explain_asprintf(3)

💖 explain_asprintf — the manual page, but make it make sense 💖

okay bestie, gather round, because this is explain_asprintf(3) from the Library Functions Manual, and it's genuinely one of those pages that sounds scary and is actually just... a friend helping you debug. no cap. 🫶

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✨ NAME ✨

explain_asprintf — the whole entire job of this thing is to explain asprintf(3) errors to you. that's it. that's the gig. 💅

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🦋 SYNOPSIS 🦋

#include <libexplain/asprintf.h>
const char *explain_asprintf(, ...);
const char *explain_errno_asprintf(int errnum, , ...);
void explain_message_asprintf(char *message, int message_size, , ...);
void explain_message_errno_asprintf(char *message, int message_size, int
errnum, , ...);

yes, those , ... bits look cursed, no, don't touch them, they are exactly what they are. 💀

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🌸 DESCRIPTION 🌸

so, these functions? they're your little translators. you can use them to obtain explanations for errors returned by the asprintf(3) system call. like, the raw error is cryptic and these guys hand you a whole sentence about what actually went wrong. iconic behaviour honestly.

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🎀 explain_asprintf

const char *explain_asprintf(, ...);

the explain_asprintf function is used to obtain an explanation of an error returned by the asprintf(3) system call. the least the message will contain is the value of strerror(errno), but usually it will do much better than that and indicate the underlying cause in more detail. like, the bare minimum is fine but she overdelivers. 👑

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

Returns:

the message explaining the error. big important vibe check here: this message buffer is shared by all libexplain functions which do not supply a buffer in their argument list. so it will be overwritten by the next call to any libexplain function which shares this buffer — including other threads. it's giving "one communal whiteboard and everyone keeps erasing it." 😭

Note: this function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library. sorry bestie, that's just the deal. 🙈

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

errno = 0;
int result = asprintf();
if (result < 0 || errno != 0)
{
    fprintf(stderr, "%s\n", explain_asprintf());
    exit(EXIT_FAILURE);
}

the above code example is available pre-packaged as the explain_asprintf_or_die(3) function. so if you don't wanna write it yourself, she already exists. periodt. ✨

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🧚 explain_errno_asprintf

const char *explain_errno_asprintf(int errnum, , ...);

the explain_errno_asprintf function is used to obtain an explanation of an error returned by the asprintf(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.

• 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 it fast, she's not gonna wait for you. 🏃‍♀️

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.

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

errno = 0;
int result = asprintf();
if (result < 0 || errno != 0)
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_asprintf(err, ));
    exit(EXIT_FAILURE);
}

the above code example is available pre-packaged as the explain_asprintf_or_die(3) function.

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🌈 explain_message_asprintf

void explain_message_asprintf(char *message, int message_size, , ...);

the explain_message_asprintf function is used to obtain an explanation of an error returned by the asprintf(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.

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 go!! 🔥
• message_size — the size in bytes of the location in which to store the returned message.

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

errno = 0;
int result = asprintf();
if (result < 0 || errno != 0)
{
    char message[3000];
    explain_message_asprintf(message, sizeof(message), );
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

the above code example is available pre-packaged as the explain_asprintf_or_die(3) function.

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⭐ explain_message_errno_asprintf

void explain_message_errno_asprintf(char *message, int message_size, int
errnum, , ...);

the explain_message_errno_asprintf function is used to obtain an explanation of an error returned by the asprintf(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.

• 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.

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

errno = 0;
int result = asprintf();
if (result < 0 || errno != 0)
{
    int err = errno;
    char message[3000];
    explain_message_errno_asprintf(message, sizeof(message), err,
    );
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

the above code example is available pre-packaged as the explain_asprintf_or_die(3) function.

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👑 SEE ALSO 👑

• asprintf(3) — print to allocated string
• explain_asprintf_or_die(3) — print to allocated string and report errors

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💜 COPYRIGHT 💜

• libexplain version 1.4
• Copyright (C) 2013 Peter Miller

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okay and that's the whole page!! you understood it, you're a genius, I'm so proud of you 🎀🦋💖

signing off from libexplain version 1.4, © 2013 Peter Miller, still serving looks in the Library Functions Manual — mwah, love u, go fix your errno 💅✨