unix: add new setfsuid/setfsgid wrappers

Added SetfsgidRetGid and SetfsuidRetUid wrappers for corresponding
syscalls, both returning previous gid or uid set.

Fixes golang/go#36649

Change-Id: I95176f4442258ca68db79cf967fbf0bbf0a57acf
Reviewed-on: https://go-review.googlesource.com/c/sys/+/215579
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

unix/syscall_linux.go

diff --git a/unix/syscall_linux.go b/unix/syscall_linux.go
index b8837fc..0efe45a 100644
--- a/unix/syscall_linux.go
+++ b/unix/syscall_linux.go
@@ -1654,6 +1654,30 @@
 	return EOPNOTSUPP
 }
 
+// SetfsgidRetGid sets fsgid for current thread and returns previous fsgid set.
+// setfsgid(2) will return a non-nil error only if its caller lacks CAP_SETUID capability.
+// If the call fails due to other reasons, current fsgid will be returned.
+func SetfsgidRetGid(gid int) (int, error) {
+	return setfsgid(gid)
+}
+
+// SetfsuidRetUid sets fsuid for current thread and returns previous fsuid set.
+// setfsgid(2) will return a non-nil error only if its caller lacks CAP_SETUID capability
+// If the call fails due to other reasons, current fsuid will be returned.
+func SetfsuidRetUid(uid int) (int, error) {
+	return setfsuid(uid)
+}
+
+func Setfsgid(gid int) error {
+	_, err := setfsgid(gid)
+	return err
+}
+
+func Setfsuid(uid int) error {
+	_, err := setfsuid(uid)
+	return err
+}
+
 func Signalfd(fd int, sigmask *Sigset_t, flags int) (newfd int, err error) {
 	return signalfd(fd, sigmask, _C__NSIG/8, flags)
 }

unix/syscall_linux_386.go

diff --git a/unix/syscall_linux_386.go b/unix/syscall_linux_386.go
index e7fa665..a8374b6 100644
--- a/unix/syscall_linux_386.go
+++ b/unix/syscall_linux_386.go
@@ -70,8 +70,8 @@
 //sys	Pwrite(fd int, p []byte, offset int64) (n int, err error) = SYS_PWRITE64
 //sys	Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) (err error)
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) = SYS_SENDFILE64
-//sys	Setfsgid(gid int) (err error) = SYS_SETFSGID32
-//sys	Setfsuid(uid int) (err error) = SYS_SETFSUID32
+//sys	setfsgid(gid int) (prev int, err error) = SYS_SETFSGID32
+//sys	setfsuid(uid int) (prev int, err error) = SYS_SETFSUID32
 //sysnb	Setregid(rgid int, egid int) (err error) = SYS_SETREGID32
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error) = SYS_SETRESGID32
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error) = SYS_SETRESUID32

unix/syscall_linux_amd64.go

diff --git a/unix/syscall_linux_amd64.go b/unix/syscall_linux_amd64.go
index 088ce0f..8ed1d54 100644
--- a/unix/syscall_linux_amd64.go
+++ b/unix/syscall_linux_amd64.go
@@ -55,8 +55,8 @@
 }
 
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error)
-//sys	Setfsgid(gid int) (err error)
-//sys	Setfsuid(uid int) (err error)
+//sys	setfsgid(gid int) (prev int, err error)
+//sys	setfsuid(uid int) (prev int, err error)
 //sysnb	Setregid(rgid int, egid int) (err error)
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error)
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error)

unix/syscall_linux_arm.go

diff --git a/unix/syscall_linux_arm.go b/unix/syscall_linux_arm.go
index 11930fc..99ae613 100644
--- a/unix/syscall_linux_arm.go
+++ b/unix/syscall_linux_arm.go
@@ -98,8 +98,8 @@
 //sys	Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) (err error)
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) = SYS_SENDFILE64
 //sys	Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err error) = SYS__NEWSELECT
-//sys	Setfsgid(gid int) (err error) = SYS_SETFSGID32
-//sys	Setfsuid(uid int) (err error) = SYS_SETFSUID32
+//sys	setfsgid(gid int) (prev int, err error) = SYS_SETFSGID32
+//sys	setfsuid(uid int) (prev int, err error) = SYS_SETFSUID32
 //sysnb	Setregid(rgid int, egid int) (err error) = SYS_SETREGID32
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error) = SYS_SETRESGID32
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error) = SYS_SETRESUID32

unix/syscall_linux_arm64.go

diff --git a/unix/syscall_linux_arm64.go b/unix/syscall_linux_arm64.go
index 251e2d9..807a0b2 100644
--- a/unix/syscall_linux_arm64.go
+++ b/unix/syscall_linux_arm64.go
@@ -42,8 +42,8 @@
 }
 
