Merge pull request #125 from yunwei37/master

Improve docs for `linux-syscall` and fix "uname" command

linux-syscall/src/file/dir.rs

@@ -16,6 +16,10 @@ use kernel_hal::user::UserOutPtr;
 use linux_object::fs::vfs::FileType;
 
 impl Syscall<'_> {
+    /// return a null-terminated string containing an absolute pathname
+    /// that is the current working directory of the calling process.
+    /// - `buf` – pointer to buffer to receive path
+    /// - `len` – size of buf
     pub fn sys_getcwd(&self, mut buf: UserOutPtr<u8>, len: usize) -> SysResult {
         info!("getcwd: buf={:?}, len={:#x}", buf, len);
         let proc = self.linux_process();
@@ -27,6 +31,8 @@ impl Syscall<'_> {
         Ok(buf.as_ptr() as usize)
     }
 
+    /// Change the current directory.
+    /// - `path` – pointer to string with name of path
     pub fn sys_chdir(&self, path: UserInPtr<u8>) -> SysResult {
         let path = path.read_cstring()?;
         info!("chdir: path={:?}", path);
@@ -41,10 +47,14 @@ impl Syscall<'_> {
         Ok(0)
     }
 
+    /// Make a directory.
+    /// - path – pointer to string with directory name
+    /// - mode – file system permissions mode
     pub fn sys_mkdir(&self, path: UserInPtr<u8>, mode: usize) -> SysResult {
         self.sys_mkdirat(FileDesc::CWD, path, mode)
     }
 
+    /// create directory relative to directory file descriptor
     pub fn sys_mkdirat(&self, dirfd: FileDesc, path: UserInPtr<u8>, mode: usize) -> SysResult {
         let path = path.read_cstring()?;
         // TODO: check pathname
@@ -62,7 +72,8 @@ impl Syscall<'_> {
         inode.create(file_name, FileType::Dir, mode as u32)?;
         Ok(0)
     }
-
+    /// Remove a directory.
+    /// - path – pointer to string with directory name
     pub fn sys_rmdir(&self, path: UserInPtr<u8>) -> SysResult {
         let path = path.read_cstring()?;
         info!("rmdir: path={:?}", path);
@@ -78,6 +89,9 @@ impl Syscall<'_> {
         Ok(0)
     }
 
+    /// get directory entries
+    /// TODO: get ino from dirent
+    /// - fd – file describe
     pub fn sys_getdents64(
         &self,
         fd: FileDesc,
@@ -111,10 +125,14 @@ impl Syscall<'_> {
         Ok(writer.written_size)
     }
 
+    /// creates a new link (also known as a hard link) to an existing file.
     pub fn sys_link(&self, oldpath: UserInPtr<u8>, newpath: UserInPtr<u8>) -> SysResult {
         self.sys_linkat(FileDesc::CWD, oldpath, FileDesc::CWD, newpath, 0)
     }
 
+    /// create file link relative to directory file descriptors
+    /// If the pathname given in oldpath is relative,
+    /// then it is interpreted relative to the directory referred to by the file descriptor olddirfd
     pub fn sys_linkat(
         &self,
         olddirfd: FileDesc,
@@ -139,10 +157,16 @@ impl Syscall<'_> {
         Ok(0)
     }
 
+    /// delete name/possibly file it refers to
+    /// If that name was the last link to a file and no processes have the file open, the file is deleted.
+    /// If the name was the last link to a file but any processes still have the file open,
+    /// the file will remain in existence until the last file descriptor referring to it is closed.
     pub fn sys_unlink(&self, path: UserInPtr<u8>) -> SysResult {
         self.sys_unlinkat(FileDesc::CWD, path, 0)
     }
 
+    /// remove directory entry relative to directory file descriptor
+    /// The unlinkat() system call operates in exactly the same way as either unlink or rmdir.
     pub fn sys_unlinkat(&self, dirfd: FileDesc, path: UserInPtr<u8>, flags: usize) -> SysResult {
         let path = path.read_cstring()?;
         let flags = AtFlags::from_bits_truncate(flags);
@@ -162,10 +186,12 @@ impl Syscall<'_> {
         Ok(0)
     }
 
