explain_fork(3)

💖 explain_fork(3) 💖

okay bestie, so this is a page from the Library Functions Manual, and we're talking about explain_fork — the little libexplain glow-up that turns your fork(2) boo-boos into actual sentences. no cap.

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✨ NAME ✨

explain_fork — explain fork(2) errors 🫶

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✨ SYNOPSIS ✨

#include <libexplain/fork.h>
const char *explain_fork(void);
const char *explain_errno_fork(int errnum);
void explain_message_fork(char *message, int message_size);
void explain_message_errno_fork(char *message, int message_size, int errnum);

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✨ DESCRIPTION ✨

so these functions? they're literally here to hand you explanations for errors that come back from the fork(2) system call. that's the whole vibe. 💅

🌸 explain_fork

const char *explain_fork(void);

explain_fork is your girl for getting an explanation of an error returned by the fork(2) system call. the least the message will contain is the value of strerror(errno) — but usually it does so much better and points at the underlying cause in way more detail. it's giving overachiever. 👑

the errno global variable is what gets used to grab the error value that needs decoding.

this function is meant to be used in a fashion similar to this example:

if (fork() < 0)
{
    fprintf(stderr, "%s\n", explain_fork());
    exit(EXIT_FAILURE);
}

Returns: the message explaining the error. this message buffer is shared by all libexplain functions that don't supply a buffer in their argument list. and bestie, it will be overwritten by the next call to any libexplain function that shares this buffer — including other threads. 😭

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

🌸 explain_errno_fork

const char *explain_errno_fork(int errnum);

explain_errno_fork is the one that gets you an explanation of an error returned by the fork(2) system call. again, the least the message will contain is the value of strerror(errnum), but usually it does much better and tells you the underlying cause in more detail. iconic. ✨

this function is meant to be used in a fashion similar to this example:

if (fork() < 0)
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_fork(err, ));
    exit(EXIT_FAILURE);
}

• errnum — the error value to be decoded, usually grabbed from the errno global variable right before this function is called. this matters if you need to run any code between the system call you're explaining and this function, because many libc functions will alter the value of errno. 🙈

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. yes, we're saying it again, it's that important. 💀

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

🌸 explain_message_fork

void explain_message_fork(char *message, int message_size);

explain_message_fork may be used to obtain an explanation of an error returned by the fork(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.

this function is meant to be used in a fashion similar to this example:

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

• message — the location in which to store the returned message. if a suitable message return buffer is supplied, this function is thread safe. slay. 🦋
• message_size — the size in bytes of the location in which to store the returned message.

🌸 explain_message_errno_fork

void explain_message_errno_fork(char *message, int message_size, int errnum);

explain_message_errno_fork may be used to obtain an explanation of an error returned by the fork(2) system call. the least the message will contain is the value of strerror(errnum), but usually it will do much better, and indicate the underlying cause in more detail.

this function is meant to be used in a fashion similar to this example:

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

• 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.

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🌈 SEE ALSO 🌈

• fork(2) — create a child process
• explain_fork_or_die(3) — create a child process and report errors

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👑 COPYRIGHT 👑

libexplain version 1.4 Copyright (C) 2008 Peter Miller

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and that's the whole page, bestie 💜 it's libexplain version 1.4, copyright (C) 2008 Peter Miller, and the manual name floating around up top is explain_fork(3) — go forth and explain those fork errors, fr fr. 🫶✨