• md5.c
  • #ifdef HAVE_CONFIG_H
    #  include <config.h>
    #endif
    
    #include <stdlib.h>		/* for malloc() */
    #include <string.h>		/* for memcpy() */
    
    #include "private/md5.h"
    #include "share/alloc.h"
    #include "share/compat.h"
    #include "share/endswap.h"
    
    /*
     * This code implements the MD5 message-digest algorithm.
     * The algorithm is due to Ron Rivest.  This code was
     * written by Colin Plumb in 1993, no copyright is claimed.
     * This code is in the public domain; do with it what you wish.
     *
     * Equivalent code is available from RSA Data Security, Inc.
     * This code has been tested against that, and is equivalent,
     * except that you don't need to include two pages of legalese
     * with every copy.
     *
     * To compute the message digest of a chunk of bytes, declare an
     * MD5Context structure, pass it to MD5Init, call MD5Update as
     * needed on buffers full of bytes, and then call MD5Final, which
     * will fill a supplied 16-byte array with the digest.
     *
     * Changed so as no longer to depend on Colin Plumb's `usual.h' header
     * definitions; now uses stuff from dpkg's config.h.
     *  - Ian Jackson <[email protected]>.
     * Still in the public domain.
     *
     * Josh Coalson: made some changes to integrate with libFLAC.
     * Still in the public domain.
     */
    
    /* The four core functions - F1 is optimized somewhat */
    
    /* #define F1(x, y, z) (x & y | ~x & z) */
    #define F1(x, y, z) (z ^ (x & (y ^ z)))
    #define F2(x, y, z) F1(z, x, y)
    #define F3(x, y, z) (x ^ y ^ z)
    #define F4(x, y, z) (y ^ (x | ~z))
    
    /* This is the central step in the MD5 algorithm. */
    #define MD5STEP(f,w,x,y,z,in,s) \
    	 (w += f(x,y,z) + in, w = (w<<s | w>>(32-s)) + x)
    
    /*
     * The core of the MD5 algorithm, this alters an existing MD5 hash to
     * reflect the addition of 16 longwords of new data.  MD5Update blocks
     * the data and converts bytes into longwords for this routine.
     */
    
    #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
    /* This tremendously speeds up undefined behaviour fuzzing */
    __attribute__((no_sanitize("unsigned-integer-overflow")))
    #endif
    static void FLAC__MD5Transform(FLAC__uint32 buf[4], FLAC__uint32 const in[16])
    {
    	register FLAC__uint32 a, b, c, d;
    
    	a = buf[0];
    	b = buf[1];
    	c = buf[2];
    	d = buf[3];
    
    	MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
    	MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
    	MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
    	MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
    	MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
    	MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
    	MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
    	MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
    	MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
    	MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
    	MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
    	MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
    	MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
    	MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
    	MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
    	MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);
    
    	MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
    	MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
    	MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
    	MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
    	MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
    	MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
    	MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
    	MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
    	MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
    	MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
    	MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
    	MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
    	MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
    	MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
    	MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
    	MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);
    
    	MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
    	MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
    	MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
    	MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
    	MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
    	MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
    	MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
    	MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
    	MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
    	MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
    	MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
    	MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
    	MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
    	MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
    	MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
    	MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);
    
    	MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
    	MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
    	MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
    	MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
    	MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
    	MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
    	MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
    	MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
    	MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
    	MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
    	MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
    	MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
    	MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
    	MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
    	MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
    	MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);
    
    	buf[0] += a;
    	buf[1] += b;
    	buf[2] += c;
    	buf[3] += d;
    }
    
    #if WORDS_BIGENDIAN
    //@@@@@@ OPT: use bswap/intrinsics
    static void byteSwap(FLAC__uint32 *buf, uint32_t words)
    {
    	register FLAC__uint32 x;
    	do {
    		x = *buf;
    		x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff);
    		*buf++ = (x >> 16) | (x << 16);
    	} while (--words);
    }
    static void byteSwapX16(FLAC__uint32 *buf)
    {
    	register FLAC__uint32 x;
    
    	x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
    	x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
    	x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
    	x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
    	x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
    	x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
    	x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
    	x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
    	x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
    	x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
    	x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
    	x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
    	x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
    	x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
    	x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
    	x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf   = (x >> 16) | (x << 16);
    }
    #else
    #define byteSwap(buf, words)
    #define byteSwapX16(buf)
    #endif
    
    /*
     * Update context to reflect the concatenation of another buffer full
     * of bytes.
     */
    static void FLAC__MD5Update(FLAC__MD5Context *ctx, FLAC__byte const *buf, uint32_t len)
    {
    	FLAC__uint32 t;
    
