From 2604f47bec44ecea8ddf61dae858f1fb268cdb48 Mon Sep 17 00:00:00 2001
From: husky <fekhesk@pm.me>
Date: Thu, 20 Jul 2023 04:36:59 -0700
Subject: [PATCH] initial implementations for call and call-method

---
 .gitignore             |   5 +
 Cargo.toml             |   8 ++
 examples/client_ppc.rs |  16 +++
 src/arch/mod.rs        |  20 +++
 src/lib.rs             | 268 +++++++++++++++++++++++++++++++++++++++++
 src/ntstr.rs           |  94 +++++++++++++++
 src/tests.rs           | 167 +++++++++++++++++++++++++
 7 files changed, 578 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Cargo.toml
 create mode 100644 examples/client_ppc.rs
 create mode 100644 src/arch/mod.rs
 create mode 100644 src/lib.rs
 create mode 100644 src/ntstr.rs
 create mode 100644 src/tests.rs

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..8398f69
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,5 @@
+/target
+/Cargo.lock
+
+# as its usage is encouraged for testing architecture-specific code, do not include the .cargo directory
+/.cargo
\ No newline at end of file
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..5990672
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "ofw"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/examples/client_ppc.rs b/examples/client_ppc.rs
new file mode 100644
index 0000000..29248ed
--- /dev/null
+++ b/examples/client_ppc.rs
@@ -0,0 +1,16 @@
+#![no_std]
+#![no_main]
+
+use ofw::arch::EntryFunction;
+use ofw::{call, service_result, ntstr, OFW_TRUE};
+
+#[no_mangle]
+#[link_section = ".text"]
+extern "C" fn _start(_r3: u32, _r4: u32, entry: EntryFunction) -> isize {
+    let mut results = service_result!(1,1);
+    call!(entry, results, ntstr!("test"), 1, 1, ntstr!("test"));
+    if results.success {
+        let _missing: bool = results.rets[0] == OFW_TRUE;
+    }
+    0
+}
\ No newline at end of file
diff --git a/src/arch/mod.rs b/src/arch/mod.rs
new file mode 100644
index 0000000..ed2466b
--- /dev/null
+++ b/src/arch/mod.rs
@@ -0,0 +1,20 @@
+// # Note to developers:
+// architecture-specific code may be tested via the usage of a filein the following
+// path: `/.cargo/config`. (where `/` is the root of the project)
+// the file should contain the following:
+// ```
+// [build]
+// # for powerpc
+// target = "powerpc-unknown-linux-gnu"
+// ```
+
+use crate::Args;
+
+/// # PowerPC
+#[cfg(target_arch = "powerpc")]
+pub type EntryFunction = extern "C" fn (*mut Args) -> i32;
+
+/// # x86_64
+/// note: x86_64 does not have an OpenFirmware implementation, this is for testing purposes only
+#[cfg(target_arch = "x86_64")]
+pub type EntryFunction = extern "C" fn (*mut Args) -> i32;
\ No newline at end of file
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..5c5efc8
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,268 @@
+#![no_std]
+
+/// # OFW_TRUE
+/// a constant representing the OpenFirmware "true" value
+pub const OFW_TRUE: i32 = -1;
+
+/// # OFW_FALSE
+/// a constant representing the OpenFirmware "false" value
+pub const OFW_FALSE: i32 = 0;
+
+/// # OFWBoolean
+/// a type representing the OpenFirmware boolean type
+/// can be either OFW_TRUE or OFW_FALSE
+pub type OFWBoolean = i32;
+
+/// # PHandle
+/// handle to a "package" in OpenFirmware
+/// usually used to access properties
+pub type PHandle = i32;
+
+/// # IHandle
+/// handle to a package instance in OpenFirmware
+/// usually used to call methods from a package
+pub type IHandle = i32;
+
+use crate::arch::EntryFunction;
+use crate::ntstr::NTSTR;
+
+/// # ntstr
+/// module for handling null-terminated strings
+pub mod ntstr;
+
+/// # arch
+/// module for architecture-specific code
+pub mod arch;
+
+
+#[cfg(test)]
+mod tests;
+
+/// # Args
+/// a base structure for all calls to the OpenFirmware entry function,
+/// shouldn't be used directly but rather used as a base for other "service" structures
+/// an example "service struct" is as follows
+/// ```
+/// use ofw::{Args, OFWBoolean};
+/// use ofw::ntstr::NTSTR;
+/// /// # test
+/// /// nargs: 1
+/// /// nrets: 1
+/// /// takes a service name string, and returns OFW_TRUE if the service is missing or OFW_FALSE if it is present
+/// #[repr(C)]
+/// pub struct TestService {
+///    pub args: Args,
+///    pub service: NTSTR,
+///    pub missing: OFWBoolean,
+/// }
+/// ```
+#[repr(C)]
+pub struct Args {
+    pub service: NTSTR,
+    // ieee 1275, 2.4.1 General conventions: "All numbers on the stack are signed integers, _32 bits[...]"
