| // Copyright 2010 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package filepath |
| |
| import ( |
| "internal/safefilepath" |
| "os" |
| "strings" |
| "syscall" |
| ) |
| |
| func isSlash(c uint8) bool { |
| return c == '\\' || c == '/' |
| } |
| |
| func toUpper(c byte) byte { |
| if 'a' <= c && c <= 'z' { |
| return c - ('a' - 'A') |
| } |
| return c |
| } |
| |
| func isLocal(path string) bool { |
| if path == "" { |
| return false |
| } |
| if isSlash(path[0]) { |
| // Path rooted in the current drive. |
| return false |
| } |
| if strings.IndexByte(path, ':') >= 0 { |
| // Colons are only valid when marking a drive letter ("C:foo"). |
| // Rejecting any path with a colon is conservative but safe. |
| return false |
| } |
| hasDots := false // contains . or .. path elements |
| for p := path; p != ""; { |
| var part string |
| part, p, _ = cutPath(p) |
| if part == "." || part == ".." { |
| hasDots = true |
| } |
| if safefilepath.IsReservedName(part) { |
| return false |
| } |
| } |
| if hasDots { |
| path = Clean(path) |
| } |
| if path == ".." || strings.HasPrefix(path, `..\`) { |
| return false |
| } |
| return true |
| } |
| |
| // IsAbs reports whether the path is absolute. |
| func IsAbs(path string) (b bool) { |
| l := volumeNameLen(path) |
| if l == 0 { |
| return false |
| } |
| // If the volume name starts with a double slash, this is an absolute path. |
| if isSlash(path[0]) && isSlash(path[1]) { |
| return true |
| } |
| path = path[l:] |
| if path == "" { |
| return false |
| } |
| return isSlash(path[0]) |
| } |
| |
| // volumeNameLen returns length of the leading volume name on Windows. |
| // It returns 0 elsewhere. |
| // |
| // See: |
| // https://learn.microsoft.com/en-us/dotnet/standard/io/file-path-formats |
| // https://googleprojectzero.blogspot.com/2016/02/the-definitive-guide-on-win32-to-nt.html |
| func volumeNameLen(path string) int { |
| switch { |
| case len(path) >= 2 && path[1] == ':': |
| // Path starts with a drive letter. |
| // |
| // Not all Windows functions necessarily enforce the requirement that |
| // drive letters be in the set A-Z, and we don't try to here. |
| // |
| // We don't handle the case of a path starting with a non-ASCII character, |
| // in which case the "drive letter" might be multiple bytes long. |
| return 2 |
| |
| case len(path) == 0 || !isSlash(path[0]): |
| // Path does not have a volume component. |
| return 0 |
| |
| case pathHasPrefixFold(path, `\\.\UNC`): |
| // We're going to treat the UNC host and share as part of the volume |
| // prefix for historical reasons, but this isn't really principled; |
| // Windows's own GetFullPathName will happily remove the first |
| // component of the path in this space, converting |
| // \\.\unc\a\b\..\c into \\.\unc\a\c. |
| return uncLen(path, len(`\\.\UNC\`)) |
| |
| case pathHasPrefixFold(path, `\\.`) || |
| pathHasPrefixFold(path, `\\?`) || pathHasPrefixFold(path, `\??`): |
| // Path starts with \\.\, and is a Local Device path; or |
| // path starts with \\?\ or \??\ and is a Root Local Device path. |
| // |
| // We treat the next component after the \\.\ prefix as |
| // part of the volume name, which means Clean(`\\?\c:\`) |
| // won't remove the trailing \. (See #64028.) |
| if len(path) == 3 { |
| return 3 // exactly \\. |
| } |
| _, rest, ok := cutPath(path[4:]) |
| if !ok { |
| return len(path) |
| } |
| return len(path) - len(rest) - 1 |
| |
| case len(path) >= 2 && isSlash(path[1]): |
| // Path starts with \\, and is a UNC path. |
| return uncLen(path, 2) |
| } |
| return 0 |
| } |
| |
| // pathHasPrefixFold tests whether the path s begins with prefix, |
| // ignoring case and treating all path separators as equivalent. |
| // If s is longer than prefix, then s[len(prefix)] must be a path separator. |
| func pathHasPrefixFold(s, prefix string) bool { |
| if len(s) < len(prefix) { |
| return false |
| } |
| for i := 0; i < len(prefix); i++ { |
| if isSlash(prefix[i]) { |
| if !isSlash(s[i]) { |
| return false |
| } |
| } else if toUpper(prefix[i]) != toUpper(s[i]) { |
| return false |
| } |
| } |
| if len(s) > len(prefix) && !isSlash(s[len(prefix)]) { |
| return false |
| } |
| return true |
| } |
| |
| // uncLen returns the length of the volume prefix of a UNC path. |
| // prefixLen is the prefix prior to the start of the UNC host; |
| // for example, for "//host/share", the prefixLen is len("//")==2. |
| func uncLen(path string, prefixLen int) int { |
