explain_getgrent(3)

💖 explain_getgrent(3) — Library Functions Manual 💖

okay bestie, sit down, hydrate, and let me tell you about explain_getgrent from the libexplain library. it's the girl whose whole job is explaining why getgrent(3) said no. she's not dramatic, she's informative. 💅

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✨ NAME ✨

explain_getgrent — explain getgrent(3) errors 🫶

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🌸 SYNOPSIS 🌸

#include <libexplain/getgrent.h>
const char *explain_getgrent(void);
const char *explain_errno_getgrent(int errnum, void);
void explain_message_getgrent(char *message, int message_size, void);
void explain_message_errno_getgrent(char *message, int message_size, int
errnum, void);

heads up, the void at the end of those signatures is literally how it's written. don't come for me, come for the header. 🙈

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🦋 DESCRIPTION 🦋

these functions are your little support group for errors that getgrent(3) throws at you. it's giving "tell me what went wrong, in detail, with love". ✨

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🎀 explain_getgrent 🎀

const char *explain_getgrent(void);

explain_getgrent hands you an explanation of an error returned by the getgrent(3) system call. the least you'll get is the value of strerror(errno), but bestie, usually it does so much better and tells you the actual underlying cause in more detail. no cap. 👑

the errno global variable is the one used to grab the error value that gets decoded.

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 will be overwritten by the next call to any libexplain function that shares this buffer, including from 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 meant to be used in a fashion similar to the following example:

errno = 0;
struct group *result = getgrent();
if (!result && errno != 0)
{
    fprintf(stderr, "%s\n", explain_getgrent());
    exit(EXIT_FAILURE);
}

the above code example is available pre-packaged as the explain_getgrent_or_die(3) function. iconic. 🌟

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💜 explain_errno_getgrent 💜

const char *explain_errno_getgrent(int errnum, void);

explain_errno_getgrent gets you an explanation of an error returned by the getgrent(3) system call. again, the least the message will contain is the value of strerror(errno), but usually it goes way harder and points at the underlying cause in more detail. 💅

• errnum — the error value to be decoded, usually grabbed from the errno global variable right before this function gets called. you need this if you have to run any code between the system call being explained and this function, because many libc functions will alter the value of errno. sneaky. 😭

Returns:

the message explaining the error. same deal as before: 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: 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:

errno = 0;
struct group *result = getgrent();
if (!result && errno != 0)
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_getgrent(err, ));
    exit(EXIT_FAILURE);
}

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

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🌈 explain_message_getgrent 🌈

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

explain_message_getgrent obtains an explanation of an error returned by the getgrent(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. she's thorough, she's that girl. 🎀

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.

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

errno = 0;
struct group *result = getgrent();
if (!result && errno != 0)
{
    char message[3000];
    explain_message_getgrent(message, sizeof(message), );
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

the above code example is available pre-packaged as the explain_getgrent_or_die(3) function. 🔥

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🧚 explain_message_errno_getgrent 🧚

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

explain_message_errno_getgrent obtains an explanation of an error returned by the getgrent(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. yes, it's the same promise every time, and yes, she keeps it. 💖

• 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. 🙈

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

errno = 0;
struct group *result = getgrent();
if (!result && errno != 0)
{
    int err = errno;
    char message[3000];
    explain_message_errno_getgrent(message, sizeof(message), err,
    );
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

the above code example is available pre-packaged as the explain_getgrent_or_die(3) function. 🌟

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👑 SEE ALSO 👑

• getgrent(3) — get group file entry
• explain_getgrent_or_die(3) — get group file entry 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 page, bestie!! 🎀 you now know every single function, every argument, every example, and the thread-safety tea. go forth and let libexplain narrate your errno for you. mwah. 💅✨

explain_getgrent(3) — signing off, stay hydrated, and may your errno always be 0. 🦋🌸