Fix heap buffer overflow in memchr_short_search function

[Bleem-Fuzzer]

Fix #26

[gemini-code-assist]

Summary of Changes

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This pull request addresses a subtle bug in the memchr_short_search function. The change reorders two lines of code to ensure that the remaining_len variable is correctly updated when a potential match fails the whole word check. This fix prevents incorrect length calculations, leading to more reliable search behavior.

Highlights

• Bug Fix: Corrected an off-by-one error in the memchr_short_search function's remaining_len calculation when handling whole word checks, ensuring accurate length reduction after skipping non-matching segments.

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[gemini-code-assist]

Code Review

This pull request fixes a critical bug in the memchr_short_search function. The original code updated current_pos before using it to calculate the change in remaining_len when a whole-word check failed. This resulted in remaining_len not being decremented, which could lead to incorrect behavior. The fix correctly reorders these two statements, ensuring remaining_len is updated based on the old current_pos value. The change is correct and resolves the issue. I have one minor suggestion to improve code consistency.

[gemini-code-assist]

This fix is correct and resolves the bug. For improved consistency with how pointer and length updates are handled elsewhere in this function (e.g., lines 4026-4027), you could introduce an advance variable. This makes the logic for updating current_pos and remaining_len more uniform throughout the function, which can improve readability and maintainability.

                size_t advance = (potential_match - current_pos) + 1;
                current_pos += advance;
                remaining_len -= advance;