runtime: revert use of __fork to work around Apple atfork bugs

An Apple engineer suggests that since __fork is not public API,
it would be better to use a different fix. With the benefit of source code,
they suggest using xpc_date_create_from_current instead of
xpc_atfork_child. The latter sets some flags that disable certain
functionality for the remainder of the process lifetime (expecting exec),
while the former should do the necessary setup.

Reverting the __fork fix in order to prepare a clean fix based
on CL 451735 using xpc_date_create_from_current.

This reverts commit c61d322d5f9e3fcffa4c523892af432dca030c12.

Change-Id: I2da293ff537237ffd2d40ad756d827c95c84635b
Reviewed-on: https://go-review.googlesource.com/c/go/+/460475
Auto-Submit: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>

diff --git a/src/syscall/exec_libc2.go b/src/syscall/exec_libc2.go
index 6e3c2bf9d7608f6671e33731248470d7a18a1577..41bc79a721e7d4fa186d1896888f5f0b88e90732 100644 (file)
--- a/src/syscall/exec_libc2.go
+++ b/src/syscall/exec_libc2.go
@@ -78,7 +78,7 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
        // About to call fork.
        // No more allocation or calls of non-assembly functions.
        runtime_BeforeFork()
-       r1, _, err1 = rawSyscall(forkTrampoline, 0, 0, 0)
+       r1, _, err1 = rawSyscall(abi.FuncPCABI0(libc_fork_trampoline), 0, 0, 0)
        if err1 != 0 {
                runtime_AfterFork()
                return 0, err1
@@ -276,6 +276,6 @@ childerror:
        // send error code on pipe
        rawSyscall(abi.FuncPCABI0(libc_write_trampoline), uintptr(pipe), uintptr(unsafe.Pointer(&err1)), unsafe.Sizeof(err1))
        for {
-               rawSyscall(exitTrampoline, 253, 0, 0)
+               rawSyscall(abi.FuncPCABI0(libc_exit_trampoline), 253, 0, 0)
        }
 }

diff --git a/src/syscall/syscall_darwin.go b/src/syscall/syscall_darwin.go
index 5ec311962a5a42d7b5018e5bb6992ced9963b3ee..a39e99dc633a86df864a1d1e820bcc138b2db4c2 100644 (file)
--- a/src/syscall/syscall_darwin.go
+++ b/src/syscall/syscall_darwin.go
@@ -22,34 +22,7 @@ func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)
 func RawSyscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno)
 func RawSyscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)
 
-// These are called from exec_libc2.go in the child of fork.
-// The names differ between macOS and OpenBSD, so we need
-// to declare the specific ones used here to keep the exec_libc2.go
-// code portable.
-//
-// We use __fork and __exit, not fork and exit, to avoid the libc atfork
-// and atexit handlers. The atfork handlers have caused fork child
-// hangs in the past (see #33565, #56784). The atexit handlers have
-// not, but the non-libc ports all invoke the system call, so doing
-// the same here makes sense. In general we wouldn't expect
-// atexit handlers to work terribly well in a fork child anyway.
-// (Also, perhaps the atfork handlers clear the atexit handlers,
-// in which case we definitely need to avoid calling the libc exit
-// if we bypass the libc fork.)
-//
-// Other calls that are made in the child after the fork are
-// ptrace, setsid, setpgid, getpid, ioctl, chroot, setgroups,
-// setgid, setuid, chdir, dup2, fcntl, close, execve, and write.
-// Those are all simple kernel wrappers that should be safe
-// to be called directly. The fcntl and ioctl functions do run
-// some code around the kernel call, but they don't call any
-// other functions, so for now we keep using them instead of
-// calling the lower-level __fcntl and __ioctl functions.
-var (
-       dupTrampoline  = abi.FuncPCABI0(libc_dup2_trampoline)
-       exitTrampoline = abi.FuncPCABI0(libc___exit_trampoline)
-       forkTrampoline = abi.FuncPCABI0(libc___fork_trampoline)
-)
+var dupTrampoline = abi.FuncPCABI0(libc_dup2_trampoline)
 
