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Tips for getting started:
1. Ask questions, edit files, or run commands.
2. Be specific for the best results.
3. /help for more information.
╭──────────────────────────────────────────────────────────────────────────╮
│ > A WIP patch to spanify the following files has been applied: │
│ - device/bluetooth/floss/floss_dbus_client.cc │
│ │
│ --- │
│ │
│ Your job is to finish/polish the patch following the instructions │
│ below. │
│ Your job is done when the patch is ready. Do not start trying to │
│ spanify files beyond the scope of this patch. │
│ You should first examine the patch with `git show HEAD`. │
│ When the job is done, say "GEMINI_JOB_COMPLETE_GEMINI". │
│ │
│ ### **LLM Prompt: Fixing Unsafe Buffer Usage in Chromium** │
│ │
│ **Role:** You are an expert C++ developer specializing in memory │
│ safety for the Chromium project. Your primary goal is to eliminate │
│ unsafe buffer operations by migrating legacy C-style code to modern, │
│ safer C++ constructs, with a strong emphasis on `base::span` and │
│ other standard library containers. You must adhere to Chromium's │
│ coding standards and the specific guidelines for this task. │
│ │
│ **Task:** Your task is to fix unsafe buffer usage in a given C++ │
│ file. You should compile the target with provided command line after │
│ removing the `#pragma allow_unsafe_buffers` and `UNSAFE_TODO` │
│ directive. You will use these errors to identify and fix the unsafe │
│ code, applying the principles and patterns outlined below. **Your │
│ changes must be minimal and targeted, directly addressing only the │
│ unsafe buffer errors.** While the primary focus is on the given │
│ file, you are expected to modify other files (e.g., header files or │
│ call sites) if necessary to ensure the code compiles and tests pass. │
│ │
│ ### **Guiding Philosophy** │
│ * **Safety Through the Type System:** The fundamental goal is to │
│ encode buffer size information into the C++ type system. A `char*` │
│ has no size information, making it unsafe. A `base::span<char>` has │
│ a size, making it safe. Every change you make should serve this │
│ principle. │
│ * **Minimalism is Essential:** Your task is not to refactor or │
│ improve the code in general. You are a specialist surgeon fixing one │
│ specific problem: unsafe buffer usage. Make the smallest possible │
│ change that fixes the compiler warning and passes tests. │
│ * **Trust, But Verify with Compilation:** Your primary feedback │
│ loop is the compiler. After removing the `allow_unsafe_buffers` │
│ pragma, the `-Wunsafe-buffer-usage` errors are your map. Use them to │
│ identify every location that needs a fix. │
│ │
│ │
│ You must refer to these documents to ensure your solutions are │
│ idiomatic and correct within the Chromium ecosystem. │
│ │
│ # Workflow Tips │
│ │
│ ## General Workflow: │
│ │
│ * **User Guidance:** Proactively communicate your plan and the │
│ reason for each │
│ step. │
│ * **File Creation Pre-check:** Before creating any new file, you │
│ MUST first │
│ perform a thorough search for existing files that can be │
│ modified or │
│ extended. This is especially critical for tests; never create a │
│ new test │
│ file if one already exists for the component in question. Always │
│ add new │
│ tests to the existing test file. │
│ * **Read Before Write/Edit:** **ALWAYS** read the entire file │
│ content │
│ immediately before writing or editing. │
│ │
│ ## MANDATORY DEBUGGING PROTOCOL (WHEN STUCK) │
│ │
│ * **Trigger:** You **MUST** activate this protocol if you │
│ encounter a │
│ **Repeated Tool or Command Failure**. │
│ │
│ * **Definition of Repeated Failure:** A tool or command (e.g., │
│ `autoninja`, `autotest.py`, `git cl format`, `replace`) │
│ fails. You apply │
│ a fix or change your approach. You run the *exact same tool │
│ or command* │
│ again, and it fails for a **second time**. │
│ * **Sensitivity:** This protocol is intentionally highly │
│ sensitive. The │
│ error message for the second failure does **NOT** need to be │
│ the same as │
│ the first. Any subsequent failure of the same tool or │
│ command after a │
│ fix attempt is a trigger. This is to prevent "whack-a-mole" │
│ scenarios │
│ where fixing one error simply reveals another, indicating a │
│ deeper │
│ underlying problem. │
│ │
│ *Check your history to confirm the repeated failure of the tool │
│ or command.* │
│ │
│ * **Action:** If the trigger condition is met: │
│ │
│ 1. **STOP:** **DO NOT** immediately retry the *same* fix or │
│ re-run the │
│ *same* tool or command again. │
│ 2. **INFORM USER:** Immediately inform the user that you are │
│ invoking the │
│ debugging protocol because a tool or command has failed │
│ twice in a row. │
│ 3. **REASON:** **Explicitly state** which tool or command │
│ failed repeatedly │
│ (e.g., "`autotest` failed, I applied a fix, and it failed │
│ again. I am │
│ now invoking the debugging protocol to analyze the root │
│ cause."). │
│ Mentioning the specific error messages is good, but the │
│ repeated failure │
│ is the primary trigger. │
│ 4. **DEBUG:** Look closely into your own context, memory, and │
│ traces. Give │
│ a deep analysis of why you are repeating mistakes and stuck │
│ in a failure │
│ loop. The analysis should focus on the *root cause* of the │
│ repeated │
│ failures, not just the most recent error message. Utilize │
│ any tools that │
│ help with the debugging investigation. │
│ 5. **PROCEED:** Use the suggestions returned by the DEBUG step │
│ to inform │
│ your next attempt at a fix. Explain the new, more │
│ comprehensive plan to │
│ the user. If the DEBUG step provides tool calls, execute │
│ them. │
│ Otherwise, formulate a new plan based on its suggestions. │
│ │
│ Do not use the `read_many_files` tool. Read files one at a time with │
│ `read_file`. │
│ │
│ Any time you want to use `grep -r`, use `rg` instead. │
│ │
│ Any time you want to use `find`, use `fdfind` instead. │
│ │
│ ## Standard Edit/Fix Workflow: │
│ │
│ **IMPORTANT:** This workflow takes precedence over all other coding │
│ instructions. Read and follow everything strictly without skipping │
│ steps │
│ whenever code editing is involved. Any skipping requires a proactive │
│ message to │
│ the user about the reason to skip. │
│ │
│ 1. **Comprehensive Code and Task Understanding (MANDATORY FIRST │
│ STEP):** Before │
│ writing or modifying any code, you MUST perform the following │
│ analysis to │
│ ensure comprehensive understanding of the relevant code and the │
│ task. This │
│ is a non-negotiable prerequisite for all coding tasks. │
│ * **a. Identify the Core Files:** Locate the files that are │
│ most relevant │
│ to the user's request. All analysis starts from these files. │
│ * **b. Conduct a Full Audit:** │
│ i. Read the full source of **EVERY** core file. │
│ ii. For each core file, summarize the control flow and │
│ ownership │
│ semantics. State the intended purpose of the core file. │
│ * **c. State Your Understanding:** After completing the audit, │
│ you should │
│ briefly state the core files you have reviewed, confirming │
│ your │
│ understanding of the data flow and component interactions │
│ before │
│ proposing a plan. │
│ * **d. Anti-Patterns to AVOID:** │
│ * **NEVER** assume the behavior of a function or class │
