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  //go:build windows
     6  // +build windows
     7  
     8  // Package windows contains an interface to the low-level operating system
     9  // primitives. OS details vary depending on the underlying system, and
    10  // by default, godoc will display the OS-specific documentation for the current
    11  // system. If you want godoc to display syscall documentation for another
    12  // system, set $GOOS and $GOARCH to the desired system. For example, if
    13  // you want to view documentation for freebsd/arm on linux/amd64, set $GOOS
    14  // to freebsd and $GOARCH to arm.
    15  //
    16  // The primary use of this package is inside other packages that provide a more
    17  // portable interface to the system, such as "os", "time" and "net".  Use
    18  // those packages rather than this one if you can.
    19  //
    20  // For details of the functions and data types in this package consult
    21  // the manuals for the appropriate operating system.
    22  //
    23  // These calls return err == nil to indicate success; otherwise
    24  // err represents an operating system error describing the failure and
    25  // holds a value of type syscall.Errno.
    26  package windows // import "golang.org/x/sys/windows"
    27  
    28  import (
    29  	"bytes"
    30  	"strings"
    31  	"syscall"
    32  	"unsafe"
    33  
    34  	"golang.org/x/sys/internal/unsafeheader"
    35  )
    36  
    37  // ByteSliceFromString returns a NUL-terminated slice of bytes
    38  // containing the text of s. If s contains a NUL byte at any
    39  // location, it returns (nil, syscall.EINVAL).
    40  func ByteSliceFromString(s string) ([]byte, error) {
    41  	if strings.IndexByte(s, 0) != -1 {
    42  		return nil, syscall.EINVAL
    43  	}
    44  	a := make([]byte, len(s)+1)
    45  	copy(a, s)
    46  	return a, nil
    47  }
    48  
    49  // BytePtrFromString returns a pointer to a NUL-terminated array of
    50  // bytes containing the text of s. If s contains a NUL byte at any
    51  // location, it returns (nil, syscall.EINVAL).
    52  func BytePtrFromString(s string) (*byte, error) {
    53  	a, err := ByteSliceFromString(s)
    54  	if err != nil {
    55  		return nil, err
    56  	}
    57  	return &a[0], nil
    58  }
    59  
    60  // ByteSliceToString returns a string form of the text represented by the slice s, with a terminating NUL and any
    61  // bytes after the NUL removed.
    62  func ByteSliceToString(s []byte) string {
    63  	if i := bytes.IndexByte(s, 0); i != -1 {
    64  		s = s[:i]
    65  	}
    66  	return string(s)
    67  }
    68  
    69  // BytePtrToString takes a pointer to a sequence of text and returns the corresponding string.
    70  // If the pointer is nil, it returns the empty string. It assumes that the text sequence is terminated
    71  // at a zero byte; if the zero byte is not present, the program may crash.
    72  func BytePtrToString(p *byte) string {
    73  	if p == nil {
    74  		return ""
    75  	}
    76  	if *p == 0 {
    77  		return ""
    78  	}
    79  
    80  	// Find NUL terminator.
    81  	n := 0
    82  	for ptr := unsafe.Pointer(p); *(*byte)(ptr) != 0; n++ {
    83  		ptr = unsafe.Pointer(uintptr(ptr) + 1)
    84  	}
    85  
    86  	var s []byte
    87  	h := (*unsafeheader.Slice)(unsafe.Pointer(&s))
    88  	h.Data = unsafe.Pointer(p)
    89  	h.Len = n
    90  	h.Cap = n
    91  
    92  	return string(s)
    93  }
    94  
    95  // Single-word zero for use when we need a valid pointer to 0 bytes.
    96  // See mksyscall.pl.
    97  var _zero uintptr
    98  
    99  func (ts *Timespec) Unix() (sec int64, nsec int64) {
   100  	return int64(ts.Sec), int64(ts.Nsec)
   101  }
   102  
   103  func (tv *Timeval) Unix() (sec int64, nsec int64) {
   104  	return int64(tv.Sec), int64(tv.Usec) * 1000
   105  }
   106  
   107  func (ts *Timespec) Nano() int64 {
   108  	return int64(ts.Sec)*1e9 + int64(ts.Nsec)
   109  }
   110  
   111  func (tv *Timeval) Nano() int64 {
   112  	return int64(tv.Sec)*1e9 + int64(tv.Usec)*1000
   113  }
   114
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