+    /// change name/location of file
     pub fn sys_rename(&self, oldpath: UserInPtr<u8>, newpath: UserInPtr<u8>) -> SysResult {
         self.sys_renameat(FileDesc::CWD, oldpath, FileDesc::CWD, newpath)
     }
 
+    /// rename file relative to directory file descriptors
     pub fn sys_renameat(
         &self,
         olddirfd: FileDesc,
@@ -189,10 +215,14 @@ impl Syscall<'_> {
         Ok(0)
     }
 
+    /// read value of symbolic link
     pub fn sys_readlink(&self, path: UserInPtr<u8>, base: UserOutPtr<u8>, len: usize) -> SysResult {
         self.sys_readlinkat(FileDesc::CWD, path, base, len)
     }
 
+    /// read value of symbolic link relative to directory file descriptor
+    /// readlink() places the contents of the symbolic link path in the buffer base, which has size len
+    /// TODO: recursive link resolution and loop detection
     pub fn sys_readlinkat(
         &self,
         dirfd: FileDesc,
@@ -234,13 +264,15 @@ pub struct LinuxDirent64 {
     name: [u8; 0],
 }
 
+/// directory entry buffer writer
 struct DirentBufWriter<'a> {
     buf: &'a mut [u8],
     rest_size: usize,
     written_size: usize,
 }
 
 impl<'a> DirentBufWriter<'a> {
+    /// create a buffer writer
     fn new(buf: &'a mut [u8]) -> Self {
         DirentBufWriter {
             rest_size: buf.len(),
@@ -249,6 +281,7 @@ impl<'a> DirentBufWriter<'a> {
         }
     }
 
+    /// write data
     fn try_write(&mut self, inode: u64, type_: u8, name: &str) -> bool {
         let len = core::mem::size_of::<LinuxDirent64>() + name.len() + 1;
         let len = (len + 7) / 8 * 8; // align up
@@ -275,6 +308,7 @@ impl<'a> DirentBufWriter<'a> {
         true
     }
 
+    /// to slice
     fn as_slice(&self) -> &[u8] {
         &self.buf[..self.written_size]
     }

linux-syscall/src/file/fd.rs

@@ -8,10 +8,12 @@
 use super::*;
 
 impl Syscall<'_> {
+    /// Opens or creates a file, depending on the flags passed to the call. Returns an integer with the file descriptor.
     pub fn sys_open(&self, path: UserInPtr<u8>, flags: usize, mode: usize) -> SysResult {
         self.sys_openat(FileDesc::CWD, path, flags, mode)
     }
 
+    /// open file relative to directory file descriptor
     pub fn sys_openat(
         &self,
         dir_fd: FileDesc,
@@ -52,13 +54,15 @@ impl Syscall<'_> {
         Ok(fd.into())
     }
 
+    /// Closes a file descriptor, so that it no longer refers to any file and may be reused.
     pub fn sys_close(&self, fd: FileDesc) -> SysResult {
         info!("close: fd={:?}", fd);
         let proc = self.linux_process();
         proc.close_file(fd)?;
         Ok(0)
     }
 
+    /// create a copy of the file descriptor oldfd.
     pub fn sys_dup2(&self, fd1: FileDesc, fd2: FileDesc) -> SysResult {
         info!("dup2: from {:?} to {:?}", fd1, fd2);
         let proc = self.linux_process();
@@ -127,14 +131,17 @@ bitflags! {
 }
 
 impl OpenFlags {
+    /// check if the OpenFlags is readable
     fn readable(self) -> bool {
         let b = self.bits() & 0b11;
         b == Self::RDONLY.bits() || b == Self::RDWR.bits()
     }
+    /// check if the OpenFlags is writable
     fn writable(self) -> bool {
         let b = self.bits() & 0b11;
         b == Self::WRONLY.bits() || b == Self::RDWR.bits()
     }
+    /// convert OpenFlags to OpenOptions
     fn to_options(self) -> OpenOptions {
         OpenOptions {
             read: self.readable(),

linux-syscall/src/file/file.rs

@@ -12,6 +12,11 @@
 use super::*;
 
 impl Syscall<'_> {
+    /// Reads from a specified file using a file descriptor. Before using this call,
+    /// you must first obtain a file descriptor using the opensyscall. Returns bytes read successfully.
+    /// - fd – file descriptor
+    /// - base – pointer to the buffer to fill with read contents
+    /// - len – number of bytes to read
     pub fn sys_read(&self, fd: FileDesc, mut base: UserOutPtr<u8>, len: usize) -> SysResult {
         info!("read: fd={:?}, base={:?}, len={:#x}", fd, base, len);
         let proc = self.linux_process();
@@ -22,6 +27,11 @@ impl Syscall<'_> {
         Ok(len)
     }
 
