syscall: add sys_link stub and epoll_ctl_mod

Signed-off-by: Andy-Python-Programmer <andypythonappdeveloper@gmail.com>

Author: Andy-Python-Programmer

patches/mlibc/mlibc.patch

@@ -1,18 +1,18 @@
-From 60f70d42c981a6c2645201d2d0997d48f91c53a0 Mon Sep 17 00:00:00 2001
+From 7dcad7c2bed4388c7692eec9b5eac31bde1de439 Mon Sep 17 00:00:00 2001
 From: Andy-Python-Programmer <andypythonappdeveloper@gmail.com>
 Date: Thu, 10 Feb 2022 19:12:25 +1100
 Subject: [PATCH] yes
 
 Signed-off-by: Andy-Python-Programmer <andypythonappdeveloper@gmail.com>
 ---
- .gitignore                          |  3 +
- options/rtdl/generic/linker.cpp     |  2 +-
- sysdeps/aero/generic/aero.cpp       | 40 +++++++++---
- sysdeps/aero/generic/filesystem.cpp | 97 ++++++++++++++++++++++++++---
- sysdeps/aero/generic/signals.cpp    |  8 ++-
- sysdeps/aero/generic/sockets.cpp    | 59 ++++++++++++++++++
- sysdeps/aero/include/aero/syscall.h | 14 +++++
- 7 files changed, 205 insertions(+), 18 deletions(-)
+ .gitignore                          |   3 +
+ options/rtdl/generic/linker.cpp     |   2 +-
+ sysdeps/aero/generic/aero.cpp       |  40 ++++++++--
+ sysdeps/aero/generic/filesystem.cpp | 110 +++++++++++++++++++++++++---
+ sysdeps/aero/generic/signals.cpp    |   8 +-
+ sysdeps/aero/generic/sockets.cpp    |  59 +++++++++++++++
+ sysdeps/aero/include/aero/syscall.h |  15 ++++
+ 7 files changed, 217 insertions(+), 20 deletions(-)
 
 diff --git a/.gitignore b/.gitignore
 index dbb35e8b..20c8d4c3 100644
@@ -118,7 +118,7 @@ index 7de909f5..8605e426 100644
  #endif
  } // namespace mlibc
 diff --git a/sysdeps/aero/generic/filesystem.cpp b/sysdeps/aero/generic/filesystem.cpp
-index 6a13f19c..8f700a38 100644
+index 6a13f19c..988190e2 100644
 --- a/sysdeps/aero/generic/filesystem.cpp
 +++ b/sysdeps/aero/generic/filesystem.cpp
 @@ -1,3 +1,4 @@
@@ -158,7 +158,25 @@ index 6a13f19c..8f700a38 100644
      return 0;
  }
 
-@@ -192,10 +213,10 @@ int sys_read_entries(int handle, void *buffer, size_t max_size,
+@@ -153,7 +174,16 @@ int sys_mkdir(const char *path) {
+ }
+ 
+ int sys_rmdir(const char *path) UNIMPLEMENTED("sys_rmdir")
+-int sys_link(const char *srcpath, const char *destpath) UNIMPLEMENTED("sys_link")
++
++int sys_link(const char *srcpath, const char *destpath) {
++    auto result = syscall(SYS_LINK, srcpath, strlen(srcpath), destpath, strlen(destpath));
++
++    if (result < 0) {
++        return -result;
++    }
++
++    return 0;
++}
+ 
+ int sys_unlinkat(int fd, const char *path, int flags) {
+     auto result = syscall(SYS_UNLINK, fd, path, strlen(path), flags);
+@@ -192,10 +222,10 @@ int sys_read_entries(int handle, void *buffer, size_t max_size,
      auto entry = (struct aero_dir_entry *)buffer;
 
      struct dirent dirent = {
@@ -173,7 +191,7 @@ index 6a13f19c..8f700a38 100644
      };
 
      // The reclen is the size of the dirent struct, plus the size of the name.
-@@ -214,7 +235,17 @@ int sys_open_dir(const char *path, int *handle) {
+@@ -214,7 +244,17 @@ int sys_open_dir(const char *path, int *handle) {
  }
 
  int sys_rename(const char *path, const char *new_path) UNIMPLEMENTED("sys_rename")
@@ -192,15 +210,20 @@ index 6a13f19c..8f700a38 100644
 
  int sys_dup(int fd, int flags, int *newfd) {
      auto result = syscall(SYS_DUP, fd, flags);
-@@ -252,7 +283,6 @@ int sys_pselect(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
+@@ -252,11 +292,10 @@ 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;
 -    *num_events = 10;
      return 0;
  }
 
-@@ -267,4 +297,55 @@ int sys_pipe(int *fds, int flags) {
+-int sys_chmod(const char *pathname, mode_t mode) UNIMPLEMENTED("sys_chmod")
++// int sys_chmod(const char *pathname, mode_t mode) UNIMPLEMENTED("sys_chmod")
+ 
+ int sys_pipe(int *fds, int flags) {
+     auto result = syscall(SYS_PIPE, fds, flags);
+@@ -267,4 +306,55 @@ int sys_pipe(int *fds, int flags) {
 
      return 0;
  }
@@ -341,10 +364,10 @@ index e69de29b..b6b18fe7 100644
 +}
 +} // namespace mlibc
 diff --git a/sysdeps/aero/include/aero/syscall.h b/sysdeps/aero/include/aero/syscall.h
-index 07b1b51b..4576d268 100644
+index 07b1b51b..12f8dc61 100644
 --- a/sysdeps/aero/include/aero/syscall.h
 +++ b/sysdeps/aero/include/aero/syscall.h
-@@ -49,6 +49,20 @@
+@@ -49,6 +49,21 @@
  #define SYS_DUP 42
  #define SYS_FCNTL 43
  #define SYS_DUP2 44
@@ -360,8 +383,9 @@ index 07b1b51b..4576d268 100644
 +#define SYS_EPOLL_CTL 54
 +#define SYS_EVENT_FD 55
 +#define SYS_KILL 56
-+#define SYS_FUTEX_WAIT 59
-+#define SYS_FUTEX_WAKE 60
++#define SYS_FUTEX_WAIT 57
++#define SYS_FUTEX_WAKE 58
++#define SYS_LINK 59
 
