drivers/pipes: Add offset support for PIPEIOC_PEEK

Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>

drivers/pipes/pipe_common.c

@@ -846,7 +846,9 @@ int pipecommon_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
 
           DEBUGASSERT(peek && peek->buf);
 
-          ret = circbuf_peek(&dev->d_buffer, peek->buf, peek->size);
+          ret = circbuf_peekat(&dev->d_buffer,
+                               dev->d_buffer.tail + peek->offset,
+                               peek->buf, peek->size);
         }
         break;
 

include/nuttx/fs/ioctl.h

@@ -717,6 +717,7 @@
 struct pipe_peek_s
 {
   FAR void *buf;
+  size_t offset;
   size_t size;
 };