From d3e59a502be4f3cc2d90a252f0604985320599cc Mon Sep 17 00:00:00 2001
From: Chris Denton <chris@chrisdenton.dev>
Date: Wed, 25 Sep 2024 17:53:57 +0000
Subject: [PATCH] Revert Break into the debugger on panic (129019)
---
library/std/src/panicking.rs | 18 +----
library/std/src/sys/dbg.rs | 152 -----------------------------------
library/std/src/sys/mod.rs | 1 -
3 files changed, 1 insertion(+), 170 deletions(-)
delete mode 100644 library/std/src/sys/dbg.rs
diff --git a/library/std/src/panicking.rs b/library/std/src/panicking.rs
index 336e34d7b95e5..1c972d3810036 100644
--- a/library/std/src/panicking.rs
+++ b/library/std/src/panicking.rs
@@ -23,8 +23,8 @@ use crate::mem::{self, ManuallyDrop};
use crate::panic::{BacktraceStyle, PanicHookInfo};
use crate::sync::atomic::{AtomicBool, Ordering};
use crate::sync::{PoisonError, RwLock};
+use crate::sys::backtrace;
use crate::sys::stdio::panic_output;
-use crate::sys::{backtrace, dbg};
use crate::{fmt, intrinsics, process, thread};
// Binary interface to the panic runtime that the standard library depends on.
@@ -859,14 +859,6 @@ pub fn rust_panic_without_hook(payload: Box<dyn Any + Send>) -> ! {
#[cfg_attr(not(test), rustc_std_internal_symbol)]
#[cfg(not(feature = "panic_immediate_abort"))]
fn rust_panic(msg: &mut dyn PanicPayload) -> ! {
- // Break into the debugger if it is attached.
- // The return value is not currently used.
- //
- // This function isn't used anywhere else, and
- // using inside `#[panic_handler]` doesn't seem
- // to count, so a warning is issued.
- let _ = dbg::breakpoint_if_debugging();
-
let code = unsafe { __rust_start_panic(msg) };
rtabort!("failed to initiate panic, error {code}")
}
@@ -874,14 +866,6 @@ fn rust_panic(msg: &mut dyn PanicPayload) -> ! {
#[cfg_attr(not(test), rustc_std_internal_symbol)]
#[cfg(feature = "panic_immediate_abort")]
fn rust_panic(_: &mut dyn PanicPayload) -> ! {
- // Break into the debugger if it is attached.
- // The return value is not currently used.
- //
- // This function isn't used anywhere else, and
- // using inside `#[panic_handler]` doesn't seem
- // to count, so a warning is issued.
- let _ = dbg::breakpoint_if_debugging();
-
unsafe {
crate::intrinsics::abort();
}
diff --git a/library/std/src/sys/dbg.rs b/library/std/src/sys/dbg.rs
deleted file mode 100644
index 7266a739e785d..0000000000000
--- a/library/std/src/sys/dbg.rs
+++ /dev/null
@@ -1,152 +0,0 @@
-//! Debugging aids.
-
-/// Presence of a debugger. The debugger being concerned
-/// is expected to use the OS API to debug this process.
-#[derive(Copy, Clone, Debug)]
-#[allow(unused)]
-pub(crate) enum DebuggerPresence {
- /// The debugger is attached to this process.
- Detected,
- /// The debugger is not attached to this process.
- NotDetected,
-}
-
-#[cfg(target_os = "windows")]
-mod os {
- use super::DebuggerPresence;
-
- #[link(name = "kernel32")]
- extern "system" {
- fn IsDebuggerPresent() -> i32;
- }
-
- pub(super) fn is_debugger_present() -> Option<DebuggerPresence> {
- // SAFETY: No state is shared between threads. The call reads
- // a field from the Thread Environment Block using the OS API
- // as required by the documentation.
- if unsafe { IsDebuggerPresent() } != 0 {
- Some(DebuggerPresence::Detected)
- } else {
- Some(DebuggerPresence::NotDetected)
- }
- }
-}
-
-#[cfg(any(target_vendor = "apple", target_os = "freebsd"))]
-mod os {
- use libc::{CTL_KERN, KERN_PROC, KERN_PROC_PID, c_int, sysctl};
-
- use super::DebuggerPresence;
- use crate::io::{Cursor, Read, Seek, SeekFrom};
- use crate::process;
-
- const P_TRACED: i32 = 0x00000800;
-
- // The assumption is that the kernel structures available to the
- // user space may not shrink or repurpose the existing fields over
- // time. The kernels normally adhere to that for the backward
- // compatibility of the user space.
-
- // The macOS 14.5 SDK comes with a header `MacOSX14.5.sdk/usr/include/sys/sysctl.h`
- // that defines `struct kinfo_proc` be of `648` bytes on the 64-bit system. That has
- // not changed since macOS 10.13 (released in 2017) at least, validated by building
- // a C program in XCode while changing the build target. Apple provides this example
- // for reference: https://developer.apple.com/library/archive/qa/qa1361/_index.html.
