explain_sprintf(3)

💖 explain_sprintf(3) — the libexplain girlie's guide to sprintf(3) errors 💖

okay bestie, welcome to explain_sprintf from the Library Functions Manual ✨ this is a libexplain page, so it's giving "your syscall errored and I'm gonna tell you why, in detail" energy 🫶

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✨ NAME ✨

explain_sprintf — explain sprintf(3) errors 💅

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🌸 SYNOPSIS 🌸

#include <libexplain/sprintf.h>
const char *explain_sprintf(char *data, const char *format, ...);
const char *explain_errno_sprintf(int errnum, char *data, const char
*format, ...);
void explain_message_sprintf(char *message, int message_size, char
*data, const char *format, ...);
void explain_message_errno_sprintf(char *message, int message_size, int
errnum, char *data, const char *format, ...);

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💜 DESCRIPTION 💜

So these functions? They exist to hand you explanations for errors that come back from the sprintf(3) system call. no cap, that's the whole vibe 💫

🎀 explain_sprintf 🎀

const char *explain_sprintf(char *data, const char *format, ...);

explain_sprintf is the one you call to get an explanation of an error returned by the sprintf(3) system call. the least the message will contain is the value of strerror(errno), but usually it's gonna do so much better than that and point at the underlying cause in way more detail 👑

The errno global variable is what gets used to obtain the error value to be decoded.

• data — the original data, exactly as it was passed to the sprintf(3) system call.
• format — the original format, exactly as it was passed to the sprintf(3) system call.

Returns:

The message explaining the error. heads up tho — this message buffer is shared by all libexplain functions that don't supply a buffer in their argument list. so it will be overwritten by the next call to any libexplain function that shares this buffer, including calls from other threads 😭

Note: this function is not thread safe, because it shares a return buffer across all threads, and so do many other functions in this library. periodt.

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

errno = EINVAL;
int result = sprintf(data, format, ...);
if (result < 0)
{
    fprintf(stderr, "%s\n", explain_sprintf(data, format, ...));
    exit(EXIT_FAILURE);
}

The above code example is available pre‐packaged as the explain_sprintf_or_die(3) function ✨

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🦋 explain_errno_sprintf 🦋

const char *explain_errno_sprintf(int errnum, char *data, const char
*format, ...);

explain_errno_sprintf is used to obtain an explanation of an error returned by the sprintf(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 grabbed from the errno global variable right before this function is called. this is necessary if you need to call any code between the system call being explained and this function, because so many libc functions will alter the value of errno 🙈
• data — the original data, exactly as passed to the sprintf(3) system call.
• format — the original format, exactly as passed to the sprintf(3) system call.

Returns:

The message explaining the error. again, this message buffer is shared by all libexplain functions that don't supply a buffer in their argument list, and it will be overwritten by the next call to any libexplain function that shares this buffer, including other threads 💀

Note: not thread safe, bestie. it shares a return buffer across all threads, and so do many other functions in this library.

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

errno = EINVAL;
int result = sprintf(data, format, ...);
if (result < 0)
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_sprintf(err, data,
    format, ...));
    exit(EXIT_FAILURE);
}

The above code example is available pre‐packaged as the explain_sprintf_or_die(3) function 🌈

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🌸 explain_message_sprintf 🌸

void explain_message_sprintf(char *message, int message_size, char
*data, const char *format, ...);

explain_message_sprintf is used to obtain an explanation of an error returned by the sprintf(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 👑
• 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 sprintf(3) system call.
• format — the original format, exactly as passed to the sprintf(3) system call.

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

errno = EINVAL;
int result = sprintf(data, format, ...);
if (result < 0)
{
    char message[3000];
    explain_message_sprintf(message, sizeof(message), data,
    format, ...);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

The above code example is available pre‐packaged as the explain_sprintf_or_die(3) function 🎀

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💅 explain_message_errno_sprintf 💅

void explain_message_errno_sprintf(char *message, int message_size, int
errnum, char *data, const char *format, ...);

explain_message_errno_sprintf is used to obtain an explanation of an error returned by the sprintf(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. 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 sprintf(3) system call.
• format — the original format, exactly as passed to the sprintf(3) system call.

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

errno = EINVAL;
int result = sprintf(data, format, ...);
if (result < 0)
{
    int err = errno;
    char message[3000];
    explain_message_errno_sprintf(message, sizeof(message), err,
    data, format, ...);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

The above code example is available pre‐packaged as the explain_sprintf_or_die(3) function 🧚

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🌈 SEE ALSO 🌈

• sprintf(3) — formatted output conversion
• explain_sprintf_or_die(3) — formatted output conversion and report errors

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💜 COPYRIGHT 💜

libexplain version 1.4 Copyright (C) 2010 Peter Miller

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and that's the whole page, bestie 🫶 tysm for reading the explain_sprintf(3) girlie edition — this was libexplain version 1.4, Copyright (C) 2010 Peter Miller, and yes, it lives in the Library Functions Manual. slay, stay safe, and always check your errno before something else clobbers it 💅💖✨