explain_close(3)

💖 explain_close — explaining close(2) errors, bestie edition 💖

okay so real talk, this is explain_close(3) from the Library Functions Manual and it's literally the glow-up your error messages deserve. sit down, grab a strawberry 🍓, and let's get into it.

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✨ NAME ✨

explain_close — explain close(2) errors 💅

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🦋 SYNOPSIS 🦋

#include <libexplain/close.h>
const char *explain_close(int fildes);
const char *explain_errno_close(int errnum, int fildes);
void explain_message_close(char *message, int message_size, int fildes);
void explain_message_errno_close(char *message, int message_size, int
errnum, int fildes);

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🌸 DESCRIPTION 🌸

these functions are your little helpers for getting actual explanations for errors that the close(2) system call hands back. not vibes-based guessing — real explanations. no cap. 👑

🎀 explain_close 🎀

const char *explain_close(int fildes);

the explain_close function gets you an explanation of an error returned by the close(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, and we're obsessed. ✨

the errno global variable is what gets used to obtain the error value to be decoded.

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

if (close(fildes) < 0)
{
    fprintf(stderr, "%s\n", explain_close(fildes));
    exit(EXIT_FAILURE);
}

• fildes — the original fildes, exactly as passed to the close(2) system call. don't get creative with it, just pass it through. 🫶

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, don't bookmark it. 😭

Note: this function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library. so if you're threading, this is a red flag bestie, heads up. 🚩

🧚 explain_errno_close 🧚

const char *explain_errno_close(int errnum, int fildes);

the explain_errno_close function gets you an explanation of an error returned by the close(2) system call. the least the message will contain is the value of strerror(errnum), but usually it does so much better and indicates the underlying cause in more detail. iconic behaviour, honestly. 💖

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

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

• 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. basically, errno is fickle and will ghost you, so capture it early. 🏃‍♀️💨
• fildes — the original fildes, exactly as passed to the close(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. tragic but true. 🥲

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

🌈 explain_message_close 🌈

void explain_message_close(char *message, int message_size, int fildes);

the explain_message_close function gets you an explanation of an error returned by the close(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. main character energy fr fr. ✨

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

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

if (close(fildes) < 0)
{
    char message[3000];
    explain_message_close(message, sizeof(message), fildes);
    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. look at her go. 👑
• message_size — the size in bytes of the location in which to store the returned message.
• fildes — the original fildes, exactly as passed to the close(2) system call.

💜 explain_message_errno_close 💜

void explain_message_errno_close(char *message, int message_size, int
errnum, int fildes);

the explain_message_errno_close function gets you an explanation of an error returned by the close(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. she ate and left no crumbs. 🔥

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

if (close(fildes) < 0)
{
    int err = errno;
    char message[3000];
    explain_message_errno_close(message, sizeof(message), err, fildes);
    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. we love a safe queen. 🎀
• 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: errno does not wait for you. 😤
• fildes — the original fildes, exactly as passed to the close(2) system call.

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👀 SEE ALSO 👀

• close — close a file descriptor
• explain_close_or_die — close a file descriptor 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, you're officially fluent in explain_close(3) 💅✨ this was explain_close(3) from the Library Functions Manual, libexplain version 1.4, Copyright (C) 2008 Peter Miller — go forth and explain your errors, you absolute legend 🦋💖