| count := 0 |
| for i := prefixLen; i < len(path); i++ { |
| if isSlash(path[i]) { |
| count++ |
| if count == 2 { |
| return i |
| } |
| } |
| } |
| return len(path) |
| } |
| |
| // cutPath slices path around the first path separator. |
| func cutPath(path string) (before, after string, found bool) { |
| for i := range path { |
| if isSlash(path[i]) { |
| return path[:i], path[i+1:], true |
| } |
| } |
| return path, "", false |
| } |
| |
| // HasPrefix exists for historical compatibility and should not be used. |
| // |
| // Deprecated: HasPrefix does not respect path boundaries and |
| // does not ignore case when required. |
| func HasPrefix(p, prefix string) bool { |
| if strings.HasPrefix(p, prefix) { |
| return true |
| } |
| return strings.HasPrefix(strings.ToLower(p), strings.ToLower(prefix)) |
| } |
| |
| func splitList(path string) []string { |
| // The same implementation is used in LookPath in os/exec; |
| // consider changing os/exec when changing this. |
| |
| if path == "" { |
| return []string{} |
| } |
| |
| // Split path, respecting but preserving quotes. |
| list := []string{} |
| start := 0 |
| quo := false |
| for i := 0; i < len(path); i++ { |
| switch c := path[i]; { |
| case c == '"': |
| quo = !quo |
| case c == ListSeparator && !quo: |
| list = append(list, path[start:i]) |
| start = i + 1 |
| } |
| } |
| list = append(list, path[start:]) |
| |
| // Remove quotes. |
| for i, s := range list { |
| list[i] = strings.ReplaceAll(s, `"`, ``) |
| } |
| |
| return list |
| } |
| |
| func abs(path string) (string, error) { |
| if path == "" { |
| // syscall.FullPath returns an error on empty path, because it's not a valid path. |
| // To implement Abs behavior of returning working directory on empty string input, |
| // special-case empty path by changing it to "." path. See golang.org/issue/24441. |
| path = "." |
| } |
| fullPath, err := syscall.FullPath(path) |
| if err != nil { |
| return "", err |
| } |
| return Clean(fullPath), nil |
| } |
| |
| func join(elem []string) string { |
| var b strings.Builder |
| var lastChar byte |
| for _, e := range elem { |
| switch { |
| case b.Len() == 0: |
| // Add the first non-empty path element unchanged. |
| case isSlash(lastChar): |
| // If the path ends in a slash, strip any leading slashes from the next |
| // path element to avoid creating a UNC path (any path starting with "\\") |
| // from non-UNC elements. |
| // |
| // The correct behavior for Join when the first element is an incomplete UNC |
| // path (for example, "\\") is underspecified. We currently join subsequent |
| // elements so Join("\\", "host", "share") produces "\\host\share". |
| for len(e) > 0 && isSlash(e[0]) { |
| e = e[1:] |
| } |
| // If the path is \ and the next path element is ??, |
| // add an extra .\ to create \.\?? rather than \??\ |
| // (a Root Local Device path). |
| if b.Len() == 1 && pathHasPrefixFold(e, "??") { |
| b.WriteString(`.\`) |
| } |
| case lastChar == ':': |
| // If the path ends in a colon, keep the path relative to the current directory |
| // on a drive and don't add a separator. Preserve leading slashes in the next |
| // path element, which may make the path absolute. |
| // |
| // Join(`C:`, `f`) = `C:f` |
| // Join(`C:`, `\f`) = `C:\f` |
| default: |
| // In all other cases, add a separator between elements. |
| b.WriteByte('\\') |
| lastChar = '\\' |
| } |
| if len(e) > 0 { |
| b.WriteString(e) |
| lastChar = e[len(e)-1] |
| } |
| } |
| if b.Len() == 0 { |
| return "" |
| } |
| return Clean(b.String()) |
| } |
| |
| func sameWord(a, b string) bool { |
| return strings.EqualFold(a, b) |
| } |
| |
| // postClean adjusts the results of Clean to avoid turning a relative path |
| // into an absolute or rooted one. |
| func postClean(out *lazybuf) { |
| if out.volLen != 0 || out.buf == nil { |
| return |
| } |
| // If a ':' appears in the path element at the start of a path, |
| // insert a .\ at the beginning to avoid converting relative paths |
| // like a/../c: into c:. |
| for _, c := range out.buf { |
| if os.IsPathSeparator(c) { |
| break |
| } |
| if c == ':' { |
| out.prepend('.', Separator) |
| return |
| } |
| } |
| // If a path begins with \??\, insert a \. at the beginning |
| // to avoid converting paths like \a\..\??\c:\x into \??\c:\x |
| // (equivalent to c:\x). |
| if len(out.buf) >= 3 && os.IsPathSeparator(out.buf[0]) && out.buf[1] == '?' && out.buf[2] == '?' { |
| out.prepend(Separator, '.') |
| } |
| } |