From d7e266d0e3a2f3fc242bbd963a8569ebb8375bfa Mon Sep 17 00:00:00 2001
From: "Tate, Hongliang Tian" <tatetian@gmail.com>
Date: Tue, 9 Apr 2019 23:01:10 +0800
Subject: [PATCH] Add access and faccessat

---
 src/libos/src/fs/access.rs   | 52 ++++++++++++++++++++++++++++++++++++
 src/libos/src/fs/mod.rs      |  2 ++
 src/libos/src/syscall/mod.rs | 25 +++++++++++++++--
 test/truncate/main.c         |  5 ++++
 4 files changed, 82 insertions(+), 2 deletions(-)
 create mode 100644 src/libos/src/fs/access.rs

diff --git a/src/libos/src/fs/access.rs b/src/libos/src/fs/access.rs
new file mode 100644
index 00000000..e2910a73
--- /dev/null
+++ b/src/libos/src/fs/access.rs
@@ -0,0 +1,52 @@
+use super::*;
+
+//int faccessat(int dirfd, const char *pathname, int mode, int flags);
+//int access(const char *pathname, int mode);
+
+bitflags! {
+    pub struct AccessModes : u32 {
+        const X_OK = 1;
+        const W_OK = 2;
+        const R_OK = 4;
+    }
+}
+
+impl AccessModes {
+    pub fn from_u32(bits: u32) -> Result<AccessModes, Error> {
+        AccessModes::from_bits(bits).ok_or_else(|| Error::new(Errno::EINVAL, "invalid mode"))
+    }
+}
+
+
+bitflags! {
+    pub struct AccessFlags : u32 {
+        const AT_SYMLINK_NOFOLLOW = 0x100;
+        const AT_EACCESS          = 0x200;
+    }
+}
+
+impl AccessFlags {
+    pub fn from_u32(bits: u32) -> Result<AccessFlags, Error> {
+        AccessFlags::from_bits(bits).ok_or_else(|| Error::new(Errno::EINVAL, "invalid flags"))
+    }
+}
+
+
+pub const AT_FDCWD : i32 = -100;
+
+pub fn do_faccessat(dirfd: Option<FileDesc>, path: &str, mode: AccessModes, flags: AccessFlags) -> Result<(), Error> {
+    match dirfd {
+        // TODO: handle dirfd
+        Some(dirfd) => errno!(ENOSYS, "cannot accept dirfd"),
+        None => do_access(path, mode),
+    }
+}
+
+pub fn do_access(path: &str, mode: AccessModes) -> Result<(), Error> {
+    let current_ref = process::get_current();
+    let mut current = current_ref.lock().unwrap();
+    let inode = current.lookup_inode(path)?;
+    //let metadata = inode.get_metadata();
+    // TODO: check metadata.mode with mode
+    Ok(())
+}
diff --git a/src/libos/src/fs/mod.rs b/src/libos/src/fs/mod.rs
index 162f7062..8142f23a 100644
--- a/src/libos/src/fs/mod.rs
+++ b/src/libos/src/fs/mod.rs
@@ -11,12 +11,14 @@ pub use self::file_table::{FileDesc, FileTable};
 pub use self::inode_file::{INodeExt, INodeFile, ROOT_INODE};
 use self::inode_file::OpenOptions;
 pub use self::pipe::Pipe;
+pub use self::access::{AccessModes, AccessFlags, AT_FDCWD, do_access, do_faccessat};
 
 mod file;
 mod file_table;
 mod inode_file;
 mod pipe;
 mod sgx_impl;
+mod access;
 
 // TODO: use the type defined in Rust libc.
 //
diff --git a/src/libos/src/syscall/mod.rs b/src/libos/src/syscall/mod.rs
index 1e642086..af0319a3 100644
--- a/src/libos/src/syscall/mod.rs
+++ b/src/libos/src/syscall/mod.rs
@@ -1,6 +1,5 @@
 use {fs, process, std, vm};
-use fs::{FileDesc, off_t};
-use fs::File;
+use fs::{File, FileDesc, off_t, AccessModes, AccessFlags, AT_FDCWD};
 use prelude::*;
 use process::{ChildProcessFilter, FileAction, pid_t, CloneFlags, FutexFlags, FutexOp};
 use std::ffi::{CStr, CString};
@@ -57,6 +56,8 @@ pub extern "C" fn dispatch_syscall(
         SYS_STAT => do_stat(arg0 as *const i8, arg1 as *mut fs::Stat),
         SYS_FSTAT => do_fstat(arg0 as FileDesc, arg1 as *mut fs::Stat),
         SYS_LSTAT => do_lstat(arg0 as *const i8, arg1 as *mut fs::Stat),
+        SYS_ACCESS => do_access(arg0 as *const i8, arg1 as u32),
+        SYS_FACCESSAT => do_faccessat(arg0 as i32, arg1 as *const i8, arg2 as u32, arg3 as u32),
         SYS_LSEEK => do_lseek(arg0 as FileDesc, arg1 as off_t, arg2 as i32),
         SYS_FSYNC => do_fsync(arg0 as FileDesc),
         SYS_FDATASYNC => do_fdatasync(arg0 as FileDesc),
@@ -730,3 +731,23 @@ fn do_prlimit(pid: pid_t, resource: u32, new_limit: *const rlimit_t, old_limit:
     };
     misc::do_prlimit(pid, resource, new_limit, old_limit).map(|_| 0)
 }
+
+fn do_access(path: *const i8, mode: u32) -> Result<isize, Error> {
+    let path = clone_cstring_safely(path)?.to_string_lossy().into_owned();
+    let mode = AccessModes::from_u32(mode)?;
+    fs::do_access(&path, mode).map(|_| 0)
+}
+
+fn do_faccessat(dirfd: i32, path: *const i8, mode: u32, flags: u32) -> Result<isize, Error> {
+    let dirfd = if dirfd >= 0 {
+        Some(dirfd as FileDesc)
+    } else if dirfd == AT_FDCWD {
+        None
+    } else {
+        return errno!(EINVAL, "invalid dirfd");
+    };
+    let path = clone_cstring_safely(path)?.to_string_lossy().into_owned();
+    let mode = AccessModes::from_u32(mode)?;
+    let flags = AccessFlags::from_u32(flags)?;
+    fs::do_faccessat(dirfd, &path, mode, flags).map(|_| 0)
+}
diff --git a/test/truncate/main.c b/test/truncate/main.c
index 021fe3a8..36a3d45a 100644
--- a/test/truncate/main.c
+++ b/test/truncate/main.c
@@ -21,6 +21,11 @@ int main(int argc, const char* argv[]) {
         return fd;
     }
 
+    if (access(FILE_NAME, F_OK) < 0) {
+        printf("cannot access the new file\n");
+        return -1;
+    }
+
     ret = ftruncate(fd, TRUNC_LEN);
     if (ret < 0) {
         printf("failed to ftruncate the file\n");