 type SockaddrDatalink struct {
        Len    uint8
@@ -237,12 +210,11 @@ func Kill(pid int, signum Signal) (err error) { return kill(pid, int(signum), 1)
 //sys  writev(fd int, iovecs []Iovec) (cnt uintptr, err error)
 //sys   mmap(addr uintptr, length uintptr, prot int, flag int, fd int, pos int64) (ret uintptr, err error)
 //sys   munmap(addr uintptr, length uintptr) (err error)
-//sysnb __fork() (pid int, err error)
+//sysnb fork() (pid int, err error)
 //sysnb ioctl(fd int, req int, arg int) (err error)
 //sysnb ioctlPtr(fd int, req uint, arg unsafe.Pointer) (err error) = SYS_ioctl
 //sysnb execve(path *byte, argv **byte, envp **byte) (err error)
 //sysnb exit(res int) (err error)
-//sysnb __exit(res int) (err error)
 //sys  sysctl(mib []_C_int, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error)
 //sys  fcntlPtr(fd int, cmd int, arg unsafe.Pointer) (val int, err error) = SYS_fcntl
 //sys   unlinkat(fd int, path string, flags int) (err error)

diff --git a/src/syscall/syscall_openbsd_libc.go b/src/syscall/syscall_openbsd_libc.go
index 6358a9a390a0c3298946e6e6bc139adc5a21317c..516d02975c530a3ea1aea3b826039f7891797c80 100644 (file)
--- a/src/syscall/syscall_openbsd_libc.go
+++ b/src/syscall/syscall_openbsd_libc.go
@@ -10,11 +10,7 @@ import (
        "internal/abi"
 )
 
-var (
-       dupTrampoline  = abi.FuncPCABI0(libc_dup3_trampoline)
-       exitTrampoline = abi.FuncPCABI0(libc_exit_trampoline)
-       forkTrampoline = abi.FuncPCABI0(libc_fork_trampoline)
-)
+var dupTrampoline = abi.FuncPCABI0(libc_dup3_trampoline)
 
 func init() {
        execveOpenBSD = execve

diff --git a/src/syscall/zsyscall_darwin_amd64.go b/src/syscall/zsyscall_darwin_amd64.go
index 5e3f6cccf0053b24db7c6b3bc5bc3df228f6f5f0..6b3fff3f3726a224ad1c6bbdc856eec18e73fdfe 100644 (file)
--- a/src/syscall/zsyscall_darwin_amd64.go
+++ b/src/syscall/zsyscall_darwin_amd64.go
@@ -1734,8 +1734,8 @@ func libc_munmap_trampoline()
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func __fork() (pid int, err error) {
-       r0, _, e1 := rawSyscall(abi.FuncPCABI0(libc___fork_trampoline), 0, 0, 0)
+func fork() (pid int, err error) {
+       r0, _, e1 := rawSyscall(abi.FuncPCABI0(libc_fork_trampoline), 0, 0, 0)
        pid = int(r0)
        if e1 != 0 {
                err = errnoErr(e1)
@@ -1743,9 +1743,9 @@ func __fork() (pid int, err error) {
        return
 }
 
-func libc___fork_trampoline()
+func libc_fork_trampoline()
 
-//go:cgo_import_dynamic libc___fork __fork "/usr/lib/libSystem.B.dylib"
+//go:cgo_import_dynamic libc_fork fork "/usr/lib/libSystem.B.dylib"
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
@@ -1801,20 +1801,6 @@ func libc_exit_trampoline()
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func __exit(res int) (err error) {
-       _, _, e1 := rawSyscall(abi.FuncPCABI0(libc___exit_trampoline), uintptr(res), 0, 0)
-       if e1 != 0 {
-               err = errnoErr(e1)
-       }
-       return
-}
-
-func libc___exit_trampoline()
-
-//go:cgo_import_dynamic libc___exit __exit "/usr/lib/libSystem.B.dylib"
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
 func sysctl(mib []_C_int, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error) {
        var _p0 unsafe.Pointer
        if len(mib) > 0 {

diff --git a/src/syscall/zsyscall_darwin_amd64.s b/src/syscall/zsyscall_darwin_amd64.s
index cbb4496a50ed16b6347b9aeaba30bf6552d552b4..90e51fb9a4f43a63b4fff6150a47626b4d6c1135 100644 (file)
--- a/src/syscall/zsyscall_darwin_amd64.s
+++ b/src/syscall/zsyscall_darwin_amd64.s
@@ -221,16 +221,14 @@ TEXT ·libc_mmap_trampoline(SB),NOSPLIT,$0-0
        JMP     libc_mmap(SB)
 TEXT ·libc_munmap_trampoline(SB),NOSPLIT,$0-0
        JMP     libc_munmap(SB)
-TEXT ·libc___fork_trampoline(SB),NOSPLIT,$0-0
-       JMP     libc___fork(SB)
+TEXT ·libc_fork_trampoline(SB),NOSPLIT,$0-0
+       JMP     libc_fork(SB)
 TEXT ·libc_ioctl_trampoline(SB),NOSPLIT,$0-0
        JMP     libc_ioctl(SB)
 TEXT ·libc_execve_trampoline(SB),NOSPLIT,$0-0
        JMP     libc_execve(SB)
 TEXT ·libc_exit_trampoline(SB),NOSPLIT,$0-0
        JMP     libc_exit(SB)
-TEXT ·libc___exit_trampoline(SB),NOSPLIT,$0-0
-       JMP     libc___exit(SB)
 TEXT ·libc_sysctl_trampoline(SB),NOSPLIT,$0-0
        JMP     libc_sysctl(SB)
 TEXT ·libc_unlinkat_trampoline(SB),NOSPLIT,$0-0

