From 3aacc160a14b3c65b4c6feeb456a495a7308a27d Mon Sep 17 00:00:00 2001
From: oddcoder <ahmedsoliman@oddcoder.com>
Date: Mon, 1 Jun 2020 11:49:38 +0200
Subject: [PATCH] Remove dependency on errno in ld.so
During early parts of ld.so, errno and other thread local variables are
not yet initialized so we cannot use function (such as unistd::access)
that depends on such thread local variables (errno). For this reason
this patch creates small wrapper around the syscall that doesn't not
touch the errno
---
src/ld_so/linker.rs | 5 ++++-
src/ld_so/mod.rs | 13 +++++++++++--
2 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/src/ld_so/linker.rs b/src/ld_so/linker.rs
index 4aea9b410..503fe1b7e 100644
--- a/src/ld_so/linker.rs
+++ b/src/ld_so/linker.rs
@@ -29,6 +29,7 @@ use super::{
debug::{RTLDDebug, RTLDState, _dl_debug_state, _r_debug},
tcb::{Master, Tcb},
PAGE_SIZE,
+ access,
};
#[cfg(target_os = "redox")]
@@ -169,7 +170,9 @@ impl Linker {
})?;
// TODO: Use R_OK | X_OK
- unistd::access(path_c.as_ptr(), unistd::F_OK) == 0
+ // We cannot use unix stdlib because errno is thead local variable
+ // and fs:[0] is not set yet.
+ access(path_c.as_ptr(), unistd::F_OK) == 0
};
if access {
diff --git a/src/ld_so/mod.rs b/src/ld_so/mod.rs
index 1d06541ac..46a7a271a 100644
--- a/src/ld_so/mod.rs
+++ b/src/ld_so/mod.rs
@@ -1,8 +1,11 @@
use goblin::elf::program_header::{self, program_header32, program_header64, ProgramHeader};
use self::tcb::{Master, Tcb};
-use crate::start::Stack;
-
+use crate::{
+start::Stack,
+c_str::CStr,
+platform::types::*
+};
pub const PAGE_SIZE: usize = 4096;
pub mod debug;
@@ -80,6 +83,12 @@ pub fn static_init(sp: &'static Stack) {
}
}
+// Wrapper over the systemcall, Do not use outside of ld_so
+pub unsafe fn access(path: *const c_char, mode: c_int) -> c_int {
+ let path = CStr::from_ptr(path);
+ syscall!(ACCESS, (path).as_ptr(), mode) as c_int
+}
+
#[cfg(target_os = "linux")]
pub unsafe fn init(sp: &'static Stack) {
let mut tp = 0usize;
--
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