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Source file src/path/filepath/path_windows.go

Documentation: path/filepath

     1  // Copyright 2010 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 filepath
     6  
     7  import (
     8  	"strings"
     9  	"syscall"
    10  )
    11  
    12  func isSlash(c uint8) bool {
    13  	return c == '\\' || c == '/'
    14  }
    15  
    16  // IsAbs reports whether the path is absolute.
    17  func IsAbs(path string) (b bool) {
    18  	l := volumeNameLen(path)
    19  	if l == 0 {
    20  		return false
    21  	}
    22  	path = path[l:]
    23  	if path == "" {
    24  		return false
    25  	}
    26  	return isSlash(path[0])
    27  }
    28  
    29  // volumeNameLen returns length of the leading volume name on Windows.
    30  // It returns 0 elsewhere.
    31  func volumeNameLen(path string) int {
    32  	if len(path) < 2 {
    33  		return 0
    34  	}
    35  	// with drive letter
    36  	c := path[0]
    37  	if path[1] == ':' && ('a' <= c && c <= 'z' || 'A' <= c && c <= 'Z') {
    38  		return 2
    39  	}
    40  	// is it UNC? https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx
    41  	if l := len(path); l >= 5 && isSlash(path[0]) && isSlash(path[1]) &&
    42  		!isSlash(path[2]) && path[2] != '.' {
    43  		// first, leading `\\` and next shouldn't be `\`. its server name.
    44  		for n := 3; n < l-1; n++ {
    45  			// second, next '\' shouldn't be repeated.
    46  			if isSlash(path[n]) {
    47  				n++
    48  				// third, following something characters. its share name.
    49  				if !isSlash(path[n]) {
    50  					if path[n] == '.' {
    51  						break
    52  					}
    53  					for ; n < l; n++ {
    54  						if isSlash(path[n]) {
    55  							break
    56  						}
    57  					}
    58  					return n
    59  				}
    60  				break
    61  			}
    62  		}
    63  	}
    64  	return 0
    65  }
    66  
    67  // HasPrefix exists for historical compatibility and should not be used.
    68  //
    69  // Deprecated: HasPrefix does not respect path boundaries and
    70  // does not ignore case when required.
    71  func HasPrefix(p, prefix string) bool {
    72  	if strings.HasPrefix(p, prefix) {
    73  		return true
    74  	}
    75  	return strings.HasPrefix(strings.ToLower(p), strings.ToLower(prefix))
    76  }
    77  
    78  func splitList(path string) []string {
    79  	// The same implementation is used in LookPath in os/exec;
    80  	// consider changing os/exec when changing this.
    81  
    82  	if path == "" {
    83  		return []string{}
    84  	}
    85  
    86  	// Split path, respecting but preserving quotes.
    87  	list := []string{}
    88  	start := 0
    89  	quo := false
    90  	for i := 0; i < len(path); i++ {
    91  		switch c := path[i]; {
    92  		case c == '"':
    93  			quo = !quo
    94  		case c == ListSeparator && !quo:
    95  			list = append(list, path[start:i])
    96  			start = i + 1
    97  		}
    98  	}
    99  	list = append(list, path[start:])
   100  
   101  	// Remove quotes.
   102  	for i, s := range list {
   103  		list[i] = strings.Replace(s, `"`, ``, -1)
   104  	}
   105  
   106  	return list
   107  }
   108  
   109  func abs(path string) (string, error) {
   110  	fullPath, err := syscall.FullPath(path)
   111  	if err != nil {
   112  		return "", err
   113  	}
   114  	return Clean(fullPath), nil
   115  }
   116  
   117  func join(elem []string) string {
   118  	for i, e := range elem {
   119  		if e != "" {
   120  			return joinNonEmpty(elem[i:])
   121  		}
   122  	}
   123  	return ""
   124  }
   125  
   126  // joinNonEmpty is like join, but it assumes that the first element is non-empty.
   127  func joinNonEmpty(elem []string) string {
   128  	if len(elem[0]) == 2 && elem[0][1] == ':' {
   129  		// First element is drive letter without terminating slash.
   130  		// Keep path relative to current directory on that drive.
   131  		return Clean(elem[0] + strings.Join(elem[1:], string(Separator)))
   132  	}
   133  	// The following logic prevents Join from inadvertently creating a
   134  	// UNC path on Windows. Unless the first element is a UNC path, Join
   135  	// shouldn't create a UNC path. See golang.org/issue/9167.
   136  	p := Clean(strings.Join(elem, string(Separator)))
   137  	if !isUNC(p) {
   138  		return p
   139  	}
   140  	// p == UNC only allowed when the first element is a UNC path.
   141  	head := Clean(elem[0])
   142  	if isUNC(head) {
   143  		return p
   144  	}
   145  	// head + tail == UNC, but joining two non-UNC paths should not result
   146  	// in a UNC path. Undo creation of UNC path.
   147  	tail := Clean(strings.Join(elem[1:], string(Separator)))
   148  	if head[len(head)-1] == Separator {
   149  		return head + tail
   150  	}
   151  	return head + string(Separator) + tail
   152  }
   153  
   154  // isUNC reports whether path is a UNC path.
   155  func isUNC(path string) bool {
   156  	return volumeNameLen(path) > 2
   157  }
   158  
   159  func sameWord(a, b string) bool {
   160  	return strings.EqualFold(a, b)
   161  }
   162  

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