄👁️. let's get into it. 💅

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✨ NAME ✨

explain_getpgrp — explain getpgrp(2) errors

like, it takes the mysterious little failure from getpgrp(2) and turns it into a whole sentence you can actually read. iconic behaviour honestly. 🫶

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🌸 SYNOPSIS 🌸

#include <libexplain/getpgrp.h>
const char *explain_getpgrp(pid_t pid);
const char *explain_errno_getpgrp(int errnum, pid_t pid);
void explain_message_getpgrp(char *message, int message_size, pid_t pid);
void explain_message_errno_getpgrp(char *message, int message_size, int errnum, pid_t pid);

four functions, four vibes. pick your fighter. ⭐

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💜 DESCRIPTION 💜

These functions may be used to obtain explanations for errors returned by the getpgrp(2) system call. basically: system call goes 😭, libexplain comes in and goes "here's why, babe."

Note: the getpgrp(2) function has two implementations. The POSIX.1 version has no arguments, while the BSD version has one argument. For simplicity of implementation, the argument list seen here includes the pid argument. so yeah, the signature you see is the libexplain-flavored one, not a moral statement about which getpgrp is "correct" 💀

The POSIX.1 getpgid() semantics can be obtained by calling getpgrp(0) on BSD systems, and this is the API for libexplain, even on systems that do not use the BSD API. so libexplain is committed to one look, no matter what your OS woke up and chose today. consistency queen. 👑

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🌈 explain_getpgrp 🌈

const char *explain_getpgrp(pid_t pid);

The explain_getpgrp function is used to obtain an explanation of an error returned by the getpgrp(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, it's not just gonna hand you "it broke", it's gonna hand you the whole story. 💖

The errno global variable will be used to obtain the error value to be decoded. so no passing it in here, bestie, it reads errno all by itself.

• pid — the original pid, exactly as passed to the getpgrp(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 don't get attached, she's not yours. 😭

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:

pid_t result = getpgrp(pid);
if (result < 0)
{
    fprintf(stderr, "%s\n", explain_getpgrp(pid));
    exit(EXIT_FAILURE);
}

The above code example is available pre-packaged as the explain_getpgrp_or_die(3) function. (yes, "or die" is literally the name, it's giving dramatic but honestly? valid.) 🎀

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🦋 explain_errno_getpgrp 🦋

const char *explain_errno_getpgrp(int errnum, pid_t pid);

The explain_errno_getpgrp function is used to obtain an explanation of an error returned by the getpgrp(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 her sister function, just with extra ✨control✨.

• 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 a copy of errno immediately, because the libc girlies are messy and will change it out from under you. 🙈
• pid — the original pid, exactly as passed to the getpgrp(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:

pid_t result = getpgrp(pid);
if (result < 0)
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_getpgrp(err, pid));
    exit(EXIT_FAILURE);
}

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

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🍓 explain_message_getpgrp 🍓

void explain_message_getpgrp(char *message, int message_size, pid_t pid);

The explain_message_getpgrp function is used to obtain an explanation of an error returned by the getpgrp(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 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. look at her, so responsible, so grown. 👑
• message_size — the size in bytes of the location in which to store the returned message.
• pid — the original pid, exactly as passed to the getpgrp(2) system call.

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

pid_t result = getpgrp(pid);
if (result < 0)
{
    char message[3000];
    explain_message_getpgrp(message, sizeof(message), pid);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

The above code example is available pre-packaged as the explain_getpgrp_or_die(3) function. and yeah, that's a 3000-byte buffer, she likes room to breathe. 💅

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🧚 explain_message_errno_getpgrp 🧚

void explain_message_errno_getpgrp(char *message, int message_size, int errnum, pid_t pid);

The explain_message_errno_getpgrp function is used to obtain an explanation of an error returned by the getpgrp(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 is the full combo meal, message buffer and explicit errno. 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. (yes, same warning as before, because it really do be like that.) 😭
• pid — the original pid, exactly as passed to the getpgrp(2) system call.

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

pid_t result = getpgrp(pid);
if (result < 0)
{
    int err = errno;
    char message[3000];
    explain_message_errno_getpgrp(message, sizeof(message), err, pid);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

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

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🌟 SEE ALSO 🌟

• getpgrp(2) — get process group
• explain_getpgrp_or_die(3) — get process group and report errors

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👑 COPYRIGHT 👑

libexplain version 1.4 Copyright (C) 2011 Peter Miller

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and that's the whole page, bestie. go forth, catch your getpgrp(2) errors, and explain them beautifully. no cap, you're gonna slay this. 💖✨🎀🦋💅

— signed off with love from the explain_getpgrp(3) era, Library Functions Manual energy, libexplain version 1.4, © 2011 Peter Miller. bye bestie!! 🌈⭐💜