explain_ptrace(3)

✨ explain_ptrace(3) ✨ — the libexplain page that decodes your ptrace(2) drama 💅

okay bestie, sit down, hydrate, because we're about to make ptrace(2) errors make sense. this is the manual page for the explain_ptrace family of functions from libexplain — they take your cursed syscall return value and turn it into a whole actual sentence about what went wrong. no cap. 🦋

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🌸 NAME 🌸

explain_ptrace — explain ptrace(2) errors 💖

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🎀 SYNOPSIS 🎀

#include <libexplain/ptrace.h>
const char *explain_ptrace(int request, pid_t pid, void *addr, void *data);
const char *explain_errno_ptrace(int errnum, int request, pid_t pid, void *addr, void *data);
void explain_message_ptrace(char *message, int message_size, int request, pid_t pid, void *addr, void *data);
void explain_message_errno_ptrace(char *message, int message_size, int errnum, int request, pid_t pid, void *addr, void *data);

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🦋 DESCRIPTION 🦋

so, these functions? they're your little translators. you use them to get explanations for errors returned by the ptrace(2) system call. that's the whole vibe. 🌈

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explain_ptrace 💫

const char *explain_ptrace(int request, pid_t pid, void *addr, void *data);

the explain_ptrace function is used to obtain an explanation of an error returned by the ptrace(2) 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 love that for it. 👑

the errno global variable will be used to obtain the error value to be decoded.

• request — the original request, exactly as passed to the ptrace(2) system call.
• pid — the original pid, exactly as passed to the ptrace(2) system call.
• addr — the original addr, exactly as passed to the ptrace(2) system call.
• data — the original data, exactly as passed to the ptrace(2) 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. bestie, do not come for this function in a multi-threaded situation, it will not survive the vibe check. 💀

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

long result = ptrace(request, pid, addr, data);
if (result < 0)
{
    fprintf(stderr, "%s\n", explain_ptrace(request, pid, addr, data));
    exit(EXIT_FAILURE);
}

the above code example is available pre-packaged as the explain_ptrace_or_die(3) function. 🫶

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explain_errno_ptrace 💫

const char *explain_errno_ptrace(int errnum, int request, pid_t pid, void *addr, void *data);

the explain_errno_ptrace function is used to obtain an explanation of an error returned by the ptrace(2) 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. same energy, but you hand it the error yourself. ✨

• 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. lowkey the most important rule here, fr fr. 🚨
• request — the original request, exactly as passed to the ptrace(2) system call.
• pid — the original pid, exactly as passed to the ptrace(2) system call.
• addr — the original addr, exactly as passed to the ptrace(2) system call.
• data — the original data, exactly as passed to the ptrace(2) 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. 🙈

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

long result = ptrace(request, pid, addr, data);
if (result < 0)
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_ptrace(err, request, pid, addr, data));
    exit(EXIT_FAILURE);
}

the above code example is available pre-packaged as the explain_ptrace_or_die(3) function. 🫶

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explain_message_ptrace 💫

void explain_message_ptrace(char *message, int message_size, int request, pid_t pid, void *addr, void *data);

the explain_message_ptrace function is used to obtain an explanation of an error returned by the ptrace(2) 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 doesn't return a string — it writes into the buffer you give it, which is iconic of it honestly. 🎀

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. slay. ✅
• message_size — the size in bytes of the location in which to store the returned message.
• request — the original request, exactly as passed to the ptrace(2) system call.
• pid — the original pid, exactly as passed to the ptrace(2) system call.
• addr — the original addr, exactly as passed to the ptrace(2) system call.
• data — the original data, exactly as passed to the ptrace(2) system call.

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

long result = ptrace(request, pid, addr, data);
if (result < 0)
{
    char message[3000];
    explain_message_ptrace(message, sizeof(message), request, pid, addr, data);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

the above code example is available pre-packaged as the explain_ptrace_or_die(3) function. 🫶

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explain_message_errno_ptrace 💫

void explain_message_errno_ptrace(char *message, int message_size, int errnum, int request, pid_t pid, void *addr, void *data);

the explain_message_errno_ptrace function is used to obtain an explanation of an error returned by the ptrace(2) 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 the "you bring the buffer, i bring the errno" one. main character energy. 💅

• 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. 🚨
• request — the original request, exactly as passed to the ptrace(2) system call.
• pid — the original pid, exactly as passed to the ptrace(2) system call.
• addr — the original addr, exactly as passed to the ptrace(2) system call.
• data — the original data, exactly as passed to the ptrace(2) system call.

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

long result = ptrace(request, pid, addr, data);
if (result < 0)
{
    int err = errno;
    char message[3000];
    explain_message_errno_ptrace(message, sizeof(message), err, request, pid, addr, data);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

the above code example is available pre-packaged as the explain_ptrace_or_die(3) function. 🫶

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🌈 SEE ALSO 🌈

• ptrace(2) — process trace 🔥
• explain_ptrace_or_die(3) — process trace and report errors 💖

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👑 COPYRIGHT 👑

libexplain version 1.4 Copyright (C) 2010 Peter Miller

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and that's the whole page, bestie 💜 tysm for reading all the way to the bottom, you're literally the strongest soldier. this was explain_ptrace(3), from the Library Functions Manual, libexplain version 1.4, copyright (C) 2010 Peter Miller — go forth and decode your errnos, periodt. 🎀✨🦋