explain_pclose(3)

💖 explain_pclose(3) — Library Functions Manual 💖

okay bestie, pull up a chair 🪑 because we're talking about explain_pclose(3) — the libexplain glow-up for pclose(3) errors. if you've ever had a pclose(3) call flop and just wanted somebody to tell you why, this is the page. no cap. 👑

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✨ NAME ✨

explain_pclose — explain pclose(3) errors 💅

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🦋 SYNOPSIS 🦋

#include <libexplain/pclose.h>
const char *explain_pclose(FILE *fp);
const char *explain_errno_pclose(int errnum, FILE *fp);
void explain_message_pclose(char *message, int message_size, FILE *fp);
void explain_message_errno_pclose(char *message, int message_size, int errnum, FILE *fp);

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🌸 DESCRIPTION 🌸

these functions are your little support group 🫶 — you use them to get actual explanations for errors handed back by the pclose(3) system call. like, instead of a cryptic nothing-burger, you get ✨lore✨.

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🎀 explain_pclose

const char *explain_pclose(FILE *fp);

the explain_pclose function is how you get an explanation of an error returned by the pclose(3) system call. the absolute bare minimum the message will contain is the value of strerror(errno), but honestly? usually it does so much better, and it'll point at the underlying cause with way more detail. it's giving detective energy 🔍.

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

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

if (pclose(fp) < 0)
{
    fprintf(stderr, "%s\n", explain_pclose(fp));
    exit(EXIT_FAILURE);
}

the above code example is available pre‐packaged as the explain_pclose_or_die(3) function. convenient, right? 😌

• fp — the original fp, exactly as passed to the pclose(3) system call. no substitutions, no swapsies.

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 will be overwritten by the next call to any libexplain function which shares this buffer, including other threads. so like... don't get attached to it. 💀

Note: this function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library. not me being a shared resource 😭

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🌈 explain_errno_pclose

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

the explain_errno_pclose function is how you get an explanation of an error returned by the pclose(3) system call. the absolute bare minimum the message will contain is the value of strerror(errnum), but usually it does so much better, and it'll indicate the underlying cause in more detail. main character of error messages fr fr.

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

if (pclose(fp) < 0)
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_pclose(err, fp));
    exit(EXIT_FAILURE);
}

the above code example is available pre‐packaged as the explain_pclose_or_die(3) function.

• 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 it early, bestie. 🏃‍♀️
• fp — the original fp, exactly as passed to the pclose(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_pclose

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

the explain_message_pclose function may be used to obtain an explanation of an error returned by the pclose(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 behaviour, honestly.

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 (pclose(fp) < 0)
{
    char message[3000];
    explain_message_pclose(message, sizeof(message), fp);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

the above code example is available pre‐packaged as the explain_pclose_or_die(3) function.

• message — the location in which to store the returned message. if a suitable message return buffer is supplied, this function is thread safe. look at her go 🎀
• message_size — the size in bytes of the location in which to store the returned message.
• fp — the original fp, exactly as passed to the pclose(3) system call.

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💜 explain_message_errno_pclose

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

the explain_message_errno_pclose function may be used to obtain an explanation of an error returned by the pclose(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 (pclose(fp) < 0)
{
    int err = errno;
    char message[3000];
    explain_message_errno_pclose(message, sizeof(message), err, fp);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

the above code example is available pre‐packaged as the explain_pclose_or_die(3) function.

• 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. (yes, same warning, it's that important 💅)
• fp — the original fp, exactly as passed to the pclose(3) system call.

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👀 SEE ALSO 👀

• pclose(3) — process I/O
• explain_pclose_or_die(3) — process I/O and report errors

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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 💖 this was explain_pclose(3) from the Library Functions Manual — libexplain version 1.4, Copyright (C) 2009 Peter Miller. go forth and debug slayfully 👑✨🌸