Ownership and lifetime: Identify who allocates, who frees, and whether a pointer is borrowed or nullable. Initialize pointers before cleanup, release each acquired resource once, and leave the caller's pointer unchanged if an allocation fails. Use a temporary pointer for realloc.
Buffers and strings: Pass lengths or capacities with pointers. Check size arithmetic for overflow before allocation, and bounds before indexing or copying. Reserve space for the terminating \0 when producing a C string; byte buffers need no terminator. Use memmove for overlapping regions.
Types and undefined behavior: Do not read uninitialized values, access outside an object, use a pointer after its lifetime, or rely on signed overflow. Distinguish an array from a pointer: sizeof pointer is not the array's byte count. Check conversions between signed sizes and size_t.
Errors and cleanup: Check return values that can fail, including allocation, I/O, and parsing. Preserve enough context to report the failure; inspect errno only when the API defines it. Make partial reads, writes, and cleanup paths explicit where the operation requires them.
Interfaces: Put declarations in guarded headers and definitions in source files. Use static for file-local functions and objects. Document ownership, buffer capacity, and error results at API boundaries.

For example, when growing an owned buffer, compute and validate the new size first, assign realloc to a temporary pointer, and update the caller's pointer and capacity only after success. On failure, the old allocation remains owned by the caller. This pattern should be visible in both implementation and API documentation.

Verify

Trace callers and ownership paths before editing. Build with the project's standard and warning settings; use compiler warnings and a focused runnable check for changed behavior. Run AddressSanitizer and UndefinedBehaviorSanitizer when the toolchain supports them and the change touches memory or arithmetic.

c-programming

C Programming

Review and implementation priorities