    	/* Update byte count */
    
    	t = ctx->bytes[0];
    	if ((ctx->bytes[0] = t + len) < t)
    		ctx->bytes[1]++;	/* Carry from low to high */
    
    	t = 64 - (t & 0x3f);	/* Space available in ctx->in (at least 1) */
    	if (t > len) {
    		memcpy((FLAC__byte *)ctx->in + 64 - t, buf, len);
    		return;
    	}
    	/* First chunk is an odd size */
    	memcpy((FLAC__byte *)ctx->in + 64 - t, buf, t);
    	byteSwapX16(ctx->in);
    	FLAC__MD5Transform(ctx->buf, ctx->in);
    	buf += t;
    	len -= t;
    
    	/* Process data in 64-byte chunks */
    	while (len >= 64) {
    		memcpy(ctx->in, buf, 64);
    		byteSwapX16(ctx->in);
    		FLAC__MD5Transform(ctx->buf, ctx->in);
    		buf += 64;
    		len -= 64;
    	}
    
    	/* Handle any remaining bytes of data. */
    	memcpy(ctx->in, buf, len);
    }
    
    /*
     * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
     * initialization constants.
     */
    void FLAC__MD5Init(FLAC__MD5Context *ctx)
    {
    	ctx->buf[0] = 0x67452301;
    	ctx->buf[1] = 0xefcdab89;
    	ctx->buf[2] = 0x98badcfe;
    	ctx->buf[3] = 0x10325476;
    
    	ctx->bytes[0] = 0;
    	ctx->bytes[1] = 0;
    
    	ctx->internal_buf.p8 = 0;
    	ctx->capacity = 0;
    }
    
    /*
     * Final wrapup - pad to 64-byte boundary with the bit pattern
     * 1 0* (64-bit count of bits processed, MSB-first)
     */
    void FLAC__MD5Final(FLAC__byte digest[16], FLAC__MD5Context *ctx)
    {
    	int count = ctx->bytes[0] & 0x3f;	/* Number of bytes in ctx->in */
    	FLAC__byte *p = (FLAC__byte *)ctx->in + count;
    
    	/* Set the first char of padding to 0x80.  There is always room. */
    	*p++ = 0x80;
    
    	/* Bytes of padding needed to make 56 bytes (-8..55) */
    	count = 56 - 1 - count;
    
    	if (count < 0) {	/* Padding forces an extra block */
    		memset(p, 0, count + 8);
    		byteSwapX16(ctx->in);
    		FLAC__MD5Transform(ctx->buf, ctx->in);
    		p = (FLAC__byte *)ctx->in;
    		count = 56;
    	}
    	memset(p, 0, count);
    	byteSwap(ctx->in, 14);
    
    	/* Append length in bits and transform */
    	ctx->in[14] = ctx->bytes[0] << 3;
    	ctx->in[15] = ctx->bytes[1] << 3 | ctx->bytes[0] >> 29;
    	FLAC__MD5Transform(ctx->buf, ctx->in);
    
    	byteSwap(ctx->buf, 4);
    	memcpy(digest, ctx->buf, 16);
    	if (0 != ctx->internal_buf.p8) {
    		free(ctx->internal_buf.p8);
    		ctx->internal_buf.p8 = 0;
    		ctx->capacity = 0;
    	}
    	memset(ctx, 0, sizeof(*ctx));	/* In case it's sensitive */
    }
    
    /*
     * Convert the incoming audio signal to a byte stream
     */
    static void format_input_(FLAC__multibyte *mbuf, const FLAC__int32 * const signal[], uint32_t channels, uint32_t samples, uint32_t bytes_per_sample)
    {
    	FLAC__byte *buf_ = mbuf->p8;
    	FLAC__int16 *buf16 = mbuf->p16;
    	FLAC__int32 *buf32 = mbuf->p32;
    	FLAC__int32 a_word;
    	uint32_t channel, sample;
    
    	/* Storage in the output buffer, buf, is little endian. */
    
    #define BYTES_CHANNEL_SELECTOR(bytes, channels)   (bytes * 100 + channels)
    
