diff options
Diffstat (limited to 'src/os/path_windows.go')
| -rw-r--r-- | src/os/path_windows.go | 32 |
1 files changed, 23 insertions, 9 deletions
diff --git a/src/os/path_windows.go b/src/os/path_windows.go index 1a4223deab..ccac1c0b64 100644 --- a/src/os/path_windows.go +++ b/src/os/path_windows.go @@ -129,26 +129,40 @@ func dirname(path string) string { } // fixLongPath returns the extended-length (\\?\-prefixed) form of -// path if possible, in order to avoid the default 260 character file -// path limit imposed by Windows. If path is not easily converted to +// path when needed, in order to avoid the default 260 character file +// path limit imposed by Windows. If path is not easily converted to // the extended-length form (for example, if path is a relative path -// or contains .. elements), fixLongPath returns path unmodified. +// or contains .. elements), or is short enough, fixLongPath returns +// path unmodified. +// +// See https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx#maxpath func fixLongPath(path string) string { + // Do nothing (and don't allocate) if the path is "short". + // Empirically (at least on the Windows Server 2013 builder), + // the kernel is arbitrarily okay with <= 248 bytes. That + // matches what the docs above say: + // "When using an API to create a directory, the specified + // path cannot be so long that you cannot append an 8.3 file + // name (that is, the directory name cannot exceed MAX_PATH + // minus 12)." Since MAX_PATH is 260, 260 - 12 = 248. + if len(path) <= 248 { + // Don't fix. (This is how Go 1.7 and earlier worked, + // not automatically generating the \\?\ form) + return path + } + // The extended form begins with \\?\, as in // \\?\c:\windows\foo.txt or \\?\UNC\server\share\foo.txt. // The extended form disables evaluation of . and .. path // elements and disables the interpretation of / as equivalent - // to \. The conversion here rewrites / to \ and elides + // to \. The conversion here rewrites / to \ and elides // . elements as well as trailing or duplicate separators. For // simplicity it avoids the conversion entirely for relative - // paths or paths containing .. elements. For now, + // paths or paths containing .. elements. For now, // \\server\share paths are not converted to // \\?\UNC\server\share paths because the rules for doing so // are less well-specified. - // - // For details of \\?\ paths, see: - // https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx#maxpath - if len(path) == 0 || (len(path) >= 2 && path[:2] == `\\`) { + if len(path) >= 2 && path[:2] == `\\` { // Don't canonicalize UNC paths. return path } |