sys_fstat: initial implementation

Signed-off-by: Andy-Python-Programmer <[email protected]>

Author: Andy-Python-Programmer

patches/mlibc/mlibc.patch

@@ -1,14 +1,14 @@
-From d1583428ad4f44bb2ca458e06e3a0c60f2c45737 Mon Sep 17 00:00:00 2001
+From 4b435231bee99fa0da6f9498c5342488e02a7bbd Mon Sep 17 00:00:00 2001
 From: Andy-Python-Programmer <[email protected]>
 Date: Thu, 10 Feb 2022 19:12:25 +1100
 Subject: [PATCH] yes
 
 Signed-off-by: Andy-Python-Programmer <[email protected]>
 ---
- .gitignore                          |  7 +++++++
- sysdeps/aero/generic/filesystem.cpp | 28 +++++++++++++++++++++-------
- sysdeps/aero/include/aero/syscall.h |  5 +++++
- 3 files changed, 33 insertions(+), 7 deletions(-)
+ .gitignore                          |  7 ++++++
+ sysdeps/aero/generic/filesystem.cpp | 34 +++++++++++++++++++++++------
+ sysdeps/aero/include/aero/syscall.h |  6 +++++
+ 3 files changed, 40 insertions(+), 7 deletions(-)
 
 diff --git a/.gitignore b/.gitignore
 index dbb35e8b..384b3395 100644
@@ -26,10 +26,15 @@ index dbb35e8b..384b3395 100644
 +# of the project directory.
 +compile_commands.json
 diff --git a/sysdeps/aero/generic/filesystem.cpp b/sysdeps/aero/generic/filesystem.cpp
-index 6a13f19c..ec81503c 100644
+index 6a13f19c..69833ae5 100644
 --- a/sysdeps/aero/generic/filesystem.cpp
 +++ b/sysdeps/aero/generic/filesystem.cpp
-@@ -84,9 +84,24 @@ int sys_access(const char *filename, int mode) {
+@@ -1,3 +1,4 @@
++#include "mlibc/fsfd_target.hpp"
+ #include <aero/syscall.h>
+ 
+ #include <sys/ioctl.h>
+@@ -84,9 +85,29 @@ int sys_access(const char *filename, int mode) {
 
  int sys_stat(fsfd_target fsfdt, int fd, const char *path, int flags,
               struct stat *statbuf) {
@@ -42,6 +47,11 @@ index 6a13f19c..ec81503c 100644
 +            break;
 +        }
 +
++        case fsfd_target::fd: {
++            result = syscall(SYS_FSTAT, fd, statbuf);
++            break;
++        }
++
 +        default: {
 +			mlibc::infoLogger() << "mlibc warning: sys_stat: unsupported fsfd target" << frg::endlog;
 +			return EINVAL;
@@ -56,7 +66,7 @@ index 6a13f19c..ec81503c 100644
      return 0;
  }
 
-@@ -192,10 +207,10 @@ int sys_read_entries(int handle, void *buffer, size_t max_size,
+@@ -192,10 +213,10 @@ int sys_read_entries(int handle, void *buffer, size_t max_size,
      auto entry = (struct aero_dir_entry *)buffer;
 
      struct dirent dirent = {
@@ -71,7 +81,7 @@ index 6a13f19c..ec81503c 100644
      };
 
      // The reclen is the size of the dirent struct, plus the size of the name.
-@@ -252,7 +267,6 @@ int sys_pselect(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
+@@ -252,7 +273,6 @@ int sys_pselect(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
                  const struct timespec *timeout, const sigset_t *sigmask,
                  int *num_events) {
      mlibc::infoLogger() << "sys_pselect() is not implemented" << frg::endlog;
@@ -80,10 +90,10 @@ index 6a13f19c..ec81503c 100644
  }
 
 diff --git a/sysdeps/aero/include/aero/syscall.h b/sysdeps/aero/include/aero/syscall.h
-index 07b1b51b..1e3178d2 100644
+index 07b1b51b..f6d7836d 100644
 --- a/sysdeps/aero/include/aero/syscall.h
 +++ b/sysdeps/aero/include/aero/syscall.h
-@@ -49,6 +49,11 @@
+@@ -49,6 +49,12 @@
  #define SYS_DUP 42
  #define SYS_FCNTL 43
  #define SYS_DUP2 44
@@ -92,6 +102,7 @@ index 07b1b51b..1e3178d2 100644
 +#define SYS_DISCOVER_ROOT 47
 +#define SYS_BECOME_ROOT 48
 +#define SYS_STAT 49
++#define SYS_FSTAT 50
 