+    pub nrets: i32,
+    pub nargs: i32,
+    // inheriting structs will continue from here
+}
+
+/// # ServiceResult
+/// a generic structure for accessing the results of a service call
+#[allow(dead_code)]
+pub struct ServiceResult<'a> {
+    pub success: bool,
+    buf: &'static mut [i32],
+    pub rets: &'a [i32],
+}
+
+/// # call!
+/// a macro for calling OpenFirmware services
+/// ## example
+/// ```
+/// use ofw::{call, service_result, ServiceResult};
+/// use ofw::arch::EntryFunction;
+/// let entry_fn: EntryFunction = unimplemented!("get the entry function from somewhere");
+/// // <# of args>, <# of rets>
+/// let mut results: ServiceResult = service_result!(1, 1);
+/// // <entry function>, <service name>, <# of args>, <# of rets>, <args...>
+/// call!(entry_fn, results, ntstr!("test"), 1, 1, ntstr!("test"));
+/// if results.success {
+///    let test_result: i32 = results.rets[0];
+/// }
+/// ```
+#[macro_export]
+macro_rules! call {
+    ($entry_fn:expr, $results:expr, $service:expr, $nargs:expr, $nrets:expr, $($args:expr),*) => {
+        #[allow(unused_assignments)]
+        {
+        let mut i = 0;
+        $(
+            $results.buf[i] = $args.into();
+            i += 1;
+        )*
+        let success: bool = $crate::ofw_call($entry_fn, $service, $nargs, $nrets, $results.buf);
+        $results.success = success;
+        $results.rets = &$results.buf[$nargs as usize..];
+    }};
+}
+
+/// # call_method!
+/// a macro for calling package methods
+/// ## example
+/// ```
+/// use ofw::arch::EntryFunction;
+/// use ofw::{call_method, method_service_result, ServiceResult};
+///
+/// let entry_fn: EntryFunction = unimplemented!("get the entry function from somewhere");
+/// let package_instance: i32 = unimplemented!("get the package instance from somewhere");
+/// // note the usage of the `method_service_result!` macro instead of `service_result!`
+/// // this is required as the `call_method!` macro requires a
+/// // slightly different ServiceResult struct configuration
+/// // <# of args>, <# of rets>
+/// let mut results: ServiceResult = method_service_result!(1, 1);
+/// // <entry function>, <package instance>, <method name>, <# of args>, <# of rets>, <args...>
+/// call_method!(entry_fn, results, package_instance, ntstr!("seek"), 2, 1, 0, 0);
+/// if results.success {
+///   let seek_result: i32 = results.rets[0];
+/// }
+/// ```
+#[macro_export]
+macro_rules! call_method {
+    ($entry_fn:expr, $package_instance:expr, $results:expr, $service:expr, $nargs:expr, $nrets:expr, $($args:expr),*) => {
+        #[allow(unused_assignments)]
+        {
+        let mut i = 0;
+        $(
+            $results.buf[i] = $args.into();
+            i += 1;
+        )*
+        let success: bool = $crate::ofw_call_method($entry_fn, $package_instance, $service, $nargs, $nrets, $results.buf);
+        $results.success = success && $results.buf[$nargs as usize] != 0;
+        $results.rets = &$results.buf[$nargs as usize + 1..];
+    }};
+}
+
+/// # service_result!
+/// a macro for creating a ServiceResult struct, used with the `call!` macro
+#[macro_export]
+macro_rules! service_result {
+    ($nargs:expr, $nrets:expr) => { unsafe {
+        static mut BUF: [i32; $nargs + $nrets] = [0; $nargs + $nrets];
+        let rets: &[i32] = &[];
+        let results = $crate::ServiceResult {
+            success: false,
+            buf: &mut BUF,
+            rets,
+        };
+        results
+    }};
+}
+
+/// # method_service_result!
