explain_fgets(3)

💖 explain_fgets — explain fgets(3) errors 💖

okay bestie, so this is a page from the Library Functions Manual, and it's all about explain_fgets(3) — the girl whose whole job is telling you why your fgets(3) call said no. no cap. 🎀

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🌸 NAME 🌸

explain_fgets — explain fgets(3) errors

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✨ SYNOPSIS ✨

#include <libexplain/fgets.h>
const char *explain_fgets(char *data, int data_size, FILE *fp);
const char *explain_errno_fgets(int errnum, char *data, int data_size, FILE *fp);
void explain_message_fgets(char *message, int message_size, char *data, int data_size, FILE *fp);
void explain_message_errno_fgets(char *message, int message_size, int errnum, char *data, int data_size, FILE *fp);

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💅 DESCRIPTION 💅

These functions may be used to obtain explanations for errors returned by the fgets(3) system call. literally their entire purpose, and they ate. 🔥

🦋 explain_fgets

const char *explain_fgets(char *data, int data_size, FILE *fp);

The explain_fgets function is used to obtain an explanation of an error returned by the fgets(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. it's giving overachiever and we're obsessed. ✨

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 (fgets(data, data_size, fp) < 0)
{
    fprintf(stderr, "%s\n", explain_fgets(data, data_size, fp));
    exit(EXIT_FAILURE);
}

• data — The original data, exactly as passed to the fgets(3) system call.
• data_size — The original data_size, exactly as passed to the fgets(3) system call.
• fp — The original fp, exactly as passed to the fgets(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. 😭 she's a shared girlie, handle with care.

Note: This function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library. 💀 do not come for her about it, she told you upfront.

🧚 explain_errno_fgets

const char *explain_errno_fgets(int errnum, char *data, int data_size, FILE *fp);

The explain_errno_fgets function is used to obtain an explanation of an error returned by the fgets(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:

if (fgets(data, data_size, fp) < 0)
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_fgets(err, data, data_size, 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. 🫶 yes bestie, save that errno FIRST, she is not gonna wait for you.
• data — The original data, exactly as passed to the fgets(3) system call.
• data_size — The original data_size, exactly as passed to the fgets(3) system call.
• fp — The original fp, exactly as passed to the fgets(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.

🌈 explain_message_fgets

void explain_message_fgets(char *message, int message_size, char *data, int data_size, FILE *fp);

The explain_message_fgets function may be used to obtain an explanation of an error returned by the fgets(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:

if (fgets(data, data_size, fp) < 0)
{
    char message[3000];
    explain_message_fgets(message, sizeof(message), data, data_size, 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. 👑 main character behaviour, honestly.
• 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 fgets(3) system call.
• data_size — The original data_size, exactly as passed to the fgets(3) system call.
• fp — The original fp, exactly as passed to the fgets(3) system call.

💜 explain_message_errno_fgets

void explain_message_errno_fgets(char *message, int message_size, int errnum, char *data, int data_size, FILE *fp);

The explain_message_errno_fgets function may be used to obtain an explanation of an error returned by the fgets(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:

if (fgets(data, data_size, fp) < 0)
{
    int err = errno;
    char message[3000];
    explain_message_errno_fgets(message, sizeof(message), err,
        data, data_size, 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.
• data — The original data, exactly as passed to the fgets(3) system call.
• data_size — The original data_size, exactly as passed to the fgets(3) system call.
• fp — The original fp, exactly as passed to the fgets(3) system call.

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🎀 SEE ALSO 🎀

• fgets(3) — input of strings
• explain_fgets_or_die(3) — input of strings 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 vibe check bestie 💖 she's the explain_fgets(3) girlie from libexplain version 1.4, copyrighted in 2008 by Peter Miller, and she has been explaining fgets(3) errors with main character energy ever since. go forth, catch your errors, stay hydrated, and remember: if fgets returns < 0, that's not a you problem — it's an explain_fgets problem now. slay. 💅✨🦋🌸