explain_munmap(3)

💖 explain_munmap — bestie's guide to munmap(2) error gossip 💖

okay so welcome to explain_munmap(3), a page from the Library Functions Manual, and honestly? it's giving "the munmap(2) system call fumbled and we're here to explain exactly why." no cap.

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🌸 NAME 🌸

explain_munmap — explain munmap(2) errors ✨

like literally, that's the whole job. it looks at an error and tells you what went wrong in human words.

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🎀 SYNOPSIS 🎀

#include <libexplain/munmap.h>
const char *explain_munmap(void *data, size_t data_size);
const char *explain_errno_munmap(int errnum, void *data, size_t
data_size);
void explain_message_munmap(char *message, int message_size, void *data,
size_t data_size);
void explain_message_errno_munmap(char *message, int message_size, int
errnum, void *data, size_t data_size);

look at those four icons. four whole functions. we love a supportive library. 🫶

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🦋 DESCRIPTION 🦋

so these functions? they're your little translators. they may be used to obtain explanations for errors returned by the munmap(2) system call. when the kernel says "nah" in cryptic, they say "nah, and here's why, bestie."

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✨ explain_munmap ✨

const char *explain_munmap(void *data, size_t data_size);

the explain_munmap function is used to obtain an explanation of an error returned by the munmap(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 ate that.

the errno global variable will be used to obtain the error value to be decoded. so like, she reads errno for you, no extra work required.

• data — the original data, exactly as passed to the munmap(2) system call.
• data_size — the original data_size, exactly as passed to the munmap(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 like, do NOT get attached. it's not yours. it's everyone's. 😭

Note: this function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library. not me finding out the hard way 💀

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

if (munmap(data, data_size) < 0)
{
    fprintf(stderr, "%s\n", explain_munmap(data, data_size));
    exit(EXIT_FAILURE);
}

the above code example is available pre‐packaged as the explain_munmap_or_die(3) function. iconic of her honestly.

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🌈 explain_errno_munmap 🌈

const char *explain_errno_munmap(int errnum, void *data, size_t
data_size);

the explain_errno_munmap function is used to obtain an explanation of an error returned by the munmap(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.

• 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 girl, errno is that fickle. save it early. 🙈
• data — the original data, exactly as passed to the munmap(2) system call.
• data_size — the original data_size, exactly as passed to the munmap(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. everybody's touching it. 💅

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:

if (munmap(data, data_size) < 0)
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_munmap(err, data,
    data_size));
    exit(EXIT_FAILURE);
}

the above code example is available pre‐packaged as the explain_munmap_or_die(3) function.

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💜 explain_message_munmap 💜

void explain_message_munmap(char *message, int message_size, void *data,
size_t data_size);

the explain_message_munmap function is used to obtain an explanation of an error returned by the munmap(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 being responsible. 🧚
• message_size — the size in bytes of the location in which to store the returned message.
• data — the original data, exactly as passed to the munmap(2) system call.
• data_size — the original data_size, exactly as passed to the munmap(2) system call.

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

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

the above code example is available pre‐packaged as the explain_munmap_or_die(3) function.

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🍓 explain_message_errno_munmap 🍓

void explain_message_errno_munmap(char *message, int message_size, int
errnum, void *data, size_t data_size);

the explain_message_errno_munmap function is used to obtain an explanation of an error returned by the munmap(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.

• 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.
• data — the original data, exactly as passed to the munmap(2) system call.
• data_size — the original data_size, exactly as passed to the munmap(2) system call.

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

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

the above code example is available pre‐packaged as the explain_munmap_or_die(3) function.

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👑 SEE ALSO 👑

• munmap(2) — unmap a file or device from memory
• explain_munmap_or_die(3) — unmap a file or device from memory and report errors

go read those too, bestie. iykyk. 🔥

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💀 COPYRIGHT 💀

libexplain version 1.4 Copyright (C) 2010 Peter Miller

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okay that's the whole page, explain_munmap(3), straight from the Library Functions Manual — and that copyright is Peter Miller's, from 2010, libexplain version 1.4, so show some respect. mwah. 💅✨