explain_lchownat(3)

💅 explain_lchownat(3) — Library Functions Manual 🎀

okay so bestie, you've stumbled into explain_lchownat(3) from the Library Functions Manual, and honestly? it's giving "my syscall failed and nobody will tell me why" energy. good news: this whole library exists specifically to tell you why. let's get into it. 🦋

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🌸 NAME 🌸

explain_lchownat — explain lchownat(2) errors 💖

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✨ SYNOPSIS ✨

#include <libexplain/lchownat.h>
const char *explain_lchownat(int fildes, const char *pathname, int uid,
int gid);
const char *explain_errno_lchownat(int errnum, int fildes, const char
*pathname, int uid, int gid);
void explain_message_lchownat(char *message, int message_size, int
fildes, const char *pathname, int uid, int gid);
void explain_message_errno_lchownat(char *message, int message_size, int
errnum, int fildes, const char *pathname, int uid, int gid);

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🌈 DESCRIPTION 🌈

These functions may be used to obtain explanations for errors returned by the lchownat(2) system call. four little helpers, one mission: tell you what actually went wrong instead of leaving you on read. 👑

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🫶 explain_lchownat

const char *explain_lchownat(int fildes, const char *pathname, int uid,
int gid);

The explain_lchownat function is used to obtain an explanation of an error returned by the lchownat(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, the bare minimum is bare minimum, but she usually serves. ✨

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

• fildes — the original fildes, exactly as passed to the lchownat(2) system call.
• pathname — the original pathname, exactly as passed to the lchownat(2) system call.
• uid — the original uid, exactly as passed to the lchownat(2) system call.
• gid — the original gid, exactly as passed to the lchownat(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. so if you're threading, beware — she is not your girl. 💀

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

if (lchownat(fildes, pathname, uid, gid) < 0)
{
    fprintf(stderr, "%s\n", explain_lchownat(fildes, pathname,
    uid, gid));
    exit(EXIT_FAILURE);
}

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

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🧚 explain_errno_lchownat

const char *explain_errno_lchownat(int errnum, int fildes, const char
*pathname, int uid, int gid);

The explain_errno_lchownat function is used to obtain an explanation of an error returned by the lchownat(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 deal as above, but now you're handing her the error number yourself. 💅

• 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 immediately, okay? don't let anyone else touch it first. 😭
• fildes — the original fildes, exactly as passed to the lchownat(2) system call.
• pathname — the original pathname, exactly as passed to the lchownat(2) system call.
• uid — the original uid, exactly as passed to the lchownat(2) system call.
• gid — the original gid, exactly as passed to the lchownat(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. iconic behaviour, terrible threading behaviour. 🙈

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

if (lchownat(fildes, pathname, uid, gid) < 0)
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_lchownat(err, fildes,
    pathname, uid, gid));
    exit(EXIT_FAILURE);
}

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

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🍓 explain_message_lchownat

void explain_message_lchownat(char *message, int message_size, int
fildes, const char *pathname, int uid, int gid);

The explain_message_lchownat function is used to obtain an explanation of an error returned by the lchownat(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's the "bring your own buffer" girlie — no shared state drama. 🫶

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. slay. ✨
• 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 lchownat(2) system call.
• pathname — the original pathname, exactly as passed to the lchownat(2) system call.
• uid — the original uid, exactly as passed to the lchownat(2) system call.
• gid — the original gid, exactly as passed to the lchownat(2) system call.

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

if (lchownat(fildes, pathname, uid, gid) < 0)
{
    char message[3000];
    explain_message_lchownat(message, sizeof(message), fildes,
    pathname, uid, gid);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

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

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💜 explain_message_errno_lchownat

void explain_message_errno_lchownat(char *message, int message_size, int
errnum, int fildes, const char *pathname, int uid, int gid);

The explain_message_errno_lchownat function is used to obtain an explanation of an error returned by the lchownat(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 final boss: your buffer and your errnum. no cap. 👑

• 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.
• fildes — the original fildes, exactly as passed to the lchownat(2) system call.
• pathname — the original pathname, exactly as passed to the lchownat(2) system call.
• uid — the original uid, exactly as passed to the lchownat(2) system call.
• gid — the original gid, exactly as passed to the lchownat(2) system call.

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

if (lchownat(fildes, pathname, uid, gid) < 0)
{
    int err = errno;
    char message[3000];
    explain_message_errno_lchownat(message, sizeof(message), err,
    fildes, pathname, uid, gid);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

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

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🔥 SEE ALSO 🔥

• lchownat(2) — Execute lchownat(2)
• explain_lchownat_or_die(3) — Execute lchownat(2) and report errors

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👑 COPYRIGHT 👑

libexplain version 1.4 Copyright (C) 2013 Peter Miller

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and that's the whole page, bestie!! 💖 go forth and explain your lchownat(2) errors with your whole chest. this was explain_lchownat(3), brought to you by libexplain version 1.4, copyright (C) 2013 Peter Miller — stan the maintainers, they did that. 🌟 mwah. 💅🌸