From e35f22b3dfe8b2727ccf3fb94430c104ef0753cd Mon Sep 17 00:00:00 2001
From: jD91mZM2 <me@krake.one>
Date: Sun, 28 Apr 2019 17:14:45 +0200
Subject: [PATCH] WIP: pthread_atfork
WIP mainly because we *should* use thread locals, but #[thread_local]
causes segfaults.
---
src/header/unistd/mod.rs | 43 +++++++++++++++++++++++++++----
tests/Makefile | 1 +
tests/expected/unistd/fork.stderr | 0
tests/expected/unistd/fork.stdout | 3 +++
tests/unistd/fork.c | 29 +++++++++++++++++++++
5 files changed, 71 insertions(+), 5 deletions(-)
create mode 100644 tests/expected/unistd/fork.stderr
create mode 100644 tests/expected/unistd/fork.stdout
create mode 100644 tests/unistd/fork.c
diff --git a/src/header/unistd/mod.rs b/src/header/unistd/mod.rs
index c7e483535..6145c2c79 100644
--- a/src/header/unistd/mod.rs
+++ b/src/header/unistd/mod.rs
@@ -2,6 +2,7 @@
use core::{mem, ptr, slice};
+use alloc::collections::LinkedList;
use c_str::CStr;
use header::errno;
use header::limits;
@@ -10,9 +11,9 @@ use header::sys_ioctl;
use header::sys_time;
use header::termios;
use header::time::timespec;
-use platform;
use platform::types::*;
use platform::{Pal, Sys};
+use platform;
pub use self::brk::*;
pub use self::getopt::*;
@@ -42,6 +43,17 @@ pub const STDIN_FILENO: c_int = 0;
pub const STDOUT_FILENO: c_int = 1;
pub const STDERR_FILENO: c_int = 2;
+#[thread_local]
+pub static mut fork_hooks_static: Option<[LinkedList<extern "C" fn()>; 3]> = None;
+
+unsafe fn init_fork_hooks<'a>() -> &'a mut [LinkedList<extern "C" fn()>; 3] {
+ // Transmute the lifetime so we can return here. Should be safe as
+ // long as one does not access the original fork_hooks.
+ mem::transmute(fork_hooks_static.get_or_insert_with(|| {
+ [LinkedList::new(), LinkedList::new(), LinkedList::new()]
+ }))
+}
+
#[no_mangle]
pub extern "C" fn _exit(status: c_int) {
Sys::exit(status)
@@ -214,7 +226,21 @@ pub extern "C" fn fdatasync(fildes: c_int) -> c_int {
#[no_mangle]
pub extern "C" fn fork() -> pid_t {
- Sys::fork()
+ let fork_hooks = unsafe { init_fork_hooks() };
+ for prepare in &fork_hooks[0] {
+ prepare();
+ }
+ let pid = Sys::fork();
+ if pid == 0 {
+ for child in &fork_hooks[2] {
+ child();
+ }
+ } else if pid != -1 {
+ for parent in &fork_hooks[1] {
+ parent();
+ }
+ }
+ pid
}
#[no_mangle]
@@ -456,9 +482,16 @@ pub extern "C" fn pthread_atfork(
parent: Option<extern "C" fn()>,
child: Option<extern "C" fn()>,
) -> c_int {
- // TODO: WIP implementation available in "atfork" branch. It's
- // segfaulting at the thread-local stuff, both in Unix and Redox.
- // unimplemented!();
+ let fork_hooks = unsafe { init_fork_hooks() };
+ if let Some(prepare) = prepare {
+ fork_hooks[0].push_back(prepare);
+ }
+ if let Some(parent) = parent {
+ fork_hooks[1].push_back(parent);
+ }
+ if let Some(child) = child {
+ fork_hooks[2].push_back(child);
+ }
0
}
diff --git a/tests/Makefile b/tests/Makefile
index 3530a5ca3..6ec439803 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -77,6 +77,7 @@ EXPECT_NAMES=\
unistd/dup \
unistd/exec \
unistd/fchdir \
+ unistd/fork \
unistd/fsync \
unistd/ftruncate \
unistd/getopt \
diff --git a/tests/expected/unistd/fork.stderr b/tests/expected/unistd/fork.stderr
new file mode 100644
index 000000000..e69de29bb
diff --git a/tests/expected/unistd/fork.stdout b/tests/expected/unistd/fork.stdout
new file mode 100644
index 000000000..98f331c9d
--- /dev/null
+++ b/tests/expected/unistd/fork.stdout
@@ -0,0 +1,3 @@
+Hello from prepare
+Hello from child
+Hello from parent
diff --git a/tests/unistd/fork.c b/tests/unistd/fork.c
new file mode 100644
index 000000000..eb9b84ac2
--- /dev/null
+++ b/tests/unistd/fork.c
@@ -0,0 +1,29 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "test_helpers.h"
+
+void prepare() {
+ puts("Hello from prepare");
+}
+void parent() {
+ // Make sure we print in the right order and also don't exit
+ // before the fork does.
+ int us_status = usleep(1000);
+ ERROR_IF(usleep, us_status, == -1);
+ UNEXP_IF(usleep, us_status, != 0);
+
+ puts("Hello from parent");
+}
+void child() {
+ puts("Hello from child");
+}
+
+int main(void) {
+ int status = pthread_atfork(prepare, parent, child);
+ ERROR_IF(pthread_atfork, status, == -1);
+
+ int pid = fork();
+ ERROR_IF(fork, pid, == -1);
+}
--
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