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Add fbounds-safety annotations for tokens
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Reasoning: The errors reported for `tokens` in `CodeRepeatedValues` (src/utils/huffman_encode_utils.c, lines 274, 283, 289, 294) indicated pointer arithmetic on a pointer assumed to be `__single`. Since `CodeRepeatedValues` is static and uses `tokens` as an iterator, its signature was changed to use `HuffmanTreeToken* __indexable` for both the parameter and return type. A similar static function, `CodeRepeatedZeros`, was also updated to use `__indexable` pointers. The caller, `VP8LCreateCompressedHuffmanTree`, passes a buffer `tokens` with size `max_tokens`. Its signature (in .c and .h files) was annotated to reflect this using `__counted_by(max_tokens)`. Because `__counted_by` requires the size parameter to be updated alongside the pointer if the pointer is modified, the implementation of `VP8LCreateCompressedHuffmanTree` was refactored. Instead of modifying the `tokens` parameter directly, a local iterator variable `current_token` was introduced and explicitly annotated as `__indexable` to ensure correct type propagation, especially when `WEBP_ASSUME_UNSAFE_INDEXABLE_ABI` is active. This local iterator is used for calls to `CodeRepeatedValues` and `CodeRepeatedZeros`. Bug: 432511821 Change-Id: I07fe553341a613a0ea4d5284817098c31f3aefeb
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@@ -265,9 +265,9 @@ static void GenerateOptimalTree(const uint32_t* const histogram,
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// -----------------------------------------------------------------------------
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// Coding of the Huffman tree values
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static HuffmanTreeToken* CodeRepeatedValues(int repetitions,
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HuffmanTreeToken* tokens, int value,
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int prev_value) {
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static HuffmanTreeToken* WEBP_INDEXABLE
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CodeRepeatedValues(int repetitions, HuffmanTreeToken* WEBP_INDEXABLE tokens,
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int value, int prev_value) {
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assert(value <= MAX_ALLOWED_CODE_LENGTH);
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if (value != prev_value) {
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tokens->code = value;
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@@ -299,8 +299,8 @@ static HuffmanTreeToken* CodeRepeatedValues(int repetitions,
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return tokens;
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}
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static HuffmanTreeToken* CodeRepeatedZeros(int repetitions,
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HuffmanTreeToken* tokens) {
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static HuffmanTreeToken* WEBP_INDEXABLE
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CodeRepeatedZeros(int repetitions, HuffmanTreeToken* WEBP_INDEXABLE tokens) {
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while (repetitions >= 1) {
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if (repetitions < 3) {
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int i;
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@@ -330,8 +330,10 @@ static HuffmanTreeToken* CodeRepeatedZeros(int repetitions,
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return tokens;
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}
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int VP8LCreateCompressedHuffmanTree(const HuffmanTreeCode* const tree,
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HuffmanTreeToken* tokens, int max_tokens) {
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int VP8LCreateCompressedHuffmanTree(
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const HuffmanTreeCode* const tree,
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HuffmanTreeToken* WEBP_COUNTED_BY(max_tokens) tokens, int max_tokens) {
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HuffmanTreeToken* WEBP_INDEXABLE current_token = tokens;
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HuffmanTreeToken* const starting_token = tokens;
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HuffmanTreeToken* const ending_token = tokens + max_tokens;
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const int depth_size = tree->num_symbols;
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@@ -345,16 +347,17 @@ int VP8LCreateCompressedHuffmanTree(const HuffmanTreeCode* const tree,
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while (k < depth_size && tree->code_lengths[k] == value) ++k;
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runs = k - i;
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if (value == 0) {
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tokens = CodeRepeatedZeros(runs, tokens);
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current_token = CodeRepeatedZeros(runs, current_token);
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} else {
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tokens = CodeRepeatedValues(runs, tokens, value, prev_value);
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current_token =
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CodeRepeatedValues(runs, current_token, value, prev_value);
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prev_value = value;
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}
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i += runs;
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assert(tokens <= ending_token);
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assert(current_token <= ending_token);
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}
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(void)ending_token; // suppress 'unused variable' warning
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return (int)(tokens - starting_token);
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return (int)(current_token - starting_token);
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}
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// -----------------------------------------------------------------------------
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@@ -48,8 +48,9 @@ typedef struct {
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// Turn the Huffman tree into a token sequence.
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// Returns the number of tokens used.
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int VP8LCreateCompressedHuffmanTree(const HuffmanTreeCode* const tree,
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HuffmanTreeToken* tokens, int max_tokens);
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int VP8LCreateCompressedHuffmanTree(
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const HuffmanTreeCode* const tree,
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HuffmanTreeToken* WEBP_COUNTED_BY(max_tokens) tokens, int max_tokens);
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// Create an optimized tree, and tokenize it.
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// 'buf_rle' and 'huff_tree' are pre-allocated and the 'tree' is the constructed
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