libsdlerror is a small library that helps C programmers write correct, readable, and maintainable error-handling code without pretending that C is something it is not.

It does not add exceptions to C.
It does not hide control flow.
It does not allocate memory at runtime.

If you want magic, look elsewhere.

Why This Library Exists

Error handling in C is not hard — but it is tedious, repetitive, and easy to get wrong.

The usual pattern:

if (foo() < 0) {
    fprintf(stderr, "%s\n", SDL_GetError());
    cleanup();
    return -1;
}

works, until it doesn’t. As programs grow:

Error checks get duplicated
Cleanup paths multiply
Context disappears
Control flow becomes fragmented

SDL compounds this by storing errors in a single thread-local string, forcing programmers to either handle errors immediately or lose information.

libsdlerror exists to impose structure and discipline on this process — without compromising the explicitness that makes C reliable.

What This Library Is — and Is Not

This library is deliberately conservative.

🚫 No `setjmp`, No `longjmp`

Many C error libraries attempt to simulate exceptions using setjmp / longjmp.

That approach is rejected here.

Non-local jumps:

Bypass normal control flow
Skip cleanup invisibly
Break assumptions about stack lifetime
Make reasoning about correctness harder, not easier

If control flow moves in libsdlerror, it does so because the source code says so.

Nothing jumps. Nothing unwinds itself. Nothing “just happens.”

🚫 No Runtime Memory Allocation — Ever

libsdlerror never performs dynamic memory allocation at runtime.

It does not call:

malloc
calloc
realloc
free

There is no allocator dependency and no runtime allocation failure mode.

📌 Explicit Storage Model

All memory used by libsdlerror falls into one of two categories:

Automatic storage (stack)
Caller-owned error contexts and local state
Static storage duration
Fixed-size internal tables allocated at program load time

There is no heap allocation and no runtime resizing.

✅ C Means C

No compiler extensions
No undefined behavior
No optimizer tricks

If it compiles as C, it works as C.

✅ Designed for SDL, Not Against It

SDL already has an error system. It is simple, global, and fragile.

libsdlerror does not replace it. It captures SDL error state at the right moment, preserves context, and makes it usable without forcing error checks everywhere.

The Six Guiding Principles

This library is opinionated, and intentionally so.

Control flow must be explicit
If execution moves, the source code must show why.
No setjmp / longjmp
Errors must not bypass the stack.
No runtime memory allocation
The library relies only on stack and static storage.
The caller owns all state
No hidden globals exposed to the user.
Cleanup must be deterministic
Cleanup always runs, exactly once.
Errors are values, not side effects
They are captured, inspected, propagated, or handled deliberately.

Quick Start

Build and Install

cmake -S . -B build
cmake --build build
cmake --install build

Compile Your Program

gcc `pkg-config --cflags sdlerror` main.c \
    `pkg-config --libs sdlerror` \
    -o app

Minimal Example

#include <sdlerror.h>

int main(void) {
    PREPARE_ERROR(err);

    ATTEMPT {
        CATCH(err, SDL_Init(SDL_INIT_VIDEO));
        CATCH(err, do_something_that_can_fail());
    }
    CLEANUP {
        SDL_Quit();
    }
    PROCESS(err) {
        fprintf(stderr, "Error: %s\n", ERROR_MESSAGE(err));
        return 1;
    }
    FINISH(err, true);

    return 0;
}

User-Configurable Error Codes

While most aspects of libsdlerror are intentionally fixed, error codes themselves are user-defined.

Defining `ERR_*` Codes

#define ERR_OK        0
#define ERR_SDL       1
#define ERR_IO        2
#define ERR_CONFIG    3

These are simple integer status values.

`MAX_ERR_VALUE`

MAX_ERR_VALUE must be greater than or equal to the highest ERR_* value you define.

It determines the size of internal static tables used to map error codes to names.

If you add new error codes, you must update MAX_ERR_VALUE and recompile.

Naming Errors: `error_name_for_status`

error_name_for_status(ERR_IO, "I/O error");
error_name_for_status(ERR_CONFIG, "Configuration error");

Names are copied into fixed-size static buffers and persist for the lifetime of the program.

No allocation occurs.

Appendix: Memory Model

Storage Duration Overview

libsdlerror uses only automatic (stack) storage and static storage duration.

No heap allocation occurs at runtime.

Compile-Time Limits (`MAX_ERR*`)

The MAX_ERR* macros in sdlerror.h define fixed upper bounds for:

Error message length
Error name length
Stacktrace buffer size
Number of error contexts

These values are not user-tunable at runtime.

If you need different limits, you are expected to edit the header and recompile.

Static Memory Usage (x86_64)

On a typical x86_64 system:

Error name table: ~1 KB
Static error pool: ~450 KB
Miscellaneous globals: a few KB

Total static footprint: ~470 KB

All of this memory is allocated at program load time.

FAQ

Why Use Static Globals Instead of the Heap?

Because error handling infrastructure must not itself fail.

Heap allocation introduces failure modes, ordering problems, and unpredictability.

Static storage avoids all of this.

The globals used by libsdlerror are fixed-size, initialized at load time, and free of allocator dependencies.

Why Not Allocate Per-Error Structures Dynamically?

Because error handling must work when memory is tight, during early startup, and during shutdown.

Dynamic allocation undermines all three.

Summary

libsdlerror is deliberately conservative.

No jumps.
No heap allocation.
No hidden control flow.

Just explicit, disciplined error handling — the way C has always worked when used correctly.

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