check whether the audio data are still enough to play

reference: https://android.googlesource.com/platform/external/tinyalsa/+/8b7274b2ec686c87673bf39328381acbdea1a333

commit	8b7274b2ec686c87673bf39328381acbdea1a333
author	Haynes Mathew George <hgeorge@codeaurora.org>

tinyplay: play PCM up to size specified in the header

tinyplay plays to the end of file without checking whether playback
goes beyond end of data section which its size is specified in the
RIFF wave header. This could lead to playing out unwanted data which
is placed at the end of file.

authored-by: Patrick Lai <plai@codeaurora.org>

Change-Id: I17bd3f6ebca4813f8987585472208c1f52696cae

1 files changed, 10 insertions, 7 deletions

diff --git a/utils/tinyplay.c b/utils/tinyplay.c
index c006acc..f6762a0 100644
--- a/utils/tinyplay.c
+++ b/utils/tinyplay.c
@@ -389,13 +389,14 @@ int sample_is_playable(const struct cmd *cmd)
 int play_sample(struct ctx *ctx)
 {
     char *buffer;
-    int size;
-    int num_read;
+    size_t buffer_size = pcm_frames_to_bytes(ctx->pcm, pcm_get_buffer_size(ctx->pcm));
+    size_t num_read = 0;
+    size_t remaining_data_size = ctx->chunk_header.sz;
+    size_t read_size = 0;
 
-    size = pcm_frames_to_bytes(ctx->pcm, pcm_get_buffer_size(ctx->pcm));
-    buffer = malloc(size);
+    buffer = malloc(buffer_size);
     if (!buffer) {
-        fprintf(stderr, "unable to allocate %d bytes\n", size);
+        fprintf(stderr, "unable to allocate %zu bytes\n", buffer_size);
         return -1;
     }
 
@@ -403,15 +404,17 @@ int play_sample(struct ctx *ctx)
     signal(SIGINT, stream_close);
 
     do {
-        num_read = fread(buffer, 1, size, ctx->file);
+        read_size = remaining_data_size > buffer_size ? buffer_size : remaining_data_size;
+        num_read = fread(buffer, 1, read_size, ctx->file);
         if (num_read > 0) {
             if (pcm_writei(ctx->pcm, buffer,
                 pcm_bytes_to_frames(ctx->pcm, num_read)) < 0) {
                 fprintf(stderr, "error playing sample\n");
                 break;
             }
+            remaining_data_size -= num_read;
         }
-    } while (!close && num_read > 0);
+    } while (!close && num_read > 0 && remaining_data_size > 0);
 
     pcm_wait(ctx->pcm, -1);