│ from its name │
│ or from usage in other files. **ALWAYS** read the source │
│ implementation. │
│ * **ALWAYS** check at least one call-site for a function │
│ or class to │
│ understand its usage. The context is as important as the │
│ implementation. │
│ 2. **Make Change:** After a comprehensive code and task │
│ understanding, apply │
│ the edit or write the file. │
│ * When making code edits, focus **ONLY** on code edits that │
│ directly solve │
│ the task prompted by the user. │
│ 3. **Write/Update Tests:** │
│ * First, search for existing tests related to the modified │
│ code and update │
│ them as needed to reflect the changes. │
│ * If no relevant tests exist, write new unit tests or │
│ integration tests if │
│ it's reasonable and beneficial for the change made. │
│ * If tests are deemed not applicable for a specific change │
│ (e.g., a │
│ trivial comment update), explicitly state this and the │
│ reason why before │
│ moving to the next step. │
│ 4. **Build:** **ALWAYS** build relevant targets after making edits. │
│ 5. **Fix compile errors:** **ALWAYS** follow these steps to fix │
│ compile errors. │
│ * **ALWAYS** take the time to fully understand the problem │
│ before making │
│ any fixes. │
│ * **ALWAYS** read at least one new file for each compile │
│ error. │
│ * **ALWAYS** find, read, and understand **ALL** files related │
│ to each │
│ compile error. For example, if an error is related to a │
│ missing member │
│ of a class, find the file that defines the interface for the │
│ class, read │
│ the whole file, and then create a high-level summary of the │
│ file that │
│ outlines all core concepts. Come up with a plan to fix the │
│ error. │
│ * **ALWAYS** check the conversation history to see if this │
│ same │
│ error occurred earlier, and analyze previous solutions to │
│ see why they │
│ didn't work. │
│ * **NEVER** make speculative fixes. You should be confident │
│ before │
│ applying any fix that it will work. If you are not │
│ confident, read more │
│ files. │
│ 6. **Test:** **ALWAYS** run relevant tests after a successful │
│ build. If you │
│ cannot find any relevant test files, you may prompt the user to │
│ ask how this │
│ change should be tested. │
│ 7. **Fix test errors**: │
│ * **ALWAYS** take the time to fully understand the problem │
│ before making │
│ any fixes. │
│ 8. **Iterate:** Repeat building and testing using the above steps │
│ until all are │
│ successful. │
│ │
│ --- │
│ │
│ ### **Core Principles for Safe Buffer Handling** │
│ │
│ Before looking at specific patterns, adhere to these fundamental │
│ principles. │
│ │
│ * **Principle 0: Clearly Distinguish Ownership** │
│ Before you change any code, your first step is to determine if │
│ the variable in question represents owning or non-owning memory. │
│ This single decision dictates the correct C++ type to use. │
│ │
│ * **Owning Buffers:** Use an owning container when the code is │
│ responsible for the memory's lifetime (allocating and freeing it). │
│ * `std::vector<T>`: This is the default and preferred │
│ choice for a dynamically-sized, owning buffer. │
│ * `std::string`: The standard choice for owning a buffer │
│ of characters. │
│ * `std::array<T, N>`: Use this for a fixed-size buffer │
│ whose lifetime is tied to its scope (typically on the stack). It's a │
│ direct, safer replacement for C-style arrays like `int │
│ my_array[10];`. │
│ * `base::HeapArray<T>`: A Chromium-specific alternative │
│ for heap-allocated arrays, sometimes useful for interfacing with │
│ legacy code. │
│ │
│ * **Non-Owning Buffers (Views/Spans):** Use a non-owning view │
│ when the code needs to safely refer to and operate on memory that is │
│ owned by another object (like a `std::vector` or `std::array`). │
│ * `base::span<T>`: This is the default and preferred │
│ choice for a non-owning, mutable, or immutable view of a contiguous │
│ sequence of objects. It's the primary tool for replacing `(T* ptr, │
│ size_t size)` parameters. │
│ * `std::string_view`: Use this for a non-owning, read-only │
│ view of a sequence of characters. It provides a rich set of │
│ string-manipulation methods (`.starts_with()`, `.find()`, etc.) that │
│ `base::span<const char>` lacks. │
│ │
│ * **Principle 1: Avoid Unsafe APIs, Even If They Look Modern.** │
│ The goal is to eliminate the *root cause* of unsafety, not just │
│ silence the compiler. Certain modern-looking APIs are still unsafe. │
│ │
│ * **DO NOT USE:** The `base::span(pointer, size)` constructor. │
│ It is marked `UNSAFE_BUFFER_USAGE` for a reason—it does not verify │
│ that `size` is a valid length for `pointer`. Using it is no safer │
│ than the original code. │
│ * **DO NOT USE:** `std::next()` or `std::advance()` to silence │
│ buffer warnings. These functions perform unchecked pointer │
│ arithmetic and are just as unsafe as `ptr + offset`. │
│ ```cpp │
│ // Old and Unsafe (silences warning, but still dangerous): │
│ auto it = std::find(std::next(vec.begin(), offset), │
│ vec.end(), 20); │
│ // New and Safe: │
│ auto it = std::ranges::find(base::span(vec).subspan(offset), │
│ 20); │
│ ``` │
│ * **DO NOT USE:** `base::StringView`. This is a legacy, │
│ deprecated type. The correct and modern type for a non-owning string │
│ view is `std::string_view`. Be mindful to use the `std` namespace │
│ for string views. │
│ * **DO NOT USE: `UNSAFE_BUFFERS` without a safety │
│ justification.** Individual expressions can be opted out with │
│ `UNSAFE_BUFFERS()`, but these are for rare cases like interfacing │
│ with C-style external APIs. They **must always** be accompanied by a │
│ `// SAFETY:` comment explaining in detail why the code has been │
│ evaluated to be safe for all possible inputs. Code without this │
│ justification should be rejected. │
│ │
│ * **Principle 3: Prefer Safe, Size-Aware Constructors and │
│ Factories.** Always create spans from sources that already know │
│ their own size. This is the key to memory safety. │
│ │
│ * **DO USE:** `base::span(container)` where `container` is an │
│ `std::vector`, `std::array`, `std::string`, `base::HeapArray`, etc. │
│ * **DO USE:** `base::span(other_span).subspan(...)` to create │
│ safe views into existing spans. │
│ * **DO USE:** `base::as_byte_span(container)` and │
│ `base::as_writable_byte_span(container)` for safe type-punning to a │
│ byte view. │
│ * **DO USE:** `base::span_from_ref(object)` to create a span │
│ of size 1 pointing to a single object. │
│ * **DO USE:** `base::byte_span_from_ref(object)` for a byte │
│ view of a single object. │
│ │
│ --- │
│ │
│ ### **Toolbox of Fixes and Patterns** │
│ │
│ Here is a comprehensive set of patterns for fixing common unsafe │
│ buffer issues. │
│ │
│ #### **1. Fundamental Replacements: Pointers and C-Arrays** │
│ │
│ The most common task is replacing raw pointers and C-style arrays │
│ with safer, bounds-checked alternatives. │
│ │
│ * **Pattern:** Replace function parameters `(T* ptr, size_t size)` │
│ with a single `base::span<T>`. │
│ │
│ * **Example:** │
│ ```cpp │
│ // Old │
│ void ProcessData(const uint8_t* data, size_t size); │
│ │
│ // New │
│ void ProcessData(base::span<const uint8_t> data); │
│ ``` │
│ │
│ * **Pattern:** Replace C-style stack arrays `T arr[N]` with │
│ `std::array<T, N>`. For string literals, `std::to_array` is a │
│ convenient helper. │
│ │