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error)
-//sys	Setfsgid(gid int) (err error)
-//sys	Setfsuid(uid int) (err error)
+//sys	setfsgid(gid int) (prev int, err error)
+//sys	setfsuid(uid int) (prev int, err error)
 //sysnb	Setregid(rgid int, egid int) (err error)
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error)
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error)

unix/syscall_linux_mips64x.go

diff --git a/unix/syscall_linux_mips64x.go b/unix/syscall_linux_mips64x.go
index 7562fe9..e9d2f1d 100644
--- a/unix/syscall_linux_mips64x.go
+++ b/unix/syscall_linux_mips64x.go
@@ -36,8 +36,8 @@
 }
 
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error)
-//sys	Setfsgid(gid int) (err error)
-//sys	Setfsuid(uid int) (err error)
+//sys	setfsgid(gid int) (prev int, err error)
+//sys	setfsuid(uid int) (prev int, err error)
 //sysnb	Setregid(rgid int, egid int) (err error)
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error)
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error)

unix/syscall_linux_mipsx.go

diff --git a/unix/syscall_linux_mipsx.go b/unix/syscall_linux_mipsx.go
index a939ff8..e286c6b 100644
--- a/unix/syscall_linux_mipsx.go
+++ b/unix/syscall_linux_mipsx.go
@@ -31,8 +31,8 @@
 //sys	Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) (err error)
 //sys	Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err error) = SYS__NEWSELECT
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) = SYS_SENDFILE64
-//sys	Setfsgid(gid int) (err error)
-//sys	Setfsuid(uid int) (err error)
+//sys	setfsgid(gid int) (prev int, err error)
+//sys	setfsuid(uid int) (prev int, err error)
 //sysnb	Setregid(rgid int, egid int) (err error)
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error)
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error)

unix/syscall_linux_ppc64x.go

diff --git a/unix/syscall_linux_ppc64x.go b/unix/syscall_linux_ppc64x.go
index 28d6d0f..ca0345a 100644
--- a/unix/syscall_linux_ppc64x.go
+++ b/unix/syscall_linux_ppc64x.go
@@ -34,8 +34,8 @@
 //sys	Seek(fd int, offset int64, whence int) (off int64, err error) = SYS_LSEEK
 //sys	Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err error) = SYS__NEWSELECT
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error)
-//sys	Setfsgid(gid int) (err error)
-//sys	Setfsuid(uid int) (err error)
+//sys	setfsgid(gid int) (prev int, err error)
+//sys	setfsuid(uid int) (prev int, err error)
 //sysnb	Setregid(rgid int, egid int) (err error)
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error)
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error)

unix/syscall_linux_riscv64.go

diff --git a/unix/syscall_linux_riscv64.go b/unix/syscall_linux_riscv64.go
index 6798c26..abdabba 100644
--- a/unix/syscall_linux_riscv64.go
+++ b/unix/syscall_linux_riscv64.go
@@ -41,8 +41,8 @@
 }
 
