stagefright: add safe versions of parseUE and parseSE (2f4555e2) · Commits · e / os / android_frameworks_av

media/libstagefright/avc_utils.cpp

+27 −0

Original line number	Diff line number	Diff line
		@@ -41,12 +41,39 @@ unsigned parseUE(ABitReader *br) {
		return x + (1u << numZeroes) - 1;
		}

		unsigned parseUEWithFallback(ABitReader *br, unsigned fallback) {
		unsigned numZeroes = 0;
		while (br->getBitsWithFallback(1, 1) == 0) {
		++numZeroes;
		}
		uint32_t x;
		if (numZeroes < 32) {
		if (br->getBitsGraceful(numZeroes, &x)) {
		return x + (1u << numZeroes) - 1;
		} else {
		return fallback;
		}
		} else {
		br->skipBits(numZeroes);
		return fallback;
		}
		}

		signed parseSE(ABitReader *br) {
		unsigned codeNum = parseUE(br);

		return (codeNum & 1) ? (codeNum + 1) / 2 : -(codeNum / 2);
		}

		signed parseSEWithFallback(ABitReader *br, signed fallback) {
		// NOTE: parseUE cannot normally return ~0 as the max supported value is 0xFFFE
		unsigned codeNum = parseUEWithFallback(br, ~0U);
		if (codeNum == ~0U) {
		return fallback;
		}
		return (codeNum & 1) ? (codeNum + 1) / 2 : -(codeNum / 2);
		}

		static void skipScalingList(ABitReader *br, size_t sizeOfScalingList) {
		size_t lastScale = 8;
		size_t nextScale = 8;

media/libstagefright/include/avc_utils.h

+26 −0

Original line number	Diff line number	Diff line
		@@ -47,8 +47,34 @@ void FindAVCDimensions(
		int32_t width, int32_t height,
		int32_t sarWidth = NULL, int32_t sarHeight = NULL);

		// Gets and returns an unsigned exp-golomb (ue) value from a bit reader \|br\|. Aborts if the value
		// is more than 64 bits long (>=0xFFFF (!)) or the bit reader overflows.
		unsigned parseUE(ABitReader *br);

		// Gets and returns a signed exp-golomb (se) value from a bit reader \|br\|. Aborts if the value is
		// more than 64 bits long (>0x7FFF \|\| <-0x7FFF (!)) or the bit reader overflows.
		signed parseSE(ABitReader *br);

		// Gets an unsigned exp-golomb (ue) value from a bit reader \|br\|, and returns it if it was
		// successful. Returns \|fallback\| if it was unsuccessful. Note: if the value was longer that 64
		// bits, it reads past the value and still returns \|fallback\|.
		unsigned parseUEWithFallback(ABitReader *br, unsigned fallback);

		// Gets a signed exp-golomb (se) value from a bit reader \|br\|, and returns it if it was successful.
		// Returns \|fallback\| if it was unsuccessful. Note: if the value was longer that 64 bits, it reads
		// past the value and still returns \|fallback\|.
		signed parseSEWithFallback(ABitReader *br, signed fallback);

		// Skips an unsigned exp-golomb (ue) value from bit reader \|br\|.
		inline void skipUE(ABitReader *br) {
		(void)parseUEWithFallback(br, 0U);
		}

		// Skips a signed exp-golomb (se) value from bit reader \|br\|.
		inline void skipSE(ABitReader *br) {
		(void)parseSEWithFallback(br, 0);
		}

		status_t getNextNALUnit(
		const uint8_t *_data, size_t _size,
		const uint8_t *nalStart, size_t nalSize,

Original line number	Diff line number	Diff line
		@@ -47,8 +47,34 @@ void FindAVCDimensions(
		int32_t width, int32_t height,
		int32_t sarWidth = NULL, int32_t sarHeight = NULL);

		// Gets and returns an unsigned exp-golomb (ue) value from a bit reader \|br\|. Aborts if the value
		// is more than 64 bits long (>=0xFFFF (!)) or the bit reader overflows.
		unsigned parseUE(ABitReader *br);

		// Gets and returns a signed exp-golomb (se) value from a bit reader \|br\|. Aborts if the value is
		// more than 64 bits long (>0x7FFF \|\| <-0x7FFF (!)) or the bit reader overflows.
		signed parseSE(ABitReader *br);

		// Gets an unsigned exp-golomb (ue) value from a bit reader \|br\|, and returns it if it was
		// successful. Returns \|fallback\| if it was unsuccessful. Note: if the value was longer that 64
		// bits, it reads past the value and still returns \|fallback\|.
		unsigned parseUEWithFallback(ABitReader *br, unsigned fallback);

		// Gets a signed exp-golomb (se) value from a bit reader \|br\|, and returns it if it was successful.
		// Returns \|fallback\| if it was unsuccessful. Note: if the value was longer that 64 bits, it reads
		// past the value and still returns \|fallback\|.
		signed parseSEWithFallback(ABitReader *br, signed fallback);

		// Skips an unsigned exp-golomb (ue) value from bit reader \|br\|.
		inline void skipUE(ABitReader *br) {
		(void)parseUEWithFallback(br, 0U);
		}

		// Skips a signed exp-golomb (se) value from bit reader \|br\|.
		inline void skipSE(ABitReader *br) {
		(void)parseSEWithFallback(br, 0);
		}

		status_t getNextNALUnit(
		const uint8_t *_data, size_t _size,
		const uint8_t *nalStart, size_t nalSize,