│ * **Example:** │
│ ```cpp │
│ // Old │
│ const char kAllowed[] = "abc"; │
│ int values[10]; │
│ │
│ // New │
│ // For C-style string literals, std::to_array is simplest. │
│ constexpr auto kAllowed = std::to_array("abc"); │
│ std::array<int, 10> values; │
│ ``` │
│ │
│ * **Pattern:** Replace raw heap-allocated arrays (`new T[size]`, │
│ `std::make_unique<T[]>(size)`) with `std::vector<T>` or │
│ `base::HeapArray<T>`. │
│ │
│ * **Reasoning:** `std::vector` and `base::HeapArray` are │
│ self-managing, provide size information, and prevent common memory │
│ management errors. They also integrate perfectly with `base::span`. │
│ * **Example:** │
│ ```cpp │
│ // Old │
│ auto buffer = std::make_unique<char[]>(1024); │
│ ReadData(fd, buffer.get(), 1024); │
│ │
│ // New │
│ std::vector<char> buffer(1024); │
│ ReadData(fd, base::as_writable_byte_span(buffer)); │
│ ``` │
│ │
│ * **Pattern:** When passing an array to a function, use │
│ `base::span` to create a non-owning view. │
│ │
│ * **Example:** │
│ ```cpp │
│ std::array<int, 10> my_array; │
│ // Old: ProcessData(my_array.data(), my_array.size()); │
│ // New │
│ ProcessData(base::span(my_array)); │
│ ``` │
│ * **Pattern:** For class member fields that are non-owning views, │
│ you must use `base::raw_span<T>` over `base::span<T>`. │
│ * **Reasoning:** This is a critical memory safety requirement. │
│ `base::raw_span` is implemented with MiraclePtr, which protects │
│ against Use-After-Free (UAF) bugs. If the underlying object is │
│ freed, any attempt to use the `raw_span` will result in a controlled │
│ crash instead of allowing dangerous memory corruption or type │
│ confusion attacks. A regular `base::span` offers no UAF protection. │
│ ```cpp │
│ class MyClass { │
│ private: │
│ // Old: base::span<int> data_; │
│ // New: │
│ base::raw_span<int> data_; │
│ }; │
│ ``` │
│ │
│ #### **2. Replacing Unsafe C-Style Library Functions** │
│ │
│ * **Pattern:** Replace `memcpy` and `memmove` with │
│ `base::span::copy_from()`. │
│ * **Reasoning:** Do not use `std::ranges::copy`. It is unsafe │
│ because it does not verify that the source and destination spans │
│ have the same size, which can lead to buffer overflows. │
│ `base::span::copy_from()` is the only safe alternative, as it │
│ includes a `CHECK` to ensure the sizes match exactly. │
│ * **Example:** │
│ ```cpp │
│ // Old │
│ memcpy(dest_ptr, src_ptr, N); │
│ │
│ // New (Safe and Idiomatic) │
│ // This CHECKs that both subspans are of size N. │
│ dest_span.first(N).copy_from(src_span.first(N)); │
│ ``` │
│ │
│ * **Pattern:** Replace `memset` with `std::ranges::fill()`. │
│ │
│ * **Example:** │
│ ```cpp │
│ // Old │
│ memset(buffer, 0, sizeof(buffer)); │
│ │
│ // New │
│ std::ranges::fill(my_span, 0); │
│ ``` │
│ │
│ * **Pattern:** Replace `memcmp` with `base::span::operator==` or │
│ `std::ranges::equal`. │
│ │
│ * **Example:** │
│ ```cpp │
│ // Old │
│ bool are_equal = memcmp(ptr1, ptr2, size) == 0; │
│ │
│ // New │
│ bool are_equal = span1 == span2; │
│ ``` │
│ │
│ #### **3. Eliminating Pointer Arithmetic and Unsafe Casting** │
│ │
│ * **Pattern:** Replace pointer arithmetic like `ptr + offset` with │
│ `span.subspan(offset)`. │
│ │
│ * **Example:** │
│ ```cpp │
│ // Old │
│ ProcessData(data + 10, size - 10); │
│ │
│ // New │
│ ProcessData(data_span.subspan(10)); │
│ ``` │
│ │
│ * **Pattern:** Avoid `reinterpret_cast` for changing element │
│ types. Use safe casting functions like `base::as_bytes()`, │
│ `base::as_writable_byte_span()`, or `base::as_chars()`. │
│ │
│ * **Example:** │
│ ```cpp │
│ // Old │
│ const uint8_t* bytes = reinterpret_cast<const │
│ uint8_t*>(str.data()); │
│ │
│ // New │
│ base::span<const uint8_t> bytes = base::as_byte_span(str); │
│ ``` │
│ * **Caution:** When using `base::as_byte_span()` on a │
│ `struct`, be aware of padding bytes. If the struct's padding is not │
│ explicitly initialized (e.g., via `memset` or aggregate │
│ initialization), reading from the resulting byte span can lead to │
│ reads of uninitialized memory. This is safest with spans of │
│ primitive types. │
│ │
│ * **Pattern:** To read or write structured data (like a │
│ `uint32_t`) from/to a byte buffer, use the endian-converting helpers │
│ from `base/numerics/byte_conversions.h`. │
│ │
│ * **Example (Writing):** │
│ ```cpp │
│ // Old (UNSAFE AND UNDEFINED BEHAVIOR) │
│ *reinterpret_cast<uint32_t*>(byte_span.data()) = my_value; │
│ │
│ // New (Safe and Idiomatic) │
│ #include "base/numerics/byte_conversions.h" │
│ auto value_bytes = base::U32ToLittleEndian(my_value); │
│ byte_span.first(value_bytes.size()).copy_from(value_bytes); │
│ ``` │
│ │
│ * **Example (Reading):** │
│ ```cpp │
│ // Old (UNSAFE) │
│ uint32_t value = *reinterpret_cast<const │
│ uint32_t*>(byte_span.data()); │
│ │
│ // New (Safe and Idiomatic) │
│ #include "base/numerics/byte_conversions.h" │
│ uint32_t value = │
│ base::U32FromLittleEndian(byte_span.first<4>()); │
│ ``` │
│ * **Pattern:** For dynamic or heterogeneous I/O, use │
│ `base::SpanReader` and `base::SpanWriter` to safely consume or │
│ populate a buffer. This is safer and more expressive than manual │
│ pointer casting and offsetting. │
│ * **Example (Writing with `SpanWriter`):** │
│ ```cpp │
│ #include "base/containers/span_writer.h" │
│ #include "base/numerics/byte_conversions.h" │
│ void WriteData(base::span<uint8_t> out, uint32_t id, float │
│ value) { │
│ auto writer = base::SpanWriter(out); │
│ writer.WriteU32BigEndian(id); │
│ writer.Write(base::FloatToLittleEndian(value)); │
│ } │
│ ``` │
│ * **Pattern:** Refactor sequential buffer filling with a │
│ "consuming span". This is for cases where a buffer is allocated │
│ once, and then a pointer is manually advanced as data is written to │
│ it sequentially. │
│ * **Reasoning:** Instead of managing a write-pointer and an │
│ end-pointer manually, a single `base::span` can represent the │
│ remaining, writable portion of the buffer. This is safer and more │
│ expressive. │
│ * **Example:** │
│ ```cpp │
│ // Helper function that writes a string and "consumes" part │
│ of the span. │
│ void WriteStringAndAdvance(base::span<char>& buffer, const │
│ char* str) { │
│ if (!str) { │
│ return; │
│ } │
│ const size_t len_with_null = strlen(str) + 1; │
│ DCHECK_GE(buffer.size(), len_with_null); │
│ memcpy(buffer.data(), str, len_with_null); │
│ // The span is sliced, now pointing to the remaining │
│ writable area. │
│ buffer = buffer.subspan(len_with_null); │
│ } │
│ │
│ // Old function that manually manages pointers. │
│ void CreateMessageUnsafe(char* buffer, size_t size, const │
│ char* str1, const char* str2) { │
│ char* ptr = buffer; │
│ const char* end = buffer + size; │
│ │
│ // Manual copy and advance │
│ size_t len1 = strlen(str1) + 1; │
│ CHECK_LE(ptr + len1, end); │
│ memcpy(ptr, str1, len1); │
│ ptr += len1; │
│ │
│ // Another manual copy and advance │
│ size_t len2 = strlen(str2) + 1; │
│ CHECK_LE(ptr + len2, end); │
│ memcpy(ptr, str2, len2); │
│ ptr += len2; │
│ } │
│ │
│ // New function using the "consuming span" pattern. │
│ void CreateMessageSafe(base::span<char> buffer, const char* │
│ str1, const char* str2) { │
│ WriteStringAndAdvance(buffer, str1); │
│ WriteStringAndAdvance(buffer, str2); │
│ // At this point, `buffer` correctly represents the │
│ unused portion. │
│ } │
│ ``` │
│ * **Key Idea:** The core of this pattern is to create a helper │
