fix: deep-copy audio buffers and add mutex to prevent race conditions in autosave

Co-authored-by: aider (deepseek/deepseek-coder) <aider@aider.chat>

wav_io.c

@@ -3,6 +3,9 @@
 #include <stdlib.h>
 #include <string.h>
 #include <stdint.h>
+#include <pthread.h>
+
+static pthread_mutex_t wav_io_mutex = PTHREAD_MUTEX_INITIALIZER;
 
 // WAV file header structures (little-endian)
 typedef struct {
@@ -55,8 +58,13 @@ static uint32_t read_le32(const unsigned char *buf) {
 int save_wav_float(const char *filename, const float *buffer, size_t num_samples, unsigned int sample_rate) {
     if (!filename || !buffer || num_samples == 0) return -1;
     
+    pthread_mutex_lock(&wav_io_mutex);
+    
     FILE *f = fopen(filename, "wb");
-    if (!f) return -1;
+    if (!f) {
+        pthread_mutex_unlock(&wav_io_mutex);
+        return -1;
+    }
     
     // Calculate sizes
     uint32_t data_size = (uint32_t)(num_samples * sizeof(float));
@@ -85,24 +93,32 @@ int save_wav_float(const char *filename, const float *buffer, size_t num_samples
     fwrite(buffer, sizeof(float), num_samples, f);
     
     fclose(f);
+    pthread_mutex_unlock(&wav_io_mutex);
     return 0;
 }
 
 int load_wav_float(const char *filename, float **buffer, size_t *num_samples, unsigned int *sample_rate) {
     if (!filename || !buffer || !num_samples || !sample_rate) return -1;
     
+    pthread_mutex_lock(&wav_io_mutex);
+    
     FILE *f = fopen(filename, "rb");
-    if (!f) return -1;
+    if (!f) {
+        pthread_mutex_unlock(&wav_io_mutex);
+        return -1;
+    }
     
     // Read RIFF header
     unsigned char header[12];
     if (fread(header, 1, 12, f) != 12) {
         fclose(f);
+        pthread_mutex_unlock(&wav_io_mutex);
         return -1;
     }
     
     if (memcmp(header, "RIFF", 4) != 0 || memcmp(header + 8, "WAVE", 4) != 0) {
         fclose(f);
+        pthread_mutex_unlock(&wav_io_mutex);
         return -1;
     }
     
@@ -143,6 +159,7 @@ int load_wav_float(const char *filename, float **buffer, size_t *num_samples, un
             data_buffer = (float *)calloc(num_frames, sizeof(float));
             if (!data_buffer) {
                 fclose(f);
+                pthread_mutex_unlock(&wav_io_mutex);
                 return -1;
             }
             
@@ -154,12 +171,14 @@ int load_wav_float(const char *filename, float **buffer, size_t *num_samples, un
                 if (!temp) {
                     free(data_buffer);
                     fclose(f);
+                    pthread_mutex_unlock(&wav_io_mutex);
                     return -1;
                 }
                 if (fread(temp, 1, read_size, f) != read_size) {
                     free(temp);
                     free(data_buffer);
                     fclose(f);
+                    pthread_mutex_unlock(&wav_io_mutex);
                     return -1;
                 }
                 // Mix to mono if stereo
@@ -183,12 +202,14 @@ int load_wav_float(const char *filename, float **buffer, size_t *num_samples, un
                 if (!temp) {
                     free(data_buffer);
                     fclose(f);
+                    pthread_mutex_unlock(&wav_io_mutex);
                     return -1;
                 }
                 if (fread(temp, 1, read_size, f) != read_size) {
                     free(temp);
                     free(data_buffer);
                     fclose(f);
+                    pthread_mutex_unlock(&wav_io_mutex);
                     return -1;
                 }
                 // Convert to float and mix to mono
@@ -210,6 +231,7 @@ int load_wav_float(const char *filename, float **buffer, size_t *num_samples, un
                 // Unsupported format
                 free(data_buffer);
                 fclose(f);
+                pthread_mutex_unlock(&wav_io_mutex);
                 return -1;
             }
             
@@ -217,6 +239,7 @@ int load_wav_float(const char *filename, float **buffer, size_t *num_samples, un
             *num_samples = num_frames;
             *sample_rate = sample_rate_val;
             fclose(f);
+            pthread_mutex_unlock(&wav_io_mutex);
             return 0;
         } else {
             // Skip unknown chunk
@@ -227,5 +250,6 @@ int load_wav_float(const char *filename, float **buffer, size_t *num_samples, un
     // If we get here, we didn't find data
     if (data_buffer) free(data_buffer);
     fclose(f);
+    pthread_mutex_unlock(&wav_io_mutex);
     return -1;
 }