    	/* First do the most commonly used combinations. */
    	switch (BYTES_CHANNEL_SELECTOR (bytes_per_sample, channels)) {
    		/* One byte per sample. */
    		case (BYTES_CHANNEL_SELECTOR (1, 1)):
    			for (sample = 0; sample < samples; sample++)
    				*buf_++ = signal[0][sample];
    			return;
    
    		case (BYTES_CHANNEL_SELECTOR (1, 2)):
    			for (sample = 0; sample < samples; sample++) {
    				*buf_++ = signal[0][sample];
    				*buf_++ = signal[1][sample];
    			}
    			return;
    
    		case (BYTES_CHANNEL_SELECTOR (1, 4)):
    			for (sample = 0; sample < samples; sample++) {
    				*buf_++ = signal[0][sample];
    				*buf_++ = signal[1][sample];
    				*buf_++ = signal[2][sample];
    				*buf_++ = signal[3][sample];
    			}
    			return;
    
    		case (BYTES_CHANNEL_SELECTOR (1, 6)):
    			for (sample = 0; sample < samples; sample++) {
    				*buf_++ = signal[0][sample];
    				*buf_++ = signal[1][sample];
    				*buf_++ = signal[2][sample];
    				*buf_++ = signal[3][sample];
    				*buf_++ = signal[4][sample];
    				*buf_++ = signal[5][sample];
    			}
    			return;
    
    		case (BYTES_CHANNEL_SELECTOR (1, 8)):
    			for (sample = 0; sample < samples; sample++) {
    				*buf_++ = signal[0][sample];
    				*buf_++ = signal[1][sample];
    				*buf_++ = signal[2][sample];
    				*buf_++ = signal[3][sample];
    				*buf_++ = signal[4][sample];
    				*buf_++ = signal[5][sample];
    				*buf_++ = signal[6][sample];
    				*buf_++ = signal[7][sample];
    			}
    			return;
    
    		/* Two bytes per sample. */
    		case (BYTES_CHANNEL_SELECTOR (2, 1)):
    			for (sample = 0; sample < samples; sample++)
    				*buf16++ = H2LE_16(signal[0][sample]);
    			return;
    
    		case (BYTES_CHANNEL_SELECTOR (2, 2)):
    			for (sample = 0; sample < samples; sample++) {
    				*buf16++ = H2LE_16(signal[0][sample]);
    				*buf16++ = H2LE_16(signal[1][sample]);
    			}
    			return;
    
    		case (BYTES_CHANNEL_SELECTOR (2, 4)):
    			for (sample = 0; sample < samples; sample++) {
    				*buf16++ = H2LE_16(signal[0][sample]);
    				*buf16++ = H2LE_16(signal[1][sample]);
    				*buf16++ = H2LE_16(signal[2][sample]);
    				*buf16++ = H2LE_16(signal[3][sample]);
    			}
    			return;
    
    		case (BYTES_CHANNEL_SELECTOR (2, 6)):
    			for (sample = 0; sample < samples; sample++) {
    				*buf16++ = H2LE_16(signal[0][sample]);
    				*buf16++ = H2LE_16(signal[1][sample]);
    				*buf16++ = H2LE_16(signal[2][sample]);
    				*buf16++ = H2LE_16(signal[3][sample]);
    				*buf16++ = H2LE_16(signal[4][sample]);
    				*buf16++ = H2LE_16(signal[5][sample]);
    			}
    			return;
    
    		case (BYTES_CHANNEL_SELECTOR (2, 8)):
    			for (sample = 0; sample < samples; sample++) {
    				*buf16++ = H2LE_16(signal[0][sample]);
    				*buf16++ = H2LE_16(signal[1][sample]);
    				*buf16++ = H2LE_16(signal[2][sample]);
    				*buf16++ = H2LE_16(signal[3][sample]);
    				*buf16++ = H2LE_16(signal[4][sample]);
    				*buf16++ = H2LE_16(signal[5][sample]);
    				*buf16++ = H2LE_16(signal[6][sample]);
    				*buf16++ = H2LE_16(signal[7][sample]);
    			}
    			return;
    
    		/* Three bytes per sample. */
    		case (BYTES_CHANNEL_SELECTOR (3, 1)):
    			for (sample = 0; sample < samples; sample++) {
    				a_word = signal[0][sample];
    				*buf_++ = (FLAC__byte)a_word; a_word >>= 8;
    				*buf_++ = (FLAC__byte)a_word; a_word >>= 8;
    				*buf_++ = (FLAC__byte)a_word;
    			}
    			return;
    
    		case (BYTES_CHANNEL_SELECTOR (3, 2)):
    			for (sample = 0; sample < samples; sample++) {
    				a_word = signal[0][sample];
    				*buf_++ = (FLAC__byte)a_word; a_word >>= 8;
    				*buf_++ = (FLAC__byte)a_word; a_word >>= 8;
    				*buf_++ = (FLAC__byte)a_word;
    				a_word = signal[1][sample];
    				*buf_++ = (FLAC__byte)a_word; a_word >>= 8;
    				*buf_++ = (FLAC__byte)a_word; a_word >>= 8;
    				*buf_++ = (FLAC__byte)a_word;
    			}
    			return;
    