│ function (like `WriteStringAndAdvance`) that takes the main buffer │
│ span by reference (`&`). The helper writes its data and then │
│ reassigns the span to a smaller subspan, effectively advancing the │
│ "write position" for the next operation in the calling function. │
│ │
│ #### **4. String and Character Manipulation** │
│ │
│ * **Pattern:** Replace C-style string literals (`const char │
│ kFoo[]`) with `constexpr std::string_view kFoo` or `constexpr │
│ std::array`. │
│ * **Pattern:** For C APIs that require a NUL-terminated string, │
│ use `base::cstring_view`. │
│ * **Pattern:** Replace C-style string functions (`strcmp`, │
│ `strstr`, etc.) with `std::string_view` methods (`operator==`, │
│ `.find()`, etc.). │
│ * **Pattern:** Replace pointer-based iteration over a buffer with │
│ a range-based for loop over a `base::span`. │
│ * **Pattern:** Choose the correct string view type based on │
│ null-termination requirements. │
│ * **Reasoning:** You must differentiate between internal C++ │
│ logic and calls to C-style APIs. A `std::string_view` is not │
│ guaranteed to be null-terminated, while `base::cstring_view` │
│ provides this guarantee. Using the wrong type can lead to buffer │
│ over-reads. │
│ * **Decision Flow:** │
│ * If the string is only used with modern C++ methods (like │
│ `.find()` or range `for` loops) that use an explicit size, use │
│ `std::string_view`. │
│ * If the string needs to be passed to an API that requires │
│ a null-terminated `const char*` (like `printf`, `sscanf`, or legacy │
│ functions), you must use `base::cstring_view`. │
│ * **Example:** │
│ ```cpp │
│ // A legacy C-style function │
│ void LogToOldSystem(const char* message); │
│ │
│ // --- │
│ // In some calling code --- │
│ std::string my_string = "Hello, World!"; │
│ std::string_view full_view = my_string; │
│ │
│ // UNSAFE: This substring is not null-terminated in │
│ my_string. │
│ std::string_view unsafe_view = full_view.substr(7, 5); // │
│ "World" │
│ // LogToOldSystem(unsafe_view.data()); // BUG! Reads past │
│ "d" into garbage. │
│ │
│ // SAFE: Create a new std::string which is guaranteed to be │
│ null-terminated. │
│ std::string safe_string(unsafe_view); │
│ LogToOldSystem(safe_string.c_str()); │
│ │
│ // IDEAL: Use a type that enforces the contract. │
│ // If the source is already a C-string, cstring_view is │
│ zero-copy. │
│ base::cstring_view safe_c_view = "Hello, World!"; │
│ LogToOldSystem(safe_c_view.c_str()); │
│ ``` │
│ │
│ │
│ #### **5. Advanced Patterns** │
│ * **Pattern:** To get a heap-allocated buffer with a specific │
│ memory alignment, use `base::AlignedUninit<T>` from │
│ `base/memory/aligned_memory.h`. │
│ ```cpp │
│ #include "base/memory/aligned_memory.h" │
│ // Get an uninitialized array of 16 floats, aligned to 32 bytes. │
│ base::AlignedHeapArray<float> array = │
│ base::AlignedUninit<float>(16, 32); │
│ ``` │
│ │
│ #### **6. Common Chromium-Specific Patterns** │
│ │
│ * **`net::IOBuffer`:** This class and its subclasses │
│ (`IOBufferWithSize`, `VectorIOBuffer`) now have span-like methods. │
│ Use them. │
│ │
│ * **Example:** │
│ ```cpp │
│ // Old │
│ auto data_view = base::span( │
│ reinterpret_cast<const uint8_t*>(io_buffer->data()), │
│ data_len); │
│ │
│ // New │
│ auto data_view = io_buffer->first(data_len); │
│ ``` │
│ │
│ * **`net::VectorIOBuffer`:** To create a buffer with known │
│ content, prefer constructing a `net::VectorIOBuffer` directly from a │
│ `std::vector` or `base::span` instead of allocating a raw buffer │
│ and using `memcpy`. │
│ │
│ * **Example:** │
│ ```cpp │
│ // Old │
│ auto buffer = │
│ base::MakeRefCounted<net::IOBufferWithSize>(data.size()); │
│ memcpy(buffer->data(), data.data(), data.size()); │
│ │
│ // New │
│ auto buffer = │
│ base::MakeRefCounted<net::VectorIOBuffer>(data); │
│ ``` │
│ │
│ #### **7. Interfacing with C-style/Third-Party APIs** │
│ │
│ * **Pattern:** When a C API returns pointers to different memory │
│ planes (e.g., video frames), create `base::span`s from those │
│ pointers and their known sizes at the API boundary. Use │
│ `UNSAFE_BUFFERS()` for this initial creation, then pass the safe │
│ spans throughout the rest of your C++ code. │
│ * **Example:** │
│ ```cpp │
│ // Old │
│ uint8_t* y_ptr = vpx_image->planes[0]; │
│ uint8_t* u_ptr = vpx_image->planes[1]; │
│ VideoFrame::WrapExternalYuvData(..., y_ptr, u_ptr, ...); │
│ │
│ // New │
│ // SAFETY: libvpx guarantees these pointers and sizes are │
│ valid. │
│ auto y_plane = │
│ UNSAFE_BUFFERS(base::span(vpx_image->planes[0], y_size)); │
│ auto u_plane = │
│ UNSAFE_BUFFERS(base::span(vpx_image->planes[1], u_size)); │
│ VideoFrame::WrapExternalYuvData(..., y_plane, u_plane, ...); │
│ ``` │
│ │
│ #### **8. The Containment Strategy: When a Full Fix is Too Complex** │
│ │
│ Sometimes, a complete refactor is not immediately feasible. In these │
│ cases, contain the unsafe operations. │
│ │
│ * **Strategy:** Instead of a file-level `#pragma`, wrap the │
│ *minimal* number of unsafe operations in the `UNSAFE_TODO()` macro. │
│ This macro acts like `UNSAFE_BUFFERS()` but signals that the code is │
│ a candidate for a future fix. │
│ * **Function-level Annotation:** If a function contains │
│ `UNSAFE_TODO()`, you must also mark the function's signature with │
│ the `UNSAFE_BUFFER_USAGE` attribute. This propagates the unsafety │
│ requirement to its callers, ensuring they are also marked or within │
│ an unsafe block. │
│ * **Example:** │
│ ```cpp │
│ // Old: │
│ // #pragma allow_unsafe_buffers │
│ // void DoSomething(const char* p) { │
│ // p++; │
│ // } │
│ │
│ // New (Contained): │
│ UNSAFE_BUFFER_USAGE void DoSomething(const char* p) { │
│ UNSAFE_TODO(p++); │
│ } │
│ ``` │
│ │
│ #### **9. Handling Redundant Parameters** │
│ │
│ * **Identify redundant parameters:** In functions that now take a │
│ base::span, find any size parameters that are now unneeded. A │
│ parameter is still considered redundant even if it's already used in │
│ a CHECK or DCHECK. │
│ │
│ * **Rename the parameter:** For any redundant parameter, rename it │
│ and all its references within the function by adding the prefix │
│ spanification_suspected_redundant_. │
│ │
│ * **Add a TODO and a CHECK:** At the top of the function body, add │
│ the following two lines: │
│ │
│ * A TODO comment: │
│ ```cpp │
│ // TODO(crbug.com/431824301): Remove unneeded parameter once │
│ validated to be redundant in M143. │
│ ``` │
│ * A CHECK to verify the redundant parameter matches the span's │
│ size: │
│ ```cpp │
│ CHECK(spanification_suspected_redundant_size_variable == │
│ span.size(), base::NotFatalUntil::M143); │
│ ``` │
│ │
│ * **Customize the CHECK:** In the CHECK you just added, you must: │
│ │
│ * Replace spanification_suspected_redundant_size_variable with │
│ the new name of the parameter you renamed in step 2. │
│ │
│ * Replace span.size() with a call to the actual base::span │
│ parameter's .size() method. │
│ │
│ * **Important constraints:** │
│ │
│ * Do not remove the parameter or update any call sites. │
│ │
│ * Do not change the function's logic to use span.size(); │
│ continue to use the newly-renamed parameter variable. │
│ │
│ * Do ensure the size parameter and the base::span's size are │
│ in the same unit before making changes. │
│ │
│ * Do not remove the parameter or the CHECK even if you │
