Add macro to check remaining length of STREAM

Avoids poking around in the internals, and also makes the code
easier to read.

channels.c

@@ -93,7 +93,7 @@ channel_send(STREAM s, VCHANNEL * channel)
 
 	/* first fragment sent in-place */
 	s_pop_layer(s, channel_hdr);
-	length = s->end - s->p - 8;
+	length = s_remaining(s) - 8;
 
 	logger(Protocol, Debug, "channel_send(), channel = %d, length = %d", channel->mcs_id,
 	       length);
@@ -186,7 +186,7 @@ channel_process(STREAM s, uint16 mcs_channel)
 			in->p = in->data;
 		}
 
-		thislength = MIN(s->end - s->p, in->data + in->size - in->p);
+		thislength = MIN(s_remaining(s), in->data + in->size - in->p);
 		memcpy(in->p, s->p, thislength);
 		in->p += thislength;
 

iso.c

@@ -177,7 +177,7 @@ iso_send(STREAM s)
 	uint16 length;
 
 	s_pop_layer(s, iso_hdr);
-	length = s->end - s->p;
+	length = s_remaining(s);
 
 	out_uint8(s, T123_HEADER_VERSION);	/* version */
 	out_uint8(s, 0);	/* reserved */

lspci.c

@@ -136,7 +136,7 @@ lspci_process(STREAM s)
 	static char *rest = NULL;
 	char *buf;
 
-	pkglen = s->end - s->p;
+	pkglen = s_remaining(s);
 	/* str_handle_lines requires null terminated strings */
 	buf = xmalloc(pkglen + 1);
 	STRNCPY(buf, (char *) s->p, pkglen + 1);

mcs.c

@@ -306,7 +306,7 @@ mcs_send_to_channel(STREAM s, uint16 channel)
 	uint16 length;
 
 	s_pop_layer(s, mcs_hdr);
-	length = s->end - s->p - 8;
+	length = s_remaining(s) - 8;
 	length |= 0x8000;
 
 	out_uint8(s, (MCS_SDRQ << 2));

rdp.c

@@ -194,7 +194,7 @@ rdp_send_data(STREAM s, uint8 data_pdu_type)
 	uint16 length;
 
 	s_pop_layer(s, rdp_hdr);
-	length = s->end - s->p;
+	length = s_remaining(s);
 
 	out_uint16_le(s, length);
 	out_uint16_le(s, (RDP_PDU_DATA | 0x10));

rdpdr.c

@@ -879,7 +879,7 @@ rdpdr_process(STREAM s)
 	uint16 pakid;
 
 	logger(Protocol, Debug, "rdpdr_process()");
-	/* hexdump(s->p, s->end - s->p); */
+	/* hexdump(s->p, s_remaining(s)); */
 
 	in_uint16(s, component);        /* RDPDR_HEADER.Component */
 	in_uint16(s, pakid);            /* RDPDR_HEADER.PacketId */

rdpsnd.c

@@ -343,7 +343,7 @@ rdpsnd_process_packet(uint8 opcode, STREAM s)
 			}
 
 			rdpsnd_queue_write(rdpsnd_dsp_process
-					   (s->p, s->end - s->p, current_driver,
+					   (s->p, s_remaining(s), current_driver,
 					    &formats[current_format]), tick, packet_index);
 			return;
 			break;
@@ -386,7 +386,7 @@ rdpsnd_process(STREAM s)
 		/* New packet */
 		if (packet.size == 0)
 		{
-			if ((s->end - s->p) < 4)
+			if (!s_check_rem(s, 4))
 			{
 				logger(Sound, Error,
 				       "rdpsnd_process(), split at packet header, things will go south from here...");
@@ -405,7 +405,7 @@ rdpsnd_process(STREAM s)
 		}
 		else
 		{
-			len = MIN(s->end - s->p, packet.end - packet.p);
+			len = MIN(s_remaining(s), s_remaining(&packet));
 
 			/* Microsoft's server is so broken it's not even funny... */
 			if (packet_opcode == SNDC_WAVE)
@@ -451,7 +451,7 @@ rdpsnddbg_process(STREAM s)
 	static char *rest = NULL;
 	char *buf;
 
-	pkglen = s->end - s->p;
+	pkglen = s_remaining(s);
 	/* str_handle_lines requires null terminated strings */
 	buf = (char *) xmalloc(pkglen + 1);
 	STRNCPY(buf, (char *) s->p, pkglen + 1);

rdpsnd_alsa.c

@@ -380,7 +380,7 @@ alsa_play(void)
 
 	next_tick = rdpsnd_queue_next_tick();
 
-	len = (out->end - out->p) / (samplewidth_out * audiochannels_out);
+	len = s_remaining(out) / (samplewidth_out * audiochannels_out);
 	if ((len = snd_pcm_writei(out_handle, out->p, ((MAX_FRAMES < len) ? MAX_FRAMES : len))) < 0)
 	{
 		snd_pcm_prepare(out_handle);

rdpsnd_libao.c

@@ -171,7 +171,7 @@ libao_play(void)
 
 	next_tick = rdpsnd_queue_next_tick();
 
