From 4e5ccbffd165bb1c0a019928ac72f2f75adfd906 Mon Sep 17 00:00:00 2001
From: 4lDO2 <4lDO2@protonmail.com>
Date: Sat, 23 Jul 2022 16:24:02 +0200
Subject: [PATCH] Allow constructors to access env vars.
---
src/ld_so/linker.rs | 8 ++++++++
src/ld_so/start.rs | 16 ++++++++++++++++
src/start.rs | 33 +++++++++++++++++++++++++--------
3 files changed, 49 insertions(+), 8 deletions(-)
diff --git a/src/ld_so/linker.rs b/src/ld_so/linker.rs
index e8cf6ccf..a1a517f7 100644
--- a/src/ld_so/linker.rs
+++ b/src/ld_so/linker.rs
@@ -472,7 +472,15 @@ impl Linker {
}
fn run_init(&self, objects: &Vec<DSO>) {
+ use crate::platform::{self, types::*};
+
for obj in objects.iter().rev() {
+ if let Some((symbol, true)) = obj.get_sym("__relibc_init_environ") {
+ unsafe {
+ symbol.as_ptr().cast::<*mut *mut c_char>().write(platform::environ);
+ }
+ }
+
obj.run_init();
}
}
diff --git a/src/ld_so/start.rs b/src/ld_so/start.rs
index 25a1f16d..e07afac1 100644
--- a/src/ld_so/start.rs
+++ b/src/ld_so/start.rs
@@ -167,6 +167,22 @@ pub extern "C" fn relibc_ld_so_start(sp: &'static mut Stack, ld_entry: usize) ->
(argv, envs, auxv)
};
+ unsafe {
+ crate::platform::OUR_ENVIRON = envs.iter().map(|(k, v)| {
+ let mut var = Vec::with_capacity(k.len() + v.len() + 2);
+ var.extend(k.as_bytes());
+ var.push(b'=');
+ var.extend(v.as_bytes());
+ var.push(b'\0');
+ let mut var = var.into_boxed_slice();
+ let ptr = var.as_mut_ptr();
+ core::mem::forget(var);
+ ptr.cast()
+ }).chain(core::iter::once(core::ptr::null_mut())).collect::<Vec<_>>();
+
+ crate::platform::environ = crate::platform::OUR_ENVIRON.as_mut_ptr();
+ }
+
let is_manual = if let Some(img_entry) = auxv.get(&AT_ENTRY) {
*img_entry == ld_entry
} else {
diff --git a/src/start.rs b/src/start.rs
index cee25f33..9ec0eb76 100644
--- a/src/start.rs
+++ b/src/start.rs
@@ -67,7 +67,16 @@ static INIT_ARRAY: [extern "C" fn(); 1] = [init_array];
static mut init_complete: bool = false;
+#[used]
+#[no_mangle]
+static mut __relibc_init_environ: *mut *mut c_char = ptr::null_mut();
+
fn alloc_init() {
+ unsafe {
+ if init_complete {
+ return;
+ }
+ }
unsafe {
if let Some(tcb) = ld_so::tcb::Tcb::current() {
if tcb.mspace != 0 {
@@ -96,6 +105,10 @@ extern "C" fn init_array() {
alloc_init();
io_init();
+ unsafe {
+ platform::environ = __relibc_init_environ;
+ }
+
extern "C" {
fn pthread_init();
}
@@ -155,15 +168,19 @@ pub unsafe extern "C" fn relibc_start(sp: &'static Stack) -> ! {
platform::program_invocation_name = *arg;
platform::program_invocation_short_name = libgen::basename(*arg);
}
-
- // Set up envp
- let envp = sp.envp();
- let mut len = 0;
- while !(*envp.add(len)).is_null() {
- len += 1;
+ // We check for NULL here since ld.so might already have initialized it for us, and we don't
+ // want to overwrite it if constructors in .init_array of dependency libraries have called
+ // setenv.
+ if platform::environ.is_null() {
+ // Set up envp
+ let envp = sp.envp();
+ let mut len = 0;
+ while !(*envp.add(len)).is_null() {
+ len += 1;
+ }
+ platform::OUR_ENVIRON = copy_string_array(envp, len);
+ platform::environ = platform::OUR_ENVIRON.as_mut_ptr();
}
- platform::OUR_ENVIRON = copy_string_array(envp, len);
- platform::environ = platform::OUR_ENVIRON.as_mut_ptr();
// Setup signal stack, otherwise we cannot handle any signals besides SIG_IGN/SIG_DFL behavior.
setup_sigstack();
--
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