unix: change Setrlimit/Prlimit to always call syscall functions

As of Go 1.21 syscall.Setrlimit and syscall.prlimit can affect
starting a new process, by restoring the original NOFILE rlimit.
That is recorded locally in the syscall package, so just always
call the syscall functions.

For golang/go#46279

Change-Id: I2f3dafe5562a7dde1297bad6f5d34a80af5d620b
Reviewed-on: https://go-review.googlesource.com/c/sys/+/476695
Run-TryBot: Ian Lance Taylor <[email protected]>
Run-TryBot: Ian Lance Taylor <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Bryan Mills <[email protected]>
Auto-Submit: Ian Lance Taylor <[email protected]>

Author: ianlancetaylor

unix/darwin_amd64_test.go

@@ -8,7 +8,6 @@
 package unix
 
 //sysnb	Getrlimit(resource int, rlim *Rlimit) (err error) = getrlimit64
-//sysnb	Setrlimit(resource int, rlim *Rlimit) (err error) = setrlimit64
 //sys	Seek(fd int, offset int64, whence int) (off int64, err error) = lseek64
 
 //sys	mmap(addr uintptr, length uintptr, prot int, flags int, fd int, offset int64) (xaddr uintptr, err error)

unix/darwin_arm64_test.go

@@ -8,7 +8,6 @@
 package unix
 
 //sysnb	Getrlimit(resource int, rlim *Rlimit) (err error)
-//sysnb	Setrlimit(resource int, rlim *Rlimit) (err error)
 //sys	Seek(fd int, offset int64, whence int) (off int64, err error) = lseek
 
 //sys	mmap(addr uintptr, length uintptr, prot int, flags int, fd int, offset int64) (xaddr uintptr, err error) = mmap64

unix/syscall_aix_ppc.go

@@ -622,7 +622,6 @@ func SysctlKinfoProcSlice(name string, args ...int) ([]KinfoProc, error) {
 //sys	Setprivexec(flag int) (err error)
 //sysnb	Setregid(rgid int, egid int) (err error)
 //sysnb	Setreuid(ruid int, euid int) (err error)
-//sysnb	Setrlimit(which int, lim *Rlimit) (err error)
 //sysnb	Setsid() (pid int, err error)
 //sysnb	Settimeofday(tp *Timeval) (err error)
 //sysnb	Setuid(uid int) (err error)

unix/syscall_aix_ppc64.go

@@ -326,7 +326,6 @@ func Sendfile(outfd int, infd int, offset *int64, count int) (written int, err e
 //sysnb	Setreuid(ruid int, euid int) (err error)
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error)
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error)
-//sysnb	Setrlimit(which int, lim *Rlimit) (err error)
 //sysnb	Setsid() (pid int, err error)
 //sysnb	Settimeofday(tp *Timeval) (err error)
 //sysnb	Setuid(uid int) (err error)

unix/syscall_darwin.go

@@ -433,7 +433,6 @@ func Dup3(oldfd, newfd, flags int) error {
 //sysnb	Setreuid(ruid int, euid int) (err error)
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error)
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error)
-//sysnb	Setrlimit(which int, lim *Rlimit) (err error)
 //sysnb	Setsid() (pid int, err error)
 //sysnb	Settimeofday(tp *Timeval) (err error)
 //sysnb	Setuid(uid int) (err error)

unix/syscall_dragonfly.go

@@ -1873,7 +1873,6 @@ func Getpgrp() (pid int) {
 //sys	OpenTree(dfd int, fileName string, flags uint) (r int, err error)
 //sys	PerfEventOpen(attr *PerfEventAttr, pid int, cpu int, groupFd int, flags int) (fd int, err error)
 //sys	PivotRoot(newroot string, putold string) (err error) = SYS_PIVOT_ROOT
-//sysnb	Prlimit(pid int, resource int, newlimit *Rlimit, old *Rlimit) (err error) = SYS_PRLIMIT64
 //sys	Prctl(option int, arg2 uintptr, arg3 uintptr, arg4 uintptr, arg5 uintptr) (err error)
 //sys	Pselect(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timespec, sigmask *Sigset_t) (n int, err error) = SYS_PSELECT6
 //sys	read(fd int, p []byte) (n int, err error)
@@ -1887,6 +1886,15 @@ func Getpgrp() (pid int) {
 //sysnb	Settimeofday(tv *Timeval) (err error)
 //sys	Setns(fd int, nstype int) (err error)
 
+//go:linkname syscall_prlimit syscall.prlimit
+func syscall_prlimit(pid, resource int, newlimit, old *syscall.Rlimit) error
+
+func Prlimit(pid, resource int, newlimit, old *Rlimit) error {
+	// Just call the syscall version, because as of Go 1.21
+	// it will affect starting a new process.
+	return syscall_prlimit(pid, resource, (*syscall.Rlimit)(newlimit), (*syscall.Rlimit)(old))
+}
+
 // PrctlRetInt performs a prctl operation specified by option and further
 // optional arguments arg2 through arg5 depending on option. It returns a
 // non-negative integer that is returned by the prctl syscall.

unix/syscall_freebsd.go

@@ -97,33 +97,6 @@ func Getrlimit(resource int, rlim *Rlimit) (err error) {
 	return
 }
 
-//sysnb	setrlimit(resource int, rlim *rlimit32) (err error) = SYS_SETRLIMIT
-
-func Setrlimit(resource int, rlim *Rlimit) (err error) {
-	err = Prlimit(0, resource, rlim, nil)
-	if err != ENOSYS {
-		return err
-	}
-
-	rl := rlimit32{}
-	if rlim.Cur == rlimInf64 {
-		rl.Cur = rlimInf32
-	} else if rlim.Cur < uint64(rlimInf32) {
-		rl.Cur = uint32(rlim.Cur)
-	} else {
-		return EINVAL
-	}
-	if rlim.Max == rlimInf64 {
-		rl.Max = rlimInf32
-	} else if rlim.Max < uint64(rlimInf32) {
-		rl.Max = uint32(rlim.Max)
-	} else {
-		return EINVAL
-	}
-
-	return setrlimit(resource, &rl)
-}
-
 func Seek(fd int, offset int64, whence int) (newoffset int64, err error) {
 	newoffset, errno := seek(fd, offset, whence)
 	if errno != 0 {

unix/syscall_linux.go

@@ -46,7 +46,6 @@ func Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error)
 //sys	setfsgid(gid int) (prev int, err error)
 //sys	setfsuid(uid int) (prev int, err error)
-//sysnb	Setrlimit(resource int, rlim *Rlimit) (err error)
 //sys	Shutdown(fd int, how int) (err error)
 //sys	Splice(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int64, err error)