From ec8bd8116d4683ae51897e8e49c62823bfdd9005 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?kleines=20Filmr=C3=B6llchen?= <malu.bertsch@gmail.com>
Date: Sun, 3 Oct 2021 16:35:07 +0200
Subject: [PATCH] LibAudio: Buffer API improvements

This consists of two changes: First, a utility function create_empty
allows the user to quickly create an empty buffer. Second, most creation
functions now return a NonnullRefPtr, as their failure causes a VERIFY
crash anyways.
---
 Userland/Libraries/LibAudio/Buffer.cpp |  4 ++--
 Userland/Libraries/LibAudio/Buffer.h   | 12 +++++++++---
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/Userland/Libraries/LibAudio/Buffer.cpp b/Userland/Libraries/LibAudio/Buffer.cpp
index a88c20184e..c58cfa5f72 100644
--- a/Userland/Libraries/LibAudio/Buffer.cpp
+++ b/Userland/Libraries/LibAudio/Buffer.cpp
@@ -122,13 +122,13 @@ static double read_norm_sample_8(InputMemoryStream& stream)
     return double(sample) / NumericLimits<u8>::max();
 }
 
-RefPtr<Buffer> Buffer::from_pcm_data(ReadonlyBytes data, int num_channels, PcmSampleFormat sample_format)
+NonnullRefPtr<Buffer> Buffer::from_pcm_data(ReadonlyBytes data, int num_channels, PcmSampleFormat sample_format)
 {
     InputMemoryStream stream { data };
     return from_pcm_stream(stream, num_channels, sample_format, data.size() / (pcm_bits_per_sample(sample_format) / 8));
 }
 
-RefPtr<Buffer> Buffer::from_pcm_stream(InputMemoryStream& stream, int num_channels, PcmSampleFormat sample_format, int num_samples)
+NonnullRefPtr<Buffer> Buffer::from_pcm_stream(InputMemoryStream& stream, int num_channels, PcmSampleFormat sample_format, int num_samples)
 {
     Vector<Sample> fdata;
     fdata.ensure_capacity(num_samples);
diff --git a/Userland/Libraries/LibAudio/Buffer.h b/Userland/Libraries/LibAudio/Buffer.h
index dbc08814e6..8f9e8457af 100644
--- a/Userland/Libraries/LibAudio/Buffer.h
+++ b/Userland/Libraries/LibAudio/Buffer.h
@@ -67,8 +67,8 @@ private:
 // A buffer of audio samples.
 class Buffer : public RefCounted<Buffer> {
 public:
-    static RefPtr<Buffer> from_pcm_data(ReadonlyBytes data, int num_channels, PcmSampleFormat sample_format);
-    static RefPtr<Buffer> from_pcm_stream(InputMemoryStream& stream, int num_channels, PcmSampleFormat sample_format, int num_samples);
+    static NonnullRefPtr<Buffer> from_pcm_data(ReadonlyBytes data, int num_channels, PcmSampleFormat sample_format);
+    static NonnullRefPtr<Buffer> from_pcm_stream(InputMemoryStream& stream, int num_channels, PcmSampleFormat sample_format, int num_samples);
     static NonnullRefPtr<Buffer> create_with_samples(Vector<Sample>&& samples)
     {
         return adopt_ref(*new Buffer(move(samples)));
@@ -77,6 +77,10 @@ public:
     {
         return adopt_ref(*new Buffer(move(buffer), buffer_id, sample_count));
     }
+    static NonnullRefPtr<Buffer> create_empty()
+    {
+        return adopt_ref(*new Buffer({}));
+    }
 
     const Sample* samples() const { return (const Sample*)data(); }
     int sample_count() const { return m_sample_count; }
@@ -87,7 +91,9 @@ public:
 
 private:
     explicit Buffer(const Vector<Sample> samples)
-        : m_buffer(Core::AnonymousBuffer::create_with_size(samples.size() * sizeof(Sample)).release_value())
+        // FIXME: AnonymousBuffers can't be empty, so even for empty buffers we create a buffer of size 1 here,
+        //        although the sample count is set to 0 to mark this.
+        : m_buffer(Core::AnonymousBuffer::create_with_size(max(samples.size(), 1) * sizeof(Sample)).release_value())
         , m_id(allocate_id())
         , m_sample_count(samples.size())
     {