│ confirmed that the unit tests pass. │
│ │
│ #### **10. Updating Function Definitions and Call Sites** │
│ │
│ * **Updating the Function Definition** │
│ * **Identify the target function:** Look for functions that │
│ have a parameter with the name pattern │
│ spanification_suspected_redundant_.... │
│ * **Remove the parameter:** In the function's definition and │
│ any corresponding declarations (e.g., in a header file), completely │
│ remove the redundant size parameter from the parameter list. │
│ * **Replace internal usages:** Inside the function's body, │
│ replace every use of the removed parameter with a call to the │
│ base::span's .size() method (e.g., my_span.size()). │
│ │
│ * **Updating the Call Sites** │
│ * **Find all call sites:** Use a command like git grep with │
│ the function name to find every location where the function is │
│ called throughout the codebase. │
│ * **Remove the argument at each call site:** For each call │
│ site you find, you must remove the argument that corresponds to the │
│ size parameter you deleted from the function's definition. │
│ * **Important:** Be very careful to only remove the specific, │
│ redundant argument. Do not change or remove any other arguments in │
│ the function call. │
│ │
│ * **Key Constraints** │
│ * You should only remove the parameter previously marked as │
│ redundant and its corresponding arguments at call sites. │
│ * Do not remove or rename any other parameters. │
│ * Do not rewrite the function's logic beyond replacing the │
│ deleted variable with span.size(). │
│ * Ensure that when you update a call site, you only remove the │
│ single, correct argument. │
│ │
│ #### **11. Handling Autogenerated Files** │
│ │
│ * **Pattern:** Another common pattern is for a change to require │
│ modification to an autogenerated file. Treat autogenerated files as │
│ unmodifiable for now. │
│ --- │
│ #### **12. Wrapping Unsafe APIs with Macros** │
│ │
│ In some cases, you will encounter functions from third-party │
│ libraries or other unmodifiable parts of the codebase that return a │
│ raw pointer to a buffer. Directly wrapping these with │
│ `UNSAFE_BUFFERS(base::span(pointer, size))` is one option, but a │
│ more robust and reusable solution is to create a dedicated wrapper │
│ macro in `base/containers/auto_spanification_helper.h`. │
│ │
│ * **Strategy:** When an unmodifiable function call returns a raw │
│ pointer instead of a safe container like `base::span`, follow this │
│ procedure: │
│ 1. **Check for an existing macro:** First, examine │
│ `base/containers/auto_spanification_helper.h` to see if a macro for │
│ this specific API call already exists. │
│ 2. **Create a new macro if needed:** If no macro exists, you │
│ must add one. │
│ * The macro should be added to │
│ `base/containers/auto_spanification_helper.h`. │
│ * The macro should take the same arguments as the original │
│ API call. │
│ * Inside the macro, call the original API, get the pointer │
│ and size, and return a `base::span`. Use `UNSAFE_TODO` to wrap the │
│ returned span. │
│ * Follow the existing macro patterns in the file, using a │
│ lambda to avoid multiple argument evaluation. │
│ 3. **Add a test for the new macro:** You must add a new test │
│ case to `base/containers/auto_spanification_helper_unittest.cc`. │
│ * The test should mock the third-party API and verify that │
│ the macro correctly creates a `base::span` with the expected data │
│ and size. │
│ 4. **Use the macro:** Replace the original unsafe API call in │
│ your target file with the new or existing macro. │
│ │
│ * **Example: Adding a macro for `SkBitmap::getAddr32`** │
│ │
│ * **Macro in `auto_spanification_helper.h`:** │
│ ```cpp │
│ // https://source.chromium.org/chromium/chromium/src/+/main: │
│ third_party/skia/include/core/SkBitmap.h;drc=f72bd467feb15edd9323e46 │
│ eab1b74ab6025bc5b;l=936 │
│ #define UNSAFE_SKBITMAP_GETADDR32(arg_self, arg_x, arg_y) \ │
│ ([](auto&& self, int x, int y) { \ │
│ uint32_t* row = self->getAddr32(x, y); \ │
│ ::base::CheckedNumeric<size_t> width = self->width(); \ │
│ size_t size = (width - x).ValueOrDie(); \ │
│ return UNSAFE_TODO(base::span<uint32_t>(row, size)); \ │
│ }(::base::spanification_internal::ToPointer(arg_self), │
│ arg_x, arg_y)) │
│ ``` │
│ │
│ * **Test in `auto_spanification_helper_unittest.cc`:** │
│ ```cpp │
│ // Minimized mock of SkBitmap class defined in │
│ // //third_party/skia/include/core/SkBitmap.h │
│ class SkBitmap { │
│ public: │
│ uint32_t* getAddr32(int x, int y) const { return &row_[x]; │
│ } │
│ int width() const { return static_cast<int>(row_.size()); │
│ } │
│ │
│ mutable std::array<uint32_t, 128> row_{}; │
│ }; │
│ │
│ TEST(AutoSpanificationHelperTest, SkBitmapGetAddr32Pointer) │
│ { │
│ SkBitmap sk_bitmap; │
│ const int x = 123; │
│ base::span<uint32_t> span = │
│ UNSAFE_SKBITMAP_GETADDR32(&sk_bitmap, x, 0); │
│ EXPECT_EQ(span.data(), &sk_bitmap.row_[x]); │
│ EXPECT_EQ(span.size(), sk_bitmap.row_.size() - x); │
│ } │
│ ``` │
│ --- │
│ │
│ Pattern: Refactor sequential buffer filling with a "consuming span". │
│ This is for cases where a buffer is allocated once, and then a │
│ pointer is manually advanced as data is written to it sequentially. │
│ │
│ Reasoning: Instead of managing a write-pointer and an end-pointer │
│ manually, a single base::span can represent the remaining, writable │
│ portion of the buffer. This is safer and more expressive. │
│ │
│ Example: │
│ │
│ C++ │
│ │
│ --- │
│ // Helper function that writes a string and "consumes" part of the │
│ span. │
│ void WriteStringAndAdvance(base::span<char>& buffer, const char* │
│ str) { │
│ if (!str) { │
│ return; │
│ } │
│ const size_t len_with_null = strlen(str) + 1; │
│ DCHECK_GE(buffer.size(), len_with_null); │
│ memcpy(buffer.data(), str, len_with_null); │
│ // The span is sliced, now pointing to the remaining writable │
│ area. │
│ buffer = buffer.subspan(len_with_null); │
│ } │
│ │
│ // Old function that manually manages pointers. │
│ void CreateMessageUnsafe(char* buffer, size_t size, const char* │
│ str1, const char* str2) { │
│ char* ptr = buffer; │
│ const char* end = buffer + size; │
│ │
│ // Manual copy and advance │
│ size_t len1 = strlen(str1) + 1; │
│ CHECK_LE(ptr + len1, end); │
│ memcpy(ptr, str1, len1); │
│ ptr += len1; │
│ │
│ // Another manual copy and advance │
│ size_t len2 = strlen(str2) + 1; │
│ CHECK_LE(ptr + len2, end); │
│ memcpy(ptr, str2, len2); │
│ ptr += len2; │
│ } │
│ │
│ // New function using the "consuming span" pattern. │
│ void CreateMessageSafe(base::span<char> buffer, const char* str1, │
│ const char* str2) { │
│ WriteStringAndAdvance(buffer, str1); │
│ WriteStringAndAdvance(buffer, str2); │
│ // At this point, `buffer` correctly represents the unused │
│ portion. │
│ } │
│ Key Idea: The core of this pattern is to create a helper function │
│ (like WriteStringAndAdvance) that takes the main buffer span by │
│ reference (&). The helper writes its data and then reassigns the │
│ span to a smaller subspan, effectively advancing the "write │
│ position" for the next operation in the calling function. │
│ --- │
╰──────────────────────────────────────────────────────────────────────────╯
✦ Okay, I need to finish the spanification patch for
device/bluetooth/floss/floss_dbus_client.cc. I'll start by reviewing the
current changes.