  // Invalid syscall used to trigger a log error in the kernel (as a hint)
  // so, that we can implement the syscall in the kernel.

src/aero_kernel/src/syscall/fs.rs

@@ -364,17 +364,36 @@ pub fn fcntl(fd: usize, command: usize, arg: usize) -> Result<usize, AeroSyscall
     }
 }
 
-pub fn stat(path: usize, path_size: usize, stat_struct: usize) -> Result<usize, AeroSyscallError> {
+/// Validates the [`aero_syscall::Stat`] struct provided by the user and returns a mutable
+/// reference to it. [`AeroSyscallError::EFAULT`] is returned if the provided pointer is outside
+/// of the user's address space.
+fn validate_stat_struct<'struc>(
+    stat_struct: usize,
+) -> Result<&'struc mut aero_syscall::Stat, AeroSyscallError> {
     let stat_struct = VirtAddr::new(stat_struct as _)
         .validate_user()
         .ok_or(AeroSyscallError::EFAULT)?;
 
     // SAFETY: The user provided address is validated above.
-    let stat_struct = unsafe { stat_struct.read_mut::<aero_syscall::Stat>() };
+    Ok(unsafe { stat_struct.read_mut::<aero_syscall::Stat>() })
+}
 
-    let path = validate_str(path as *mut u8, path_size).ok_or(AeroSyscallError::EINVAL)?;
-    log::debug!("sys_stat: {path}");
+pub fn fstat(fd: usize, stat_struct: usize) -> Result<usize, AeroSyscallError> {
+    let stat_struct = validate_stat_struct(stat_struct)?;
+    let handle = scheduler::get_scheduler()
+        .current_task()
+        .file_table
+        .get_handle(fd)
+        .ok_or(AeroSyscallError::EBADFD)?;
+
+    *stat_struct = handle.inode().stat()?;
+    Ok(0)
+}
 
+pub fn stat(path: usize, path_size: usize, stat_struct: usize) -> Result<usize, AeroSyscallError> {
+    let stat_struct = validate_stat_struct(stat_struct)?;
+
+    let path = validate_str(path as *mut u8, path_size).ok_or(AeroSyscallError::EINVAL)?;
     let path = Path::new(path);
 
     let file = fs::lookup_path(path)?;

src/aero_kernel/src/syscall/mod.rs

@@ -70,6 +70,8 @@
 //! | 46     | ipc_recv                |
 //! | 47     | ipc_discover_root       |
 //! | 48     | ipc_become_root         |
+//! | 49     | stat                    |
+//! | 50     | fstat                   |
 
 use core::mem::MaybeUninit;
 
@@ -185,6 +187,7 @@ pub fn generic_do_syscall(
         SYS_DUP2 => fs::dup2(b, c, d),
         SYS_FCNTL => fs::fcntl(b, c, d),
         SYS_STAT => fs::stat(b, c, d),
+        SYS_FSTAT => fs::fstat(b, c),
 
         SYS_SOCKET => net::socket(b, c, d),
         SYS_BIND => net::bind(b, c, d),

src/aero_syscall/src/consts.rs

@@ -68,6 +68,7 @@ pub const SYS_IPC_RECV: usize = 46;
 pub const SYS_IPC_DISCOVER_ROOT: usize = 47;
 pub const SYS_IPC_BECOME_ROOT: usize = 48;
 pub const SYS_STAT: usize = 49;
+pub const SYS_FSTAT: usize = 50;
 
 // fcntl constants:
 pub const F_GETFD: usize = 3;

src/aero_syscall/src/lib.rs

@@ -939,3 +939,8 @@ pub fn sys_stat(path: &str, stat: &mut Stat) -> Result<usize, AeroSyscallError>
 
     isize_as_syscall_result(value as _)
 }
+
+pub fn sys_fstat(fd: usize, stat: &mut Stat) -> Result<usize, AeroSyscallError> {
+    let value = syscall2(prelude::SYS_FSTAT, fd, stat as *mut Stat as usize);
+    isize_as_syscall_result(value as _)
+}