Initial support for application specific overrides.

tests/ninjam_null_audio.c

@@ -0,0 +1,35 @@
+/* Copyright (c) 2026 Storm Dragon
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ * Test-only preload for cninjam configured with ALSA null input/output at 48kHz.
+ * Null capture is not clocked and need not initialize its buffer. Supply silence
+ * and real-time pacing without accessing a microphone or playback device.
+ */
+#define _GNU_SOURCE
+#include <alsa/asoundlib.h>
+#include <dlfcn.h>
+#include <errno.h>
+#include <pthread.h>
+#include <string.h>
+#include <time.h>
+
+static pthread_once_t readOnce = PTHREAD_ONCE_INIT;
+static snd_pcm_sframes_t (*realRead)(snd_pcm_t *, void *, snd_pcm_uframes_t);
+
+static void resolve_read(void) {
+    *(void **)(&realRead) = dlsym(RTLD_NEXT, "snd_pcm_readi");
+}
+
+snd_pcm_sframes_t snd_pcm_readi(snd_pcm_t *pcm, void *buffer, snd_pcm_uframes_t frames) {
+    pthread_once(&readOnce, resolve_read);
+    if (!realRead) return -ENOSYS;
+    snd_pcm_sframes_t count = realRead(pcm, buffer, frames);
+    if (count > 0) {
+        memset(buffer, 0, snd_pcm_frames_to_bytes(pcm, count));
+        struct timespec delay = {
+            .tv_sec = count / 48000,
+            .tv_nsec = (count % 48000) * 1000000000LL / 48000,
+        };
+        while (nanosleep(&delay, &delay) < 0 && errno == EINTR) {}
+    }
+    return count;
+}