╭─────────────────────────────────────────────────────╮
│ ✔ Shell git show HEAD (Examine the current patch) │
│ │
│ commit │
│ cbba755e406c6e35b25d32cdab2db725a3b7ba0 │
│ 8 │
│ Author: Keishi Hattori │
│ <keishi@chromium.org> │
│ Date: Sun Aug 17 20:28:19 2025 +0000 │
│ │
│ Apply initial patch from │
│ group_112.txt │
│ │
│ diff --git │
│ a/device/bluetooth/floss/floss_dbus_cli │
│ ent.cc │
│ b/device/bluetooth/floss/floss_dbus_cli │
│ ent.cc │
│ index 8d3a0ce337098..219bb2ac4642a │
│ 100644 │
│ --- │
│ a/device/bluetooth/floss/floss_dbus_cli │
│ ent.cc │
│ +++ │
│ b/device/bluetooth/floss/floss_dbus_cli │
│ ent.cc │
│ @@ -6,6 +6,7 @@ │
│ │
│ #include <string> │
│ │
│ +#include "base/containers/span.h" │
│ #include "base/compiler_specific.h" │
│ #include "base/logging.h" │
│ #include "base/strings/stringprintf.h" │
│ @@ -371,7 +372,7 @@ bool │
│ FlossDBusClient::ReadDBusParam( │
│ template <> │
│ bool │
│ FlossDBusClient::ReadDBusParam(dbus::Me │
│ ssageReader* reader, │
│ │
│ device::BluetoothUUID* uuid) { │
│ - const uint8_t* bytes = nullptr; │
│ + base::span<const uint8_t>bytes = {}; │
│ size_t length = 0; │
│ │
│ if (reader->PopArrayOfBytes(&bytes, │
│ &length)) { │
│ │
╰─────────────────────────────────────────────────────╯
╭──────────────────────────────────────────────────────────────────────────╮
│ x Shell {"command":"find . -name \"message.h\"","description":"Find th… │
│ │
│ Command 'find . -name "message.h"' is │
│ blocked by configuration │
╰──────────────────────────────────────────────────────────────────────────╯
✦ The patch modifies bytes to a base::span. The original code used
dbus::MessageReader::PopArrayOfBytes, which I suspect takes a const
uint8_t** and size_t*. I'll verify its signature in dbus/message.h.
✦ find is blocked. I'll use fdfind.
╭──────────────────────────────────────────────────────────────────╮
│ ✔ Shell fdfind message.h (Find the dbus message.h header file) │
│ │
│ ... first 792 lines hidden ... │
│ message_handler_unittest.cc │
│ third_party/blink/web_tests/fast/canvas │
│ /canvas-messagechannel-imagebitmap-tran │
│ sfer.html │
│ third_party/blink/web_tests/external/wp │
│ t/html/semantics/forms/the-input-elemen │
│ t/input-validationmessage.html │
│ third_party/blink/web_tests/fast/events │
│ /onunload-postmessage.html │
│ third_party/blink/web_tests/fast/canvas │
│ /OffscreenCanvas-MessageChannel-transfe │
│ r.html │
│ third_party/blink/web_tests/fast/forms/ │
│ validationMessage.html │
│ components/ntp_tiles/webui/ntp_tiles_in │
│ ternals_message_handler.h │
│ components/ntp_tiles/webui/ntp_tiles_in │
│ ternals_message_handler_client.cc │
│ components/ntp_tiles/webui/ntp_tiles_in │
│ ternals_message_handler_client.h │
│ components/ntp_tiles/webui/ntp_tiles_in │
│ ternals_message_handler.cc │
│ third_party/blink/web_tests/fast/forms/ │
│ range/input-range-validation-message.ht │
│ ml │
│ third_party/blink/web_tests/fast/forms/ │
│ select/customizable-select/nested-selec │
│ t-console-message.html │
│ third_party/blink/web_tests/fast/forms/ │
│ select/customizable-select/allowed-sele │
│ ct-descendants-console-message.html │
│ third_party/blink/web_tests/fast/forms/ │
│ number/number-validation-message.html │
│ components/media_router/common/provider │
│ s/cast/channel/cast_message_handler_uni │
│ ttest.cc │
│ components/media_router/common/provider │
│ s/cast/channel/cast_message_handler.h │
│ components/media_router/common/provider │
│ s/cast/channel/cast_message_handler.cc │
│ third_party/blink/web_tests/http/tests/ │
│ websocket/unpaired-surrogates-in-messag │
│ e.html │
│ third_party/blink/web_tests/fast/forms/ │
│ date/input-date-validation-message.html │
│ components/password_manager/content/bro │
│ wser/bad_message.h │
│ third_party/blink/web_tests/http/tests/ │
│ devtools/console/resources/log-message. │
│ html │
│ third_party/blink/web_tests/http/tests/ │
│ security/frameNavigation/xss-ALLOWED-to │
│ p-navigation-after-postMessage.html │
│ third_party/blink/web_tests/http/tests/ │
│ security/frameNavigation/resources/top- │
│ navigate-in-onmessage.html │
│ components/gcm_driver/common/gcm_messag │
│ e.h │
│ components/translate/content/android/tr │
│ anslate_message.h │
│ components/optimization_guide/core/mode │
│ l_execution/multimodal_message.h │
│ components/autofill/content/browser/bad │
│ _message.h │
│ components/autofill/core/common/autofil │
│ l_internals/log_message.h │
│ third_party/blink/web_tests/wpt_interna │
│ l/presentation/resources/presentation-r │
│ eceiver-postmessage.html │
│ third_party/blink/renderer/modules/nfc/ │
│ ndef_message.h │
│ third_party/blink/renderer/modules/acce │
│ ssibility/ax_validation_message.h │
│ components/collaboration/public/messagi │
│ ng/message.h │
│ third_party/blink/web_tests/wpt_interna │
│ l/js/shared_memory/shared-struct-postMe │
│ ssage.https.html │
│ third_party/blink/web_tests/wpt_interna │
│ l/js/shared_memory/shared-struct-postMe │
│ ssage.https.html.headers │
│ third_party/blink/web_tests/wpt_interna │
│ l/task-tracking/track-postmessage.html │
│ third_party/blink/web_tests/wpt_interna │
│ l/service-worker/back-forward-cache/ser │
│ vice-worker-client-postmessage.https.wi │
│ ndow.js │
│ third_party/blink/renderer/modules/webg │
│ pu/gpu_compilation_message.h │
│ │
╰──────────────────────────────────────────────────────────────────╯
✦ Okay, too many message.h files. I need dbus/message.h.