diff --git a/src/syscall/zsyscall_darwin_arm64.go b/src/syscall/zsyscall_darwin_arm64.go
index d4c56be8188518e6702f10d59ee74ea7f4d54c68..61601449a04043f185cd640cd3599af492d565cd 100644 (file)
--- a/src/syscall/zsyscall_darwin_arm64.go
+++ b/src/syscall/zsyscall_darwin_arm64.go
@@ -1734,8 +1734,8 @@ func libc_munmap_trampoline()
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func __fork() (pid int, err error) {
-       r0, _, e1 := rawSyscall(abi.FuncPCABI0(libc___fork_trampoline), 0, 0, 0)
+func fork() (pid int, err error) {
+       r0, _, e1 := rawSyscall(abi.FuncPCABI0(libc_fork_trampoline), 0, 0, 0)
        pid = int(r0)
        if e1 != 0 {
                err = errnoErr(e1)
@@ -1743,9 +1743,9 @@ func __fork() (pid int, err error) {
        return
 }
 
-func libc___fork_trampoline()
+func libc_fork_trampoline()
 
-//go:cgo_import_dynamic libc___fork __fork "/usr/lib/libSystem.B.dylib"
+//go:cgo_import_dynamic libc_fork fork "/usr/lib/libSystem.B.dylib"
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
@@ -1801,20 +1801,6 @@ func libc_exit_trampoline()
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func __exit(res int) (err error) {
-       _, _, e1 := rawSyscall(abi.FuncPCABI0(libc___exit_trampoline), uintptr(res), 0, 0)
-       if e1 != 0 {
-               err = errnoErr(e1)
-       }
-       return
-}
-
-func libc___exit_trampoline()
-
-//go:cgo_import_dynamic libc___exit __exit "/usr/lib/libSystem.B.dylib"
-
-// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
-
 func sysctl(mib []_C_int, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error) {
        var _p0 unsafe.Pointer
        if len(mib) > 0 {

diff --git a/src/syscall/zsyscall_darwin_arm64.s b/src/syscall/zsyscall_darwin_arm64.s
index ce1850e0aef5a81d1694d2eb59f24c8dc3adb3bb..f00747939efa36d38d2f920b79169fe31eab8e64 100644 (file)
--- a/src/syscall/zsyscall_darwin_arm64.s
+++ b/src/syscall/zsyscall_darwin_arm64.s
@@ -221,16 +221,14 @@ TEXT ·libc_mmap_trampoline(SB),NOSPLIT,$0-0
        JMP     libc_mmap(SB)
 TEXT ·libc_munmap_trampoline(SB),NOSPLIT,$0-0
        JMP     libc_munmap(SB)
-TEXT ·libc___fork_trampoline(SB),NOSPLIT,$0-0
-       JMP     libc___fork(SB)
+TEXT ·libc_fork_trampoline(SB),NOSPLIT,$0-0
+       JMP     libc_fork(SB)
 TEXT ·libc_ioctl_trampoline(SB),NOSPLIT,$0-0
        JMP     libc_ioctl(SB)
 TEXT ·libc_execve_trampoline(SB),NOSPLIT,$0-0
        JMP     libc_execve(SB)
 TEXT ·libc_exit_trampoline(SB),NOSPLIT,$0-0
        JMP     libc_exit(SB)
-TEXT ·libc___exit_trampoline(SB),NOSPLIT,$0-0
-       JMP     libc___exit(SB)
 TEXT ·libc_sysctl_trampoline(SB),NOSPLIT,$0-0
        JMP     libc_sysctl(SB)
 TEXT ·libc_unlinkat_trampoline(SB),NOSPLIT,$0-0