Use 'while (rp < wp)' idiom for filter output buffering state.

1 files changed, 63 insertions, 57 deletions

diff --git a/fitz/filt_basic.c b/fitz/filt_basic.c
index e5c54518..a0369282 100644
--- a/fitz/filt_basic.c
+++ b/fitz/filt_basic.c
@@ -91,11 +91,12 @@ readahxd(fz_stream *stm, unsigned char *buf, int len)
 {
 	fz_ahxd *state = stm->state;
 	unsigned char *p = buf;
+	unsigned char *ep = buf + len;
 	int a, b, c, odd;
 
 	odd = 0;
 
-	while (p < buf + len)
+	while (p < ep)
 	{
 		if (state->eod)
 			return p - buf;
@@ -160,8 +161,8 @@ typedef struct fz_a85d_s fz_a85d;
 struct fz_a85d_s
 {
 	fz_stream *chain;
-	unsigned char buf[4];
-	int remain;
+	unsigned char bp[4];
+	unsigned char *rp, *wp;
 	int eod;
 };
 
@@ -170,14 +171,15 @@ reada85d(fz_stream *stm, unsigned char *buf, int len)
 {
 	fz_a85d *state = stm->state;
 	unsigned char *p = buf;
+	unsigned char *ep = buf + len;
 	int count = 0;
 	int word = 0;
 	int c;
 
-	while (state->remain > 0 && p < buf + len)
-		*p++ = state->buf[4 - state->remain--];
+	while (state->rp < state->wp && p < ep)
+		*p++ = *state->rp++;
 
-	while (p < buf + len)
+	while (p < ep)
 	{
 		if (state->eod)
 			return p - buf;
@@ -192,11 +194,12 @@ reada85d(fz_stream *stm, unsigned char *buf, int len)
 			{
 				word = word * 85 + (c - '!');
 
-				state->buf[0] = (word >> 24) & 0xff;
-				state->buf[1] = (word >> 16) & 0xff;
-				state->buf[2] = (word >> 8) & 0xff;
-				state->buf[3] = (word) & 0xff;
-				state->remain = 4;
+				state->bp[0] = (word >> 24) & 0xff;
+				state->bp[1] = (word >> 16) & 0xff;
+				state->bp[2] = (word >> 8) & 0xff;
+				state->bp[3] = (word) & 0xff;
+				state->rp = state->bp;
+				state->wp = state->bp + 4;
 
 				word = 0;
 				count = 0;
@@ -210,11 +213,12 @@ reada85d(fz_stream *stm, unsigned char *buf, int len)
 
 		else if (c == 'z' && count == 0)
 		{
-			state->buf[0] = 0;
-			state->buf[1] = 0;
-			state->buf[2] = 0;
-			state->buf[3] = 0;
-			state->remain = 4;
+			state->bp[0] = 0;
+			state->bp[1] = 0;
+			state->bp[2] = 0;
+			state->bp[3] = 0;
+			state->rp = state->bp;
+			state->wp = state->bp + 4;
 		}
 
 		else if (c == '~')
@@ -230,21 +234,24 @@ reada85d(fz_stream *stm, unsigned char *buf, int len)
 				return fz_throw("partial final byte in a85d");
 			case 2:
 				word = word * (85 * 85 * 85) + 0xffffff;
-				state->buf[3] = word >> 24;
-				state->remain = 1;
+				state->bp[0] = word >> 24;
+				state->rp = state->bp;
+				state->wp = state->bp + 1;
 				break;
 			case 3:
 				word = word * (85 * 85) + 0xffff;
-				state->buf[2] = word >> 24;
-				state->buf[3] = word >> 16;
-				state->remain = 2;
+				state->bp[0] = word >> 24;
+				state->bp[1] = word >> 16;
+				state->rp = state->bp;
+				state->wp = state->bp + 2;
 				break;
 			case 4:
 				word = word * 85 + 0xff;
-				state->buf[1] = word >> 24;
-				state->buf[2] = word >> 16;
-				state->buf[3] = word >> 8;
-				state->remain = 3;
+				state->bp[0] = word >> 24;
+				state->bp[1] = word >> 16;
+				state->bp[2] = word >> 8;
+				state->rp = state->bp;
+				state->wp = state->bp + 3;
 				break;
 			}
 			state->eod = 1;
@@ -255,8 +262,8 @@ reada85d(fz_stream *stm, unsigned char *buf, int len)
 			return fz_throw("bad data in a85d: '%c'", c);
 		}
 
