From d3a8b67604b8de75de14fcc72b060406ee1b5131 Mon Sep 17 00:00:00 2001
From: Mark Poliakov <mark@alnyan.me>
Date: Tue, 14 Nov 2023 11:51:31 +0200
Subject: [PATCH] alnyan/yggdrasil: change how args are passed from the kernel

---
 library/std/src/sys/yggdrasil/args.rs   | 69 +++++++++++++++----------
 library/std/src/sys/yggdrasil/fs/mod.rs |  3 +-
 2 files changed, 43 insertions(+), 29 deletions(-)

diff --git a/library/std/src/sys/yggdrasil/args.rs b/library/std/src/sys/yggdrasil/args.rs
index d502e6c0264..184f9080ab7 100644
--- a/library/std/src/sys/yggdrasil/args.rs
+++ b/library/std/src/sys/yggdrasil/args.rs
@@ -1,5 +1,6 @@
 use crate::ffi::OsString;
 use crate::fmt;
+use crate::mem::size_of;
 use crate::str::FromStr;
 
 #[allow(dead_code)]
@@ -12,15 +13,10 @@ pub struct Args {
 
 // Argument structure layout:
 //
-// 0x000: args len
-// 0x008: arg ptr 0
-// 0x010: arg len 0
-// 0x018: arg ptr 1
-// 0x020: arg len 1
-// ...
-// .....: arg data 0
-// .....: arg data 1
+// 0x000: args pointer
+// 0x008: envs pointer
 static mut ARGS: usize = 0;
+static mut ENVS: usize = 0;
 
 pub fn args() -> Args {
     let base = unsafe { ARGS };
@@ -31,12 +27,33 @@ pub fn args() -> Args {
 
     let len = unsafe {
         #[allow(fuzzy_provenance_casts)]
-        (base as *mut usize).read()
+        (base as *const usize).read()
     };
 
     Args { base, len, index: 0 }
 }
 
+impl Args {
+    const fn item(base: usize, index: usize) -> usize {
+        base + (/* array len */1 + /* pair */ 2 * index) * size_of::<usize>()
+    }
+
+    fn get(&self, index: usize) -> &'static str {
+        assert!(index < self.len);
+        let len = unsafe {
+            #[allow(fuzzy_provenance_casts)]
+            (Self::item(self.base, index) as *const usize).read()
+        };
+        let ptr = unsafe {
+            #[allow(fuzzy_provenance_casts)]
+            ((Self::item(self.base, index) + size_of::<usize>()) as *const *const u8).read()
+        };
+        let slice = unsafe { core::slice::from_raw_parts(ptr, len) };
+
+        core::str::from_utf8(slice).unwrap()
+    }
+}
+
 impl fmt::Debug for Args {
     fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
         todo!()
@@ -51,26 +68,12 @@ impl Iterator for Args {
             return None;
         }
 
-        let ptr_ptr_addr = self.base + (1 + self.index * 2) * 8;
-        let arg_ptr = unsafe {
-            #[allow(fuzzy_provenance_casts)]
-            (ptr_ptr_addr as *mut usize).read()
-        };
-        let arg_len = unsafe {
-            #[allow(fuzzy_provenance_casts)]
-            ((ptr_ptr_addr + 8) as *mut usize).read()
-        };
-
-        let slice = unsafe {
-            #[allow(fuzzy_provenance_casts)]
-            crate::slice::from_raw_parts(arg_ptr as *const u8, arg_len)
-        };
-        let arg_str = crate::str::from_utf8(slice).unwrap();
-        let arg_os_string = OsString::from_str(arg_str).unwrap();
-
+        let str = self.get(self.index);
         self.index += 1;
 
-        Some(arg_os_string)
+        let os_str = OsString::from_str(str).unwrap();
+
+        Some(os_str)
     }
 }
 
@@ -87,5 +90,15 @@ impl DoubleEndedIterator for Args {
 }
 
 pub unsafe fn init(program_arg: usize) {
-    ARGS = program_arg;
+    #[repr(C)]
+    struct Header {
+        args_ptr: usize,
+        envs_ptr: usize,
+    };
+
+    #[allow(fuzzy_provenance_casts)]
+    let hdr = program_arg as *const Header;
+
+    ARGS = (*hdr).args_ptr;
+    ENVS = (*hdr).envs_ptr;
 }
diff --git a/library/std/src/sys/yggdrasil/fs/mod.rs b/library/std/src/sys/yggdrasil/fs/mod.rs
index bbeb1348e36..74a652fd831 100644
--- a/library/std/src/sys/yggdrasil/fs/mod.rs
+++ b/library/std/src/sys/yggdrasil/fs/mod.rs
@@ -88,7 +88,8 @@ impl FileType {
     }
 
     pub fn is_symlink(&self) -> bool {
-        todo!()
+        // TODO: symlinks NYI
+        false
     }
 }