6.2 KiB
libsdlerror
Explicit, disciplined error handling for C — built on SDL3.
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:
malloccallocreallocfree
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.