syscall: fix a few Linux system calls
These functions claimed to return error (an interface)
and be implemented entirely in assembly, but it's not
possible to create an interface from assembly
(at least not easily).
In reality the functions were written to return an errno uintptr
despite the Go prototype saying error.
When the errno was 0, they coincidentally filled out a nil error
by writing the 0 to the type word of the interface.
If the errno was ever non-zero, the functions would
create a non-nil error that would crash when trying to
call err.Error().
Luckily these functions (Seek, Time, Gettimeofday) pretty
much never fail, so it was all kind of working.
Found by go vet.
LGTM=bradfitz, r
R=golang-codereviews, bradfitz, r
CC=golang-codereviews
https://golang.org/cl/99320043
diff --git a/src/pkg/syscall/syscall_linux_amd64.go b/src/pkg/syscall/syscall_linux_amd64.go
index 9e8663d..1e330dd 100644
--- a/src/pkg/syscall/syscall_linux_amd64.go
+++ b/src/pkg/syscall/syscall_linux_amd64.go
@@ -58,8 +58,28 @@
func Getpagesize() int { return 4096 }
-func Gettimeofday(tv *Timeval) (err error)
-func Time(t *Time_t) (tt Time_t, err error)
+//go:noescape
+func gettimeofday(tv *Timeval) (err Errno)
+
+func Gettimeofday(tv *Timeval) (err error) {
+ errno := gettimeofday(tv)
+ if errno != 0 {
+ return errno
+ }
+ return nil
+}
+
+func Time(t *Time_t) (tt Time_t, err error) {
+ var tv Timeval
+ errno := gettimeofday(&tv)
+ if errno != 0 {
+ return errno
+ }
+ if t != nil {
+ *t = tv.Sec
+ }
+ return Time_t(tv.Sec), nil
+}
func TimespecToNsec(ts Timespec) int64 { return int64(ts.Sec)*1e9 + int64(ts.Nsec) }
