explain_freopen(3)

💖 explain_freopen — the manual, but make it make sense 💖

okay so bestie, this is explain_freopen(3), a page from the Library Functions Manual, and it's literally all about translating freopen(3) errors into something a human can actually read. no cap. 🦋

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✨ NAME ✨

explain_freopen — the girlies who explain freopen(3) errors to you 💅

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🌸 SYNOPSIS 🌸

#include <libexplain/freopen.h>
const char *explain_freopen(const char *pathname, const char *flags,
FILE *fp);
const char *explain_errno_freopen(int errnum, const char *pathname,
const char *flags, FILE *fp);
void explain_message_freopen(char *message, int message_size, const char
*pathname, const char *flags, FILE *fp);
void explain_message_errno_freopen(char *message, int message_size, int
errnum, const char *pathname, const char *flags, FILE *fp);

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👑 DESCRIPTION 👑

These functions may be used to obtain explanations for freopen(3) errors. that's the whole vibe. you call one, it hands you back a lil explanation instead of leaving you staring at errno like 👁️👄👁️

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🎀 explain_freopen 🎀

const char *explain_freopen(const char *pathname, const char *flags,
FILE *fp);

The explain_freopen function is used to obtain an explanation of an error returned by the freopen(3) 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 an overachiever 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 (!freopen(pathname, flags, fp))
{
    fprintf(stderr, '%s0, explain_freopen(pathname, flags, fp));
    exit(EXIT_FAILURE);
}

• pathname — The original pathname, exactly as passed to the freopen(3) system call.
• flags — The original flags, exactly as passed to the freopen(3) system call.
• fp — The original fp, exactly as passed to the freopen(3) 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. like, she's one girl, she can't be everywhere 💀

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💜 explain_errno_freopen 💜

const char *explain_errno_freopen(int errnum, const char *pathname,
const char *flags, FILE *fp);

The explain_errno_freopen function is used to obtain an explanation of an error returned by the freopen(3) 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. same energy, different source of truth 🫶

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

if (freopen(pathname, flags, fp))
{
    int err = errno;
    fprintf(stderr, '%s0, explain_errno_freopen(err, pathname,
        flags, fp));
    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. ⚠️ so like, grab errno first, bestie, or it's gone
• pathname — The original pathname, exactly as passed to the freopen(3) system call.
• flags — The original flags, exactly as passed to the freopen(3) system call.
• fp — The original fp, exactly as passed to the freopen(3) 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.

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🧚 explain_message_freopen 🧚

void explain_message_freopen(char *message, int message_size, const char
*pathname, const char *flags, FILE *fp);

The explain_message_freopen function is used to obtain an explanation of an error returned by the freopen(3) 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 got her OWN buffer, iconic behavior 🌈

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 (!freopen(pathname, flags, fp))
{
    char message[3000];
    explain_message_freopen(message, sizeof(message), pathname, flags,
        fp);
    fprintf(stderr, '%s0, message);
    exit(EXIT_FAILURE);
}

• message — The location in which to store the returned message. Because a message return buffer has been supplied, this function is thread safe. slay 🎀
• message_size — The size in bytes of the location in which to store the returned message.
• pathname — The original pathname, exactly as passed to the freopen(3) system call.
• flags — The original flags, exactly as passed to the freopen(3) system call.
• fp — The original fp, exactly as passed to the freopen(3) system call.

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🍓 explain_message_errno_freopen 🍓

void explain_message_errno_freopen(char *message, int message_size, int
errnum, const char *pathname, const char *flags, FILE *fp);

The explain_message_errno_freopen function is used to obtain an explanation of an error returned by the freopen(3) 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. the full combo meal, errno edition 🍟

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

if (!freopen(pathname, flags, fp))
{
    int err = errno;
    char message[3000];
    explain_message_errno_freopen(message, sizeof(message), err,
        pathname, flags, fp);
    fprintf(stderr, '%s0, message);
    exit(EXIT_FAILURE);
}

• message — The location in which to store the returned message. Because a message return buffer has been 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. ⚠️
• pathname — The original pathname, exactly as passed to the freopen(3) system call.
• flags — The original flags, exactly as passed to the freopen(3) system call.
• fp — The original fp, exactly as passed to the freopen(3) system call.

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🌟 COPYRIGHT 🌟

libexplain version 1.4 Copyright (C) 2008 Peter Miller

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💌 AUTHOR 💌

Written by Peter Miller <pmiller@opensource.org.au>

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and that's the page, bestie!! 🦋✨ explain_freopen(3) — she's part of the Library Functions Manual, she's running libexplain version 1.4, and the copyright has been held down by Peter Miller since 2008. periodt. 💅💖