+/// a macro for creating a ServiceResult struct, used with the `call_method!` macro
+#[macro_export]
+macro_rules! method_service_result {
+    ($nargs:expr, $nrets:expr) => { unsafe {
+        static mut BUF: [i32; $nargs + $nrets + 1] = [0; $nargs + $nrets + 1];
+        let rets: &[i32] = &[];
+        let results = $crate::ServiceResult {
+            success: false,
+            buf: &mut BUF,
+            rets,
+        };
+        results
+    }};
+}
+
+/// # ofw_call
+/// a function to call any OpenFirmware-provided service
+/// usage of the macro `call!` is preferred, but this function can be used directly
+/// ## example
+/// ```
+/// use ofw::arch::EntryFunction;
+/// use ofw::{ntstr, ofw_call};
+/// let entry_fn: EntryFunction = unimplemented!("get the entry function from somewhere");
+/// let mut args: [i32; 2] = [ntstr!("test") as i32, 0];
+/// let was_service_successfully_called: bool = ofw_call(entry_fn, ntstr!("test"), 1, 1, &mut args);
+/// let test_result: i32 = args[1];
+/// ```
+pub fn ofw_call(entry_fn: EntryFunction, service: NTSTR, num_args: i32, num_rets: i32, args_and_rets: &mut [i32]) -> bool {
+    #[repr(C)]
+    struct GenericArgs {
+        args: Args,
+        buffer: *mut i32,
+    }
+    let mut generic_args = GenericArgs {
+        args: Args {
+            service,
+            nrets: num_rets,
+            nargs: num_args,
+        },
+        buffer: args_and_rets.as_mut_ptr(),
+    };
+
+    let result: bool;
+
+    #[cfg(target_arch = "powerpc")]
+    {
+        result = entry_fn(&mut generic_args as *mut _ as *mut Args) == OFW_TRUE;
+    }
+    #[cfg(target_arch = "x86_64")]
+    {
+        result = entry_fn(&mut generic_args as *mut _ as *mut Args) == OFW_TRUE;
+    }
+
+    result
+}
+
+/// # ofw_call_method
+/// a function to call a method provided by a package instance
+/// usage of the `call_method!` macro is preferred, but this function can be used directly
+/// ## example
+/// ```
+/// // we will be calling the "seek" method on an imaginary block device
+/// // the seek method takes 2 arguments, and returns 1 value
+/// // addr_hi, addr_lo -- okay?
+/// // however, we must add another cell in order to account for the catch-result
+/// // (see ieee 1275, 6.3.2.2 Device tree)
+/// use ofw::{ntstr, ofw_call_method};
+/// // addr_hi, addr_lo, catch-result, okay?
+/// let mut args: [i32; 4] = [0, 0, 0, 0];
+/// // note that num_args and num_rets are not the same as the length of args, this is intentional
+/// let was_service_successfully_called: bool = ofw_call_method(entry_fn, instance, ntstr!("seek"), 2, 1, &mut args);
+/// if was_service_successfully_called && args[2] != 0 {
+///     let seek_result: i32 = args[3];
+/// }
+/// ```
+pub fn ofw_call_method(entry_fn: EntryFunction, ihandle: IHandle, method: NTSTR, num_args: i32, num_rets: i32, args_and_rets: &mut [i32]) -> bool {
+    #[repr(C)]
+    struct CallMethodArgs {
+        args: Args,
+        method: NTSTR,
+        ihandle: IHandle,
+        buffer: *mut i32,
+    }
+
+    let mut call_method_args = CallMethodArgs {
+        args: Args {
+            service: ntstr!("call-method"),
+            nrets: num_rets + 1,
+            nargs: num_args + 2,
+        },
+        method,
+        ihandle,
+        buffer: args_and_rets.as_mut_ptr(),
+    };
+
+    let result: bool;
+
+    #[cfg(target_arch = "powerpc")]
+    {
+        result = entry_fn(&mut call_method_args as *mut _ as *mut Args) == OFW_TRUE;
+    }
+    #[cfg(target_arch = "x86_64")]
+    {
+        result = entry_fn(&mut call_method_args as *mut _ as *mut Args) == OFW_TRUE;
+    }
+
+    result
+}
\ No newline at end of file
diff --git a/src/ntstr.rs b/src/ntstr.rs
new file mode 100644
index 0000000..314e344
--- /dev/null
+++ b/src/ntstr.rs
@@ -0,0 +1,94 @@
+use core::fmt::{Debug, Display, Formatter, Write};
+
+/// # ntstr!
