From 547baa9ecd20510efd1331f248a0faf45646f05b Mon Sep 17 00:00:00 2001
From: Jiajie Chen <noc@jiegec.ac.cn>
Date: Sat, 23 Mar 2019 15:47:44 +0800
Subject: [PATCH] Implement symlink following

---
 kernel/Cargo.lock             | 4 ++--
 kernel/src/fs/mod.rs          | 2 ++
 kernel/src/process/structs.rs | 6 ++++--
 kernel/src/syscall/fs.rs      | 4 ++--
 kernel/src/syscall/proc.rs    | 4 ++--
 5 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/kernel/Cargo.lock b/kernel/Cargo.lock
index 02a7ef8..5fa45bd 100644
--- a/kernel/Cargo.lock
+++ b/kernel/Cargo.lock
@@ -338,12 +338,12 @@ dependencies = [
 [[package]]
 name = "rcore-fs"
 version = "0.1.0"
-source = "git+https://github.com/rcore-os/rcore-fs?branch=sefs#47df4e1cc97f061fa6eadf66eaacf774d22bb806"
+source = "git+https://github.com/rcore-os/rcore-fs?branch=sefs#c9322710b4ba67c086f500befb8208c6ae353493"
 
 [[package]]
 name = "rcore-fs-sfs"
 version = "0.1.0"
-source = "git+https://github.com/rcore-os/rcore-fs?branch=sefs#47df4e1cc97f061fa6eadf66eaacf774d22bb806"
+source = "git+https://github.com/rcore-os/rcore-fs?branch=sefs#c9322710b4ba67c086f500befb8208c6ae353493"
 dependencies = [
  "bitvec 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/kernel/src/fs/mod.rs b/kernel/src/fs/mod.rs
index 342871f..0fad557 100644
--- a/kernel/src/fs/mod.rs
+++ b/kernel/src/fs/mod.rs
@@ -56,6 +56,8 @@ lazy_static! {
     };
 }
 
+pub const FOLLOW_MAX_DEPTH: usize = 1;
+
 pub trait INodeExt {
     fn read_as_vec(&self) -> Result<Vec<u8>>;
 }
diff --git a/kernel/src/process/structs.rs b/kernel/src/process/structs.rs
index c3f06aa..9998bdd 100644
--- a/kernel/src/process/structs.rs
+++ b/kernel/src/process/structs.rs
@@ -6,11 +6,12 @@ use spin::{Mutex, RwLock};
 use xmas_elf::{ElfFile, header, program::{Flags, Type}};
 use rcore_memory::PAGE_SIZE;
 use rcore_thread::Tid;
+use rcore_fs::vfs::FileType;
 use core::str;
 
 use crate::arch::interrupt::{Context, TrapFrame};
 use crate::memory::{ByFrame, GlobalFrameAlloc, KernelStack, MemoryAttr, MemorySet};
-use crate::fs::{FileHandle, OpenOptions, INodeExt};
+use crate::fs::{FileHandle, OpenOptions, INodeExt, FOLLOW_MAX_DEPTH};
 use crate::sync::Condvar;
 use crate::net::{SocketWrapper, SOCKETS};
 
@@ -204,7 +205,8 @@ impl Thread {
             let size = interp.file_size() as usize - 1; // skip last '\0'
             if offset + size < data.len() {
                 if let Ok(loader_path) = str::from_utf8(&data[offset..(offset+size)]) {
-                    if let Ok(inode) = crate::fs::ROOT_INODE.lookup(&loader_path[1..]) {
+                    // assuming absolute path
+                    if let Ok(inode) = crate::fs::ROOT_INODE.lookup_follow(&loader_path[1..], FOLLOW_MAX_DEPTH) {
                         if let Ok(buf) = inode.read_as_vec() {
                             debug!("using loader {}", &loader_path);
                             // Elf loader should not have INTERP
diff --git a/kernel/src/syscall/fs.rs b/kernel/src/syscall/fs.rs
index f2863cd..055dd1d 100644
--- a/kernel/src/syscall/fs.rs
+++ b/kernel/src/syscall/fs.rs
@@ -683,12 +683,12 @@ impl Process {
         if path.len() > 0 && path.as_bytes()[0] == b'/' {
             // absolute path
             let abs_path = path.split_at(1).1; // skip start '/'
-            let inode = ROOT_INODE.lookup(abs_path)?;
+            let inode = ROOT_INODE.lookup_follow(abs_path, FOLLOW_MAX_DEPTH)?;
             Ok(inode)
         } else {
             // relative path
             let cwd = self.cwd.split_at(1).1; // skip start '/'
-            let inode = ROOT_INODE.lookup(cwd)?.lookup(path)?;
+            let inode = ROOT_INODE.lookup(cwd)?.lookup_follow(path, FOLLOW_MAX_DEPTH)?;
             Ok(inode)
         }
     }
diff --git a/kernel/src/syscall/proc.rs b/kernel/src/syscall/proc.rs
index 01cf63f..ed0ccfc 100644
--- a/kernel/src/syscall/proc.rs
+++ b/kernel/src/syscall/proc.rs
@@ -1,7 +1,7 @@
 //! Syscalls for process
 
 use super::*;
-use crate::fs::INodeExt;
+use crate::fs::{INodeExt, FOLLOW_MAX_DEPTH};
 
 /// Fork the current process. Return the child's PID.
 pub fn sys_fork(tf: &TrapFrame) -> SysResult {
@@ -120,7 +120,7 @@ pub fn sys_exec(name: *const u8, argv: *const *const u8, envp: *const *const u8,
 
     // Read program file
     let path = args[0].as_str();
-    let inode = crate::fs::ROOT_INODE.lookup(path)?;
+    let inode = crate::fs::ROOT_INODE.lookup_follow(path, FOLLOW_MAX_DEPTH)?;
     let buf = inode.read_as_vec()?;
 
     // Make new Thread