C

Write safe C avoiding memory corruption, buffer overflows, and undefined behavior traps.

Pass

Agentic behavior and permission review.

Pattern checks against bundled files.

Multi-engine malware detections and file reputation.

openclaw skills install c

Quick Reference

Topic	File
malloc/free, leaks, double free	`memory.md`
Null, dangling, pointer arithmetic	`pointers.md`
Null terminator, buffer overflow	`strings.md`
Integer overflow, signed/unsigned	`types.md`
Macro traps, include guards	`preprocessor.md`
Common undefined behavior	`undefined.md`

malloc returns void* — cast required in C++, optional in C but check for NULL
free(ptr); ptr = NULL; — always null after free to prevent double-free
sizeof(array) in function gives pointer size, not array size — pass length separately
char str[5] = "hello"; — no room for null terminator, UB when used as string
strcpy doesn't check bounds — use strncpy and manually null-terminate
Signed overflow is UB — compiler can optimize assuming it never happens
i++ + i++ is UB — no sequence point between modifications
Returning pointer to local variable — dangling pointer, UB on use
#define SQUARE(x) x*x — SQUARE(1+2) = 1+2*1+2 = 5, not 9
memcpy with overlapping regions — use memmove instead
Uninitialized variables — contain garbage, UB if used
Array out of bounds — no runtime check, silent corruption or crash