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error)
-//sys	Setfsgid(gid int) (err error)
-//sys	Setfsuid(uid int) (err error)
+//sys	setfsgid(gid int) (prev int, err error)
+//sys	setfsuid(uid int) (prev int, err error)
 //sysnb	Setregid(rgid int, egid int) (err error)
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error)
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error)

unix/syscall_linux_s390x.go

diff --git a/unix/syscall_linux_s390x.go b/unix/syscall_linux_s390x.go
index eb5cb1a..533e930 100644
--- a/unix/syscall_linux_s390x.go
+++ b/unix/syscall_linux_s390x.go
@@ -34,8 +34,8 @@
 //sys	Seek(fd int, offset int64, whence int) (off int64, err error) = SYS_LSEEK
 //sys	Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err error)
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error)
-//sys	Setfsgid(gid int) (err error)
-//sys	Setfsuid(uid int) (err error)
+//sys	setfsgid(gid int) (prev int, err error)
+//sys	setfsuid(uid int) (prev int, err error)
 //sysnb	Setregid(rgid int, egid int) (err error)
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error)
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error)

unix/syscall_linux_sparc64.go

diff --git a/unix/syscall_linux_sparc64.go b/unix/syscall_linux_sparc64.go
index 37321c1..d890a22 100644
--- a/unix/syscall_linux_sparc64.go
+++ b/unix/syscall_linux_sparc64.go
@@ -30,8 +30,8 @@
 //sys	Seek(fd int, offset int64, whence int) (off int64, err error) = SYS_LSEEK
 //sys	Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err error)
 //sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error)
-//sys	Setfsgid(gid int) (err error)
-//sys	Setfsuid(uid int) (err error)
+//sys	setfsgid(gid int) (prev int, err error)
+//sys	setfsuid(uid int) (prev int, err error)
 //sysnb	Setregid(rgid int, egid int) (err error)
 //sysnb	Setresgid(rgid int, egid int, sgid int) (err error)
 //sysnb	Setresuid(ruid int, euid int, suid int) (err error)

unix/zsyscall_linux_386.go

diff --git a/unix/zsyscall_linux_386.go b/unix/zsyscall_linux_386.go
index c18f6c6..0e68c14 100644
--- a/unix/zsyscall_linux_386.go
+++ b/unix/zsyscall_linux_386.go
@@ -2121,8 +2121,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsgid(gid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSGID32, uintptr(gid), 0, 0)
+func setfsgid(gid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSGID32, uintptr(gid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}
@@ -2131,8 +2132,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsuid(uid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSUID32, uintptr(uid), 0, 0)
+func setfsuid(uid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSUID32, uintptr(uid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}

unix/zsyscall_linux_amd64.go

diff --git a/unix/zsyscall_linux_amd64.go b/unix/zsyscall_linux_amd64.go
index 54c0f39..c038e52 100644
--- a/unix/zsyscall_linux_amd64.go
+++ b/unix/zsyscall_linux_amd64.go
@@ -2137,8 +2137,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsgid(gid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+func setfsgid(gid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}
@@ -2147,8 +2148,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsuid(uid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+func setfsuid(uid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}

unix/zsyscall_linux_arm.go

diff --git a/unix/zsyscall_linux_arm.go b/unix/zsyscall_linux_arm.go
index 3eaa45f..333683d 100644
--- a/unix/zsyscall_linux_arm.go
+++ b/unix/zsyscall_linux_arm.go
@@ -2257,8 +2257,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsgid(gid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSGID32, uintptr(gid), 0, 0)
+func setfsgid(gid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSGID32, uintptr(gid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}
@@ -2267,8 +2268,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsuid(uid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSUID32, uintptr(uid), 0, 0)
+func setfsuid(uid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSUID32, uintptr(uid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}

unix/zsyscall_linux_arm64.go

diff --git a/unix/zsyscall_linux_arm64.go b/unix/zsyscall_linux_arm64.go
index be7f2db..838bbdb 100644
--- a/unix/zsyscall_linux_arm64.go
+++ b/unix/zsyscall_linux_arm64.go
@@ -2060,8 +2060,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsgid(gid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+func setfsgid(gid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}
@@ -2070,8 +2071,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsuid(uid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+func setfsuid(uid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}

unix/zsyscall_linux_mips.go

diff --git a/unix/zsyscall_linux_mips.go b/unix/zsyscall_linux_mips.go
index 3a0d910..7da49ae 100644
--- a/unix/zsyscall_linux_mips.go
+++ b/unix/zsyscall_linux_mips.go
@@ -2051,8 +2051,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsgid(gid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+func setfsgid(gid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}
@@ -2061,8 +2062,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsuid(uid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+func setfsuid(uid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}

