libgo/go/syscall/syscall.go

   1 // Copyright 2009 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // Package syscall contains an interface to the low-level operating system
   6 // primitives. The details vary depending on the underlying system, and
   7 // by default, godoc will display the syscall documentation for the current
   8 // system. If you want godoc to display syscall documentation for another
   9 // system, set $GOOS and $GOARCH to the desired system. For example, if
  10 // you want to view documentation for freebsd/arm on linux/amd64, set $GOOS
  11 // to freebsd and $GOARCH to arm.
  12 // The primary use of syscall is inside other packages that provide a more
  13 // portable interface to the system, such as "os", "time" and "net".  Use
  14 // those packages rather than this one if you can.
  15 // For details of the functions and data types in this package consult
  16 // the manuals for the appropriate operating system.
  17 // These calls return err == nil to indicate success; otherwise
  18 // err is an operating system error describing the failure.
  19 // On most systems, that error has type syscall.Errno.
  20 //
  21 // NOTE: This package is locked down. Code outside the standard
  22 // Go repository should be migrated to use the corresponding
  23 // package in the golang.org/x/sys repository. That is also where updates
  24 // required by new systems or versions should be applied.
  25 // See https://golang.org/s/go1.4-syscall for more information.
  26 //
  27 package syscall
  28
  29 import "unsafe"
  30
  31 // StringByteSlice converts a string to a NUL-terminated []byte,
  32 // If s contains a NUL byte this function panics instead of
  33 // returning an error.
  34 //
  35 // Deprecated: Use ByteSliceFromString instead.
  36 func StringByteSlice(s string) []byte {
  37         a, err := ByteSliceFromString(s)
  38         if err != nil {
  39                 panic("syscall: string with NUL passed to StringByteSlice")
  40         }
  41         return a
  42 }
  43
  44 // ByteSliceFromString returns a NUL-terminated slice of bytes
  45 // containing the text of s. If s contains a NUL byte at any
  46 // location, it returns (nil, EINVAL).
  47 func ByteSliceFromString(s string) ([]byte, error) {
  48         for i := 0; i < len(s); i++ {
  49                 if s[i] == 0 {
  50                         return nil, EINVAL
  51                 }
  52         }
  53         a := make([]byte, len(s)+1)
  54         copy(a, s)
  55         return a, nil
  56 }
  57
  58 // StringBytePtr returns a pointer to a NUL-terminated array of bytes.
  59 // If s contains a NUL byte this function panics instead of returning
  60 // an error.
  61 //
  62 // Deprecated: Use BytePtrFromString instead.
  63 func StringBytePtr(s string) *byte { return &StringByteSlice(s)[0] }
  64
  65 // BytePtrFromString returns a pointer to a NUL-terminated array of
  66 // bytes containing the text of s. If s contains a NUL byte at any
  67 // location, it returns (nil, EINVAL).
  68 func BytePtrFromString(s string) (*byte, error) {
  69         a, err := ByteSliceFromString(s)
  70         if err != nil {
  71                 return nil, err
  72         }
  73         return &a[0], nil
  74 }
  75
  76 // Single-word zero for use when we need a valid pointer to 0 bytes.
  77 // See mksyscall.pl.
  78 var _zero uintptr
  79
  80 var dummy *byte
  81
  82 const sizeofPtr uintptr = uintptr(unsafe.Sizeof(dummy))
  83
  84 func (ts *Timespec) Unix() (sec int64, nsec int64) {
  85         return int64(ts.Sec), int64(ts.Nsec)
  86 }
  87
  88 func (tv *Timeval) Unix() (sec int64, nsec int64) {
  89         return int64(tv.Sec), int64(tv.Usec) * 1000
  90 }
  91
  92 func (ts *Timespec) Nano() int64 {
  93         return int64(ts.Sec)*1e9 + int64(ts.Nsec)
  94 }
  95
  96 func (tv *Timeval) Nano() int64 {
  97         return int64(tv.Sec)*1e9 + int64(tv.Usec)*1000
  98 }
  99
 100 // use is a no-op, but the compiler cannot see that it is.
 101 // Calling use(p) ensures that p is kept live until that point.
 102 // This was needed until Go 1.6 to call syscall.Syscall correctly.
 103 // As of Go 1.6 the compiler handles that case automatically.
 104 // The uses and definition of use can be removed early in the Go 1.7 cycle.
 105 //go:noescape
 106 func use(p unsafe.Pointer)