syscall: restore original NOFILE rlimit in child process

If we increased the NOFILE rlimit when starting the program,
restore the original rlimit when forking a child process.

For #46279

Change-Id: Ia5d2af9ef435e5932965c15eec2e428d2130d230
Reviewed-on: https://go-review.googlesource.com/c/go/+/476097
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Bypass: Ian Lance Taylor <iant@google.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/src/syscall/syscall_linux_loong64.go b/src/syscall/syscall_linux_loong64.go
index 5a0fa0834d..f8f01c2d22 100644
--- a/src/syscall/syscall_linux_loong64.go
+++ b/src/syscall/syscall_linux_loong64.go
@@ -187,11 +187,17 @@ func Getrlimit(resource int, rlim *Rlimit) error {
 	return prlimit(0, resource, nil, rlim)
 }
 
-// Setrlimit prefers the prlimit64 system call.
-func Setrlimit(resource int, rlim *Rlimit) error {
+// setrlimit prefers the prlimit64 system call.
+func setrlimit(resource int, rlim *Rlimit) error {
 	return prlimit(0, resource, rlim, nil)
 }
 
+//go:nosplit
+func rawSetrlimit(resource int, rlim *Rlimit) Errno {
+	_, _, errno := RawSyscall6(SYS_PRLIMIT64, 0, uintptr(resource), uintptr(unsafe.Pointer(rlim)), 0, 0, 0)
+	return errno
+}
+
 func (r *PtraceRegs) GetEra() uint64 { return r.Era }
 
 func (r *PtraceRegs) SetEra(era uint64) { r.Era = era }