+    /// Writes to a specified file using a file descriptor. Before using this call,
+    /// you must first obtain a file descriptor using the open syscall. Returns bytes written successfully.
+    /// - fd – file descriptor
+    /// - base – pointer to the buffer write
+    /// - len – number of bytes to write
     pub fn sys_write(&self, fd: FileDesc, base: UserInPtr<u8>, len: usize) -> SysResult {
         info!("write: fd={:?}, base={:?}, len={:#x}", fd, base, len);
         let proc = self.linux_process();
@@ -31,6 +41,9 @@ impl Syscall<'_> {
         Ok(len)
     }
 
+    /// read from or write to a file descriptor at a given offset
+    /// reads up to count bytes from file descriptor fd at offset offset
+    /// (from the start of the file) into the buffer starting at buf. The file offset is not changed.
     pub fn sys_pread(
         &self,
         fd: FileDesc,
@@ -50,6 +63,8 @@ impl Syscall<'_> {
         Ok(len)
     }
 
+    /// writes up to count bytes from the buffer
+    /// starting at buf to the file descriptor fd at offset offset. The file offset is not changed.
     pub fn sys_pwrite(
         &self,
         fd: FileDesc,
@@ -68,6 +83,9 @@ impl Syscall<'_> {
         Ok(len)
     }
 
+    /// works just like read except that multiple buffers are filled.
+    /// reads iov_count buffers from the file
+    /// associated with the file descriptor fd into the buffers described by iov ("scatter input")
     pub fn sys_readv(
         &self,
         fd: FileDesc,
@@ -84,6 +102,9 @@ impl Syscall<'_> {
         Ok(len)
     }
 
+    /// works just like write except that multiple buffers are written out.
+    /// writes iov_count buffers of data described
+    /// by iov to the file associated with the file descriptor fd ("gather output").
     pub fn sys_writev(
         &self,
         fd: FileDesc,
@@ -102,6 +123,8 @@ impl Syscall<'_> {
         Ok(len)
     }
 
+    /// repositions the offset of the open file associated with the file descriptor fd
+    /// to the argument offset according to the directive whence
     pub fn sys_lseek(&self, fd: FileDesc, offset: i64, whence: u8) -> SysResult {
         const SEEK_SET: u8 = 0;
         const SEEK_CUR: u8 = 1;
@@ -121,6 +144,7 @@ impl Syscall<'_> {
         Ok(offset as usize)
     }
 
+    /// cause the regular file named by path to be truncated to a size of precisely length bytes.
     pub fn sys_truncate(&self, path: UserInPtr<u8>, len: usize) -> SysResult {
         let path = path.read_cstring()?;
         info!("truncate: path={:?}, len={}", path, len);
@@ -129,13 +153,15 @@ impl Syscall<'_> {
         Ok(0)
     }
 
+    /// cause the regular file referenced by fd to be truncated to a size of precisely length bytes.
     pub fn sys_ftruncate(&self, fd: FileDesc, len: usize) -> SysResult {
         info!("ftruncate: fd={:?}, len={}", fd, len);
         let proc = self.linux_process();
         proc.get_file(fd)?.set_len(len as u64)?;
         Ok(0)
     }
 
+    /// copies data between one file descriptor and another.
     pub fn sys_sendfile(
         &self,
         out_fd: FileDesc,
@@ -146,6 +172,7 @@ impl Syscall<'_> {
         self.sys_copy_file_range(in_fd, offset_ptr, out_fd, 0.into(), count, 0)
     }
 
+    /// copies data between one file descriptor and anothe, read from specified offset and write new offset back
     pub fn sys_copy_file_range(
         &self,
         in_fd: FileDesc,
@@ -223,26 +250,32 @@ impl Syscall<'_> {
         Ok(total_written)
     }
 
