explain_endgrent(3)

💖 explain_endgrent — bestie, let's decode those endgrent(3) errors 💖

okay so real talk, this is page three of the Library Functions Manual situation, and it's the glow-up guide for explain_endgrent(3) — the lil squad of functions that tell you why your endgrent(3) call fumbled. no cap, it's giving "translator for errno" energy and we're obsessed. 🦋

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✨ SYNOPSIS ✨

#include <libexplain/endgrent.h>
const char *explain_endgrent(void);
const char *explain_errno_endgrent(int errnum, void);
void explain_message_endgrent(char *message, int message_size, void);
void explain_message_errno_endgrent(char *message, int message_size, int
errnum, void);

like, copy that include line exactly bestie, #include <libexplain/endgrent.h>, don't get cute with it 💅

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🌸 DESCRIPTION 🌸

so these functions? they exist purely to hand you explanations for errors returned by the endgrent(3) system call. that's it, that's the whole job, and they do it beautifully. 🎀

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🌈 explain_endgrent

const char *explain_endgrent(void);

the explain_endgrent function gets you an explanation of an error returned by the endgrent(3) system call. the least the message will contain is the value of strerror(errno) — but lowkey it usually does much better than that and tells you the actual underlying cause in more detail. main character behavior fr fr. ✨

the errno global variable is the one it peeks at to grab the error value it's gonna decode.

Returns:

the message explaining the error. this message buffer is shared by all libexplain functions that don't supply a buffer in their argument list. so it gets overwritten by the next call to any libexplain function that shares this buffer — including other threads. yes, other threads. iykyk. 😭

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 = 0;
void result = endgrent();
if (result < 0 && errno != 0)
{
    fprintf(stderr, "%s\n", explain_endgrent());
    exit(EXIT_FAILURE);
}

the above code example is available pre-packaged as the explain_endgrent_or_die(3) function. convenient much? 💅

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🦋 explain_errno_endgrent

const char *explain_errno_endgrent(int errnum, void);

the explain_errno_endgrent function gets you an explanation of an error returned by the endgrent(3) system call. again, the least the message will contain is the value of strerror(errno), but usually it does way better and points at the underlying cause in more detail. she ate. 🔥

• 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 run any code between the system call being explained and this function, because many libc functions will alter the value of errno. sneaky of them honestly. 🙈

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. it'll be overwritten by the next call to any libexplain function that 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 do too.

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

errno = 0;
void result = endgrent();
if (result < 0 && errno != 0)
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_endgrent(err, ));
    exit(EXIT_FAILURE);
}

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

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🎀 explain_message_endgrent

void explain_message_endgrent(char *message, int message_size, void);

the explain_message_endgrent function gets you an explanation of an error returned by the endgrent(3) system call. least it'll contain is the value of strerror(errno), but usually it does much better and indicates the underlying cause in more detail. slay. ✨

the errno global variable is what it uses to get the error value to be decoded.

• message — the location in which to store the returned message. if you supply a suitable message return buffer, this function is thread safe. (!!) 🫶
• 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;
void result = endgrent();
if (result < 0 && errno != 0)
{
    char message[3000];
    explain_message_endgrent(message, sizeof(message), );
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

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

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💜 explain_message_errno_endgrent

void explain_message_errno_endgrent(char *message, int message_size, int
errnum, void);

the explain_message_errno_endgrent function gets you an explanation of an error returned by the endgrent(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. iconic behavior ngl. 🌸

• 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. the audacity fr fr. 😭

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

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

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

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⭐ SEE ALSO ⭐

• endgrent(3) — finish group file accesses
• explain_endgrent_or_die(3) — finish group file accesses and report errors

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👑 COPYRIGHT 👑

libexplain version 1.4 Copyright (C) 2013 Peter Miller

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and that's the whole vibe check bestie — this was explain_endgrent(3) from the Library Functions Manual, brought to you by libexplain version 1.4, with copyright held down by Peter Miller, 2013. go forth and decode your errnos, you absolute legend. 💖✨🦋