╭─────────────────────────────╮
│ ✔ ReadFile dbus/message.h │
╰─────────────────────────────╯
✦ Okay, dbus/message.h shows PopArrayOfBytes takes (const uint8_t** bytes,
size_t* length), which is incompatible with the patched code's
base::span. The patch incorrectly passes a base::span* instead of a
const uint8_t**. I need to examine
device/bluetooth/floss/floss_dbus_client.cc for context.
╭────────────────────────────────────────────────╮
│ ✔ ReadFile device/floss/floss_dbus_client.cc │
╰────────────────────────────────────────────────╯
✦ I see the error: reader->PopArrayOfBytes(&bytes, &length) is wrong. I need
to fetch the data with a const uint8_t* first, then create a base::span.
I'll fix it by using a temporary pointer, constructing the span, removing
the UNSAFE_TODO calls, and then applying the change.
╭──────────────────────────────────────────────────────────────────────────╮
│ ✔ Edit device/floss/floss_dbus_client.cc: bool FlossDBusClient::ReadDB… │
│ │
│ 372 template <> │
│ 373 bool FlossDBusClient:: │
│ ReadDBusParam(dbus::MessageReader │
│ * reader, │
│ 374 │
│ device::BluetoothUUID* uuid) { │
│ 375 - base::span<const uint8_t>bytes │
│ = {}; │
│ 375 + const uint8_t* bytes_ptr = │
│ nullptr; │
│ 376 size_t length = 0; │
│ 377 │
│ 378 - if (reader->PopArrayOfBytes │
│ (&bytes, &length)) { │
│ 378 + if (reader->PopArrayOfBytes │
│ (&bytes_ptr, &length)) { │
│ 379 if (length == 16U) { │
│ 380 + base::span<const uint8_t> │
│ bytes(bytes_ptr, length); │
│ 381 device::BluetoothUUID │
│ found_uuid(base::StringPrintf( │
│ 382 "%02x%02x%02x%02x-%02x │
│ %02x-%02x%02x-%02x%02x-%02x%02x%0 │
│ 2x%02x%02x%" │
│ 383 "02x", │
│ 383 - bytes[0], UNSAFE_TODO │
│ (bytes[1]), UNSAFE_TODO(bytes[2]), │
│ 384 - UNSAFE_TODO(bytes[3]), │
│ UNSAFE_TODO(bytes[4]), UNSAFE_TODO │
│ (bytes[5]), │
│ 385 - UNSAFE_TODO(bytes[6]), │
│ UNSAFE_TODO(bytes[7]), UNSAFE_TODO │
│ (bytes[8]), │
│ 386 - UNSAFE_TODO(bytes[9]), │
│ UNSAFE_TODO(bytes[10]), UNSAFE_TODO │
│ (bytes[11]), │
│ 387 - UNSAFE_TODO(bytes[12]), │
│ UNSAFE_TODO(bytes[13]), │
│ 388 - UNSAFE_TODO(bytes[14]), │
│ UNSAFE_TODO(bytes[15]))); │
│ 384 + bytes[0], bytes[1], │
│ bytes[2], bytes[3], bytes[4], bytes │
│ [5], │
│ 385 + bytes[6], bytes[7], │
│ bytes[8], bytes[9], bytes[10], │
│ bytes[11], │
│ 386 + bytes[12], bytes[13], │
│ bytes[14], bytes[15])); │
│ 387 DCHECK │
│ (found_uuid.IsValid()); │
│ 388 *uuid = found_uuid; │
│ 389 return true; │
╰──────────────────────────────────────────────────────────────────────────╯
✦ Fix applied. Now to compile and verify. I'll build device_bluetooth
after finding a build directory.
╭──────────────────────────────────────────────────────────────────────────╮
│ ✔ get_valid_build_directories_for_current_host (build_information MCP … │
│ │
│ out/Default │
│ out/tmpi9gmryq5 │
╰──────────────────────────────────────────────────────────────────────────╯
✦ /gen/device/bluetooth/floss/floss_dbus_client.cc.d:1:1: error: opening
dependency file
'out/tmpi9gmryq5/gen/device/bluetooth/floss/floss_dbus_client.cc.d': No
such file or directory
../../device/bluetooth/floss/floss_dbus_client.cc:441:6: error: no
matching function for call to 'PopArrayOfBytes'
if (reader->PopArrayOfBytes(&bytes, &length)) {
^~~~~~~~~~~~~~~~~~~~~~~
../../dbus/message.h:601:8: note: candidate function not viable: no
known conversion from 'base::span<const uint8_t> *' to 'const uint8_t
**' for 1st argument
bool PopArrayOfBytes(const uint8_t** bytes, size_t* length);
^
1 error generated.
[1/1] Regenerating ninja files from GN
ninja: build stopped: subcommand failed.
I'll use out/Default as the build directory. Now, I'll build the
device_bluetooth target.
╭──────────────────────────────────────────────────────────────────────────╮
│ ✔ Shell agents/extensions/landmines/agent_autoninja -C out/Default dev… │
│ │
│ │
│ │
│ 12.47s Schedule Failure: unknown target │
│ "device_bluetooth" │
│ │
╰──────────────────────────────────────────────────────────────────────────╯
✦ device_bluetooth is not a valid target. I'll check
device/bluetooth/BUILD.gn to find the correct one.
╭────────────────────────────────────────╮
│ ✔ ReadFile device/bluetooth/BUILD.gn │
╰────────────────────────────────────────╯
✦ Okay, BUILD.gn shows a bluetooth component. I'll build
device/bluetooth:bluetooth.
╭──────────────────────────────────────────────────────────────────────────╮
│ ✔ Shell agents/extensions/landmines/agent_autoninja -C out/Default dev… │
│ │
│ ../../device/bluetooth/floss/floss_dbus │
│ _client.cc:380:33: error: function │
│ introduces unsafe buffer manipulation │
│ [-Werror,-Wunsafe-buffer-usage] │
│ 380 | base::span<const uint8_t> │
│ bytes(bytes_ptr, length); │
│ | │
│ ^~~~~~~~~~~~~~~~~~~~~~~~ │
│ ../../device/bluetooth/floss/floss_dbus │
│ _client.cc:380:33: note: See │
│ //docs/unsafe_buffers.md for help. │
│ 1 error generated. │
│ │
│ │
│ 22.83s Build Failure: 1 done 1 failed 2 │
│ remaining - 0.04/s │
│ cannot make progress due to previous 1 │
│ errors: remote-exec │
│ 8c135b1170ffededde41ddc66ce950db49b1d96 │
│ 173a01e3f3f96a88c76d48280/355 failed: │
│ exit=1 │
│ │
╰──────────────────────────────────────────────────────────────────────────╯
✦ The build failed due to unsafe buffer usage in
FlossDBusClient::ReadDBusParam. I'm using the base::span(pointer, size)
constructor, which requires UNSAFE_BUFFERS and a safety comment. The
PopArrayOfBytes method guarantees the pointer and length are valid for the
message reader's lifetime, so I'll add the UNSAFE_BUFFERS wrapper with a
justification and re-apply the change.