- #[cfg(target_vendor = "apple")]
- const KINFO_PROC_SIZE: usize = if cfg!(target_pointer_width = "64") { 648 } else { 492 };
- #[cfg(target_vendor = "apple")]
- const KINFO_PROC_FLAGS_OFFSET: u64 = if cfg!(target_pointer_width = "64") { 32 } else { 16 };
-
- // Works for FreeBSD stable (13.3, 13.4) and current (14.0, 14.1).
- // The size of the structure has stayed the same for a long time,
- // at least since 2005:
- // https://lists.freebsd.org/pipermail/freebsd-stable/2005-November/019899.html
- #[cfg(target_os = "freebsd")]
- const KINFO_PROC_SIZE: usize = if cfg!(target_pointer_width = "64") { 1088 } else { 768 };
- #[cfg(target_os = "freebsd")]
- const KINFO_PROC_FLAGS_OFFSET: u64 = if cfg!(target_pointer_width = "64") { 368 } else { 296 };
-
- pub(super) fn is_debugger_present() -> Option<DebuggerPresence> {
- debug_assert_ne!(KINFO_PROC_SIZE, 0);
-
- let mut flags = [0u8; 4]; // `ki_flag` under FreeBSD and `p_flag` under macOS.
- let mut mib = [CTL_KERN, KERN_PROC, KERN_PROC_PID, process::id() as c_int];
- let mut info_size = KINFO_PROC_SIZE;
- let mut kinfo_proc = [0u8; KINFO_PROC_SIZE];
-
- // SAFETY: No state is shared with other threads. The sysctl call
- // is safe according to the documentation.
- if unsafe {
- sysctl(
- mib.as_mut_ptr(),
- mib.len() as u32,
- kinfo_proc.as_mut_ptr().cast(),
- &mut info_size,
- core::ptr::null_mut(),
- 0,
- )
- } != 0
- {
- return None;
- }
- debug_assert_eq!(info_size, KINFO_PROC_SIZE);
-
- let mut reader = Cursor::new(kinfo_proc);
- reader.seek(SeekFrom::Start(KINFO_PROC_FLAGS_OFFSET)).ok()?;
- reader.read_exact(&mut flags).ok()?;
- // Just in case, not limiting this to the little-endian systems.
- let flags = i32::from_ne_bytes(flags);
-
- if flags & P_TRACED != 0 {
- Some(DebuggerPresence::Detected)
- } else {
- Some(DebuggerPresence::NotDetected)
- }
- }
-}
-
-#[cfg(not(any(target_os = "windows", target_vendor = "apple", target_os = "freebsd")))]
-mod os {
- pub(super) fn is_debugger_present() -> Option<super::DebuggerPresence> {
- None
- }
-}
-
-/// Detect the debugger presence.
-///
-/// The code does not try to detect the debugger at all costs (e.g., when anti-debugger
-/// tricks are at play), it relies on the interfaces provided by the OS.
-///
-/// Return value:
-/// * `None`: it's not possible to conclude whether the debugger is attached to this
-/// process or not. When checking for the presence of the debugger, the detection logic
-/// encountered an issue, such as the OS API throwing an error or the feature not being
-/// implemented.
-/// * `Some(DebuggerPresence::Detected)`: yes, the debugger is attached
-/// to this process.
-/// * `Some(DebuggerPresence::NotDetected)`: no, the debugger is not
-/// attached to this process.
-pub(crate) fn is_debugger_present() -> Option<DebuggerPresence> {
- if cfg!(miri) { None } else { os::is_debugger_present() }
-}
-
-/// Execute the breakpoint instruction if the debugger presence is detected.
-/// Useful for breaking into the debugger without the need to set a breakpoint
-/// in the debugger.
-///
-/// Note that there is a race between attaching or detaching the debugger, and running the
-/// breakpoint instruction. This is nonetheless memory-safe, like [`crate::process::abort`]
-/// is. In case the debugger is attached and the function is about
-/// to run the breakpoint instruction yet right before that the debugger detaches, the
-/// process will crash due to running the breakpoint instruction and the debugger not
-/// handling the trap exception.
-pub(crate) fn breakpoint_if_debugging() -> Option<DebuggerPresence> {
- let debugger_present = is_debugger_present();
- if let Some(DebuggerPresence::Detected) = debugger_present {
- // SAFETY: Executing the breakpoint instruction. No state is shared
- // or modified by this code.
- unsafe { core::intrinsics::breakpoint() };
- }
-
- debugger_present
-}
diff --git a/library/std/src/sys/mod.rs b/library/std/src/sys/mod.rs
index df25b84fbbe5a..f17dd47decedc 100644
--- a/library/std/src/sys/mod.rs
+++ b/library/std/src/sys/mod.rs
@@ -11,7 +11,6 @@ mod personality;
pub mod anonymous_pipe;
pub mod backtrace;
pub mod cmath;
-pub mod dbg;
pub mod exit_guard;
pub mod os_str;
pub mod path;