    		/* Four bytes per sample. */
    		case (BYTES_CHANNEL_SELECTOR (4, 1)):
    			for (sample = 0; sample < samples; sample++)
    				*buf32++ = H2LE_32(signal[0][sample]);
    			return;
    
    		case (BYTES_CHANNEL_SELECTOR (4, 2)):
    			for (sample = 0; sample < samples; sample++) {
    				*buf32++ = H2LE_32(signal[0][sample]);
    				*buf32++ = H2LE_32(signal[1][sample]);
    			}
    			return;
    
    		case (BYTES_CHANNEL_SELECTOR (4, 4)):
    			for (sample = 0; sample < samples; sample++) {
    				*buf32++ = H2LE_32(signal[0][sample]);
    				*buf32++ = H2LE_32(signal[1][sample]);
    				*buf32++ = H2LE_32(signal[2][sample]);
    				*buf32++ = H2LE_32(signal[3][sample]);
    			}
    			return;
    
    		case (BYTES_CHANNEL_SELECTOR (4, 6)):
    			for (sample = 0; sample < samples; sample++) {
    				*buf32++ = H2LE_32(signal[0][sample]);
    				*buf32++ = H2LE_32(signal[1][sample]);
    				*buf32++ = H2LE_32(signal[2][sample]);
    				*buf32++ = H2LE_32(signal[3][sample]);
    				*buf32++ = H2LE_32(signal[4][sample]);
    				*buf32++ = H2LE_32(signal[5][sample]);
    			}
    			return;
    
    		case (BYTES_CHANNEL_SELECTOR (4, 8)):
    			for (sample = 0; sample < samples; sample++) {
    				*buf32++ = H2LE_32(signal[0][sample]);
    				*buf32++ = H2LE_32(signal[1][sample]);
    				*buf32++ = H2LE_32(signal[2][sample]);
    				*buf32++ = H2LE_32(signal[3][sample]);
    				*buf32++ = H2LE_32(signal[4][sample]);
    				*buf32++ = H2LE_32(signal[5][sample]);
    				*buf32++ = H2LE_32(signal[6][sample]);
    				*buf32++ = H2LE_32(signal[7][sample]);
    			}
    			return;
    
    		default:
    			break;
    	}
    
    	/* General version. */
    	switch (bytes_per_sample) {
    		case 1:
    			for (sample = 0; sample < samples; sample++)
    				for (channel = 0; channel < channels; channel++)
    					*buf_++ = signal[channel][sample];
    			return;
    
    		case 2:
    			for (sample = 0; sample < samples; sample++)
    				for (channel = 0; channel < channels; channel++)
    					*buf16++ = H2LE_16(signal[channel][sample]);
    			return;
    
    		case 3:
    			for (sample = 0; sample < samples; sample++)
    				for (channel = 0; channel < channels; channel++) {
    					a_word = signal[channel][sample];
    					*buf_++ = (FLAC__byte)a_word; a_word >>= 8;
    					*buf_++ = (FLAC__byte)a_word; a_word >>= 8;
    					*buf_++ = (FLAC__byte)a_word;
    				}
    			return;
    
    		case 4:
    			for (sample = 0; sample < samples; sample++)
    				for (channel = 0; channel < channels; channel++)
    					*buf32++ = H2LE_32(signal[channel][sample]);
    			return;
    
    		default:
    			break;
    	}
    }
    
    /*
     * Convert the incoming audio signal to a byte stream and FLAC__MD5Update it.
     */
    FLAC__bool FLAC__MD5Accumulate(FLAC__MD5Context *ctx, const FLAC__int32 * const signal[], uint32_t channels, uint32_t samples, uint32_t bytes_per_sample)
    {
    	const size_t bytes_needed = (size_t)channels * (size_t)samples * (size_t)bytes_per_sample;
    
    	/* overflow check */
    	if ((size_t)channels > SIZE_MAX / (size_t)bytes_per_sample)
    		return false;
    	if ((size_t)channels * (size_t)bytes_per_sample > SIZE_MAX / (size_t)samples)
    		return false;
    
    	if (ctx->capacity < bytes_needed) {
    		if (0 == (ctx->internal_buf.p8 = safe_realloc_(ctx->internal_buf.p8, bytes_needed))) {
    			if (0 == (ctx->internal_buf.p8 = safe_malloc_(bytes_needed))) {
    				ctx->capacity = 0;
    				return false;
    			}
    		}
    		ctx->capacity = bytes_needed;
    	}
    
    	format_input_(&ctx->internal_buf, signal, channels, samples, bytes_per_sample);
    
    	FLAC__MD5Update(ctx, ctx->internal_buf.p8, bytes_needed);
    
    	return true;
    }