+/// macro for creating a null-terminated string
+/// ## example
+/// ```
+/// use ofw::ntstr;
+/// let ntstr = ntstr!("Hello, world!");
+/// ```
+/// becomes
+/// ```
+/// let ntstr = ofw::ntstr::NTSTR::new(b"Hello, world!\0".as_ptr());
+/// ```
+#[macro_export]
+macro_rules! ntstr {
+    ($str:expr) => {
+        $crate::ntstr::NTSTR::new(concat!($str, "\0").as_ptr())
+    };
+}
+
+/// # NTSTR
+/// a null-terminated string, defined as a pointer to an array of u8 characters ending with a null byte
+/// not mutable
+#[repr(C)]
+pub struct NTSTR {
+    ptr: *const u8,
+}
+
+impl From<usize> for NTSTR {
+    fn from(ptr: usize) -> Self {
+        Self { ptr: ptr as *const u8 }
+    }
+}
+
+impl From<*const u8> for NTSTR {
+    fn from(ptr: *const u8) -> Self {
+        Self { ptr }
+    }
+}
+
+#[allow(clippy::from_over_into)]
+impl Into<i32> for NTSTR {
+    fn into(self) -> i32 {
+        self.ptr as i32
+    }
+}
+
+impl NTSTR {
+    pub const fn new(ptr: *const u8) -> Self {
+        Self { ptr }
+    }
+
+    fn print(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        let mut i = 0;
+        loop {
+            let a = unsafe { *self.ptr.add(i) };
+            if a == 0 {
+                break;
+            }
+            f.write_char(a as char)?;
+            i += 1;
+        }
+        Ok(())
+    }
+}
+
+impl PartialEq for NTSTR {
+    fn eq(&self, other: &Self) -> bool {
+        let mut i = 0;
+        loop {
+            let a = unsafe { *self.ptr.add(i) };
+            let b = unsafe { *other.ptr.add(i) };
+            if a != b {
+                return false;
+            }
+            if a == 0 {
+                return true;
+            }
+            i += 1;
+        }
+    }
+}
+
+impl Debug for NTSTR {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        self.print(f)
+    }
+}
+
+impl Display for NTSTR {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        self.print(f)
+    }
+}
\ No newline at end of file
diff --git a/src/tests.rs b/src/tests.rs
new file mode 100644
index 0000000..54387c2
--- /dev/null
+++ b/src/tests.rs
@@ -0,0 +1,167 @@
+use crate::arch::EntryFunction;
+use crate::{Args, call, call_method, IHandle, method_service_result, ntstr, OFW_FALSE, OFW_TRUE, service_result};
+use crate::ntstr::NTSTR;
+
+#[test]
+fn ntstr_macro() {
+    let a = ntstr!("Hello, world!");
+    let b = NTSTR::new(b"Hello, world!\0".as_ptr());
+    assert_eq!(a, b);
+}
+
+#[test]
+fn call_ofw() {
+    pub extern "C" fn test_entry_function(args: *mut Args) -> i32 {
+        #[repr(C)]
+        struct GenericArgs {
+            args: Args,
+            buffer: *mut i32,
+        }
+        let args = unsafe { &mut *(args as *mut GenericArgs) };
+        assert_eq!(args.args.service, ntstr!("test"));
+        assert_eq!(args.args.nargs, 1);
+        assert_eq!(args.args.nrets, 1);
+        // 1 offset from args in buffer
+        unsafe { *(args.buffer.offset(1)) = OFW_FALSE }; // set "missing" to false
+        OFW_TRUE
+    }
+
+    let entry_fn: EntryFunction = test_entry_function;
+    let mut results = service_result!(1,1);
+    call!(entry_fn, results, ntstr!("test"), 1, 1, ntstr!("test"));
+    assert!(results.success);
+    assert_eq!(results.rets[0], OFW_FALSE);
+}
+
+#[test]
+fn call_ofw_missing() {
+    pub extern "C" fn test_entry_function(args: *mut Args) -> i32 {
+        #[repr(C)]
+        struct GenericArgs {
+            args: Args,
+            buffer: *mut i32,
+        }
+        let args = unsafe { &mut *(args as *mut GenericArgs) };
+        assert_eq!(args.args.service, ntstr!("test"));
+        assert_eq!(args.args.nargs, 1);
+        assert_eq!(args.args.nrets, 1);
+        // 1 offset from args in buffer
+        unsafe { *(args.buffer.offset(1)) = OFW_TRUE }; // set "missing" to true
+        OFW_TRUE
+    }
+
+    let entry_fn: EntryFunction = test_entry_function;
+    let mut results = service_result!(1,1);
+    call!(entry_fn, results, ntstr!("test"), 1, 1, ntstr!("aioshjfoahwfi"));
+    assert!(results.success);