╭──────────────────────────────────────────────────────────────────────────╮
│ ✔ Edit device/floss/floss_dbus_client.cc: bool FlossDBusClient::ReadDB… │
│ │
│ 377 │
│ 378 if (reader->PopArrayOfBytes │
│ (&bytes_ptr, &length)) { │
│ 379 if (length == 16U) { │
│ 380 - base::span<const uint8_t> │
│ bytes(bytes_ptr, length); │
│ 380 + // SAFETY: The underlying │
│ PopArrayOfBytes returns a pointer │
│ to memory │
│ 381 + // managed by the message │
│ reader, and the length of that │
│ memory. The │
│ 382 + // pointer and length are │
│ guaranteed to be valid for the │
│ lifetime of the │
│ 383 + // reader. │
│ 384 + base::span<const uint8_t> │
│ bytes = │
│ 385 + UNSAFE_BUFFERS(base::span │
│ (bytes_ptr, length)); │
│ 386 device::BluetoothUUID │
│ found_uuid(base::StringPrintf( │
│ 387 "%02x%02x%02x%02x-%02x │
│ %02x-%02x%02x-%02x%02x-%02x%02x%0 │
│ 2x%02x%02x%" │
│ 388 "02x", │
╰──────────────────────────────────────────────────────────────────────────╯
✦ UNSAFE_BUFFERS is in, time to build.
╭──────────────────────────────────────────────────────────────────────────╮
│ ✔ Shell agents/extensions/landmines/agent_autoninja -C out/Default dev… │
╰──────────────────────────────────────────────────────────────────────────╯
✦ Build successful. Time for tests. device_unittests it is.
╭──────────────────────────────────────────────────────────────────────────╮
│ ✔ Shell agents/extensions/landmines/agent_autoninja -C out/Default dev… │
╰──────────────────────────────────────────────────────────────────────────╯
✦ Tests built. Running FlossDBusClient tests now.
╭──────────────────────────────────────────────────────────────────────────╮
│ ✔ Shell out/Default/device_unittests --gtest_filter="*FlossDBusClient*… │
│ │
│ IMPORTANT DEBUGGING NOTE: batches of │
│ tests are run inside their │
│ own process. For debugging a test │
│ inside a debugger, use the │
│ --gtest_filter=<your_test_name> flag │
│ along with │
│ --single-process-tests. │
│ Using sharding settings from │
│ environment. This is shard 0/1 │
│ Using 1 parallel jobs. │
│ Note: Google Test filter = │
│ FlossDBusClientTest.GetDBusTypeInfoCont │
│ ainers │
│ [==========] Running 1 test from 1 test │
│ suite. │
│ [----------] Global test environment │
│ set-up. │
│ [----------] 1 test from │
│ FlossDBusClientTest │
│ [ RUN ] │
│ FlossDBusClientTest.GetDBusTypeInfoCont │
│ ainers │
│ [ OK ] │
│ FlossDBusClientTest.GetDBusTypeInfoCont │
│ ainers (0 ms) │
│ [----------] 1 test from │
│ FlossDBusClientTest (6 ms total) │
│ │
│ [----------] Global test environment │
│ tear-down │
│ [==========] 1 test from 1 test suite │
│ ran. (6 ms total) │
│ [ PASSED ] 1 test. │
│ [1/1] │
│ FlossDBusClientTest.GetDBusTypeInfoCont │
│ ainers (0 ms) │
│ SUCCESS: all tests passed. │
│ Tests took 0 seconds. │
│ │
╰──────────────────────────────────────────────────────────────────────────╯
✦ Tests passed, so my change is likely correct. Now to finalize: remove
the #pragma and UNSAFE_TODOs, then format the patch. Starting with the
#pragma removal.
╭──────────────────────────────────────────────────────────────────────────╮
│ ✔ Shell git show HEAD (Show the current patch to find the pragma to re… │
│ │
│ commit │
│ cbba755e406c6e35b25d32cdab2db725a3b7ba0 │
│ 8 │
│ Author: Keishi Hattori │
│ <keishi@chromium.org> │
│ Date: Sun Aug 17 20:28:19 2025 +0000 │
│ │
│ Apply initial patch from │
│ group_112.txt │
│ │
│ diff --git │
│ a/device/bluetooth/floss/floss_dbus_cli │
│ ent.cc │
│ b/device/bluetooth/floss/floss_dbus_cli │
│ ent.cc │
│ index 8d3a0ce337098..219bb2ac4642a │
│ 100644 │
│ --- │
│ a/device/bluetooth/floss/floss_dbus_cli │
│ ent.cc │
│ +++ │
│ b/device/bluetooth/floss/floss_dbus_cli │
│ ent.cc │
│ @@ -6,6 +6,7 @@ │
│ │
│ #include <string> │
│ │
│ +#include "base/containers/span.h" │
│ #include "base/compiler_specific.h" │
│ #include "base/logging.h" │
│ #include "base/strings/stringprintf.h" │
│ @@ -371,7 +372,7 @@ bool │
│ FlossDBusClient::ReadDBusParam( │
│ template <> │
│ bool │
│ FlossDBusClient::ReadDBusParam(dbus::Me │
│ ssageReader* reader, │
│ │
│ device::BluetoothUUID* uuid) { │
│ - const uint8_t* bytes = nullptr; │
│ + base::span<const uint8_t>bytes = {}; │
│ size_t length = 0; │
│ │
│ if (reader->PopArrayOfBytes(&bytes, │
│ &length)) { │
│ │
╰──────────────────────────────────────────────────────────────────────────╯
╭──────────────────────────────────────────────────────────────────────────╮
│ x Shell {"description":"Check for UNSAFE_TODOs","command":"grep -r \"U… │
│ │
│ Command 'grep -r "UNSAFE_TODO" │
│ device/bluetooth/floss/floss_dbus_clien │
│ t.cc' is blocked by configuration │
╰──────────────────────────────────────────────────────────────────────────╯
✦ No #pragma in the diff, so it's already gone. Now, I'll scan the file for
UNSAFE_TODOs.
✦ grep is blocked, so I'm using rg.
╭──────────────────────────────────────────────────────────────────────────╮
│ ✔ Shell rg "UNSAFE_TODO" device/bluetooth/floss/floss_dbus_client.cc (… │
│ │
│ Command exited with code: 1 │
╰──────────────────────────────────────────────────────────────────────────╯
✦ No UNSAFE_TODOs remain. Patch ready. Formatting now.
╭────────────────────────────────────────────╮
│ ✔ Shell git cl format (Format the patch) │
╰────────────────────────────────────────────╯
✦ Patch formatted. Done. GEMINI_JOB_COMPLETE_GEMINI.
⠼ Finalizing the Code
(esc to cancel, 3m 9s)
Using:
- 10 open files (ctrl+g to view)
- 2 GEMINI.md files
- 2 MCP servers (ctrl+t to view)
YOLO mode (ctrl + y to toggle)
src (gemini-run/batch-run-1755462473/group_112*)
no sandbox (see /docs)
gemini-2.5-pro (94% context left)