-	len = (WAVEOUTLEN > (out->end - out->p)) ? (out->end - out->p) : WAVEOUTLEN;
+	len = MIN(WAVEOUTLEN, s_remaining(out));
 	ao_play(o_device, (char *) out->p, len);
 	out->p += len;
 

rdpsnd_oss.c

@@ -412,7 +412,7 @@ oss_play(void)
 	packet = rdpsnd_queue_current_packet();
 	out = &packet->s;
 
-	len = out->end - out->p;
+	len = s_remaining(out);
 
 	len = write(dsp_fd, out->p, (len > MAX_LEN) ? MAX_LEN : len);
 	if (len == -1)

rdpsnd_pulse.c

@@ -1192,7 +1192,7 @@ pulse_play(void)
 			playback_seek = PA_SEEK_RELATIVE;
 
 		avail_space = pa_stream_writable_size(playback_stream);
-		audio_size = out->end - out->p <= avail_space ? out->end - out->p : avail_space;
+		audio_size = MIN(s_remaining(out), avail_space);
 		if (audio_size)
 		{
 			if (pa_stream_write

rdpsnd_sgi.c

@@ -256,7 +256,7 @@ sgi_play(void)
 		packet = rdpsnd_queue_current_packet();
 		out = (STREAM) (void *) &(packet->s);
 
-		len = out->end - out->p;
+		len = s_remaining(out);
 
 		alWriteFrames(output_port, out->p, len / combinedFrameSize);
 

rdpsnd_sun.c

@@ -419,7 +419,7 @@ sun_play(void)
 	packet = rdpsnd_queue_current_packet();
 	out = &packet->s;
 
-	len = out->end - out->p;
+	len = s_remaining(out);
 
 	len = write(dsp_fd, out->p, (len > MAX_LEN) ? MAX_LEN : len);
 	if (len == -1)

seamless.c

@@ -377,7 +377,7 @@ seamless_process(STREAM s)
 	unsigned int pkglen;
 	char *buf;
 
-	pkglen = s->end - s->p;
+	pkglen = s_remaining(s);
 	/* str_handle_lines requires null terminated strings */
 	buf = xmalloc(pkglen + 1);
 	STRNCPY(buf, (char *) s->p, pkglen + 1);

secure.c

@@ -352,7 +352,7 @@ sec_send_to_channel(STREAM s, uint32 flags, uint16 channel)
 	if (flags & SEC_ENCRYPT)
 	{
 		flags &= ~SEC_ENCRYPT;
-		datalen = s->end - s->p - 8;
+		datalen = s_remaining(s) - 8;
 		sec_sign(s->p, 8, g_sec_sign_key, g_rc4_key_len, s->p + 8, datalen);
 		sec_encrypt(s->p + 8, datalen);
 	}
@@ -885,7 +885,7 @@ sec_recv(RD_BOOL * is_fastpath)
 				}
 
 				in_uint8s(s, 8);	/* signature */
-				sec_decrypt(s->p, s->end - s->p);
+				sec_decrypt(s->p, s_remaining(s));
 			}
 			return s;
 		}
@@ -905,7 +905,7 @@ sec_recv(RD_BOOL * is_fastpath)
 					}
 
 					in_uint8s(s, 8);	/* signature */
-					sec_decrypt(s->p, s->end - s->p);
+					sec_decrypt(s->p, s_remaining(s));
 				}
 
 				if (sec_flags & SEC_LICENSE_PKT)
@@ -923,7 +923,7 @@ sec_recv(RD_BOOL * is_fastpath)
 					}
 
 					in_uint8s(s, 8);	/* signature */
-					sec_decrypt(s->p, s->end - s->p);
+					sec_decrypt(s->p, s_remaining(s));
 
 					/* Check for a redirect packet, starts with 00 04 */
 					if (s->p[0] == 0 && s->p[1] == 4)

stream.h

@@ -60,7 +60,9 @@ size_t in_ansi_string(STREAM s, char *string, size_t len);
 #define s_push_layer(s,h,n)	{ (s)->h = (s)->p; (s)->p += n; }
 #define s_pop_layer(s,h)	(s)->p = (s)->h;
 #define s_mark_end(s)		(s)->end = (s)->p;
-#define s_check_rem(s,n)	(((s)->p <= (s)->end) && ((size_t)n <= (size_t)((s)->end - (s)->p)))
+/* Returns number of bytes that can still be read from STREAM */
+#define s_remaining(s)		(size_t)((s)->end - (s)->p)
+#define s_check_rem(s,n)	(((s)->p <= (s)->end) && ((size_t)n <= s_remaining(s)))
 #define s_check_end(s)		((s)->p == (s)->end)
 #define s_length(s)		((s)->end - (s)->data)
 #define s_left(s)		((s)->size - (size_t)((s)->p - (s)->data))