-		while (state->remain > 0 && p < buf + len)
-			*p++ = state->buf[4 - state->remain--];
+		while (state->rp < state->wp && p < ep)
+			*p++ = *state->rp++;
 	}
 
 	return p - buf;
@@ -277,7 +284,8 @@ fz_opena85d(fz_stream *chain)
 
 	state = fz_malloc(sizeof(fz_a85d));
 	state->chain = chain;
-	state->remain = 0;
+	state->rp = state->bp;
+	state->wp = state->bp;
 	state->eod = 0;
 
 	return fz_newstream(state, reada85d, closea85d);
@@ -298,8 +306,9 @@ readrld(fz_stream *stm, unsigned char *buf, int len)
 {
 	fz_rld *state = stm->state;
 	unsigned char *p = buf;
+	unsigned char *ep = buf + len;
 
-	while (p < buf + len)
+	while (p < ep)
 	{
 		if (state->run == 128)
 			return p - buf;
@@ -322,7 +331,7 @@ readrld(fz_stream *stm, unsigned char *buf, int len)
 
 		if (state->run < 128)
 		{
-			while (p < buf + len && state->n--)
+			while (p < ep && state->n--)
 			{
 				int c = fz_readbyte(state->chain);
 				if (c < 0)
@@ -333,7 +342,7 @@ readrld(fz_stream *stm, unsigned char *buf, int len)
 
 		if (state->run > 128)
 		{
-			while (p < buf + len && state->n--)
+			while (p < ep && state->n--)
 				*p++ = state->c;
 		}
 	}
@@ -417,8 +426,8 @@ struct fz_aesd_s
 	fz_aes aes;
 	unsigned char iv[16];
 	int ivcount;
-	unsigned char buf[16];
-	int remain;
+	unsigned char bp[16];
+	unsigned char *rp, *wp;
 };
 
 static int
@@ -426,48 +435,44 @@ readaesd(fz_stream *stm, unsigned char *buf, int len)
 {
 	fz_aesd *state = stm->state;
 	unsigned char *p = buf;
+	unsigned char *ep = buf + len;
 
 	while (state->ivcount < 16)
 	{
 		int c = fz_readbyte(state->chain);
 		if (c < 0)
-			return fz_throw("premature end in AES filter");
+			return fz_throw("premature end in aes filter");
 		state->iv[state->ivcount++] = c;
 	}
 
-	while (state->remain > 0 && p < buf + len)
-		*p++ = state->buf[16 - state->remain--];
+	while (state->rp < state->wp && p < ep)
+		*p++ = *state->rp++;
 
-	while (p < buf + len)
+	while (p < ep)
 	{
-		while (state->remain < 16)
-		{
-			int c = fz_readbyte(state->chain);
-			if (c < 0)
-			{
-				if (state->remain > 0)
-					return fz_throw("premature end in AES filter");
-				return p - buf;
-			}
-			state->buf[state->remain++] = c;
-		}
+		int n = fz_read(state->chain, state->bp, 16);
+		if (n < 0)
+			return fz_rethrow(n, "read error in aes filter");
+		else if (n == 0)
+			return p - buf;
+		else if (n < 16)
+			return fz_throw("partial block in aes filter");
 
-		aes_crypt_cbc(&state->aes, AES_DECRYPT, 16, state->iv, state->buf, state->buf);
+		aes_crypt_cbc(&state->aes, AES_DECRYPT, 16, state->iv, state->bp, state->bp);
+		state->rp = state->bp;
+		state->wp = state->bp + 16;
 
 		/* strip padding at end of file */
 		if (fz_peekbyte(state->chain) == EOF)
 		{
-			int pad = state->buf[15];
+			int pad = state->bp[15];
 			if (pad < 1 || pad > 16)
 				return fz_throw("aes padding out of range: %d", pad);
-			state->remain -= pad;
-			memmove(&state->buf[16 - state->remain],
-				&state->buf[0],
-				state->remain);
+			state->wp -= pad;
 		}
 
-		while (state->remain > 0 && p < buf + len)
-			*p++ = state->buf[16 - state->remain--];
+		while (state->rp < state->wp && p < ep)
+			*p++ = *state->rp++;
 	}
 
 	return p - buf;
@@ -490,7 +495,8 @@ fz_openaesd(fz_stream *chain, unsigned char *key, unsigned keylen)
 	state->chain = chain;
 	aes_setkey_dec(&state->aes, key, keylen * 8);
 	state->ivcount = 0;
-	state->remain = 0;
+	state->rp = state->bp;
+	state->wp = state->bp;
 
 	return fz_newstream(state, readaesd, closeaesd);
 }