  // 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/fs/epoll.rs

@@ -55,6 +55,22 @@ impl EPoll {
         Ok(())
     }
 
+    /// Change the settings associated with file derscriptor in the interest list to the
+    /// new settings specified in event.
+    ///
+    /// ## Errors
+    /// * `ENOENT`: The event does not exist at `fd`.
+    pub fn update_event(&self, fd: usize, event: EPollEvent) -> Result<(), SyscallError> {
+        let mut events = self.events.lock_irq();
+
+        if !events.contains_key(&fd) {
+            return Err(SyscallError::ENOENT);
+        }
+
+        events.insert(fd, event);
+        Ok(())
+    }
+
     /// Retrieves ready events, and delivers them to the caller-supplied event buffer.
     ///
     /// ## Arguments

src/aero_kernel/src/fs/mod.rs

@@ -219,7 +219,7 @@ pub fn lookup_path_with(
     mode: LookupMode,
 ) -> Result<DirCacheItem> {
     // Iterate and resolve each component. For example `a`, `b`, and `c` in `a/b/c`.
-    for (i, component) in path.components().enumerate() {
+    for component in path.components() {
         match component {
             // Handle some special cases that might occur in a relative path.
             "." => continue,
@@ -248,7 +248,6 @@ pub fn lookup_path_with(
 
                         Err(err)
                             if err == FileSystemError::EntryNotFound
-                                && i == path.components().count() - 1
                                 && mode == LookupMode::Create =>
                         {
                             cwd = cwd.inode().touch(cwd.clone(), component)?;
@@ -306,6 +305,7 @@ pub fn init() -> Result<()> {
     root_dir().inode().mkdir("home")?;
     root_dir().inode().mkdir("tmp")?;
     root_dir().inode().mkdir("proc")?;
+    root_dir().inode().mkdir("var")?;
 
     initramfs::init()?;
     log::info!("installed initramfs");

src/aero_kernel/src/syscall/fs.rs

@@ -425,17 +425,22 @@ pub fn epoll_ctl(
         .get_handle(epfd)
         .ok_or(SyscallError::EBADFD)?;
 
+    let epoll = epfd
+        .inode()
+        .downcast_arc::<EPoll>()
+        .ok_or(SyscallError::EINVAL)?;
+
     match mode {
         EPOLL_CTL_ADD => {
-            let epoll = epfd
-                .inode()
-                .downcast_arc::<EPoll>()
-                .ok_or(SyscallError::EINVAL)?;
-
             epoll.add_event(fd, event.clone())?;
             Ok(0)
         }
 
+        EPOLL_CTL_MOD => {
+            epoll.update_event(fd, event.clone())?;
+            Ok(0)
+        }
+
         _ => unreachable!("epoll_ctl: unknown mode {mode}"),
     }
 }
@@ -488,3 +493,9 @@ pub fn event_fd(_initval: usize, flags: usize) -> Result<usize, SyscallError> {
         .file_table
         .open_file(entry, OpenFlags::O_RDWR)?)
 }
+
+#[syscall]
+pub fn link(src_path: &Path, dest_path: &Path) -> Result<usize, SyscallError> {
+    log::warn!("sys_link: is a stub! (src_path={src_path:?}, dest_path={dest_path:?})");
+    Ok(0)
+}

src/aero_kernel/src/syscall/mod.rs

@@ -205,6 +205,7 @@ pub fn generic_do_syscall(
         SYS_FSTAT => fs::fstat(b, c),
         SYS_READ_LINK => fs::read_link(b, c, d, e),
         SYS_EVENT_FD => fs::event_fd(b, c),
+        SYS_LINK => fs::link(b, c, d, e),
 
         // epoll calls:
         SYS_EPOLL_CREATE => fs::epoll_create(b),

src/aero_syscall/src/consts.rs

@@ -77,8 +77,9 @@ pub const SYS_EPOLL_PWAIT: usize = 53;
 pub const SYS_EPOLL_CTL: usize = 54;
 pub const SYS_EVENT_FD: usize = 55;
 pub const SYS_KILL: usize = 56;
-pub const SYS_FUTEX_WAIT: usize = 59;
-pub const SYS_FUTEX_WAKE: usize = 60;
+pub const SYS_FUTEX_WAIT: usize = 57;
+pub const SYS_FUTEX_WAKE: usize = 58;
+pub const SYS_LINK: usize = 59;
 
 // constants for fcntl()'s command argument:
 pub const F_DUPFD: usize = 1;

src/aero_syscall/src/lib.rs

@@ -228,6 +228,7 @@ pub fn syscall_as_str(syscall: usize) -> &'static str {
         prelude::SYS_KILL => "kill",
         prelude::SYS_FUTEX_WAIT => "futex_wait",
         prelude::SYS_FUTEX_WAKE => "futex_wake",
+        prelude::SYS_LINK => "link",
 
         _ => unreachable!("unknown syscall {syscall}"),
     }