unix/zsyscall_linux_mips64.go

diff --git a/unix/zsyscall_linux_mips64.go b/unix/zsyscall_linux_mips64.go
index 05f62cb..f22f83f 100644
--- a/unix/zsyscall_linux_mips64.go
+++ b/unix/zsyscall_linux_mips64.go
@@ -2081,8 +2081,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsgid(gid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+func setfsgid(gid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}
@@ -2091,8 +2092,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsuid(uid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+func setfsuid(uid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}

unix/zsyscall_linux_mips64le.go

diff --git a/unix/zsyscall_linux_mips64le.go b/unix/zsyscall_linux_mips64le.go
index 29bdea9..307c430 100644
--- a/unix/zsyscall_linux_mips64le.go
+++ b/unix/zsyscall_linux_mips64le.go
@@ -2081,8 +2081,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsgid(gid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+func setfsgid(gid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}
@@ -2091,8 +2092,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsuid(uid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+func setfsuid(uid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}

unix/zsyscall_linux_mipsle.go

diff --git a/unix/zsyscall_linux_mipsle.go b/unix/zsyscall_linux_mipsle.go
index 1dac219..0997b6e 100644
--- a/unix/zsyscall_linux_mipsle.go
+++ b/unix/zsyscall_linux_mipsle.go
@@ -2051,8 +2051,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsgid(gid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+func setfsgid(gid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}
@@ -2061,8 +2062,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsuid(uid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+func setfsuid(uid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}

unix/zsyscall_linux_ppc64.go

diff --git a/unix/zsyscall_linux_ppc64.go b/unix/zsyscall_linux_ppc64.go
index 7b76d60..a601e72 100644
--- a/unix/zsyscall_linux_ppc64.go
+++ b/unix/zsyscall_linux_ppc64.go
@@ -2163,8 +2163,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsgid(gid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+func setfsgid(gid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}
@@ -2173,8 +2174,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsuid(uid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+func setfsuid(uid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}

unix/zsyscall_linux_ppc64le.go

diff --git a/unix/zsyscall_linux_ppc64le.go b/unix/zsyscall_linux_ppc64le.go
index 5f2e31c..6e4cb19 100644
--- a/unix/zsyscall_linux_ppc64le.go
+++ b/unix/zsyscall_linux_ppc64le.go
@@ -2163,8 +2163,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsgid(gid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+func setfsgid(gid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}
@@ -2173,8 +2174,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsuid(uid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+func setfsuid(uid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}

unix/zsyscall_linux_riscv64.go

diff --git a/unix/zsyscall_linux_riscv64.go b/unix/zsyscall_linux_riscv64.go
index ea52bd3..e690f19 100644
--- a/unix/zsyscall_linux_riscv64.go
+++ b/unix/zsyscall_linux_riscv64.go
@@ -2040,8 +2040,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsgid(gid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+func setfsgid(gid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}
@@ -2050,8 +2051,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsuid(uid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+func setfsuid(uid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}

unix/zsyscall_linux_s390x.go

diff --git a/unix/zsyscall_linux_s390x.go b/unix/zsyscall_linux_s390x.go
index 3f1e461..f4cd086 100644
--- a/unix/zsyscall_linux_s390x.go
+++ b/unix/zsyscall_linux_s390x.go
@@ -2133,8 +2133,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsgid(gid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+func setfsgid(gid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}
@@ -2143,8 +2144,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsuid(uid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+func setfsuid(uid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}

unix/zsyscall_linux_sparc64.go

diff --git a/unix/zsyscall_linux_sparc64.go b/unix/zsyscall_linux_sparc64.go
index 6bcd0a3..2447f2a 100644
--- a/unix/zsyscall_linux_sparc64.go
+++ b/unix/zsyscall_linux_sparc64.go
@@ -2132,8 +2132,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsgid(gid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+func setfsgid(gid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSGID, uintptr(gid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}
@@ -2142,8 +2143,9 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func Setfsuid(uid int) (err error) {
-	_, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+func setfsuid(uid int) (prev int, err error) {
+	r0, _, e1 := Syscall(SYS_SETFSUID, uintptr(uid), 0, 0)
+	prev = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
 	}