From a2991cc9c0092f0bab182971900a89442126581f Mon Sep 17 00:00:00 2001
From: LI Qing <geding.lq@antgroup.com>
Date: Thu, 14 Jul 2022 17:02:16 +0800
Subject: [PATCH] Add seek support for stdin and stdout

---
 src/libos/src/fs/stdio.rs | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/libos/src/fs/stdio.rs b/src/libos/src/fs/stdio.rs
index 66a26b8a..f11f6bc5 100644
--- a/src/libos/src/fs/stdio.rs
+++ b/src/libos/src/fs/stdio.rs
@@ -231,6 +231,16 @@ impl File for StdoutFile {
         Ok(())
     }
 
+    fn seek(&self, pos: SeekFrom) -> Result<off_t> {
+        let (off, whence) = match pos {
+            SeekFrom::Start(off) => (off as off_t, 0 /* SEEK_SET */),
+            SeekFrom::Current(off) => (off as off_t, 1 /* SEEK_CUR */),
+            SeekFrom::End(off) => (off as off_t, 2 /* SEEK_END */),
+        };
+        let offset = try_libc!(libc::ocall::lseek(self.host_fd() as i32, off, whence));
+        Ok(offset)
+    }
+
     fn as_any(&self) -> &dyn Any {
         self
     }
@@ -411,6 +421,16 @@ impl File for StdinFile {
         Ok(())
     }
 
+    fn seek(&self, pos: SeekFrom) -> Result<off_t> {
+        let (off, whence) = match pos {
+            SeekFrom::Start(off) => (off as off_t, 0 /* SEEK_SET */),
+            SeekFrom::Current(off) => (off as off_t, 1 /* SEEK_CUR */),
+            SeekFrom::End(off) => (off as off_t, 2 /* SEEK_END */),
+        };
+        let offset = try_libc!(libc::ocall::lseek(self.host_fd() as i32, off, whence));
+        Ok(offset)
+    }
+
     fn as_any(&self) -> &dyn Any {
         self
     }