Fix out of bound access in src_linear

Fix #208 about out of bount access in linear resampler.

Also migrates to count the sumber of frames instead of the number of
samples and remove some redundant member of the private state.

Signed-off-by: Lionel Koenig Gélas <[email protected]>

Author: lkoenig

src/src_linear.c

@@ -32,9 +32,7 @@ static void linear_close (SRC_STATE *state) ;
 
 typedef struct
 {	int		linear_magic_marker ;
-	bool	dirty ;
-	long	in_count, in_used ;
-	long	out_count, out_gen ;
+	bool	initialized ;
 	float	*last_value ;
 } LINEAR_DATA ;
 
@@ -54,7 +52,6 @@ static SRC_ERROR
 linear_vari_process (SRC_STATE *state, SRC_DATA *data)
 {	LINEAR_DATA *priv ;
 	double		src_ratio, input_index, rem ;
-	int			ch ;
 
 	if (data->input_frames <= 0)
 		return SRC_ERR_NO_ERROR ;
@@ -64,16 +61,14 @@ linear_vari_process (SRC_STATE *state, SRC_DATA *data)
 
 	priv = (LINEAR_DATA*) state->private_data ;
 
-	if (!priv->dirty)
+	if (!priv->initialized)
 	{	/* If we have just been reset, set the last_value data. */
-		for (ch = 0 ; ch < state->channels ; ch++)
+		for (int ch = 0 ; ch < state->channels ; ch++)
 			priv->last_value [ch] = data->data_in [ch] ;
-		priv->dirty = true ;
+		priv->initialized = true ;
 		} ;
 
-	priv->in_count = data->input_frames * state->channels ;
-	priv->out_count = data->output_frames * state->channels ;
-	priv->in_used = priv->out_gen = 0 ;
+	data->input_frames_used = data->output_frames_gen = 0 ;
 
 	src_ratio = state->last_ratio ;
 
@@ -83,72 +78,70 @@ linear_vari_process (SRC_STATE *state, SRC_DATA *data)
 	input_index = state->last_position ;
 
 	/* Calculate samples before first sample in input array. */
-	while (input_index < 1.0 && priv->out_gen < priv->out_count)
+	float* current_out = data->data_out;
+	while (input_index < 1.0 && data->output_frames_gen < data->output_frames)
 	{
-		if (priv->in_used + state->channels * (1.0 + input_index) >= priv->in_count)
-			break ;
+		if (data->output_frames > 0 && fabs (state->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
+			src_ratio = state->last_ratio + data->output_frames_gen * (data->src_ratio - state->last_ratio) / data->output_frames ;
 
-		if (priv->out_count > 0 && fabs (state->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
-			src_ratio = state->last_ratio + priv->out_gen * (data->src_ratio - state->last_ratio) / priv->out_count ;
-
-		for (ch = 0 ; ch < state->channels ; ch++)
-		{	data->data_out [priv->out_gen] = (float) (priv->last_value [ch] + input_index *
+		for (int ch = 0 ; ch < state->channels ; ch++)
+		{	*current_out++ = (float) (priv->last_value [ch] + input_index *
 										((double) data->data_in [ch] - priv->last_value [ch])) ;
-			priv->out_gen ++ ;
 			} ;
+		data->output_frames_gen ++ ;
 
 		/* Figure out the next index. */
 		input_index += 1.0 / src_ratio ;
 		} ;
 
 	rem = fmod_one (input_index) ;
-	priv->in_used += state->channels * psf_lrint (input_index - rem) ;
+	data->input_frames_used += psf_lrint (input_index - rem) ;
 	input_index = rem ;
 
 	/* Main processing loop. */
-	while (priv->out_gen < priv->out_count && priv->in_used + state->channels * input_index < priv->in_count)
-	{
-		if (priv->out_count > 0 && fabs (state->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
-			src_ratio = state->last_ratio + priv->out_gen * (data->src_ratio - state->last_ratio) / priv->out_count ;
-
 #if SRC_DEBUG
-		if (priv->in_used < state->channels && input_index < 1.0)
-		{	printf ("Whoops!!!!   in_used : %ld     channels : %d     input_index : %f\n", priv->in_used, state->channels, input_index) ;
-			exit (1) ;
-			} ;
+	assert(data->output_frames_gen >= data->output_frames || data->input_frames_used > 0);
 #endif
+	while (data->output_frames_gen < data->output_frames && data->input_frames_used + input_index < data->input_frames)
+	{
+		if (data->output_frames > 0 && fabs (state->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
+			src_ratio = state->last_ratio + data->output_frames_gen * (data->src_ratio - state->last_ratio) / data->output_frames ;
 
-		for (ch = 0 ; ch < state->channels ; ch++)
-		{	data->data_out [priv->out_gen] = (float) (data->data_in [priv->in_used - state->channels + ch] + input_index *
-						((double) data->data_in [priv->in_used + ch] - data->data_in [priv->in_used - state->channels + ch])) ;
-			priv->out_gen ++ ;
-			} ;
+		const float* current_in = data->data_in + data->input_frames_used * state->channels;
+		const float* prev_in = current_in - state->channels;
+		for (int ch = 0 ; ch < state->channels ; ch++)
+		{
+		  *current_out++ = (float) (prev_in[ch] + input_index *
+						((double) current_in[ch] - prev_in[ch])) ;
+		}
+		data->output_frames_gen ++ ;
 
 		/* Figure out the next index. */
 		input_index += 1.0 / src_ratio ;
 		rem = fmod_one (input_index) ;
 
-		priv->in_used += state->channels * psf_lrint (input_index - rem) ;
+		const int num_frame_used = psf_lrint (input_index - rem);
+		data->input_frames_used += num_frame_used ;
 		input_index = rem ;
-		} ;
+        }
 
-	if (priv->in_used > priv->in_count)
-	{	input_index += (priv->in_used - priv->in_count) / state->channels ;
-		priv->in_used = priv->in_count ;
-		} ;
+	if (data->input_frames_used > data->input_frames)
+	{
+          input_index += (data->input_frames_used - data->input_frames) ;
+          data->input_frames_used = data->input_frames ;
+        }
 
 	state->last_position = input_index ;
 
-	if (priv->in_used > 0)
-		for (ch = 0 ; ch < state->channels ; ch++)
-			priv->last_value [ch] = data->data_in [priv->in_used - state->channels + ch] ;
+	if (data->input_frames_used > 0) {
+          const float *last_value = data->data_in + (data->input_frames_used - 1) * state->channels;
+          for (int ch = 0 ; ch < state->channels ; ch++)
+            priv->last_value [ch] = last_value[ch];
+        }
 
 	/* Save current ratio rather then target ratio. */
 	state->last_ratio = src_ratio ;
 
-	data->input_frames_used = priv->in_used / state->channels ;
-	data->output_frames_gen = priv->out_gen / state->channels ;
-
 	return SRC_ERR_NO_ERROR ;
 } /* linear_vari_process */
 
@@ -237,7 +230,7 @@ linear_reset (SRC_STATE *state)
 	if (priv == NULL)
 		return ;
 
-	priv->dirty = false ;
+	priv->initialized = false ;
 	memset (priv->last_value, 0, sizeof (priv->last_value [0]) * state->channels) ;
 
 	return ;