From 4e146ec491a6dbcf7b89b7a6c8d3003722281be3 Mon Sep 17 00:00:00 2001
From: WangRunji <wangrunji0408@163.com>
Date: Tue, 26 Feb 2019 17:01:38 +0800
Subject: [PATCH] impl sys_lseek

---
 kernel/src/fs/file.rs     | 28 ++++++++++++++++++++++------
 kernel/src/syscall/fs.rs  | 21 ++++++++++++++++++++-
 kernel/src/syscall/mod.rs |  2 +-
 3 files changed, 43 insertions(+), 8 deletions(-)

diff --git a/kernel/src/fs/file.rs b/kernel/src/fs/file.rs
index 6a0cb246..6efa7c3c 100644
--- a/kernel/src/fs/file.rs
+++ b/kernel/src/fs/file.rs
@@ -7,7 +7,7 @@ use rcore_fs::vfs::{Metadata, INode, Result, FsError};
 #[derive(Clone)]
 pub struct FileHandle {
     inode: Arc<INode>,
-    offset: usize,
+    offset: u64,
     options: OpenOptions,
 }
 
@@ -19,6 +19,13 @@ pub struct OpenOptions {
     pub append: bool,
 }
 
+#[derive(Debug)]
+pub enum SeekFrom {
+    Start(u64),
+    End(i64),
+    Current(i64),
+}
+
 impl FileHandle {
     pub fn new(inode: Arc<INode>, options: OpenOptions) -> Self {
         FileHandle {
@@ -32,8 +39,8 @@ impl FileHandle {
         if !self.options.read {
             return Err(FsError::InvalidParam);  // FIXME: => EBADF
         }
-        let len = self.inode.read_at(self.offset, buf)?;
-        self.offset += len;
+        let len = self.inode.read_at(self.offset as usize, buf)?;
+        self.offset += len as u64;
         Ok(len)
     }
 
@@ -43,13 +50,22 @@ impl FileHandle {
         }
         if self.options.append {
             let info = self.inode.metadata()?;
-            self.offset = info.size;
+            self.offset = info.size as u64;
         }
-        let len = self.inode.write_at(self.offset, buf)?;
-        self.offset += len;
+        let len = self.inode.write_at(self.offset as usize, buf)?;
+        self.offset += len as u64;
         Ok(len)
     }
 
+    pub fn seek(&mut self, pos: SeekFrom) -> Result<u64> {
+        self.offset = match pos {
+            SeekFrom::Start(offset) => offset,
+            SeekFrom::End(offset) => (self.inode.metadata()?.size as i64 + offset) as u64,
+            SeekFrom::Current(offset) => (self.offset as i64 + offset) as u64,
+        };
+        Ok(self.offset)
+    }
+
     pub fn info(&self) -> Result<Metadata> {
         self.inode.metadata()
     }
diff --git a/kernel/src/syscall/fs.rs b/kernel/src/syscall/fs.rs
index ea41ac4f..1934a730 100644
--- a/kernel/src/syscall/fs.rs
+++ b/kernel/src/syscall/fs.rs
@@ -2,7 +2,7 @@
 
 use super::*;
 
-use crate::fs::{ROOT_INODE, OpenOptions};
+use crate::fs::*;
 use rcore_fs::vfs::Timespec;
 
 pub fn sys_read(fd: usize, base: *mut u8, len: usize) -> SysResult {
@@ -89,6 +89,21 @@ pub fn sys_fstat(fd: usize, stat_ptr: *mut Stat) -> SysResult {
     Ok(0)
 }
 
+pub fn sys_lseek(fd: usize, offset: i64, whence: u8) -> SysResult {
+    let pos = match whence {
+        SEEK_SET => SeekFrom::Start(offset as u64),
+        SEEK_END => SeekFrom::End(offset),
+        SEEK_CUR => SeekFrom::Current(offset),
+        _ => return Err(SysError::Inval),
+    };
+    info!("lseek: fd: {}, pos: {:?}", fd, pos);
+
+    let mut proc = process();
+    let file = get_file(&mut proc, fd)?;
+    let offset = file.seek(pos)?;
+    Ok(offset as isize)
+}
+
 /// entry_id = dentry.offset / 256
 /// dentry.name = entry_name
 /// dentry.offset += 256
@@ -309,3 +324,7 @@ impl From<Metadata> for Stat {
         }
     }
 }
+
+const SEEK_SET: u8 = 1;
+const SEEK_CUR: u8 = 2;
+const SEEK_END: u8 = 4;
diff --git a/kernel/src/syscall/mod.rs b/kernel/src/syscall/mod.rs
index 6998e4c7..ff45f709 100644
--- a/kernel/src/syscall/mod.rs
+++ b/kernel/src/syscall/mod.rs
@@ -36,7 +36,7 @@ pub fn syscall(id: usize, args: [usize; 6], tf: &mut TrapFrame) -> isize {
 //        004 => sys_stat(),
         005 => sys_fstat(args[0], args[1] as *mut Stat),
 //        007 => sys_poll(),
-//        008 => sys_lseek(),
+        008 => sys_lseek(args[0], args[1] as i64, args[2] as u8),
         009 => sys_mmap(args[0], args[1], MmapProt::from_bits_truncate(args[2]), MmapFlags::from_bits_truncate(args[3]), args[4] as i32, args[5]),
         011 => sys_munmap(args[0], args[1]),
 //        019 => sys_readv(),