Use gsl::narrow in asm files

[elazarg]

Summary by CodeRabbit

• New Features

  • Enhanced type safety and error handling across multiple components, improving overall stability.
  • Expanded test cases for instruction marshaling and unmarshaling, ensuring comprehensive coverage.

• Bug Fixes

  • Improved error reporting and handling in various functions, addressing potential overflow and invalid type conversions.

• Documentation

  • Updated parameter names for clarity in function signatures, enhancing readability and maintainability.

[coderabbitai]

Walkthrough

The pull request introduces a series of modifications across multiple files, primarily focusing on enhancing type safety and improving error handling. Key changes include the adoption of gsl::narrow and gsl::narrow_cast for safer type conversions, updates to function signatures for clarity, and refinements in error handling mechanisms. The changes aim to ensure robust type handling and clearer code structure without altering the core logic of the existing functionality.

Changes

Files	Change Summary
src/asm_files.cpp, src/asm_files.hpp, src/asm_ostream.hpp, src/asm_unmarshal.cpp, src/ebpf_yaml.cpp	Modifications focus on enhancing type safety through the use of gsl::narrow and gsl::narrow_cast, updates to function signatures for clarity, and improvements in error handling and instruction processing.
src/test/test_marshal.cpp	Enhancements to the testing framework for instruction marshaling and unmarshaling, including new test cases and refinements to ensure comprehensive coverage of various instruction types and behaviors.

Possibly related PRs

• Use explicit width for finite width parameters #687: Enhances type safety through explicit width specifications for finite width parameters.
• Cleanup and modernize array_domain #691: Improves type safety and consistency in src/asm_files.cpp with modifications to function signatures and type checks.
• Support bpf2bpf calls from ELF files #693: Enhances handling of function relocations and subprogram management, relating to overall structure and type safety improvements.
• Cleanup asm_files.cpp #694: Performs a cleanup of asm_files.cpp, enhancing type safety and clarity.
• Prepare to use GSL, and particularly gsl::narrow #707: Introduces gsl::narrow for safer type conversions, relevant to the main PR's changes.
• Use gsl::narrow in ebpf_domain.cpp #709: Implements the use of gsl::narrow in ebpf_domain.cpp, directly applying type safety improvements discussed in the main PR.

🐇 In the code we hop and play,
With types so safe, we leap all day!
Gsl's magic makes it right,
Errors vanish, out of sight.
So here's to safety, bright and clear,
In every function, we have no fear! 🐇

---

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[coderabbitai]

Actionable comments posted: 6

🧹 Outside diff range comments (3)

src/test/test_marshal.cpp (3)

Line range hint 15-16: Fix the typographical error in the comment.

The word "tample" should be corrected to "sample" for clarity.

---

Line range hint 793-794: Correct the invalid shift operator in the comment.

The operator >>>= is not valid in C++. Use >>= for the right shift operation.

---

Line range hint 506-511: Use consistent named constants for opcode components.

Consistently using named constants like INST_OPSRC_REG instead of magic numbers enhances readability and reduces potential errors.

📜 Review details

Configuration used: CodeRabbit UI
Review profile: ASSERTIVE

📥 Commits

Files that changed from the base of the PR and between 1ef02eb and 6cf3b1b.

📒 Files selected for processing (6)

• src/asm_files.cpp (5 hunks)
• src/asm_files.hpp (1 hunks)
• src/asm_ostream.hpp (2 hunks)
• src/asm_unmarshal.cpp (12 hunks)
• src/ebpf_yaml.cpp (2 hunks)
• src/test/test_marshal.cpp (1 hunks)

🔇 Additional comments (26)

src/asm_files.hpp (3)

13-13: LGTM: Improved parameter naming

The change from section to desired_section enhances code readability by making the parameter's purpose more explicit. This aligns well with best practices for clear and self-documenting code.

---

15-15: LGTM: Consistent parameter naming

The change from section to desired_section in this overload maintains consistency with the previous function declaration. This consistency is crucial for code maintainability and reduces potential confusion for developers using these functions.

---

16-17: LGTM: Improved code formatting

The adjustment in line breaks and indentation enhances the readability of this long function declaration. It's consistent with common C++ style guidelines and makes the code easier to scan and understand.

src/asm_ostream.hpp (5)

12-12: Inclusion of crab_utils/num_safety.hpp enhances type safety

Including crab_utils/num_safety.hpp provides access to gsl::narrow, ensuring safer type conversions in the code that follows.

---

48-48: Use of crab::to_signed improves immediate value handling

Replacing direct casting with crab::to_signed(imm.v) ensures correct sign interpretation of immediate values, enhancing code correctness and type safety.

---

49-49: Safe conversion in operator<< for Reg using gsl::narrow

Using gsl::narrow<int>(a.v) ensures safe conversion of the register value to an int, preventing potential overflows or truncation issues.

---

57-70: Simplified operator<< overloads improve maintainability

Delegating the output to Instruction{a} in the operator<< overloads enhances code maintainability and ensures consistent output formatting across different instruction types.

---

28-31: Ensure exception safety when using gsl::narrow in label_to_offset32

As gsl::narrow can throw exceptions if the value cannot be narrowed safely, verify that any potential exceptions are properly handled or documented.

