From c5994dd390cb9b61259301c64b9e0f3469975a0d Mon Sep 17 00:00:00 2001
From: Mark Poliakov <mark@alnyan.me>
Date: Sun, 9 Mar 2025 14:42:38 +0200
Subject: [PATCH] libc: implement program_invocation_[short_]name

---
 userspace/dyn-loader/src/env.rs               |  6 +++++-
 userspace/dyn-loader/src/main.rs              |  3 ++-
 userspace/lib/ygglibc/src/env.rs              | 19 +++++++++++++++++++
 .../lib/ygglibc/src/headers/langinfo/mod.rs   |  2 +-
 userspace/lib/ygglibc/src/process.rs          |  8 --------
 5 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/userspace/dyn-loader/src/env.rs b/userspace/dyn-loader/src/env.rs
index d67e53c1..2fd2bdbe 100644
--- a/userspace/dyn-loader/src/env.rs
+++ b/userspace/dyn-loader/src/env.rs
@@ -73,7 +73,7 @@ impl<'a> ArgPlacer<'a> {
     }
 }
 
-pub fn build_argument(args: &[String], auxv: &[AuxValue]) -> Result<usize, Error> {
+pub fn build_argument(args: &[String], binary: &str, auxv: &[AuxValue]) -> Result<usize, Error> {
     let mut buffer = Mapping::new(0x1000, MappingFlags::WRITE)?;
     let arg_base = buffer.as_ptr().addr();
     let mut placer = ArgPlacer::new(&mut buffer[..]);
@@ -93,12 +93,16 @@ pub fn build_argument(args: &[String], auxv: &[AuxValue]) -> Result<usize, Error
     let argv = placer.put_ptr_array(&argv)? + arg_base;
     let envp = placer.put_ptr_array(&envp)? + arg_base;
     let auxv = placer.put_aux_array(auxv)? + arg_base;
+    let real_program = placer.put_str(binary)? + arg_base;
+
+    placer.align(size_of::<usize>())?;
 
     let argument = placer.position + arg_base;
 
     placer.put(&argv)?;
     placer.put(&envp)?;
     placer.put(&auxv)?;
+    placer.put(&real_program)?;
 
     buffer.leak();
 
diff --git a/userspace/dyn-loader/src/main.rs b/userspace/dyn-loader/src/main.rs
index c72eaa20..9a964374 100644
--- a/userspace/dyn-loader/src/main.rs
+++ b/userspace/dyn-loader/src/main.rs
@@ -38,6 +38,7 @@ pub struct Args {
 static mut OBJECTS: MaybeUninit<ObjectSet> = MaybeUninit::uninit();
 
 fn run(binary: &Path, args: &Args) -> Result<!, Error> {
+    let binary_str = binary.to_str().unwrap();
     let mut config = Config::load_or_default()?;
     config.extend_from_env();
 
@@ -128,7 +129,7 @@ fn run(binary: &Path, args: &Args) -> Result<!, Error> {
         OBJECTS.write(objects)
     };
 
-    let argument = env::build_argument(&args.args, &auxv)?;
+    let argument = env::build_argument(&args.args, binary_str, &auxv)?;
     unsafe { enter(entry, argument) };
 }
 
diff --git a/userspace/lib/ygglibc/src/env.rs b/userspace/lib/ygglibc/src/env.rs
index ab6514d8..62e6f47f 100644
--- a/userspace/lib/ygglibc/src/env.rs
+++ b/userspace/lib/ygglibc/src/env.rs
@@ -22,6 +22,11 @@ use crate::{
 
 #[no_mangle]
 pub static mut environ: *mut *mut c_char = null_mut();
+#[no_mangle]
+pub static mut program_invocation_short_name: *mut c_char = null_mut();
+#[no_mangle]
+pub static mut program_invocation_name: *mut c_char = null_mut();
+
 static mut shadow: Vec<*mut c_char> = Vec::new();
 
 unsafe fn get_key(var: NonNull<c_char>) -> Option<&'static [u8]> {
@@ -224,6 +229,20 @@ pub fn handle_kernel_argument(arg: usize) -> Vec<CString> {
         args.push(c_arg);
     }
 
+    if let Some(arg0) = args.get(0) {
+        let invocation_name_str = arg0.to_str().unwrap();
+        let invocation_name = arg0.clone();
+        let invocation_name_short_str =
+            if let Some((_, basename)) = invocation_name_str.rsplit_once('/') {
+                basename.trim()
+            } else {
+                invocation_name_str
+            };
+        let invocation_name_short = CString::new(invocation_name_short_str).unwrap();
+        unsafe { program_invocation_name = invocation_name.into_raw() };
+        unsafe { program_invocation_short_name = invocation_name_short.into_raw() };
+    }
+
     unsafe { setup_env(arg.envs()) };
 
     // Setup TLS from argument
diff --git a/userspace/lib/ygglibc/src/headers/langinfo/mod.rs b/userspace/lib/ygglibc/src/headers/langinfo/mod.rs
index cbb1cd32..2b66d8ac 100644
--- a/userspace/lib/ygglibc/src/headers/langinfo/mod.rs
+++ b/userspace/lib/ygglibc/src/headers/langinfo/mod.rs
@@ -1,4 +1,4 @@
-use core::{ffi::c_char, ptr::null_mut};
+use core::ffi::c_char;
 
 use super::{locale::locale_t, nl_types::nl_item};
 
diff --git a/userspace/lib/ygglibc/src/process.rs b/userspace/lib/ygglibc/src/process.rs
index bae932db..da105559 100644
--- a/userspace/lib/ygglibc/src/process.rs
+++ b/userspace/lib/ygglibc/src/process.rs
@@ -1,7 +1,6 @@
 use core::{
     ffi::{c_char, c_int, c_void, CStr},
     mem::MaybeUninit,
-    ptr::null_mut,
     time::Duration,
 };
 
@@ -30,13 +29,6 @@ impl DsoDestructor {
     }
 }
 
-#[allow(non_upper_case_globals)]
-#[no_mangle]
-static mut program_invocation_short_name: *mut c_char = null_mut();
-#[allow(non_upper_case_globals)]
-#[no_mangle]
-static mut program_invocation_name: *mut c_char = null_mut();
-
 static AT_EXIT: Mutex<Vec<extern "C" fn()>> = Mutex::new(Vec::new());
 // TODO this will be in the linker instead
 static AT_DSO_EXIT: Mutex<Vec<DsoDestructor>> = Mutex::new(Vec::new());