From 77fdcba2c2662209bea69c214c32293fa7739f8c Mon Sep 17 00:00:00 2001
From: Eric <erlavigne@gmail.com>
Date: Fri, 30 Aug 2024 14:52:02 +0200
Subject: [PATCH] Fix a few bugs in buffers chaining management (particularly
 when buffer was full) and add a conditional mutex to protect from concurrent
 access

---
 src/buffer.c | 74 +++++++++++++++++++++++++++++-----------------------
 src/config.h |  4 +++
 2 files changed, 45 insertions(+), 33 deletions(-)

diff --git a/src/buffer.c b/src/buffer.c
index a0bf938..60945a2 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -6,6 +6,19 @@
 #include "utils.h"
 #include "buffer.h"
 
+#if BUFFER_USE_MUTEX
+# include <pthread.h>
+# define PEER_MUTEX_INIT(X)    static pthread_mutex_t X = PTHREAD_MUTEX_INITIALIZER
+# define PEER_MUTEX_LOCK(X)    pthread_mutex_lock(X)
+# define PEER_MUTEX_UNLOCK(X)  pthread_mutex_unlock(X)
+#else
+# define PEER_MUTEX_INIT(X)
+# define PEER_MUTEX_LOCK(X)
+# define PEER_MUTEX_UNLOCK(X)
+#endif
+
+PEER_MUTEX_INIT(g_buffer_mutex);
+
 Buffer* buffer_new(int size) {
 
   Buffer *rb;
@@ -20,100 +33,95 @@ Buffer* buffer_new(int size) {
 }
 
 void buffer_clear(Buffer *rb) {
-
-  rb->head = 0;
-  rb->tail = 0;
+  PEER_MUTEX_LOCK(&g_buffer_mutex);
+  if (rb) {
+    rb->head = 0;
+    rb->tail = 0;
+  }
+  PEER_MUTEX_UNLOCK(&g_buffer_mutex);
 }
 
 void buffer_free(Buffer *rb) {
-
+  PEER_MUTEX_LOCK(&g_buffer_mutex);
   if (rb) {
-
     free(rb->data);
     rb->data = NULL;
-    rb = NULL;
+    free(rb);  // Now properly freeing the buffer itself
   }
+  PEER_MUTEX_UNLOCK(&g_buffer_mutex);
 }
 
 int buffer_push_tail(Buffer *rb, const uint8_t *data, int size) {
+  PEER_MUTEX_LOCK(&g_buffer_mutex);
 
   int free_space = (rb->size + rb->head - rb->tail - 1) % rb->size;
-
   int align_size = ALIGN32(size + 4);
 
   if (align_size > free_space) {
     LOGE("no enough space");
+    PEER_MUTEX_UNLOCK(&g_buffer_mutex);
     return -1;
   }
 
   int tail_end = (rb->tail + align_size) % rb->size;
 
   if (tail_end < rb->tail) {
-
+    // Handle wrap-around
     if (rb->head < align_size) {
-
       LOGE("no enough space");
+      PEER_MUTEX_UNLOCK(&g_buffer_mutex);
       return -1;
     }
 
     int *p = (int*)(rb->data + rb->tail);
     *p = size;
-    memcpy(rb->data, data, size);    
-    rb->tail = size;
-
+    memcpy(rb->data + rb->tail + 4, data, rb->size - rb->tail - 4);
+    memcpy(rb->data, data + (rb->size - rb->tail - 4), tail_end);
   } else {
-
     int *p = (int*)(rb->data + rb->tail);
     *p = size;
     memcpy(rb->data + rb->tail + 4, data, size);
-    rb->tail = tail_end;
   }
 
+  rb->tail = tail_end;
+
+  PEER_MUTEX_UNLOCK(&g_buffer_mutex);
   return size;
 }
 
 uint8_t* buffer_peak_head(Buffer *rb, int *size) {
-
+  PEER_MUTEX_LOCK(&g_buffer_mutex);
   if (!rb || rb->head == rb->tail) {
-
+    (*size) = 0;
+    PEER_MUTEX_UNLOCK(&g_buffer_mutex);
     return NULL;
   }
 
   *size = *((int*)(rb->data + rb->head));
 
   int align_size = ALIGN32(*size + 4);
-
   int head_end = (rb->head + align_size) % rb->size;
 
-  if (head_end < rb->head) {
-
-    return rb->data;
+  PEER_MUTEX_UNLOCK(&g_buffer_mutex);
 
+  if (head_end < rb->head) {
+    return rb->data;  // Returns pointer to start of buffer in case of wrap-around
   } else {
-
     return rb->data + (rb->head + 4);
   }
 }
 
 void buffer_pop_head(Buffer *rb) {
+  PEER_MUTEX_LOCK(&g_buffer_mutex);
 
   if (!rb || rb->head == rb->tail) {
+    PEER_MUTEX_UNLOCK(&g_buffer_mutex);
     return;
   }
 
   int *size = (int*)(rb->data + rb->head);
-
   int align_size = ALIGN32(*size + 4);
+  rb->head = (rb->head + align_size) % rb->size;
 
-  int head_end = (rb->head + align_size) % rb->size;
-
-  if (head_end < rb->head) {
-
-    rb->head = *size;
-
-  } else {
-
-    rb->head = rb->head + align_size;
-  }
+  PEER_MUTEX_UNLOCK(&g_buffer_mutex);
 }
-
diff --git a/src/config.h b/src/config.h
index 1c6a0c2..06f0d3e 100644
--- a/src/config.h
+++ b/src/config.h
@@ -25,4 +25,8 @@
 //#define LOG_LEVEL LEVEL_DEBUG
 #define LOG_REDIRECT	0
 
+#ifndef BUFFER_USE_MUTEX
+#define BUFFER_USE_MUTEX  0
+#endif
+
 #endif // CONFIG_H_