explain_raise(3)

💖 explain_raise(3) — or, "bestie, why did my raise(3) flop?"

okay so this is a Library Functions Manual page, and it's all about the libexplain glow-up for raise(3) errors. sit down, grab a strawberry 🍓, and let's get into it.

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✨ NAME ✨

explain_raise — explain raise(3) errors. that's it. that's the whole name. iconic behavior honestly.

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🌸 SYNOPSIS 🌸

#include <libexplain/raise.h>
const char *explain_raise(int sig);
const char *explain_errno_raise(int errnum, int sig);
void explain_message_raise(char *message, int message_size, int sig);
void explain_message_errno_raise(char *message, int message_size, int errnum, int sig);

like, four whole functions. four. we ate. 💅

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🦋 DESCRIPTION 🦋

so these functions exist to hand you explanations for errors that came back from the raise(3) system call. that's the vibe. that's the whole job.

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🎀 explain_raise

const char *explain_raise(int sig);

the explain_raise function gets you an explanation of an error returned by the raise(3) system call. the least the message will contain is the value of strerror(errno) — but usually it goes so much harder and points at the actual underlying cause in more detail. lowkey overachiever energy.

the errno global variable is what gets used to grab the error value that needs decoding.

• sig — the original sig, exactly as passed to the raise(3) system call.

Returns:

the message explaining the error. and here's the tea ☕ — this message buffer is shared by all libexplain functions that don't supply a buffer in their argument list. it gets overwritten by the next call to any libexplain function that shares this buffer, including from other threads. so like, screenshot it, don't just point at it.

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. not the moment for multitasking bestie.

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

if (raise(sig) < 0)
{
    fprintf(stderr, "%s\n", explain_raise(sig));
    exit(EXIT_FAILURE);
}

the above code example is available pre-packaged as the explain_raise_or_die(3) function. so if you don't wanna write it yourself, that one's already dressed and ready. 🫶

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🌈 explain_errno_raise

const char *explain_errno_raise(int errnum, int sig);

the explain_errno_raise function gets you an explanation of an error returned by the raise(3) system call. the least the message will contain is the value of strerror(errno), but usually it does much better and indicates 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 being explained and this function, because many libc functions will alter the value of errno. so yeah, capture it early or it's gone, fr fr.
• sig — the original sig, exactly as passed to the raise(3) system call.

Returns:

the message explaining the error. same deal as before: this message buffer is shared by all libexplain functions which do not supply a buffer in their argument list. it 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:

if (raise(sig) < 0)
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_raise(err, sig));
    exit(EXIT_FAILURE);
}

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

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💜 explain_message_raise

void explain_message_raise(char *message, int message_size, int sig);

the explain_message_raise function gets you an explanation of an error returned by the raise(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. okayyyyy we love a safe queen 👑
• message_size — the size in bytes of the location in which to store the returned message.
• sig — the original sig, exactly as passed to the raise(3) system call.

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

if (raise(sig) < 0)
{
    char message[3000];
    explain_message_raise(message, sizeof(message), sig);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

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

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⭐ explain_message_errno_raise

void explain_message_errno_raise(char *message, int message_size, int errnum, int sig);

the explain_message_errno_raise function gets you an explanation of an error returned by the raise(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.
• sig — the original sig, exactly as passed to the raise(3) system call.

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

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

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

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🔥 SEE ALSO 🔥

• raise(3) — send a signal to the caller
• explain_raise_or_die(3) — send a signal to the caller and report errors

the way these two just... complement each other. the dynamic duo. iykyk.

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👑 COPYRIGHT 👑

libexplain version 1.4 Copyright (C) 2009 Peter Miller

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and that's the whole page, bestie. it's giving explain_raise(3), it's giving Library Functions Manual, and it's giving 2009 Peter Miller with libexplain version 1.4 energy — go forth and explain those errors, you main character 💅✨