explain_fgetc(3)

💖 explain_fgetc — bestie, let's decode ur fgetc(3) drama 💖

okay so real talk: this is a page from the Library Functions Manual, and it's all about the explain_fgetc crew — four little functions from libexplain whose whole job is turning ur cryptic fgetc(3) errors into actual sentences a human can read. no cap. ✨

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🌸 NAME 🌸

explain_fgetc — explain fgetc(3) errors 🫶

like. it explains them. that's the gig. that's the whole vibe. 💅

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✨ SYNOPSIS ✨

#include <libexplain/fgetc.h>
const char *explain_fgetc(FILE *fp);
const char *explain_errno_fgetc(int errnum, FILE *fp);
void explain_message_fgetc(char *message, int message_size, FILE *fp);
void explain_message_errno_fgetc(char *message, int message_size, int
errnum, FILE *fp);

four functions, four lil personalities, one shared mission: make the error make sense 🌈

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🦋 DESCRIPTION 🦋

These functions may be used to obtain explanations for errors returned by the fgetc(3) system call. 🎀

translation bestie: fgetc fails, u get a sad little errno, and instead of staring at it like 🧍 u call one of these and it tells u what actually went down. iconic behaviour, honestly.

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💜 explain_fgetc

const char *explain_fgetc(FILE *fp);

The explain_fgetc function is used to obtain an explanation of an error returned by the fgetc(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.

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

int c = fgetc(fp);
if (c == EOF && ferror(fp))
{
    fprintf(stderr, "%s\n", explain_fgetc(fp));
    exit(EXIT_FAILURE);
}

• fp — The original fp, exactly as passed to the fgetc(3) system call. like, exactly exactly. don't get cute with it. 🙈

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 ur threading, pls babe, use the message versions instead. 🫶

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💖 explain_errno_fgetc

const char *explain_errno_fgetc(int errnum, FILE *fp);

The explain_errno_fgetc function is used to obtain an explanation of an error returned by the fgetc(3) 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:

int c = fgetc(fp);
if (c == EOF && ferror(fp))
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_fgetc(err, fp));
    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. 🚨 so grab errno early, bestie, before somebody else ruins it.
• fp — The original fp, exactly as passed to the fgetc(3) 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.

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🎀 explain_message_fgetc

void explain_message_fgetc(char *message, int message_size, FILE *fp);

The explain_message_fgetc function may be used to obtain an explanation of an error returned by the fgetc(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.

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

int c = fgetc(fp);
if (c == EOF && ferror(fp))
{
    char message[3000];
    explain_message_fgetc(message, sizeof(message), fp);
    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. 🥳 ur own buffer, ur own rules, no shared drama.
• message_size — The size in bytes of the location in which to store the returned message. (the example above rolls with 3000, just saying. 👀)
• fp — The original fp, exactly as passed to the fgetc(3) system call.

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🌈 explain_message_errno_fgetc

void explain_message_errno_fgetc(char *message, int message_size, int
errnum, FILE *fp);

The explain_message_errno_fgetc function may be used to obtain an explanation of an error returned by the fgetc(3) 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:

int c = fgetc(fp);
if (c == EOF && ferror(fp))
{
    int err = errno;
    char message[3000];
    explain_message_errno_fgetc(message, sizeof(message), err, fp);
    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. fr fr, save that errno. 😤
• fp — The original fp, exactly as passed to the fgetc(3) system call.

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🧚 SEE ALSO 🧚

• fgetc(3) — input of characters 💜
• explain_fgetc_or_die(3) — input of characters and report errors 💀 (yes the _or_die version, she's dramatic, she exits for u)

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👑 COPYRIGHT 👑

okay so that's the whole page, and here's the lil legal moment bestie, we keep it cute but we keep it accurate:

libexplain version 1.4 🌸 Copyright (C) 2008 Peter Miller 🎀

and that's a wrap on explain_fgetc(3) from the Library Functions Manual — go forth and never read a raw errno alone again. slay. 💅✨🦋