dsi_buffered_stream_read wasn't always reading the requested amount of bytes

diff --git a/libatalk/dsi/dsi_stream.c b/libatalk/dsi/dsi_stream.c
index b3581d2709ec51a007cee5185e813f98e0ef1e30..73e8ba41949aabf411dfcb69f7af4f4368a58f3d 100644 (file)
--- a/libatalk/dsi/dsi_stream.c
+++ b/libatalk/dsi/dsi_stream.c
@@ -235,8 +235,9 @@ ssize_t dsi_stream_read_file(DSI *dsi, int fromfd, off_t offset, const size_t le
 }
 #endif
 
-/* ---------------------------------
-*/
+/* 
+ * Return all bytes up to count from dsi->buffer if there are any buffered there
+ */
 static size_t from_buf(DSI *dsi, u_int8_t *buf, size_t count)
 {
     size_t nbe = 0;
@@ -257,6 +258,14 @@ static size_t from_buf(DSI *dsi, u_int8_t *buf, size_t count)
     return nbe;
 }
 
+/*
+ * Get bytes from buffer dsi->buffer or read from socket
+ *
+ * 1. Check if there are bytes in the the dsi->buffer buffer.
+ * 2. Return bytes from (1) if yes.
+ *    Note: this may return fewer bytes then requested in count !!
+ * 3. If the buffer was empty, read from the socket.
+ */
 static ssize_t buf_read(DSI *dsi, u_int8_t *buf, size_t count)
 {
     ssize_t nbe;
@@ -264,17 +273,16 @@ static ssize_t buf_read(DSI *dsi, u_int8_t *buf, size_t count)
     if (!count)
         return 0;
 
-    nbe = from_buf(dsi, buf, count);
+    nbe = from_buf(dsi, buf, count); /* 1. */
     if (nbe)
-        return nbe;
+        return nbe;             /* 2. */
   
-    return read(dsi->socket, buf, count);
-
+    return read(dsi->socket, buf, count); /* 3. */
 }
 
-/* ---------------------------------------
- * read raw data. return actual bytes read. this will wait until 
- * it gets length bytes 
+/*
+ * Essentially a loop around buf_read() to ensure "length" bytes are read
+ * from dsi->buffer and/or the socket.
  */
 size_t dsi_stream_read(DSI *dsi, void *data, const size_t length)
 {
@@ -301,9 +309,9 @@ size_t dsi_stream_read(DSI *dsi, void *data, const size_t length)
   return stored;
 }
 
-/* ---------------------------------------
- * read raw data. return actual bytes read. this will wait until 
- * it gets length bytes 
+/*
+ * Get "length" bytes from buffer and/or socket. In order to avoid frequent small reads
+ * this tries to read larger chunks (8192 bytes) into a buffer.
  */
 static size_t dsi_buffered_stream_read(DSI *dsi, u_int8_t *data, const size_t length)
 {
@@ -311,12 +319,13 @@ static size_t dsi_buffered_stream_read(DSI *dsi, u_int8_t *data, const size_t le
   size_t buflen;
   
   dsi_init_buffer(dsi);
-  len = from_buf(dsi, data, length);
+  len = from_buf(dsi, data, length); /* read from buffer dsi->buffer */
   dsi->read_count += len;
-  if (len == length) {
-      return len;
+  if (len == length) {          /* got enough bytes from there ? */
+      return len;               /* yes */
   }
-  
+
+  /* fill the buffer with 8192 bytes or until buffer is full */
   buflen = min(8192, dsi->end - dsi->eof);
   if (buflen > 0) {
       ssize_t ret;
@@ -324,7 +333,10 @@ static size_t dsi_buffered_stream_read(DSI *dsi, u_int8_t *data, const size_t le
       if (ret > 0)
           dsi->eof += ret;
   }
-  return dsi_stream_read(dsi, data, length -len);
+
+  /* now get the remaining data */
+  len += dsi_stream_read(dsi, data + len, length - len);
+  return len;
 }
 
 /* ---------------------------------------