Run the following script to check for exception handling around label_to_offset32 usage:

#!/bin/bash
# Description: Search for usages of `label_to_offset32` and check for exception handling.

# Test: Find calls to `label_to_offset32` and include surrounding lines. Expect: Exception handling code present.
rg --type cpp -A 5 'label_to_offset32\('

src/ebpf_yaml.cpp (2)

147-147: Good use of gsl::narrow<int> for safe type conversion.

By using gsl::narrow<int>(raw_block.size()), you ensure that any narrowing from size_t to int is checked at runtime, preventing potential data loss or overflow. This enhances the robustness of the code.

---

299-299: Good use of gsl::narrow<int> for safe type conversion.

Wrapping memory_bytes.size() with gsl::narrow<int> ensures that the conversion from size_t to int is safe, and any value that cannot be represented in an int will throw an exception. This adds safety to the code by preventing unintended behavior due to integer overflow or data loss.

src/asm_files.cpp (5)

17-17: Including necessary header for gsl::narrow functions

Including "crab_utils/num_safety.hpp" is appropriate to enable the use of gsl::narrow and gsl::narrow_cast functions for safer type conversions.

---

41-41: Handle potential overflow when casting cache.size()

Using gsl::narrow<int> on global_program_info->cache.size() assumes that the cache size will always fit within an int. If the cache size exceeds INT_MAX, this will throw an exception.

Please confirm that global_program_info->cache.size() cannot exceed INT_MAX. If it can, consider using a larger integer type or handling the exception accordingly.

---

253-254: Ensure safe narrowing of reloc.source_offset

Casting reloc.source_offset with gsl::narrow<int64_t> assumes that its value fits within int64_t. If reloc.source_offset exceeds the range of int64_t, this will throw an exception.

Please verify that reloc.source_offset is guaranteed to be within the range of int64_t. If not, consider using a wider integer type or handling potential exceptions.

---

269-269: Safely casting map.type_id to int

Using gsl::narrow_cast<int> to cast map.type_id ensures type safety. Confirm that map.type_id is within the range of int to prevent unexpected behavior.

Please ensure that map.type_id cannot exceed the limits of an int. If there's a possibility, consider using a larger type or handling the casting carefully.

---

383-383: Confirm that program_offset fits within uint32_t

Casting program_offset with gsl::narrow_cast<uint32_t> assumes that its value is within the range of uint32_t. If program_offset exceeds UINT32_MAX, this could lead to incorrect behavior.

Please verify that program_offset will always be less than or equal to UINT32_MAX. If not, consider using a wider integer type or adding checks to handle large values.

src/asm_unmarshal.cpp (11)

9-9: Proper inclusion of crab_utils/num_safety.hpp

The inclusion of crab_utils/num_safety.hpp is appropriate to utilize numerical safety functions like crab::to_unsigned.

---

222-222: Appropriate use of gsl::narrow<Atomic::Op> for safe type conversion

Using gsl::narrow<Atomic::Op> ensures that the narrowing conversion from inst.imm & ~INST_FETCH to Atomic::Op is safe at runtime, throwing an exception if the value cannot be represented. This enhances type safety.

---

236-236: Correct use of crab::to_unsigned for sign extension

Replacing the previous casting with crab::to_unsigned(int64_t{imm}) in sign_extend ensures accurate sign extension from a 32-bit integer to an unsigned 64-bit integer, enhancing readability and safety.

---

238-238: Correct use of crab::to_unsigned for zero extension

Using crab::to_unsigned(imm) in zero_extend effectively zero-extends a 32-bit integer to an unsigned 64-bit integer, providing a clearer and safer conversion.

---

508-508: Ensure safe narrowing with gsl::narrow<uint8_t>(i)

Using gsl::narrow<uint8_t>(i) safely converts the index i to uint8_t, ensuring it fits within the expected range. Since i ranges from 1 to 5 in this context, the narrowing should not cause issues.

---

541-542: Validate indices when narrowing to uint8_t

When using gsl::narrow<uint8_t>(i) and gsl::narrow<uint8_t>(i + 1), ensure that i and i + 1 are within the uint8_t range to prevent exceptions. Given the controlled range of i in this context, this usage is appropriate.

---

559-559: Appropriate use of gsl::narrow<int> for label conversion

Converting new_pc to label_t using gsl::narrow<int>(new_pc) ensures that the program counter fits into an int, providing type safety.

---

585-585: Safe narrowing of inst.imm to uint8_t

Using gsl::narrow<uint8_t>(inst.imm) in Callx{} ensures that inst.imm is within the valid range for a uint8_t, enhancing type safety.

---

691-693: Correct use of sign_extend for immediate values in jump conditions

Using sign_extend(inst.imm) when setting up the right-hand side of the jump condition ensures that negative immediate values are correctly sign-extended, preserving the intended logic of conditional jumps.

---

714-714: Proper call to makeLddw with updated parameters

The call to makeLddw(inst, next_imm, insts, pc) appropriately passes next_imm, ensuring that the 64-bit immediate value is correctly constructed from two instructions.

---

780-780: Ensure pc fits into int when creating labels

Using gsl::narrow<int>(pc) when constructing label_t ensures that the program counter value fits into an int, adding type safety to label handling.

[coveralls]

coverage: 90.4% (+0.02%) from 90.385%
when pulling 6cf3b1b on narrow-asm
into 1ef02eb on main.