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/asm_linux_arm.s b/src/pkg/syscall/asm_linux_arm.s
index bf54b4f..8499a73 100644
--- a/src/pkg/syscall/asm_linux_arm.s
+++ b/src/pkg/syscall/asm_linux_arm.s
@@ -98,7 +98,7 @@
RET
#define SYS__LLSEEK 140 /* from zsysnum_linux_arm.go */
-// func Seek(fd int, offset int64, whence int) (newoffset int64, errno int)
+// func seek(fd int, offset int64, whence int) (newoffset int64, errno int)
// Implemented in assembly to avoid allocation when
// taking the address of the return value newoffset.
// Underlying system call is