+    assert_eq!(results.rets[0], OFW_TRUE);
+}
+
+#[test]
+fn call_ofw_failure() {
+    pub extern "C" fn test_entry_function(args: *mut Args) -> i32 {
+        #[repr(C)]
+        struct GenericArgs {
+            args: Args,
+            buffer: *mut i32,
+        }
+        let args = unsafe { &mut *(args as *mut GenericArgs) };
+        assert_eq!(args.args.service, ntstr!("this-method-does-not-exist"));
+        assert_eq!(args.args.nargs, 1);
+        assert_eq!(args.args.nrets, 1);
+        OFW_FALSE
+    }
+
+    let entry_fn: EntryFunction = test_entry_function;
+    let mut results = service_result!(1,1);
+    call!(entry_fn, results, ntstr!("this-method-does-not-exist"), 1, 1, ntstr!("aioshjfoahwfi"));
+    assert!(!results.success);
+}
+
+#[test]
+fn call_method_ofw() {
+    pub extern "C" fn test_entry_function(args: *mut Args) -> i32 {
+        #[repr(C)]
+        struct CallMethodArgs {
+            args: Args,
+            method: NTSTR,
+            ihandle: IHandle,
+            buffer: *mut i32,
+        }
+        let args = unsafe { &mut *(args as *mut CallMethodArgs) };
+        assert_eq!(args.args.service, ntstr!("call-method"));
+        assert_eq!(args.method, ntstr!("seek"));
+        assert_eq!(args.ihandle, 0);
+        assert_eq!(args.args.nargs, 2 + 2);
+        assert_eq!(args.args.nrets, 1 + 1);
+        // 2 offset from args in buffer
+        unsafe { *(args.buffer.offset(2)) = 1 }; // set catch-result to non-zero
+        unsafe { *(args.buffer.offset(2 + 1)) = OFW_TRUE }; // set okay? to true
+        OFW_TRUE
+    }
+
+    let entry_fn: EntryFunction = test_entry_function;
+    let ih: IHandle = 0;
+    let mut results = method_service_result!(2,1);
+    call_method!(entry_fn, ih, results, ntstr!("seek"), 2, 1, 0, 0);
+    assert!(results.success);
+    assert_eq!(results.rets[0], OFW_TRUE);
+}
+
+#[test]
+fn call_method_ofw_seek_failure() {
+    pub extern "C" fn test_entry_function(args: *mut Args) -> i32 {
+        #[repr(C)]
+        struct CallMethodArgs {
+            args: Args,
+            method: NTSTR,
+            ihandle: IHandle,
+            buffer: *mut i32,
+        }
+        let args = unsafe { &mut *(args as *mut CallMethodArgs) };
+        assert_eq!(args.args.service, ntstr!("call-method"));
+        assert_eq!(args.method, ntstr!("seek"));
+        assert_eq!(args.ihandle, 0);
+        assert_eq!(args.args.nargs, 2 + 2);
+        assert_eq!(args.args.nrets, 1 + 1);
+        // 2 offset from args in buffer
+        unsafe { *(args.buffer.offset(2)) = 1 }; // set catch-result to non-zero
+        unsafe { *(args.buffer.offset(2 + 1)) = OFW_FALSE }; // set okay? to false
+        OFW_TRUE
+    }
+
+    let entry_fn: EntryFunction = test_entry_function;
+    let ih: IHandle = 0;
+    let mut results = method_service_result!(2,1);
+    call_method!(entry_fn, ih, results, ntstr!("seek"), 2, 1, 0, 0);
+    assert!(results.success);
+    assert_eq!(results.rets[0], OFW_FALSE);
+}
+
+#[test]
+fn call_method_ofw_failure() {
+    pub extern "C" fn test_entry_function(args: *mut Args) -> i32 {
+        #[repr(C)]
+        struct CallMethodArgs {
+            args: Args,
+            method: NTSTR,
+            ihandle: IHandle,
+            buffer: *mut i32,
+        }
+        let args = unsafe { &mut *(args as *mut CallMethodArgs) };
+        assert_eq!(args.args.service, ntstr!("call-method"));
+        assert_eq!(args.method, ntstr!("asiofhawoptgh"));
+        assert_eq!(args.ihandle, 0);
+        assert_eq!(args.args.nargs, 2 + 2);
+        assert_eq!(args.args.nrets, 1 + 1);
+        // 2 offset from args in buffer
+        unsafe { *(args.buffer.offset(2)) = 0 }; // set catch-result to 0 (caught error, package doesn't have this method)
+        OFW_TRUE
+    }
+
+    let entry_fn: EntryFunction = test_entry_function;
+    let ih: IHandle = 0;
+    let mut results = method_service_result!(2,1);
+    call_method!(entry_fn, ih, results, ntstr!("asiofhawoptgh"), 2, 1, 0, 0);
+    assert!(!results.success);
+}
\ No newline at end of file