+    /// causes all buffered modifications to file metadata and data to be written to the underlying file systems.
     pub fn sys_sync(&self) -> SysResult {
         info!("sync:");
         let proc = self.linux_process();
         proc.root_inode().fs().sync()?;
         Ok(0)
     }
 
+    /// transfers ("flushes") all modified in-core data of (i.e., modified buffer cache pages for) the file
+    /// referred to by the file descriptor fd to the disk device
     pub fn sys_fsync(&self, fd: FileDesc) -> SysResult {
         info!("fsync: fd={:?}", fd);
         let proc = self.linux_process();
         proc.get_file(fd)?.sync_all()?;
         Ok(0)
     }
 
+    /// is similar to fsync(), but does not flush modified metadata unless that metadata is needed
     pub fn sys_fdatasync(&self, fd: FileDesc) -> SysResult {
         info!("fdatasync: fd={:?}", fd);
         let proc = self.linux_process();
         proc.get_file(fd)?.sync_data()?;
         Ok(0)
     }
+
+    /// Set parameters of device files.
     pub fn sys_ioctl(
         &self,
         fd: FileDesc,
@@ -260,17 +293,23 @@ impl Syscall<'_> {
         file_like.ioctl(request, arg1, arg2, arg3)
     }
 
+    /// Manipulate a file descriptor.
+    /// - cmd – cmd flag
+    /// - arg – additional parameters based on cmd
     pub fn sys_fcntl(&self, fd: FileDesc, cmd: usize, arg: usize) -> SysResult {
         info!("fcntl: fd={:?}, cmd={:x}, arg={}", fd, cmd, arg);
         let proc = self.linux_process();
         let file_like = proc.get_file_like(fd)?;
         file_like.fcntl(cmd, arg)
     }
 
+    /// Checks whether the calling process can access the file pathname
     pub fn sys_access(&self, path: UserInPtr<u8>, mode: usize) -> SysResult {
         self.sys_faccessat(FileDesc::CWD, path, mode, 0)
     }
 
+    /// Check user's permissions of a file relative to a directory file descriptor
+    /// TODO: check permissions based on uid/gid
     pub fn sys_faccessat(
         &self,
         dirfd: FileDesc,

linux-syscall/src/file/mod.rs

@@ -1,3 +1,5 @@
+//! Syscalls for files
+#![deny(missing_docs)]
 use super::*;
 use bitflags::bitflags;
 use linux_object::fs::vfs::{FileType, FsError};

linux-syscall/src/file/stat.rs

@@ -8,6 +8,10 @@ use super::*;
 use linux_object::fs::vfs::{FileType, Metadata};
 
 impl Syscall<'_> {
+    /// Works exactly like the stat syscall, but if the file in question is a symbolic link,
+    /// information on the link is returned rather than its target.
+    /// - `path` – full path to file
+    /// - `stat_ptr` – pointer to stat buffer
     pub fn sys_lstat(&self, path: UserInPtr<u8>, stat_ptr: UserOutPtr<Stat>) -> SysResult {
         self.sys_fstatat(
             FileDesc::CWD,
@@ -17,6 +21,9 @@ impl Syscall<'_> {
         )
     }
 
+    /// Works exactly like the stat syscall except a file descriptor (fd) is provided instead of a path.
+    /// - `fd` – file descriptor
+    /// - `stat_ptr` – pointer to stat buffer
     pub fn sys_fstat(&self, fd: FileDesc, mut stat_ptr: UserOutPtr<Stat>) -> SysResult {
         info!("fstat: fd={:?}, stat_ptr={:?}", fd, stat_ptr);
         let proc = self.linux_process();
@@ -26,6 +33,7 @@ impl Syscall<'_> {
         Ok(0)
     }
 
+    /// get file status relative to a directory file descriptor
     pub fn sys_fstatat(
         &self,
         dirfd: FileDesc,
@@ -48,6 +56,9 @@ impl Syscall<'_> {
         Ok(0)
     }
 
+    /// Returns information about a file in a structure named stat.
+    /// - `path` – pointer to the name of the file
+    /// - `stat_ptr` –  pointer to the structure to receive file information
     pub fn sys_stat(&self, path: UserInPtr<u8>, stat_ptr: UserOutPtr<Stat>) -> SysResult {
         self.sys_fstatat(FileDesc::CWD, path, stat_ptr, 0)
     }