explain_fcntl(3)

💅 explain_fcntl(3) — Library Functions Manual 🎀

okay bestie, sit DOWN, because we're decoding fcntl(2) errors and it's genuinely so good of these functions to exist 💖 this is page explain_fcntl(3), and it's here to turn your cursed cryptic errno situation into an actual sentence that makes sense.

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✨ NAME ✨

explain_fcntl — explain fcntl(2) errors 🦋

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🌸 SYNOPSIS 🌸

#include <libexplain/fcntl.h>
const char *explain_fcntl(int fildes, int command, long arg);
const char *explain_errno_fcntl(int errnum, int fildes, int command,
long arg);
void explain_message_fcntl(char *message, int message_size, int fildes,
int command, long arg);
void explain_message_errno_fcntl(char *message, int message_size, int
errnum, int fildes, int command, long arg);

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👑 DESCRIPTION 👑

These functions may be used to obtain explanations for errors returned by the fcntl(2) system call. That's the whole vibe. You got a bad return value, these give you the why 💅

🧚 explain_fcntl

const char *explain_fcntl(int fildes, int command, long arg);

The explain_fcntl function is used to obtain an explanation of an error returned by the fcntl(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, it's giving actual insight ✨

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 (fcntl(fildes, command, arg) < 0)
{
    fprintf(stderr, "%s\n", explain_fcntl(fildes, command, arg));
    exit(EXIT_FAILURE);
}

• fildes — The original fildes, exactly as passed to the fcntl(2) system call.
• command — The original command, exactly as passed to the fcntl(2) system call.
• arg — The original arg, exactly as passed to the fcntl(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. bestie pls do not forget this part 😭

💀 explain_errno_fcntl

const char *explain_errno_fcntl(int errnum, int fildes, int command,
long arg);

The explain_errno_fcntl function is used to obtain an explanation of an error returned by the fcntl(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 intended to be used in a fashion similar to the following example:

if (fcntl(fildes, command, arg) < 0)
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_fcntl(err, fildes, command, arg));
    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. yeah she's sneaky like that 🙈
• fildes — The original fildes, exactly as passed to the fcntl(2) system call.
• command — The original command, exactly as passed to the fcntl(2) system call.
• arg — The original arg, exactly as passed to the fcntl(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.

🫶 explain_message_fcntl

void explain_message_fcntl(char *message, int message_size, int fildes,
int command, long arg);

The explain_message_fcntl function may be used to obtain an explanation of an error returned by the fcntl(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 intended to be used in a fashion similar to the following example:

if (fcntl(fildes, command, arg) < 0)
{
    char message[3000];
    explain_message_fcntl(message, sizeof(message), fildes, command, arg);
    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, she said safe 💅
• 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 fcntl(2) system call.
• command — The original command, exactly as passed to the fcntl(2) system call.
• arg — The original arg, exactly as passed to the fcntl(2) system call.

🌈 explain_message_errno_fcntl

void explain_message_errno_fcntl(char *message, int message_size, int
errnum, int fildes, int command, long arg);

The explain_message_errno_fcntl function may be used to obtain an explanation of an error returned by the fcntl(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 intended to be used in a fashion similar to the following example:

if (fcntl(fildes, command, arg) < 0)
{
    int err = errno;
    char message[3000];
    explain_message_errno_fcntl(message, sizeof(message), err, fildes,
        command, arg);
    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.
• fildes — The original fildes, exactly as passed to the fcntl(2) system call.
• command — The original command, exactly as passed to the fcntl(2) system call.
• arg — The original arg, exactly as passed to the fcntl(2) system call.

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🔥 SEE ALSO 🔥

• fcntl(2) — manipulate a file descriptor
• explain_fcntl_or_die(3) — manipulate 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, no cap 🌸 this was explain_fcntl(3) from the Library Functions Manual, brought to you by libexplain version 1.4, Copyright (C) 2008 Peter Miller — mwah, go fix ur errors, ily 💜🎀