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